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PICList Thread
'PIC based spectrum analyzer'
2000\02\03@213457 by Anthony Clay

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I know it's crazy to build one, but I have found a great new project to
start.  A spectrum analyzer.  The first one I build will probably work from
0~200 MHz.  I have designed an excellent PLL that delivers quite acceptable
performance.

The part I am having to think about is how to accurately measure the final
dB signal level. Here is the situation:

For those of you into RF: The analyzer is a built as a AM receiver with a
455kHz final IF.

Should I run the IF into a Full wave rectifier, filter it, then feed the
voltage to the PIC via a high-res D/A?

   -or-

Should I run the IF into a half wave rectifier, then to the D/A, and let the
PIC analyze the "Pulse" to determine it's maximum voltage?

Or am I going about this wrong?  I just want to know the amplitide of a
455kHz signal, with precision.

Anthony
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2000\02\04@082345 by Peter L. Berghold

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On Thu, Feb 03, 2000 at 07:44:05PM -0600, Anthony Clay wrote:
> The part I am having to think about is how to accurately measure the final
> dB signal level. Here is the situation:
>
Hmmm.... I remember reading somewhere an article in a trade rag that showed
using some derivative of an AGC circuit to measure signal output.  If I can
find the article in my archives (fat chance) I'll re-read it and post what
I find.

I would be tempted to use the full wave rectifier approach, using a filter
cap to smooth it out, and sampling.   The trick here as I recall is to keep
the value of the cap sufficiently large enough to do the filtering but not
so large as to cause a "rubber screwdriver" effect.

On the other end of the scale is a problem of aliasing. If your sample is
taken at the wrong time you could be reading "off peak" values for amplitude
and therefore not the real amplitude.  Of course this is where your filter
cap comes in.

It's been a while since I have thought about these subjects so I may well be
off here....


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2000\02\05@135814 by Dwayne Reid

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>On Thu, Feb 03, 2000 at 07:44:05PM -0600, Anthony Clay wrote:
> The part I am having to think about is how to accurately measure the final
> dB signal level.

Do a search on 'RSSI'.  Both AD and Phillips make chips that give a
reasonably good log response to input level.

You might also want to search on 'poor mans spectrum analyser' - the author
shows how to use TV tuners as the front end of a low cost unit.  His log
detector is based upon a chain of cmos invertors operating in the linear
region with a resistive sum of the individual outputs.  As each stage
saturates, it quits adding to the output.  It seems reasonably accurate, is
incredibly cheap, and uses parts made by many suppliers.

dwayne


Dwayne Reid   <dwaynerspamKILLspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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'[PICLIST] Spectrum Analyzer'
2000\06\27@005305 by Peter Grey
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Can anyone recommend a reasonably priced spectrum analyzer that can be used
in the development of 2.4GHz products?

TIA

Peter

2000\06\27@082033 by 8859-1?q?Jochen=20Feldhear?=
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--- Peter Grey <.....martechKILLspamspam.....OZEMAIL.COM.AU> schrieb: > Can
anyone recommend a reasonably priced spectrum
> analyzer that can be used
> in the development of 2.4GHz products?
>
> TIA
>
> Peter
Hello Peter,

I think I can recommend some models, as I am writing a
book on the subject of spectrum analysis right now and
use several of these instruments myself on a daily
basis.

You will need something to see the 3rd or 5th harmonic
to be sure not to interfere (above certain levels), so
a 12 GHz or 18 GHz will do for you.

Personally I would recommend a model 141T from HP,
with the 8555 and 8552(?) RF and IF units. This will
give you a minimum filter resolution of 100 Hz and 18
GHz of usable range, also available with a analog
storage tube. will cost ~2K$...

If your budget is bigger, get a HP 8569, it is more
modern and also great performance for moderate budget,
but starting at ~5K$.

A used TEK 492 or 494 would also give great
performance, but will be still around 7K$.

Just for comparison: A new unit by Agilent (the HP
cover name) will cost about 20K$ with the required
capabilities, only added feature will be the digital
frequency synthesizing and fully digital signal
processing for the display, but IMHO you will not need
this for designing a 2.4 GHz device.

Hope this was helpful, if there are questions left,
feel free to mail me... (also concerning usage...)

Greetings to the list!

Jochen Feldhaar

"If it works, it is no fun any more"

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'[PICLIST] Spectrum Analyzer'
2000\07\03@000501 by Peter Grey
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Can anyone recommend a reasonably priced spectrum analyzer that can be used
in the development of 2.4GHz products?

TIA

Peter

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'[EE]: Spectrum analyzer'
2000\09\19@003854 by Michael Shiloh
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Hi gang,

I'm looking to purchase or rent a spectrum analyzer. I do
a lot of work installing a/v modulators (like thost at
http://www.channelvision.com) and I need a way to see what affects
my picture quality, like amplitude and bleed through from
one channel to the next.

I'm not sure what to look for in a spectrum analyzer. Are
there any features that will be particularly useful for TV
work?

Thanks,
Michael

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2000\09\19@043813 by J.Feldhaar

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Hello Michael,

there are a fewAnalyzers by several manufacturers that can even work as a
normal TV for demodulating the RF TV signal, can be triggered by video
and so on. Anritsu for one makes them, and IIRC IFR does too.

If this is somewhat too expensive, I recommend to get a used HP 182T /
HP8558B combination, if 1.5 (1.8?) GHz is high enough for you, or get a
HAMEG 5014 with digital storage, Interface to PC ( I did the RF part of
that analyzer, but for 2 years am out of HAMEG... no commercial interest
any more).

If there is still not the model you feel at ease with, mail me privately,
as I'm some aficionado for Spectrum analyzers.....

Greetings

Jochen Feldhaar

Michael Shiloh schrieb:

{Quote hidden}

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2000\09\19@045917 by Sam Laur

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Michael Shiloh wrote:
> I'm looking to purchase or rent a spectrum analyzer. I do

Hmm... by coincidence, I've started looking for one, too. Something that's not too expensive. I would be using it to test
some radio stuff (on the 434 MHz ISM band, here in Europe).

I've found a "spectrum anlyzer adaptor" to connect to an
oscilloscope (TSA1000 by Thurlby-Thandar Instruments) but I'm
having doubts about it because there is only bandwidth (250 kHz)
which sounds too wide, even for this stuff. Another thing is
that the frequency only goes up to 1 GHz. But the price is only
about £500.
Then there are several places selling old (some refurbished,
some not) spectrum analyzers, like HP modular stuff, or Tek 491.
But I really can't be sure of what I get there, either. So
it's a big question mark - do I scrap the whole project because
measuring equipment would cost too much, or try to get it
measured somewhere else (which would probably cost too much, too),
or just get something and hope it'll work?

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2000\09\19@134736 by Nigel Goodwin

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In message <EraseMEPine.LNX.4.10.10009182132230.15879-100000spam_OUTspamTakeThisOuTmichael.channeldot> .com>, Michael Shiloh <mshilohspamspam_OUTMEDIABOLIC.COM> writes
>Hi gang,
>
>I'm looking to purchase or rent a spectrum analyzer. I do
>a lot of work installing a/v modulators (like thost at
>http://www.channelvision.com) and I need a way to see what affects
>my picture quality, like amplitude and bleed through from
>one channel to the next.
>
>I'm not sure what to look for in a spectrum analyzer. Are
>there any features that will be particularly useful for TV
>work?

You can get relatively 'cheap' simple spectrum spectrum analysers
designed expressly for the purpose of TV installations (including
satellite systems). Try looking in any large aerial or component
suppliers catalogue.
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'[PICLIST] A/D spectrum analyzer'
2001\06\26@094608 by Joe Denehan
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I would like to use a pic to function as an Audio Spectrum Analyzer, does
anyone know what Pic I could use or where I could find more info.

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2001\06\26@105241 by Herbert Graf

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This is going to sound odd, but this sort of thing is usually best left with
analog electronics. You CAN do it digitally but the amount of hardware
(and/or software) needed to accomplish the same thing a mess of op amps and
passive components can do is simply overkill. Unless of couse you NEED to do
it digitally, in which case a PIC could not do it alone in real time, you
would need something like a DSP to do it. TTYL

{Original Message removed}

2001\06\26@114302 by Kyle Stemen

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AN542 on Microchip's site talks about using a 17C42 to do a fast fourier
transform, but its abilities are severely limited. So I agree with Mr.
Graf that you really should have something more powerful.

Herbert Graf wrote:
>
> This is going to sound odd, but this sort of thing is usually best left with
> analog electronics. You CAN do it digitally but the amount of hardware
> (and/or software) needed to accomplish the same thing a mess of op amps and
> passive components can do is simply overkill. Unless of couse you NEED to do
> it digitally, in which case a PIC could not do it alone in real time, you
> would need something like a DSP to do it. TTYL
>
> {Original Message removed}

2001\06\26@114453 by Douglas Butler

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If he were asking for realtime digital filtering I would agree, but he
is only asking for a spectrum analyzer.  He can digitize a chunk, then
chew on it for a while before outputting the result and grabbing another
chunk.  I don't have an answer for him, but somewhere there must be some
FFT code for a PIC.

Sherpa Doug

>This is going to sound odd, but this sort of thing is usually best left with
>analog electronics. You CAN do it digitally but the amount of hardware
>(and/or software) needed to accomplish the same thing a mess of op amps and
>passive components can do is simply overkill. Unless of couse you NEED to do
>it digitally, in which case a PIC could not do it alone in real time, you
>would need something like a DSP to do it. TTYL
>
>{Original Message removed}

2001\06\26@115118 by Dan Michaels

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At 12:10 PM 6/25/01 -0400, you wrote:
>AN542 on Microchip's site talks about using a 17C42 to do a fast fourier
>transform, but its abilities are severely limited. So I agree with Mr.
>Graf that you really should have something more powerful.
>

If you go back about a year ago in the piclist archives,
there were several discussions on doing FFT spectrum analysis
on PICs. IIRC, Robert A. LaBudde is the guy who did it.

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2001\06\26@150617 by Olin Lathrop

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> If he were asking for realtime digital filtering I would agree, but he
> is only asking for a spectrum analyzer.  He can digitize a chunk, then
> chew on it for a while before outputting the result and grabbing another
> chunk.  I don't have an answer for him, but somewhere there must be some
> FFT code for a PIC.

This sounds like a job for the DSPics that are coming out.  Some DSPs (I'm
not sure about the DSPics) have special support for doing the butterfly
addressing for doing power of 2 FFTs.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, KILLspamolinKILLspamspamembedinc.com, http://www.embedinc.com

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2001\06\26@164547 by Bob Ammerman

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----- Original Message -----
From: "Olin Lathrop" <RemoveMEolin_piclistTakeThisOuTspamEMBEDINC.COM>
To: <spamBeGonePICLISTspamBeGonespamMITVMA.MIT.EDU>
Sent: Tuesday, June 26, 2001 3:05 PM
Subject: Re: [PIC]: A/D spectrum analyzer


{Quote hidden}

The dsPIC (note the strange capitalization) does supposedly handle butterfly
addressing, tho' for the life of me I can't figure out how based on the
publicly released information on the mChip site.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\06\26@170329 by Joe Denehan

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I would like to use a pic to function as an Audio Spectrum Analyzer, does
anyone know what Pic I could use or where I could find more info.

Re-posting as forgot topic indicator

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2001\06\26@171736 by jamesnewton

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www.piclist.com/techref/microchip/math/filter.htm
http://www.piclist.com/techref/microchip/fft/picspect.htm

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{Original Message removed}

2001\06\26@171945 by info

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Joe,

You could use almost any of the mid-range PICS.

If you use a superhet typology to obtain a 0 Hz IF and the maximum
resolution bandwidth is say 5khz, then you only need to have and ADC sample
at 10kHz.
If you want multi-channel, use LTC2345C 11channel, 12bit ADC connected to
PIC via SPI interface. You can sample at these frequencies no problem at
all.

Regards

David Huisman

{Original Message removed}

2001\06\26@171950 by jamesnewton

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www.piclist.com/techref/microchip/math/filter.htm
http://www.piclist.com/techref/microchip/fft/picspect.htm

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{Original Message removed}

2001\06\26@210704 by Olin Lathrop

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> I would like to use a pic to function as an Audio Spectrum Analyzer, does
> anyone know what Pic I could use or where I could find more info.

What is your highest frequency, 20KHz?  Does it need to be real time, or can
you sample a snapshot of the audio signal and do post processing on it?
Does all the signal need to be sampled, or only occasionally?

If it needs to be real time or you are expecting it to keep up with a
continuous "audio" stream of reasonable bandwith, then a PIC isn't going to
do it.  You will need a DSP.  Note that Microchip is coming out with the new
dsPIC line, which is PIC-flavored DSPs.

At best you can expect a PIC to sample a chunk of audio, go "off line" while
is runs an FFT to find the frequencies in the chunk, output those somehow,
then do the next chunk.  PICs and other general purpose microcontrollers are
not well suited to this kind of task.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olinEraseMEspam.....embedinc.com, http://www.embedinc.com

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2001\06\26@215139 by Dan Larson

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Ages ago....

There was the Radio Shack Color Computer (AKA the "CoCo"), which ran at a mere 1/4 of the
frequency of a common color burst crystal.  (a 6809 @ less than 1 Mhz!). It had
an R2R resistor ladder style D/A converter and a single analog comparator
with which one could implement an A/D in software.  They sold a ROM cartridge
which contained an audio spectrum analyzer program. Does anyone else
remember this? I have a hard time believing that a clever programmer could
not achieve the same with a PIC (at 20Mhz + hardware A/D) today.

Dan (a Radio Shack "CoCo" owner!)



On Tue, 26 Jun 2001 18:25:24 -0400, Olin Lathrop wrote:

{Quote hidden}

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2001\06\26@224631 by Robert A. LaBudde

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At 08:56 PM 6/26/01 -0600, Dan wrote:
>Ages ago....
>
>There was the Radio Shack Color Computer (AKA the "CoCo"), which ran at a
>mere 1/4 of the
>frequency of a common color burst crystal.  (a 6809 @ less than 1 Mhz!).
>It had
>an R2R resistor ladder style D/A converter and a single analog comparator
>with which one could implement an A/D in software.  They sold a ROM cartridge
>which contained an audio spectrum analyzer program. Does anyone else
>remember this? I have a hard time believing that a clever programmer could
>not achieve the same with a PIC (at 20Mhz + hardware A/D) today.

The key to the whole audio spectrum analyzer question is the required
bandwidth and the required frequency resolution.

The RS Color Computer only measured up to 5KSPS as I recollect, and the
microprocessor had an 8-bit hardware multiply.

An FFT is an orthogonal transformation, so it would be possible to do a
reasonable job with low accuracy fixed point arithmetic.

The real killer is the memory needed for the job.

A 16F877 or the like with a static ram attached would probably allow a
small-scale FFT to be done.

So:

1. What bandwidth? If audio, one would assume 20Hz-20kHz would be
necessary. This is tough to do as a 'continuum' on a PIC.

2. What resolution in frequency? If only 8-16 individual frequencies were
needed (sort of like the LED bar graph spectrum displays), then fixed
frequency transforms might be viable.

3. What accuracy is needed? If only 4-bits or so, then memory requirements
are much easier. If 8-bits, you need an external memory.

In summary, it should be possible to do a 32-, 64- or even 128-sample DFT
on a PIC, if you're willing to tolerate a less than 8-bit resulting
accuracy. The maximum sampling rate would probably be only 1-2 kSPS
real-time, expandable if delays in reporting are allowed (1st record, then
analyze).

This kind of application is much better suited to a microcomputer with a
larger address space and hardware 8-bit multiply at least. E.g., 8051,
etc., or better.



================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: RemoveMEralEraseMEspamEraseMElcfltd.com
Least Cost Formulations, Ltd.            URL: http://lcfltd.com/
824 Timberlake Drive                     Tel: 757-467-0954
Virginia Beach, VA 23464-3239            Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

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2001\06\26@233917 by Dan Larson

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On Tue, 26 Jun 2001 22:45:49 -0400, Robert A. LaBudde wrote:

{Quote hidden}

Yes, I agree with you.  A 17Cxx part with external RAM *might* be enough.

It could certainly be done with an AVR AT90S8515 or ATMega161 with external
RAM with ease. Even an ATMega103 with external RAM might be enough, though
it has no hardware multiply.

I still get the feeling that the Audio Spectrum Analyzer program on the CoCo was
cheating some how. Perhaps some sort of "Binning" of samples or zero-crossing
times may have been used. I was only a kid then, so I was not sophisticated enough
to really analyze it very well at the time.

[SNIP]

>
>This kind of application is much better suited to a microcomputer with a
>larger address space and hardware 8-bit multiply at least. E.g., 8051,
>etc., or better.
>

Are there any 18FXX or 18CXX parts that can interface external RAM?

In either case, a top end device with 1.5K  RAM might be enough.

The CoCo orignally only had 4K of RAM. Back in those days we really
had to sequeeze all we could out of expensive hardware. Much like with
MCU's today.

Dan

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2001\06\27@020959 by dr. Imre Bartfai

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Ubicom has (at least, Scenix had) an AN dealing with this subject,
AFAIK. I got it, too. Unfortunately, it is not public as I should sign an
Undisclosure Agreement before. It is free from them, though.

Regards,

Imre


On Tue, 26 Jun 2001, Olin Lathrop wrote:

{Quote hidden}

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2001\06\27@021621 by Kari Lehikko

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Joe,

I have also decided to do a simple spectrum analyzer as my first DSP
project. (Just something to install in my car to make friends jealous :)

What I have thought so far:

- I'll use PIC18C452, because:
 - We already have emulators and chips here in my work (free tools and
chips :)
 - Chip is capable of 40MHz max (10 MIPS), has hardware multiply,
buildin ADC, three indirect registers and 1,5k ram (organized in nice
256 long circular buffers :)

- I'll use the maximum sample rate possible, whatever it is (PIC's ADC
is capable of doing 52ksps, the maximum sample rate will probably be
defined by the speed of my DSP-code)

- I'll probably write the FFT-code myself, because I like to believe
that 18 years of assembler-coding experience will allow me to optimize
the code tighter than using libraries.

- I'll probably use very rude filtering, output device for my analyzer
is a bunch of leds, and it just have to look cool, not to be very
accurate.

Some of these thoughts may and probably will change as I learn more
about DSP. First I was thinking of using sample rate as high as 44.1k
(same as CD's), but that would only have given me 227 instructions per
sample and I already know that that is too few.

Good luck with your project :)

- Kari -


Joe Denehan wrote:
>
> I would like to use a pic to function as an Audio Spectrum Analyzer, does
> anyone know what Pic I could use or where I could find more info.
>
> Re-posting as forgot topic indicator
>
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2001\06\27@042857 by Raymond Choat

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part 1 3593 bytes content-type:text/plain; (decoded 7bit)

I do pic chips now and did CoCo years ago. 16-18 yrs ago I built a carving
machine using the coco (when it first came out) and programmed it in basic.
It only had 4 k when I got it and upgraded to 16k. Boy was that a lot of
programing space....ha. Yes the 6809E has a lot in common with the pics. But
at 20Mhz these pics can do laps around the old coco. The CoCo had no hard
drive but did have 4 single sided low density 4.25 drives. The ROM Packs
were most of the time just an eprom with a program in it. Here is picture of
carve machine made from a COCO and a radial arm saw......(me in mask)  You
can read the code from the old ROM Packs by putting a piece of tape over the
clock pin on the ROM Pack edge. This stops the Rom from self starting and
you can use PEEK command to see the code in the ROM Pack. If I remember the
program you are talking about it was just a ROM Pack.
Wrong Way Ray (Raymond Choat)

{Original Message removed}
part 2 16409 bytes content-type:image/jpeg; (decode)


part 3 144 bytes
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2001\06\27@090712 by Olin Lathrop

face picon face
> There was the Radio Shack Color Computer (AKA the "CoCo"), which ran at a
mere 1/4 of the
> frequency of a common color burst crystal.  (a 6809 @ less than 1 Mhz!).
It had
> an R2R resistor ladder style D/A converter and a single analog comparator
> with which one could implement an A/D in software.  They sold a ROM
cartridge
> which contained an audio spectrum analyzer program. Does anyone else
> remember this? I have a hard time believing that a clever programmer could
> not achieve the same with a PIC (at 20Mhz + hardware A/D) today.
>
> Dan (a Radio Shack "CoCo" owner!)

But again, until we know the frequency range, whether it's OK to sample
occasional bursts, the frequency resolution, etc, there is no way to know
what the compute requirements are.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, RemoveMEolinTakeThisOuTspamspamembedinc.com, http://www.embedinc.com

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2001\06\27@090716 by Olin Lathrop

face picon face
> Are there any 18FXX or 18CXX parts that can interface external RAM?

Any PIC can interface to an external RAM with enough I/O pins.  There 18xx
parts that use external program memory: 18C601, 18C801.  I haven't looked at
these parts enough to know how easy it is to read/write to this memory under
program control when it is implemented as RAM.


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Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, EraseMEolinspamspamspamBeGoneembedinc.com, http://www.embedinc.com

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2001\06\27@092952 by Silvio Borges

flavicon
face
Robert:

I was looking for this kind of analyzer for a while, could you point me some piece
of code?
A 20Hz-20KHz bandwidth, 10-16 frequencies and 4 bit resolution would be great for
this aplication, if some realtime could be achieved, like 3 chunks/s better.
I just need the basics for DFT calculation if someone could help me...


{Quote hidden}

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2001\06\27@094028 by Russell McMahon

picon face
> ....ha. Yes the 6809E has a lot in common with the pics.


Heresy!
How can you compare the near ultimate 8 bit microprocessor (and I don't mean
the PIC :-) ) with one of the most abominably ornery processors know to man
(or woman). Mind you, the PIC looks quite good and almost normal next to say
an F8. Anyone remember *them*???

RM

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2001\06\27@103644 by Silvio Borges

flavicon
face
Are you saying that we could not download this AN from Scenix?

"dr. Imre Bartfai" gravada:

> Ubicom has (at least, Scenix had) an AN dealing with this subject,
> AFAIK. I got it, too. Unfortunately, it is not public as I should sign an
> Undisclosure Agreement before. It is free from them, though.
>
> Regards,
>
> Imre
>

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2001\06\27@104059 by Bob Barr

picon face
Russell McMahon wrote:

>
>Heresy!
>How can you compare the near ultimate 8 bit microprocessor (and I don't
>mean
>the PIC :-) ) with one of the most abominably ornery processors know to man
>(or woman). Mind you, the PIC looks quite good and almost normal next to
>say
>an F8. Anyone remember *them*???
>

Ahhh, yes. That goes back a ways. As I recall, it only took 3 40-pin dips to
implement one of those beasties. My first 'home computer' was a salvaged
Fairchild F8 demo board.

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2001\06\27@234459 by Robert A. LaBudde

flavicon
face
At 10:25 AM 6/27/01 -0300, Silvio wrote:
>I was looking for this kind of analyzer for a while, could you point me
>some piece
>of code?
>A 20Hz-20KHz bandwidth, 10-16 frequencies and 4 bit resolution would be
>great for
>this aplication, if some realtime could be achieved, like 3 chunks/s better.
>I just need the basics for DFT calculation if someone could help me...

If you want to do this real-time for an audio LED bargraph-type display,
and only need 10 frequency points (octaves from 20 Hz, 40 Hz, ... , 20 kHz)
and only need 4 bits of accuracy, then the simplest approach might be to
just create 10 bandpass digital filters centered at the frequencies of
interest.

Or, you can do a 16-point FFT and then treat it as a fixed transform (i.e.,
a fixed linear transformation of the samples.

You can approximate the multiplies (losing accuracy in the process) in
order to avoid full multiplies.

There has been an implementation of a 256-pt FFT on a 17C756 by Robert
LaCoste. It should be available in the Piclist archives. It was called the
"PIC'Scope Audio Spectrum Analyzer".


================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS  e-mail: ralSTOPspamspamspam_OUTlcfltd.com
Least Cost Formulations, Ltd.            URL: http://lcfltd.com/
824 Timberlake Drive                     Tel: 757-467-0954
Virginia Beach, VA 23464-3239            Fax: 757-467-2947

"Vere scire est per causas scire"
================================================================

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2001\06\28@054749 by dr. Imre Bartfai

flavicon
face
Hi,

as I did it, I must register myself or so (accept LA etc). It was a long
time ago, sorry.

Imre

On Wed, 27 Jun 2001, Silvio Borges wrote:

{Quote hidden}

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2001\06\29@010509 by HEV

picon face
Silvio, you  can   find a PIC based audio spectrum analyzer in the September
1998 (issue 98) of Circuit Cellar  INK (http://www.circuitcellar.com). Both the PDF
and the source code are available.  If you experience any prob in finding it
just let me know and I'll send them to you.

Regards, HEV

{Original Message removed}

2001\06\30@123248 by Joe Denehan

flavicon
face
The purpose I wish to use the Spectrum Analyzer is just for a visual effect
for use with any line input for music use. I would hope to use a 15-wide by
10-high LED matrix ( Lot of LED's ) and possible scroll text also, which
shouldn't be too much of a problem. Can it be done?

{Original Message removed}

2001\06\30@123837 by Herbert Graf

flavicon
face
As per my previous post I still recommend you do the spectrum part with
analog parts (an op amp and a few passive components are all that you need
for each frequency you wish to display, if you want to go REALLY cheap then
just a few passive components are all that is needed, along of course with a
bargraph driver IC, but you can multiplex that), it's just much easier. You
can use the pic to blank the screen's spectrum display and drive it's own
sort of message. Just my opinion, but unless you WANT to do this completely
digitally this is a case of the analog method simply being easier. TTYL

{Original Message removed}

2001\06\30@144414 by Dan Michaels

flavicon
face
Joe Denehan wrote:

>The purpose I wish to use the Spectrum Analyzer is just for a visual effect
>for use with any line input for music use. I would hope to use a 15-wide by
>10-high LED matrix ( Lot of LED's ) and possible scroll text also, which
>shouldn't be too much of a problem. Can it be done?


Joe, something like this might be much more easily done, and
also produce a real-time display, with a set of very cheap and
easy to build bandpass filters made out of opamps. You can use
the PIC to sample filter outputs and control the LED matrix.

- dan michaels
==================

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'[PIC:] Spectrum Analyzer software'
2004\01\08@080629 by Digiled dot com
flavicon
face
Hello Piclist,

     I4m looking for a Spectrum analyzer software (freeware) where I can define a periodic
     waveform.
     Is to analyze harmonics in waveforms.

     Thanks in advance,
                       Gus


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2004\01\08@092137 by Mike Hord

picon face
I'm not entirely clear on what it is you're looking for, but here's
a page that has a lot of test equipment-like software, mostly
using the sound card for input.

http://www.dazyweblabs.com/shannonsoft/page3.html

Mike H.

{Quote hidden}

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2004\01\09@095855 by Digiled dot com

flavicon
face
Hello Mike,

     Simply a simulator where I can define a perdiodic waveform and
     it calculates the harmonic content of the signal...
     It4s to evaluate a filter and a PWM signal.
     Any ideas ?

MH> I'm not entirely clear on what it is you're looking for, but here's
MH> a page that has a lot of test equipment-like software, mostly
MH> using the sound card for input.

MH> http://www.dazyweblabs.com/shannonsoft/page3.html

MH> Mike H.

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2004\01\09@143239 by Mike Hord

picon face
Nope, but if you still can't find anything else, take a look at
http://www.scilab.org, which is a free version of MatLab.  It can
do things with FFT and so forth, but would require a good
working understanding of the math involved, so it isn't
what I would call a "turnkey" solution.

Mike H.

{Quote hidden}

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'[OT]:Used Spectrum Analyzer'
2004\02\28@233000 by Richard Graziano
picon face
Clear DayI am looking for a (low cost) used spectrum analyzer.  Frequency
range does not need to exceed 30 MHz.

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'[AD] [EE] 0-6GHz spectrum analyzer, need european '
2005\08\03@075702 by Vasile Surducan
face picon face
Hi all,

I'm interested in a refurbished or second hand (low cost anyway) min.
6GHz bandwidth spectrum analyzer, the seller must be located in the
Europe. Any hints ?

thank you in advance,
Vasile

'[OT] 0-6GHz spectrum analyzer, need european selle'
2005\08\03@125842 by Vasile Surducan

face picon face
> Hi all,
>
> I'm interested in a refurbished or second hand (low cost anyway) min.
> 6GHz bandwidth spectrum analyzer, the seller must be located in the
> Europe. Any hints ?
>
> thank you in advance,
> Vasile
>

'[OT]: need 0-6GHz spectrum analyzer, european sell'
2005\08\04@050956 by Vasile Surducan

face picon face
Hi there, this is the third email which I'm sending to the list with
this topic, the other two seems being lost somewhere...

I'm interested in a refurbished, used (inexpensive) spectrum analyzer
covering a
0-6GHz range minimum (preferable with tracking generator), not very
old, from an european seller.

Any hints will be appreciated,
Vasile

2005\08\04@052801 by Stef Mientki

flavicon
face
hi Vasile,

Unfornuatly I cann't help you with the spectrum analyzer,
but there seems something wrong with your mail system:
this indeed is the third message, as I see it !

cheers,
Stef Mientki

Vasile Surducan wrote:

{Quote hidden}

'[OT] need 0-6GHz spectrum analyzer, european selle'
2005\08\04@052936 by Jinx

face picon face
> this topic, the other two seems being lost somewhere...

They all arrived Vasile, with [OT] [AD] or untagged

'need 0-6GHz spectrum analyzer, european seller'
2005\08\04@055453 by Alan B. Pearce

face picon face
>I'm interested in a refurbished, used (inexpensive) spectrum
>analyzer covering a 0-6GHz range minimum (preferable with
>tracking generator), not very old, from an european seller.

I doubt you will get something that you will consider "inexpensive" ;))

There are a number of dealers in the UK who sell refurbished/recalibrated
test equipment, but I would think that a 6GHz one would be state of the art
enough that finding a second hand one will be only a small possibility.
Check out the Electronics World magazine for UK dealers.

As to not seeing your own posts, is there an option in the mailserver to not
have your own posts sent back to you, and is it turned on for you?

2005\08\04@064330 by Dan Smith

face picon face
On 8/4/05, Vasile Surducan <.....piclist9spam_OUTspamgmail.com> wrote:
> Hi there, this is the third email which I'm sending to the list with
> this topic, the other two seems being lost somewhere...

Hi Vasile,

I notice that you're using Gmail.  One thing that Gmail does is 'hide'
any posts on mailing lists that have come from your own email address
- in other words, you won't see any of your own Piclist posts arriving
from the Piclist mailserver.  Rest assured though, all of your posts
have appeared on the list :-)

Dan

2005\08\04@070307 by Jinx

face picon face

> - in other words, you won't see any of your own Piclist posts
> arriving from the Piclist mailserver

......and you can see them in the archives

2005\08\04@085152 by Vasile Surducan

face picon face
On 8/4/05, Alan B. Pearce <TakeThisOuTA.B.Pearce.....spamTakeThisOuTrl.ac.uk> wrote:
> >I'm interested in a refurbished, used (inexpensive) spectrum
> >analyzer covering a 0-6GHz range minimum (preferable with
> >tracking generator), not very old, from an european seller.
>
> I doubt you will get something that you will consider "inexpensive" ;))
>
> There are a number of dealers in the UK who sell refurbished/recalibrated
> test equipment, but I would think that a 6GHz one would be state of the art
> enough that finding a second hand one will be only a small possibility.
> Check out the Electronics World magazine for UK dealers.
>
> As to not seeing your own posts, is there an option in the mailserver to not
> have your own posts sent back to you, and is it turned on for you?

Results:
  Your current option settings:
      ack off
      digest off
      delivery on
      myposts on
      hide off
      duplicates off
      reminders on

- Done.

2005\08\04@122526 by Dmitriy Kiryashov

picon face
Vasile I've seen all of your emails as everybody else did.
I'm not sure about such thing being "inexpensive" and don't
live currently in europe either.

Why don't you try to locate somebody from Europe selling
equipment on Ebay first then call their office and check
their price list ?

WBR Dmitry.


Vasile Surducan wrote:
{Quote hidden}

> -

': need 0-6GHz spectrum analyzer, european seller'
2005\08\04@130904 by Vasile Surducan

face picon face
On 8/4/05, Dmitriy Kiryashov <TakeThisOuTvze27bymKILLspamspamspamverizon.net> wrote:
> Vasile I've seen all of your emails as everybody else did.
> I'm not sure about such thing being "inexpensive" and don't
> live currently in europe either.
>
> Why don't you try to locate somebody from Europe selling
> equipment on Ebay first then call their office and check
> their price list ?

 There isn't any similar item on Ebay from the Europe. Everything is
from the US!
Only once per month an old T141... By inexpensive I mean less than
3000$, I know the prices... Shipping from the US any parcel of 30-50lb
via air is the hell. Insurance + shipping cost = almost 50% more added
to the innitial price. Not talking about no money back guarantee ( 15
days is not enough). So who is buying from Ebay US if lives in the
Europe ?

thx even for good thoughts,
Vasile


{Quote hidden}

'[AD] 0-6GHz spectrum analyzer, need european selle'
2005\08\11@062123 by Alan B. Pearce

face picon face
Further to my previous reply, you may like to check these outfits out. They
advertise in the UK magazine Electronics World.

http://www.testequipmenthq.com/ was advertising a number of Agilent/HP 8561B
& E, 8595E with various options, prices to sell in range of GBP6k to 10k, to
rent GBP200 to 300 per week, for 4 weeks.

http://www.telnet.uk.com/ is advertising a range of Agilent/HP instruments,
with spectrum Analysers among them, but their advert does not list any 6GHz.
Other stuff looks to be price commensurate with the previous link.

These would be the order of price I would expect to pay for something
second-hand of this performance, but do not know if this matches your
original request for "cheap".

'[EE] Re: 0-6GHz spectrum analyzer, need european s'
2005\08\11@111223 by Vasile Surducan

face picon face
On 8/11/05, Alan B. Pearce <.....A.B.PearcespamRemoveMErl.ac.uk> wrote:
> Further to my previous reply, you may like to check these outfits out. They
> advertise in the UK magazine Electronics World.
>
> http://www.testequipmenthq.com/ was advertising a number of Agilent/HP
> 8561B
> & E, 8595E with various options, prices to sell in range of GBP6k to 10k,

Thank you Alan,

I'm affraid this price will be a little too much even for Beckham's wife...
:)

I found a Tektronix up to 22GHz with 3300 euro, but unfortunately it
was on Ebay with a seller which can't be trusted too much.


> to
> rent GBP200 to 300 per week, for 4 weeks.

This might be a good option for an english, unfortunately not for me,
there are some problems with insurance, custom and deliver in both
directions.
Still searching.

If any serious potential seller on this list, contact me privately please.

Vasile

>
> http://www.telnet.uk.com/ is advertising a range of Agilent/HP instruments,
> with spectrum Analysers among them, but their advert does not list any
> 6GHz.
> Other stuff looks to be price commensurate with the previous link.
>
> These would be the order of price I would expect to pay for something
> second-hand of this performance, but do not know if this matches your
> original request for "cheap".
>
> --


'[EE]: Nice spectrum analyzer'
2006\05\28@121431 by Peter
picon face

Excite DUT with white noise, convert output down to audio band using XO
and use spectrum analyzer running on PC audio card to visualise.
Schematic supplied. The nice part is that given a good mixer and LO this
whould work way up into microwave. Finally an affordable solution for
filter and amplifier design for homebrew UHF and microwave ?

http://www.qsl.net/7n3wvm/Fil_Meas.html

Peter

2006\05\28@125406 by Vasile Surducan

face picon face
On 5/28/06, Peter <RemoveMEplpspamspamBeGoneactcom.co.il> wrote:
>
> Excite DUT with white noise, convert output down to audio band using XO
> and use spectrum analyzer running on PC audio card to visualise.
> Schematic supplied. The nice part is that given a good mixer and LO this
> whould work way up into microwave.

Would work yes, but will be almost unuseless. The simple mixer must
be replaced with an IQ one, else would be necessary two or three IF
stages with all the problems. The biggest one will be the frequency
fluctuation in the audio side and the limited bandwith or distortion.
Also will be necessary a real VCO and not a white noise generator.
There are many analyzers like this one on the web, the best one is
using a tuner
and claim to work ok till 2Ghz. I'm seeing every day  how works a good
spectrum analyzer (for it's 30 years old age) TEK492 and if that one
can't be used for fast signal analyses, all analyzers having the same
principle (unfortunately) can't.
So depends what do you need.

greetings,
Vasile



Finally an affordable solution for
> filter and amplifier design for homebrew UHF and microwave ?
>
> http://www.qsl.net/7n3wvm/Fil_Meas.html
>
> Peter
> -

2006\05\28@155234 by Peter

picon face
Vasile Surducan <piclist9 <at> gmail.com> writes:

>  Would work yes, but will be almost unuseless. The simple mixer must
> be replaced with an IQ one, else would be necessary two or three IF
> stages with all the problems. The biggest one will be the frequency
> fluctuation in the audio side and the limited bandwith or distortion.
> Also will be necessary a real VCO and not a white noise generator.
>  There are many analyzers like this one on the web, the best one is
> using a tuner
> and claim to work ok till 2Ghz. I'm seeing every day  how works a good
> spectrum analyzer (for it's 30 years old age) TEK492 and if that one
> can't be used for fast signal analyses, all analyzers having the same
> principle (unfortunately) can't.
> So depends what do you need.

I wrote:

> > Finally an affordable solution for
> > filter and amplifier design for homebrew UHF and microwave ?
> >
> > http://www.qsl.net/7n3wvm/Fil_Meas.html
> >
> > Peter

Could you elaborate on this ? Why is an IQ mixer needed ? The way I see it the
most needed thing is low (very low) phase noise of the carrier so the LO does
not swamp the mixer and the audio after it (although I am unsure what happens
with the phase noise in a direct conversion receiver when an actual signal is
not present). The scheme is the same as used in DSB/CW direct conversion
receivers, whose performance is rather good usually. Also using a noise source
as input makes it possible to go to very high frequencies without the usual
problems. No ? Also it is a very simple and inexpensive scheme. With a $10 mixer
it could cover dc to 4GHz. If a stabilised Gunnplexer is used then microwave
filter (and Gunn and varactor bias, by voltage, to match an existing filter or
structure) tuning becomes possible. What am I missing ? Ok, dynamic range is
probably 55dB or less (sound card dynamic range). With a good sound card and a
preamplifier this could be 90-100dB. Many people already have such a good sound
card. If the LO is replaced with a stepwise DSS or PLL then a spectrum can be
taken with say 40kHz 'windows' from DC (almost) to 1GHz. The DSS could be
controlled by a USB to parallel control for example.

Peter


2006\05\28@163120 by Dave Tweed

face
flavicon
face
Peter <spamBeGoneplp@spam@spamspam_OUTactcom.co.il> wrote:
> Could you elaborate on this? Why is an IQ mixer needed? The way I see
> it the most needed thing is low (very low) phase noise of the carrier
> so the LO does not swamp the mixer and the audio after it (although I
> am unsure what happens with the phase noise in a direct conversion
> receiver when an actual signal is not present). The scheme is the
> same as used in DSB/CW direct conversion receivers, whose performance
> is rather good usually. Also using a noise source as input makes it
> possible to go to very high frequencies without the usual problems.
> No? Also it is a very simple and inexpensive scheme. With a $10 mixer
> it could cover dc to 4GHz. If a stabilised Gunnplexer is used then
> microwave filter (and Gunn and varactor bias, by voltage, to match
> an existing filter or structure) tuning becomes possible. What am
> I missing? Ok, dynamic range is probably 55dB or less (sound card
> dynamic range). With a good sound card and a preamplifier this could
> be 90-100dB. Many people already have such a good sound card. If the
> LO is replaced with a stepwise DSS or PLL then a spectrum can be
> taken with say 40kHz 'windows' from DC (almost) to 1GHz. The DSS
> could be controlled by a USB to parallel control for example.

Your enthusiasm is causing you to extrapolate way beyond the concept
of the original project, which was to evaluate the details of a crystal
filter's amplitude response, which was already known to be less than
the bandwidth of the sound card. This isn't a "spectrum analyzer" so
much as a magnitude-only "network analyzer" (no phase information).

In order to turn this into a direct-conversion spectrum analyzer,
you'd need to build a filter with a fixed 20 kHz bandwidth whose
center frequency could be varied from "DC to 1 GHz". Good luck!

If you want a rather good design for a low-cost spectrum analyzer,
as well as a discussion of some of the design issues, look for the
article by Neal Martini in the next issue (#192) of Circuit Cellar.
It's based on a MAX3550 and a PIC18F4520.

-- Dave Tweed

2006\05\28@173045 by Peter

picon face
Dave Tweed <pic <at> dtweed.com> writes:

> Your enthusiasm is causing you to extrapolate way beyond the concept
> of the original project, which was to evaluate the details of a crystal
> filter's amplitude response, which was already known to be less than
> the bandwidth of the sound card. This isn't a "spectrum analyzer" so
> much as a magnitude-only "network analyzer" (no phase information).
>
> In order to turn this into a direct-conversion spectrum analyzer,
> you'd need to build a filter with a fixed 20 kHz bandwidth whose
> center frequency could be varied from "DC to 1 GHz". Good luck!
>
> If you want a rather good design for a low-cost spectrum analyzer,
> as well as a discussion of some of the design issues, look for the
> article by Neal Martini in the next issue (#192) of Circuit Cellar.
> It's based on a MAX3550 and a PIC18F4520.

Thanks for answering.

My enthusiasm is that of an optimist with experience. I have specan
experience with homebrew, HP, and Elbonian devices. I think that I
know what can be built, bought and rented, and what it's worth.

My question was, assuming this is a $20 project including 1 hour of
soldering, and that it will be used for low signal work, in closed
circuit (not exposed to QRM for example), and that the user can always
turn off the power to the DUT and to the signal source if suspecting
something is not right about the output, are there any serious flaws
in this scheme, which would prevent it from being used to tune VHF,
UHF and microwave circuits using the noise input method (noise which
is inherently incoherent and thus makes an IQ demodulator unnecessary) ?

<aside> It could also be extended with another mixer fed with output from
a sound card and from the LO, so an analyzer signal with DSB could be
applied to the DUT - but for now, I am referring only to the circuit as
shown </aside>

As to the CC article, thanks for posting that.

Peter


2006\05\29@074848 by Vasile Surducan

face picon face
On 5/28/06, Peter <TakeThisOuTplpspamspamactcom.co.il> wrote:
{Quote hidden}

Well, a DC to microwave spectrum analyzer can't be made with one IF stage
only if you're using an zero IF IQ mixer, a damn good reference oscillator
-not a DDS which has a really poor SFDR on the whole oscillator band
(50-60dB if you're a very good PCB and filter designer) with the
eliptical filter adjusted on the maximum frequency range and a sinx/x
amplitude dependence (and you need about 90...120 dB SNR if you want
to see something on your screen with small signals on the input)
-nor a PLL oscillator which has a poor signal to noise ratio  (dBc)
because of it's working principle. So you need something else or a
combinations above...
A mixer from DC to 4GHz is good, but not if you're trying to get
audio, mixing 4.000.000,000 MHz local oscilator with an input signal
of 4.000.000,010 MHz, and you believe you'll really get 10KHz without
crazy fluctuations...
If you're interested I could send you a few links about home made
spectrum analyzers. But I don't recommend building any if you  may buy
a new one, with about $1500, covering 1Mhz to 7GHz range and showing
you at least the frequency and amplitude.

greetings,
Vasile




The way I see it the
{Quote hidden}

> -


'[PIC]: Audio spectrum analyzer'
2006\06\04@010043 by Charles Craft
picon face
Caught the YES 35th anniversary show on PBS tonight and went back in time.

Back before MP3, iPod and ear buds there were people tweaking equalizers and watching bouncing
LEDs on spectrum analyzers.

To build a 8 or 16 channel spectrum analyzer would you go analog using bandpass filters into
A/D into on perhaps a PIC 18F or 24F, or is it something that a dsPIC is a better fit for?

The bandpass filters would (could?) take a fare chunk of board space but the firmware would be simpler.
dsPIC would just suck the signal into a single input but require high power software to split it out inside?




2006\06\04@011503 by Herbert Graf

flavicon
face
On Sun, 2006-06-04 at 01:00 -0400, Charles Craft wrote:
> Caught the YES 35th anniversary show on PBS tonight and went back in time.
>
> Back before MP3, iPod and ear buds there were people tweaking equalizers and watching bouncing
> LEDs on spectrum analyzers.
>
> To build a 8 or 16 channel spectrum analyzer would you go analog using bandpass filters into
> A/D into on perhaps a PIC 18F or 24F, or is it something that a dsPIC is a better fit for?
>
> The bandpass filters would (could?) take a fare chunk of board space but the firmware would be simpler.
> dsPIC would just suck the signal into a single input but require high power software to split it out inside?

Without question I'd use a dsPIC for that.

Not much power needed either since while you are dealing with audio
frequencies, your update rate is relatively long (human eye).

TTYL

'EE Spectrum Analyzer circuit'
2006\06\04@022257 by Rich Graziano

picon face
Hi All:  Does anyone have a proven circuit for a spectrum analyzer for a frequency range 20 Hz to 20 MHz:?  Something I could fit on a small PC Card?
Rich

2006\06\04@035037 by Vasile Surducan

face picon face
Just to make an ideea about what a spectrum analyzer means
(using multiple FI stages and no DDS or IQ arhitecture):

http://www.hanssummers.com/electronics/equipment/spectrumanalyser/index.htm

greetings,
Vasile

On 6/4/06, Rich Graziano <rgrazia1EraseMEspamrochester.rr.com> wrote:
> Hi All:  Does anyone have a proven circuit for a spectrum analyzer for a frequency range 20 Hz to 20 MHz:?  Something I could fit on a small PC Card?
> Rich
> -

2006\06\04@040333 by Gus S Calabrese

face picon face
You might say a little more about the performance you want
out of the unit.  For example: If your resolution bandwidth
is 20MHz, then all you need is an RMS detector or maybe
a peak detector.


On 2006-Jun 04, at 01:50hrs AM, Vasile Surducan wrote:

Just to make an ideea about what a spectrum analyzer means
(using multiple FI stages and no DDS or IQ arhitecture):

http://www.hanssummers.com/electronics/equipment/spectrumanalyser/
index.htm

greetings,
Vasile

On 6/4/06, Rich Graziano <RemoveMErgrazia1EraseMEspamspam_OUTrochester.rr.com> wrote:

> Hi All:  Does anyone have a proven circuit for a spectrum analyzer  
> for a frequency range 20 Hz to 20 MHz:?  Something I could fit on a  
> small PC Card?
> Rich
> -

'[PIC]: Audio spectrum analyzer'
2006\06\04@110822 by Martin K

flavicon
face
The math for a discrete FFT isn't too complicated, especially at low
resolutions. Try doing a little reading about it - it's fascinating stuff.
--
Martin K

Charles Craft wrote:

{Quote hidden}

2006\06\04@203225 by Russell McMahon

face
flavicon
face
> The math for a discrete FFT isn't too complicated, especially at low
> resolutions. Try doing a little reading about it - it's fascinating
> stuff.

We did it on an MC6800 long long ago.

The memory gives me Butterflies :-)




       RM

2006\06\04@204156 by Zik Saleeba

picon face
Here's some FFT code which may be handy:

http://rustam.uwp.edu/499/programs/math/fft.c

Cheers,
Zik

On 05/06/06, Russell McMahon <@spam@apptechRemoveMEspamEraseMEparadise.net.nz> wrote:
{Quote hidden}

> -

2006\06\04@204600 by Martin K

flavicon
face
The days of simple motorola MCUs or the discrete FFT?
Have you looked at the HCS12? My my.. I'd need a week to get going with it.
The MSP430s seem pretty nice. I'd like to find a decent eval board for one.
--
Martin K

Russell McMahon wrote:

{Quote hidden}

'EE Spectrum Analyzer circuit'
2006\06\04@214311 by Rich Graziano

picon face
Thank you for the reply Vasile.
Very useful.
Rich
----- Original Message -----
From: "Vasile Surducan" <EraseMEpiclist9spam@spam@gmail.com>
To: "Microcontroller discussion list - Public." <@spam@piclistspam_OUTspam.....mit.edu>
Sent: Sunday, June 04, 2006 3:50 AM
Subject: Re: EE Spectrum Analyzer circuit


{Quote hidden}

>> --

2006\06\05@005001 by Vasile Surducan

face picon face
Rich,
There are many like this. Before buying a spectrum analyzer I've
played with many
"homebrewed" solutions. For 0 to 20Mhz I have two clues for the main oscillator:
1. for a programable span rate use AD9851, a nice DDS, unfortunately
you'll not be able to get a SNR better than 60dB (SFDR=40dBc) only
with programable filters which are quite difficult to buid and to
switch.
This is not a masked AD (no more modules available left):
http://www.surducan.netfirms.com/modul.html
at the bottom of the page, just for the pictures

2. for a fixed span of 28MHz there are some very cheap FM single IC
tuner covering 80-108MHz with fixed sweep time. Mixing the result with
80MHz you'll be able to get 80+/-(80...108) = 0 ...+/- 28MHz.
Filtering the unwanted image and bingo (not easy!). SNR could be
better if the 80MHz will be clean (at least 100-110 dBc)

3. using a fractional PLL looks to be the best choice but at this
small frequency is difficult to found (you have to design your own
PLL) and you need a good VCO in this range. However theoretically you
could go up to 80-90dB SNR (I didn't succeed yet).

I don't want to make you some false illusions, you can't do it without
already having a spectrum analyzer (or at least an oscilloscope with
FFT analyses) because the border of 60dB SNR is very difficult to pass
(seems to be much difficult than from Mexic to USA...:)

greetings,
Vasile

On 6/5/06, Rich Graziano <rgrazia1spamBeGonespamrochester.rr.com> wrote:
> Thank you for the reply Vasile.
> Very useful.
> Rich
> {Original Message removed}

2006\06\05@032120 by Rich Graziano

picon face
Thank you for the helpful information, Vasile.  I appreciate it.  I do have
a Hewlett Packard Spectrum analyzer, a Tektronics Spectrum analyzer and
another in my lab for actually looking for harmonics, transients, etc.  But
I want to put one in an instrument I am designing and I was hoping to find
someone who has already designed and built one as a guide line that I could
follow.  Thank you.  You are the recourse I was hoping for.  I was hoping
also to find some receiver components and IF components to design into the
overall circuit.  I have see the front end for receivers in small metal
boxes in TVs and Radios.  I built some oscillators but the sinewave
distorted over a range of 10MHz.  I think I need to readjust the LC ratios.
That will probably lower the Q but it may not matter if selective sharp
resonance is not a factor.  I find that theory only works after you adjust
it by trial and error and error and error :-)
I am very grateful for your help.  You have anticipated several of my
questions. Thank you.
Regards
Rich
{Original Message removed}

'[PIC]: Audio spectrum analyzer'
2006\06\05@035732 by Michael Rigby-Jones

picon face
Martin,

Russell's pun refers to a type of computation known as the FFT butterfly:
http://www.skylondaworks.com/sc_admpy.htm

Regards

Mike

>{Original Message removed}

'EE Spectrum Analyzer circuit'
2006\06\05@102351 by w d myrick

picon face
Rich,  Look at this site it may help
you.

http://www.science-workshop.com/

Derward Myrick

----- Original Message -----
From: "Rich Graziano"
<RemoveMErgrazia1@spam@spamspamBeGonerochester.rr.com>
To: "Microcontroller discussion list -
Public." <.....piclist@spam@spamEraseMEmit.edu>
Sent: Monday, June 05, 2006 2:21 AM
Subject: Re: EE Spectrum Analyzer
circuit


> Thank you for the helpful information,
Vasile.  I appreciate it.  I do have
> a Hewlett Packard Spectrum analyzer, a
Tektronics Spectrum analyzer and
> another in my lab for actually looking
for harmonics, transients, etc.  But
> I want to put one in an instrument I
am designing and I was hoping to find
> someone who has already designed and
built one as a guide line that I could
> follow.  Thank you.  You are the
recourse I was hoping for.  I was hoping
> also to find some receiver components
and IF components to design into the
> overall circuit.  I have see the front
end for receivers in small metal
> boxes in TVs and Radios.  I built some
oscillators but the sinewave
> distorted over a range of 10MHz.  I
think I need to readjust the LC ratios.
> That will probably lower the Q but it
may not matter if selective sharp
> resonance is not a factor.  I find
that theory only works after you adjust
> it by trial and error and error and
error :-)
> I am very grateful for your help.  You
have anticipated several of my
> questions. Thank you.
> Regards
> Rich

2006\06\05@112632 by Rich Graziano

picon face
Thank you, Derward.  The LIST is sure a great place when you need help!  I
have learned a lot just by listening to what others say.  Thanks to you and
Vasile I have some direction to go in on this project.
Regards
Rich
{Original Message removed}


'[EE] Help with Tek 492 Spectrum Analyzer'
2009\08\15@191524 by Sean Breheny
face picon face
Hi all,

Can someone who is familiar with the Tek 492 spectrum analyzer please
email me offlist? I recently bought one on eBay and I am trying to
check it out before giving feedback. There are a couple of items which
seem like they may be quirks or problems, but the manual doesn't seem
to address them. I'd like to ask someone who is knowledgeable or
someone who can compare results with his own Tek 492. Email address is
shb7 AT cornell.edu

Thanks very much in advance!

Sean

2009\08\15@195741 by enkitec

picon face
Sean Breheny wrote:
> Hi all,
>
> Can someone who is familiar with the Tek 492 spectrum analyzer please
> email me offlist? I recently bought one on eBay and I am trying to
> check it out before giving feedback. There are a couple of items which
> seem like they may be quirks or problems, but the manual doesn't seem
> to address them. I'd like to ask someone who is knowledgeable or
> someone who can compare results with his own Tek 492. Email address is
> shb7 AT cornell.edu
>
> Thanks very much in advance!
>
> Sean
>  

   Try here:

   http://groups.yahoo.com/group/TekScopes/

   Mark Jordan

2009\08\15@225410 by Sean Breheny

face picon face
Thanks, Mark. I just posted my questions there.

Sean


On Sat, Aug 15, 2009 at 7:57 PM, <.....enkitecRemoveMEspamgmail.com> wrote:
{Quote hidden}

>


'[PIC] PIC-based Spectrum Analyzer'
2011\03\15@152009 by Richard
picon face
It seems that someone recently (past 6 months) posted information about a
PIC-based spectrum analyzer. If anyone remembers where or who, please let me
know.

Thanks,
Richard the senile

2011\03\15@153024 by Oli Glaser

flavicon
face
On 15/03/2011 19:19, Richard wrote:
> It seems that someone recently (past 6 months) posted information about a
> PIC-based spectrum analyzer. If anyone remembers where or who, please let me
> know.
>
> Thanks,
> Richard the senile
>

I can't remember such a post recently.
Might be worth doing a search of the archives if you haven't tried that already.

2011\03\15@153641 by Michael Watterson

face picon face
On 15/03/2011 19:19, Richard wrote:
> It seems that someone recently (past 6 months) posted information about a
> PIC-based spectrum analyzer. If anyone remembers where or who, please let me
> know.
>
> Thanks,
> Richard the senile
>
>
>
I did a PIC based Cat controller for FT817 ND radio. A Pseudo Spectrum analyser feature in it,
A philips I2C TV  tuner 42MHz to 862 MHz can also be hooked to PIC with GLCD and make a toy spectrum analyser. Add 35MHz to 42MHz filter of desired bandwidth and detector.

2011\03\15@155127 by Scott

picon face
On Tue, Mar 15, 2011 at 1:19 PM, Richard <.....rseriani48STOPspamspam@spam@cox.net> wrote:
> It seems that someone recently (past 6 months) posted information about a
> PIC-based spectrum analyzer. If anyone remembers where or who, please let me
> know.
>
> Thanks,
> Richard the senile
>


This is from January:

http://hackaday.com/2011/01/08/pic-spectrum-analyzer-uses-fast-fourier-transform-routine/

http://www.waitingforfriday.com/index.php/Real-Time_Audio_Spectrum_Analyser

-Scot

2011\03\15@172834 by Michael Watterson

face picon face
Scott wrote:
> On Tue, Mar 15, 2011 at 1:19 PM, Richard <rseriani48EraseMEspam@spam@cox.net> wrote:
>  
>> It seems that someone recently (past 6 months) posted information about a
>> PIC-based spectrum analyzer. If anyone remembers where or who, please let me
>> know.
>>
>> Thanks,
>> Richard the senile
>>
>>    
>
>
> This is from January:
>
> http://hackaday.com/2011/01/08/pic-spectrum-analyzer-uses-fast-fourier-transform-routine/
>
> http://www.waitingforfriday.com/index.php/Real-Time_Audio_Spectrum_Analyser
>
> -Scott
>   Ah a real one, but only audio, like PC sound card, but more portable but not as good.
Nice though.

I always think of 100KHz to 18GHz when people talk about Spectrum Analysers :-)

2011\03\15@192444 by Richard

picon face


:-----Original Message-----
:From: RemoveMEpiclist-bouncesspamspamBeGonemit.edu [spamBeGonepiclist-bouncesKILLspamspam@spam@mit.edu] On Behalf
:Of Oli Glaser
:Sent: Tuesday, March 15, 2011 3:30 PM
:To: Microcontroller discussion list - Public.
:Subject: Re: [PIC] PIC-based Spectrum Analyzer
:
:On 15/03/2011 19:19, Richard wrote:
:> It seems that someone recently (past 6 months) posted information
:about a
:> PIC-based spectrum analyzer. If anyone remembers where or who, please
:let me
:> know.
:>
:> Thanks,
:> Richard the senile
:>
:
:I can't remember such a post recently.
:Might be worth doing a search of the archives if you haven't tried that
:already.
:

Thanks, Oli. I tried a search, but it returned an error. Based on Scott's
reply, I must have been doing something wrong.

2011\03\15@210858 by Richard

picon face


:-----Original Message-----
:From: piclist-bouncesspam_OUTspam@spam@mit.edu [spamBeGonepiclist-bounces@spam@spammit.edu] On Behalf
:Of Scott
:Sent: Tuesday, March 15, 2011 3:51 PM
:To: Microcontroller discussion list - Public.
:Subject: Re: [PIC] PIC-based Spectrum Analyzer
:
:On Tue, Mar 15, 2011 at 1:19 PM, Richard <RemoveMErseriani48EraseMEspamKILLspamcox.net> wrote:
:> It seems that someone recently (past 6 months) posted information
:about a
:> PIC-based spectrum analyzer. If anyone remembers where or who, please
:let me
:> know.
:>
:> Thanks,
:> Richard the senile
:>
:
:
:This is from January:
:
:hackaday.com/2011/01/08/pic-spectrum-analyzer-uses-fast-fourier-
:transform-routine/
:
:www.waitingforfriday.com/index.php/Real-
:Time_Audio_Spectrum_Analyser
:
:-Scott
:--

Thank you, Scott. That is what I was looking for.

Richard

2011\03\16@060150 by alan.b.pearce

face picon face
> :This is from January:
> :
> :hackaday.com/2011/01/08/pic-spectrum-analyzer-uses-fast-fourier-
> :transform-routine/
> :
> :www.waitingforfriday.com/index.php/Real-
> :Time_Audio_Spectrum_Analyser
> :
> :-Scott
> :--
>
> Thank you, Scott. That is what I was looking for.
>
> Richard

There was also one in a recent (last 3 or 4 months) Circuit Cellar, using a dsPic to do a similar display using LEDs. Apparently it is very fast in updating the display in real time.
-- Scanned by iCritical.

'[PIC] PIC Based Spectrum Analyzer'
2011\03\16@123513 by Chadwick, Robert

picon face
Richard

Try here...
http://www.cliftonlaboratories.com/Z90.htm

This is a panadaptor but might be worth a look.
IIRC, the author is an occasional PICList contributor.

Bob C


'[EE] Build a spectrum analyzer'
2011\06\28@110033 by Herbert Graf
picon face
So, in my huge amounts of free time I've been thinking that the one area
of electronics I don't really have much experience is radio.

I've been experimenting and having some fun, but I've convinced myself
that something that might turn out to be a really fun and educational
adventure is building a spectrum analyzer.

There's not of google links out there to half finished or ancient
projects.
I'm not looking at creating laboratory grade equipment, just something
that'll help me see that the circuits I'm building are actually doing.

So, any suggestions?

I'm not to concerned about the interface or display, that's the kind of
stuff I've done before so I'd probably just take the easy way out and
use a PC initially.

My main area of concern is the actual RF stuff.

I'd like the analyzer to at least cover up to about 1GHz (the 2.4GHz
band would be nice (and very useful in the future) but I feel I might be
overreaching there).

Alot of projects use the tuners in VCRs for the RF front end. Any
recommendations on something that might work well?

Ideally if I could get a tuner to do most of the dirty work (something
like feed it a voltage to select which frequency to tune, and output an
RSSI signal to indicate signal strength) that would be a great way to
start.
Any suggestions? Anybody do something similar?

Thanks for your ideas!

TTYL

2011\06\28@110711 by Ariel Rocholl

picon face
Hi Herbert,

That is more or less what I did for RF Explorer, see
http://www.rf-explorer.com . Current versions are limited to narrow ISM
bands, but wider band models are coming in a few weeks, including a 2.4Ghz
and 240-960Mhz.

The circuit is published on the "hacker's corner" wiki. You may get some
ideas out of it.

Hope this helps,

-- Ariel Rocholl
http://www.rf-explorer.com


On Tue, Jun 28, 2011 at 5:00 PM, Herbert Graf <spamBeGonehkgrafspam_OUTspamRemoveMEgmail.com> wrote:

{Quote hidden}

>

2011\06\28@111655 by Herbert Graf

picon face
On Tue, 2011-06-28 at 17:07 +0200, Ariel Rocholl wrote:
> Hi Herbert,
>
> That is more or less what I did for RF Explorer, see
> http://www.rf-explorer.com . Current versions are limited to narrow ISM
> bands, but wider band models are coming in a few weeks, including a 2.4Ghz
> and 240-960Mhz.
>
> The circuit is published on the "hacker's corner" wiki. You may get some
> ideas out of it.

Hello Ariel,

neat, thanks!

I've looked at other units that are kinda similar to that. Thing is, I
don't really want to build something restricted to one band, I'd like
something that covers a wide range.

TTYL

2011\06\28@113302 by Ariel Rocholl

flavicon
face
Hi Herbert,

Absolutely, the wider the span, the more fun you get experimenting.

A 1Ghz bandwidth is doable with a tuned circuit in the middle of the band,
and some software tricks to calibrate the results and overcome the lack of
linearity. For wider than 1Ghz bandwidth the tuned circuitry becomes very
complex for a reasonable linearity and cost, and you would find easier to
split the wider band in chunks and downconvert higher part of the spectrum
into lower band, and thus reuse the same tuned circuitry. This is what most
full size SA do, have 2 or 3 IF stages to limit the bandwidth you need to
process after some point.

Cheers,
Ariel

On Tue, Jun 28, 2011 at 5:16 PM, Herbert Graf <.....hkgrafspamRemoveMEgmail.com> wrote:

{Quote hidden}

>

2011\06\28@114439 by Sean Breheny

face picon face
One fairly common way to make a cheap spectrum analyzer for <1GHz is
to use a surplus TV tuner module, the kind which used to be on
computer analog TV input cards. These can be set up to take RF in,
give a single IF frequency out (often 45MHz or 10.7 MHz), and take a
tuning voltage input. These would allow you to tune from about 40MHz
to 1GHz. They also often have built-in AGC with a signal strength out
pin. You then can amplify the output, apply a much narrower filter,
and feed it to a log-amp detector IC. Then, the combination of the AGC
level out plus the output of the log amp would be your signal strength
in the BW of the narrow filter.

I bought a few of these tuner modules on eBay for only a dollar or two
each just a few months ago. They came with documentation, too.

Sean


On Tue, Jun 28, 2011 at 11:00 AM, Herbert Graf <hkgrafspam@spam@gmail.com> wrote:
{Quote hidden}

>

2011\06\28@114857 by Herbert Graf

picon face
On Tue, 2011-06-28 at 11:44 -0400, Sean Breheny wrote:
> One fairly common way to make a cheap spectrum analyzer for <1GHz is
> to use a surplus TV tuner module, the kind which used to be on
> computer analog TV input cards. These can be set up to take RF in,
> give a single IF frequency out (often 45MHz or 10.7 MHz), and take a
> tuning voltage input. These would allow you to tune from about 40MHz
> to 1GHz. They also often have built-in AGC with a signal strength out
> pin. You then can amplify the output, apply a much narrower filter,
> and feed it to a log-amp detector IC. Then, the combination of the AGC
> level out plus the output of the log amp would be your signal strength
> in the BW of the narrow filter.
>
> I bought a few of these tuner modules on eBay for only a dollar or two
> each just a few months ago. They came with documentation, too.

Thats exactly the kind of thing I'd like to find! Any pointers? Willing
to sell the ones you've got? :)

How would I go about searching for something like that? The
documentation would of course be key, don't want to try and figure
pinouts of modules on my own?

Thanks, TTYL

2011\06\28@121435 by Derward Myrick

picon face
Hebert,

There is a spectrum analyzer group that has just done a 1 Ghz
unit that uaed a laptop fpr display.
This is the group EraseMEspectrumanalyzerRemoveMEspamSTOPspamyahoogroups.com <RemoveMEspectrumanalyzerKILLspamspamTakeThisOuTyahoogroups.com>
This is a very good SA not a piece of junk.

look at this URL  http://www.scottyspectrumanalyzer.com/

Derward Myrick   KD5WWI






{Original Message removed}

2011\06\28@123558 by jim

flavicon
face

Check the Radio Amateur's Handbook.  There is a little of everything in
there.  And most of the projects
and equipment in there was designed and built by amateur radio
operators.  And if you know anything about
amateur radio operators, they want to get the most bang from their
buck.  Which means they use more
ingenuity than money, and design needed equipment to do a job well, but
not necessarily fancy.  And they
do it on the cheap.  Cheap meaning inexpensive, not low quality.

Regards (73),
Jim (KA9QHR)

> ---{Original Message removed}

2011\06\28@143834 by Sean Breheny

face picon face
Hi Herbert,

Try searching for "tuner" under the business&industrial category on
eBay. I just did that and found several, although the only one which
had a datasheet link was a digital-output tuner for DBS. However, most
likely some of the others have datasheets which can be found online.

I will take a look to see if I can find the ones I got and I may sell
them if I can find them.

Sean


On Tue, Jun 28, 2011 at 11:49 AM, Herbert Graf <spamBeGonehkgrafspam@spam@gmail.com> wrote:
{Quote hidden}

>

2011\06\28@161834 by Bob Chadwick

picon face

Go have a look here. Somewhat dated; I don't see anything that indicates
recent updates, but a lot of good data and links. http://www.nitehawk.com/rasmit/sa50.html

Bob Chadwick
PICList Lurker



Herbert Graf-5 wrote:
{Quote hidden}

> -

2011\06\28@172619 by Derward Myrick

picon face
Herbert, look at this http://www.science-workshop.com/

This one goes 2150 mhz.

Derward Myrick




{Original Message removed}

2011\06\28@183253 by David Bley

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Well I looked at my Google Bookmarks and found this:  http://scottyspectrumanalyzer.com/

While not a spectrum analyzer, a component of a VNA is a comb generator, found here:
http://www.thegleam.com/ke5fx/cg.htm

Instead of searching for spectrum analyzers, you may find more help looking for VNA's.  There are several of those projects on the 'net, although they don't make it to 1GHz.
http://sdr-kits.net/DG8SAQ/VNWA/baier_VNWA10_QEX.pd

2011\06\28@215421 by Dwayne Reid

flavicon
face
At 09:00 AM 6/28/2011, Herbert Graf wrote:
>So, in my huge amounts of free time I've been thinking that the one area
>of electronics I don't really have much experience is radio.

I played with the science workshop spectrum analyzer <http://www.science-workshop.com/> many years ago and wasn't all that happy with it.  I don't remember the details but one major problem was inability to calibrate the frequency accurately.  It was useful to get a general idea of what the spectrum looked like but that was about it.  The last time I used it was probably 10 years ago.

I've been using an old HP 8559 for the past many years but late last year, I finally bought something better: its called a Signal Hound <http://www.signalhound.com> .  I also purchased its companion tracking generator when they became available early this year.  Both go up to 4.2GHz..

If you do purchase one of the Signal Hound units used, make sure that you get the "B" version.  The earliest units (non "B") spew significant amounts of the first LO out the input connector which can (DID!) cause significant problems.

I also recently purchased a VNA (vector network analyzer) from <http://www.SDR-kits.com> .  This is a NICE little box that does one and two port measurements.  It will function as a rudimentary spectrum analyzer but there are limitations that are at least well documented.  Its good up to 1.3GHz.

Both of the units I mentioned are fully assembled, not kits and not parts collections that can be gathered up.  Sorry about that.  But they both work well.

dwayne

-- Dwayne Reid   <RemoveMEdwaynerspam_OUTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2011\06\29@013018 by Sean Breheny

face picon face
part 1 2331 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

OK, I looked at what I have and it is less impressive than what I
remember. Frequency range is only about 400 to 900 MHz. I have
attempted to attach a GIF image which I was sent by the eBay seller
when I bought them (qty 2). I also have a schematic but please ask me
offlist if you want it as it is a little bit bigger file and I do not
think that I should try to send it on-list.

Also, I came across this archived discussion on this topic of spectrum
analyzers from TV tuners:

http://www.nitehawk.com/rasmit/sa_notes1.html

The modules I have were made by Mitsumi, they have only one label on
them which seems to say TIF4-A41. Also appears to have a date code of
8447 (47th week of 1984 I'd guess). These are probably not the best
bet for this project as there are more modern ones available, some
even with I2C-controlled digital tuning.

I would be willing to sell them if you are still interested.

Sean


On Tue, Jun 28, 2011 at 11:49 AM, Herbert Graf <hkgrafspamspamgmail.com> wrote:
{Quote hidden}

> -

2011\06\29@040017 by Peter Loron

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I've got a pile of Sharp tuners (or at least they look like tuners). I don't have any data on them. Link to an image is below. If you're interested make me an offer.

http://standingwave.org/webdav/xe6095.JPG

-Pete


On Jun 28, 2011, at 10:29 PM, Sean Breheny wrote:

{Quote hidden}

>> -


'[OT] Spectrum analyzer'
2011\08\08@200051 by V G
picon face
Hi all,

I bought a cheap guitar-computer interface off of dealextreme:
http://www.dealextreme.com/p/guitar-to-usb-interface-link-cable-for-pc-mac-recording-130cm-32874

It works very well and GarageBand/Guitar Rig totally rock. Latency is
minimal as well. I don't think I can notice it with the proper
settings.

Anyway, there seems to be a very high frequency hiss sound on certain
amp models/configurations on both GarageBand and Guitar Rig (have yet
to try logic studio) which makes me question whether or not the guitar
interface is at fault. I want to do a spectrum analysis on the output
of the thing and see what's going on. Does anyone here know of any
good (free if possible) real time spectrum analyzer software for
Windows? I want to be able to view what audio is coming out of this
guitar interface

2011\08\08@210407 by RussellMc

face picon face
>  Does anyone here know of any
> good (free if possible) real time spectrum analyzer software for
> Windows? I want to be able to view what audio is coming out of this
> guitar interface.

Mayhaps

PC soundcard based:

          http://www.techmind.org/audio/#specanaly

        From:  http://www.techmind.org/audio/#intro


Mod for DC response
YMMV
Caveat Emptor

    http://blog.makezine.com/archive/2008/05/how-to-modify-a-pc-sound.html

Related

    http://www.edaboard.com/thread136601.html

Zelscope $10

   http://www.zelscope.com/

TrueRTA
Versions for $0

  http://www.trueaudio.com/rta_abt1.htm

Legion

    http://www.dxzone.com/catalog/Software/Spectrum_analyzers/

Virtins
21 day trial free

       http://www.virtins.com

2011\08\08@211810 by Carl Denk

flavicon
face
Check this out:
http://audacity.sourceforge.net/

On 8/8/2011 9:03 PM, RussellMc wrote:
{Quote hidden}

>

2011\08\09@032806 by Michael Watterson

face picon face
On 09/08/2011 01:00, V G wrote:
> I want to do a spectrum analysis on the output
> of the thing and see what's going on. Does anyone here know of any
> good (free if possible) real time spectrum analyzer software for
> Windows?

http://www.sillanumsoft.org/

Visual Analyser 2011
Fabulous

Signal Generator, Spectrum Analyser + waterfall, Phase, Scope and more

2011\08\09@033134 by Michael Watterson

face picon face
On 09/08/2011 01:00, V G wrote:
> I want to do a spectrum analysis on the output
> of the thing and see what's going on. Does anyone here know of any
> good (free if possible) real time spectrum analyzer software for
> Windows?

http://www.sillanumsoft.org/

Visual Analyser 2011
Fabulous

Signal Generator, Spectrum Analyser + waterfall, Phase, Scope and more

2011\08\09@131532 by YES NOPE9

flavicon
face
>
> On Aug 9, 2011, at 1:26 AM, Michael Watterson wrote:
>
> On 09/08/2011 01:00, V G wrote:
>> I want to do a spectrum analysis on the output
>> of the thing and see what's going on. Does anyone here know of any
>> good (free if possible) real time spectrum analyzer software for
>> Windows?
>
> http://www.sillanumsoft.org/
>
> Visual Analyser 2011
> Fabulous
>
> Signal Generator, Spectrum Analyser + waterfall, Phase, Scope and more.


I took a look at this and it is apparently FREE and NOT Open Sourced.
It is Windows based.   It can be made to run on Linux with WINE.
( I wonder if it will run under a VM ? )
99guspuppet

'[OT] USB audio interface (was Spectrum analyzer)'
2011\08\09@204925 by V G

picon face
On Mon, Aug 8, 2011 at 8:00 PM, V G <x.solarwind.xspam_OUTspamgmail.com> wrote:

{Quote hidden}

Thank you everyone for the software suggestions. I analyzed the output of my
guitar interface and this is what I got:

Nothing plugged into the input: http://solarwind.byethost7.com/noinput.png

Guitar 1/4" analog cable plugged into the input:
http://solarwind.byethost7.com/input.png

Input or not, there seems to be some significant high frequency noise (not
the obvious 60Hz) that doesn't seem to be coming from the guitar. My regular
amp is completely noise free (as far as I can hear at the volumes I use, and
I can hear very well).

It's not a deal breaker, but it's still there and it's annoying to use on
some amp models/pedals/effects that tend to boost those frequencies.


I think I have two options now: either buy a better quality guitar
interface, or make my own.

I think I have the ability to make my own since it's just pretty much:
opamp, etc -> ADC -> microcontroller -> USB client chip -> computer

The USB drivers also seem to be standard and ASIO4all is a very good driver..

The question is, do you guys think this would be hard? Waste of time? What
are your opinions on this?

The advantage of making one myself is that I could add as my inputs/outputs
as I want and build in a mixer, etc. I could also use high quality and low
noise components and build in hardware filters for annoying frequencies
(50/60Hz)

2011\08\10@030644 by Michael Watterson

face picon face
On 10/08/2011 01:49, V G wrote:
> I think I have the ability to make my own since it's just pretty much:
> opamp, etc ->  ADC ->  microcontroller ->  USB client chip ->  computer

Or just use Texas PCM2900 and Low noise Op-Amps.

It's 1.98V FS i/o 16bit 48KHz USB

Should be automatically detected on Windows or Linux as USB Audio

2011\08\10@121340 by YES NOPE9

flavicon
face
>
> On Aug 10, 2011, at 1:05 AM, Michael Watterson wrote:
>
> On 10/08/2011 01:49, V G wrote:
>> I think I have the ability to make my own since it's just pretty much:
>> opamp, etc ->  ADC ->  microcontroller ->  USB client chip ->  computer
>
> Or just use Texas PCM2900 and Low noise Op-Amps.
    PCM2900 is obsolete .... replaced by PCM2900B
focus.ti.com/docs/prod/folders/print/pcm2900b.html
> It's 1.98V FS i/o 16bit 48KHz USB
>
> Should be automatically detected on Windows or Linux as USB Audio

2011\08\10@123400 by Michael Watterson

face picon face
On 10/08/2011 17:13, YES NOPE9 wrote:
>> Or just use Texas PCM2900 and Low noise Op-Amps.
>       PCM2900 is obsolete .... replaced by PCM2900B
> focus.ti.com/docs/prod/folders/print/pcm2900b.html
Thanks. I was thinking of buying a few to have cheap simple built-in USB audio on some "gadgets".

What's the difference? Do you know off hand

2011\08\10@165214 by V G

picon face
On Wed, Aug 10, 2011 at 12:13 PM, YES NOPE9 <RemoveMEyesKILLspamspam@spam@nope9.com> wrote:

> >
> > On Aug 10, 2011, at 1:05 AM, Michael Watterson wrote:
> >
> > On 10/08/2011 01:49, V G wrote:
> >> I think I have the ability to make my own since it's just pretty much:
> >> opamp, etc ->  ADC ->  microcontroller ->  USB client chip ->  computer
> >
> > Or just use Texas PCM2900 and Low noise Op-Amps.
>      PCM2900 is obsolete .... replaced by PCM2900B
> focus.ti.com/docs/prod/folders/print/pcm2900b.html
> > It's 1.98V FS i/o 16bit 48KHz USB
> >
> > Should be automatically detected on Windows or Linux as USB Audio.
>

Damn. I love these guys and you guys more and more every day

2011\08\10@171250 by Michael Watterson

face picon face
On 10/08/2011 17:32, Michael Watterson wrote:
> What's the difference? Do you know off hand?

Listed http://www.ti.com/litv/pdf/slel058

2011\08\10@174545 by Robert Rolf

picon face
>
> Input or not, there seems to be some significant high frequency noise (not
> the obvious 60Hz) that doesn't seem to be coming from the guitar. My regular
> amp is completely noise free (as far as I can hear at the volumes I use, and
> I can hear very well).
>
> It's not a deal breaker, but it's still there and it's annoying to use on
> some amp models/pedals/effects that tend to boost those frequencies.
>
>
> I think I have two options now: either buy a better quality guitar
> interface, or make my own.

Or just change out the op amp in the existing amplifier for one with a much better noise figure. One MEANT for low noise operation, rather than cheapness.

There are op amps designed specifically for ultra low noise audio operations with low internal bias currents and low shot noise as a result.  LT1115 comes to mind, AD8597 series, OPA827, etc.

Saves a lot of time is all you do is swap out the noise maker for one that isn't so intrinsically noisy.
Have you looked at what is in there currently? I'll bet its a general purpose, super cheap, op amp.


R

2011\08\10@215008 by Oli Glaser

flavicon
face
On 10/08/2011 01:49, V G wrote:
> Nothing plugged into the input:http://solarwind.byethost7.com/noinput.png
>
> Guitar 1/4" analog cable plugged into the input:
> http://solarwind.byethost7.com/input.png
>
> Input or not, there seems to be some significant high frequency noise (not
> the obvious 60Hz) that doesn't seem to be coming from the guitar. My regular
> amp is completely noise free (as far as I can hear at the volumes I use, and
> I can hear very well).

Hmm, the highest level there is around -60dBu (at a low frequency ~200Hz so unlikely to be the high frequency noise you are hearing), and most is under -80dBu which I wouldn't call significant noise. 0dBu is 0.775V RMS, so -80dBu is 0.0000775V.
Have you tested the signal before it goes into the box you bought? Can you describe your audio chain in detail so we can get a good idea of what you are doing and why you think the box is causing the problem?

When exactly does the noise turn up? As soon as you plug the guitar in? When you turn a certain effect/amp on? If it doesn't happen on a clean sound then maybe it's either intentional (e.g part of the intended character of an old amp sound) or some issue with the processing/drivers? I saw on the link that someone suggested using the Behringer Guitar Link UCG102 drivers instead:
http://club.dealextreme.com/forums/Forums.dx/threadid.579785

To find out where the noise is coming from you need to make it happen, then follow the signal chain right from the start to see where the unwanted accentuation/distortion appears. Some white noise at the input during this might be useful to see what is happening to all frequencies easily - whatever the input is it needs to be reliable and a known quantity (i.e. not suddenly likely to burst into high end distortion).
If you narrow down a likely culprit, then we can try and figure out what is causing it, but I would first try and confirm beyond reasonable doubt it's actually the box causing the problem.
I suspect that it will have a cheap opamp in there as RR suggested, and I agree (if it's actually causing a significant problem) swapping it would be an easy way to improve performance.
If you want to build your own I'd be prepared to spend some time and effort on it. If the goal is just to get a decent guitar recording setup I'd say forget it and stick with that (or make a simple improvement like swapping the opamp) or buy another better one. If you want to increase your understanding of audio/USB/DSP then go for it, I'm sure you will learn plenty.

2011\08\11@024433 by V G

picon face
On Wed, Aug 10, 2011 at 9:49 PM, Oli Glaser <oli.glaserspamBeGonespam.....talktalk.net> wrote:

> Hmm, the highest level there is around -60dBu (at a low frequency ~200Hz
> so unlikely to be the high frequency noise you are hearing), and most is
> under -80dBu which I wouldn't call significant noise. 0dBu is 0.775V
> RMS, so -80dBu is 0.0000775V.
> Have you tested the signal before it goes into the box you bought? Can
> you describe your audio chain in detail so we can get a good idea of
> what you are doing and why you think the box is causing the problem?
>

I did not test the signal going into the box. But I do know that when I plug
the guitar into the dedicated amp, there is no noise at all (very little
60Hz noise, and nothing other than that).

The setup I have is this:

guitar (analog signal from pickups) -> guitar link box -> computer (via USB)
-> various software that was tested produced the same noise (Guitar Rig,
Garage Band)

headphones or mini stereo system (via regular analog stereo headphone cable)
<- guitar link box <- computer <- software


When exactly does the noise turn up? As soon as you plug the guitar in?
>

The noise is there regardless of if anything is plugged into the guitar
interface box or not. Plugging the guitar and/or headphones in and out does
not really change the level of noise that much.

When you turn a certain effect/amp on? If it doesn't happen on a clean
> sound then maybe it's either intentional (e.g part of the intended
> character of an old amp sound)


Good question. It is still there on the clean setting (no particular amp or
effect selected), but it is very low intensity and I have to turn the
software input gain up to hear it. It is still there though.

However, when a particular amp/distortion pedal is selected, the noise
becomes much more prominent. I think that the distortion pedals are somehow
amplifying the noise (perhaps by boosting the treble).


> or some issue with the
> processing/drivers? I saw on the link that someone suggested using the
> Behringer Guitar Link UCG102 drivers instead:
> http://club.dealextreme.com/forums/Forums.dx/threadid.579785
>

It doesn't matter which drivers I use. The ASIO4All drivers are far superior
anyway. MUCH lower latency. Exact same issue on my Macbook Pro laptop. Same
symptoms and behavior. The drivers on the Mac are "built in" by Apple I
assume.

To find out where the noise is coming from you need to make it happen,
> then follow the signal chain right from the start to see where the
> unwanted accentuation/distortion appears. Some white noise at the input
> during this might be useful to see what is happening to all frequencies
> easily - whatever the input is it needs to be reliable and a known
> quantity (i.e. not suddenly likely to burst into high end distortion).
> If you narrow down a likely culprit, then we can try and figure out what
> is causing it, but I would first try and confirm beyond reasonable doubt
> it's actually the box causing the problem.
>

I'm /pretty sure/ it is the box, but I could be wrong. My dedicated amp and
distortion don't have any noise other than the 60Hz which becomes much more
prominent when I touch something like a 60Hz power line.

I suspect that it will have a cheap opamp in there as RR suggested, and
> I agree (if it's actually causing a significant problem) swapping it

would be an easy way to improve performance.
>

Could it also be the ADC?


> If you want to build your own I'd be prepared to spend some time and
> effort on it. If the goal is just to get a decent guitar recording setup
> I'd say forget it and stick with that (or make a simple improvement like
> swapping the opamp) or buy another better one. If you want to increase
> your understanding of audio/USB/DSP then go for it, I'm sure you will
> learn plenty.
>

Yes, I would also like to increase my understanding of those things. I'll
work on it slowly as I get time I guess.

Unfortunately, I don't have a good spectrum analyzer to pinpoint the noise.
And it's hard to prototype an opamp setup when all the good ones are SSOP
and stuff. I just have to design it using LTSPICE/DipTrace and hope I'm
doing it right and send in the board for fabrication

2011\08\11@032357 by V G

picon face
On Wed, Aug 10, 2011 at 5:45 PM, Robert Rolf <KILLspamRobert.Rolfspam.....ualberta.ca>wrote:

>  Or just change out the op amp in the existing amplifier for one with a
> much better noise figure. One MEANT for low noise operation, rather than
> cheapness.
>
> There are op amps designed specifically for ultra low noise audio
> operations with low internal bias currents and low shot noise as a
> result.  LT1115 comes to mind, AD8597 series, OPA827, etc.
>
> Saves a lot of time is all you do is swap out the noise maker for one
> that isn't so intrinsically noisy.
> Have you looked at what is in there currently? I'll bet its a general
> purpose, super cheap, op amp.
>

LOL! So I opened up the device and it's using a PCM2902 (
http://focus.ti.com/docs/prod/folders/print/pcm2902.html) inside. The opamp
is an LMV824 quad opamp (http://www.national.com/pf/LM/LMV824.html)

What do you guys think of the opamp? Is it suitable for this purpose? Is it
a noisy opamp?

What do you guys think of the LT1028 (I hear lots of people love this one
for audio) and LT1115?

The LMV824 noise spec is 24nV/rt(Hz) @ 1KHz

The LT1028 is 0.85nV

The LT1115 is 0.9nV

So yeah, it's a pretty unsuitable opamp in the guitar interface box. Would
it be possible that the noise spec on the LMEV824 is causing the noise
problem? I was reading up on the noise spec calculations and how to use
them, but I forgot. How /bad/ is 24nV/rt(Hz) for audio purposes?

I would ideally like to use 4 of LT1028 opamps but they're expensive to buy
4 of. What other opamps would you guys recommend? 4-in-a-chip would be nice,
but I would guess that quality is compromised for quantity for these opamps.

2011\08\11@034257 by V G

picon face
On Thu, Aug 11, 2011 at 3:23 AM, V G <spam_OUTx.solarwind.xspamKILLspamgmail.com> wrote:

{Quote hidden}

Actually, I think I just found a good one: LME49740 (
http://www.national.com/pf/LM/LME49740.html) 2.7nV/rt(Hz) What do you guys
think?. Not too expensive ($5 ish). Also, the pinout and package seems to be
the same, so possibly a drop in replacement?

My only concern is that the LME49740 does not state that it has rail to rail
outputs like the LMV824 does. It does, however, specify that the voltage
supply range is +/-2.5V to +/-17V, so is it safe for me to assume that the
outputs swing rail to rail

2011\08\11@205215 by V G

picon face
part 1 754 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

On Thu, Aug 11, 2011 at 3:42 AM, V G <KILLspamx.solarwind.xspamspamBeGonegmail.com> wrote:

> Actually, I think I just found a good one: LME49740 (
> http://www.national.com/pf/LM/LME49740.html) 2.7nV/rt(Hz) What do you guys
> think?. Not too expensive ($5 ish). Also, the pinout and package seems to be
> the same, so possibly a drop in replacement?
>
> My only concern is that the LME49740 does not state that it has rail to
> rail outputs like the LMV824 does. It does, however, specify that the
> voltage supply range is +/-2.5V to +/-17V, so is it safe for me to assume
> that the outputs swing rail to rail?
>

Found some more awesome ones I'm going to sample first: csv file attached


part 2 1647 bytes content-type:text/csv; name="Operational Amplifiers (Op Amps).1313110030.csv"
(decoded base64)

"Product","Channels  (#)","Vos  (mV)","GBW  (MHz)","SR  (V/us)","Is  (mA)","Rail-to-Rail Out  (yes/no)","Type ","Packages ","Enoise Density  (nV/rtHz)","Inoise  (pA/rtHz)","LF Enoise  (uVpp)" "LTC2052","4","0.0005","3","2","0.85","yes","ZD","SO-14,SSOP-16","","","1.5" "LTC2052","4","0.0005","3","2","0.85","yes","ZD","SO-14,SSOP-16","","","1.5" "LT6204","4","0.1","100","25","2.8","yes","VFB","SO-14,SSOPN-16","1.9","0.75","0.8" "LT1679","4","0.035","20","6","2","yes","VFB","SO-14","3.9","0.3","" "LT1631","4","0.15","30","9.2","3.5","yes","VFB","SO-14","6","0.9","0.3" "LT1802","4","0.075","80","25","1.6","yes","VFB","SO-14","8.5","1","1.4" "LT1885","4","0.03","2","0.9","0.65","yes","VFB","SO-14","9.5","0.05","0.4" "LT1499","4","0.15","10.5","4.5","1.7","yes","VFB","SO-14","12","0.3","0.4" "LT1633","4","0.4","45","27","4.3","yes","VFB","SO-14","12","1.6","0.4" "LT1882","4","0.03","1","0.35","0.65","yes","VFB","SO-14","14","0.3","0.5" "LT6012","4","0.02","0.33","0.09","0.135","yes","VFB","SO-14,SSOPN-16","14","0.1","0.4" "LT1639","4","0.2","1.075","0.38","0.17","yes","VFB","DIP-14,SO-14","20","0.3","1" "LT1805","4","0.35","85","100","2.7","yes","VFB","SO-14","21","2.5","4" "LT1367","4","0.15","0.4","0.13","0.34","yes","VFB","SO-14","29","0.07","" "LT1369","4","0.15","0.16","0.065","0.34","yes","VFB","SO-14","29","0.07","" "LT1491A","4","0.22","0.18","0.06","0.04","yes","VFB","DIP-14,SO-14,DFN-16","50","0.015","1" "LT1496","4","0.15","0.0027","0.001","0.001","yes","VFB","DIP-14,SO-14","185","0.01","4" "LT1674","4","0.15","0.012","0.005","0.0015","yes","VFB","DIP-14,SO-14","185","0.01","4"
part 3 181 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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'[EE] TV Tuner Based Spectrum Analyzer'
2012\05\24@151325 by Herbert Graf
picon face
Hello all,

well, after a long delay, I've been able to dedicate a little time to my
idle project: a home built spectrum analyzer based on a TV tuner front
end.

I've found what I believe the perfect tuner for me (mostly because it's
something I have in my hands):

http://www.datasheetarchive.com/indexdl/Datasheet-028/DSA00488547.pdf

It's a Temic 4036 RF front end module. I found it on a WinTV PC TV tuner
PCI card.
It's a I2C based tuner, with single 5V power supply (has an onboard
DC-DC to get the 33V needed by the tuner). I stuck the card in a PC,
booted Ubuntu, attached a protocol analyzer (thank you beta version of
the BitScope software, was a major time saver!) on the I2C pins, started
TVTime and changed channels. The module is being programmed exactly as
the datasheet says it should be!

So, with that out of the way, what would be my next step?

First off, the module outputs CVBS (at baseband), and something labelled
IF2 (at 45.75 MHZ). Obviously I need an RSSI circuit. But do I first
have to "tune" the output somehow?
What I'm envisioning (and note, I no NOTHING about RF stuff, so this is
very much a learning project for me) is using a second tuner (some sort
of home built one chip thing with RSSI output perhaps?) that "tunes"
somewhere in the CVBS output with a bandwidth of say 10kHz? So basically
sweeping would be two steps, set the TV tuner to a channel, then sweep
the second tuner across the ~4MHz bandwidth of the CVBS or IF output.
Then step the TV tuner to the next range, and sweep the CVBS or IF
output. Combined I could get everything I need.

Does this sound at all reasonable or am I WAY out of wack here?

Should use the CVBS or the IF output?

Anybody have chip recommendations for how I might build the second
tuner, one hopefully with an RSSI output?

Is there a simpler way to what I'm after? What kind of resolution should
I aim for?

Thanks for any pointers!

TTYL

2012\05\24@174857 by Dwayne Reid

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Have you checked out the "Poor Man's Spectrum Analyzer" at <http://www.science-workshop.com/> ?  They may have circuit blocks that are useful for you.

Searching out "poor mans spectrum analyzer" yields lots of hits - some of those may also be useful.

dwayne


At 01:15 PM 5/24/2012, Herbert Graf wrote:
{Quote hidden}

2012\05\24@233824 by Herbert Graf

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I have seen that before. That site seems to just offer for purchase the details, or parts.

I will have a look to see what kind of hits "poor mans spectrum analyzer" gets me. Thanks for the pointer.

TTYL


On 2012-05-24, at 5:48 PM, Dwayne Reid wrote:

{Quote hidden}

>> -

2012\05\25@090830 by Joe McCauley

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A bit removed from what the OP wanted, but.... This was not designed as a spectrum analyser, but you can get a nice spectrum between 45MHz & 870MHz. Takes 45 seconds to get a full range spectrum though!

http://www.e-callisto.org/

We use them for solar monitoring at http://www.rosseobservatory.ie. I tried to attach 2 spectra, but the list would not let them pass. If anyone wants to see, I can send directly to them as an attachment.

One of these shows frequencies below 45MHz, an up converter was used for this part.

Another option might be http://www.funcubedongle.com/. I've not used one (its on my long list of cool things to try) so I don't know if spectrum analyser type output is possible.

Joe


{Original Message removed}

2012\05\25@104015 by Sean Breheny

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For what it's worth, I think that you are basically on the right
track, Herbert. Good Tektronix or HP spectrum analyzers have
resolution bandwidths down to at least 1kHz and many go down to 100Hz
or even 10Hz (or even lower but that is almost always done in
post-processing by digitizing and then doing an FFT on each block of
samples).

You will see the terms "resolution bandwidth (RBW)" and "video
bandwidth (VBW)". Then there is also averaging or peak detection on
top of this. The distinction is as follows: RBW is the bandwidth of
the RF chain before the detector (power measurement device). VBW is
the bandwidth of the signal chain after the detector. Averaging or
peak detection then refer to how the digital storage portion of the
device records samples - it takes several samples per time step and
saves only one sample and it can save either the average of the
samples or the highest one.

The RBW determines the RF noise floor and also how close two signals
can be and still be resolved by the analyzer into two separate peaks.

The VBW determines how finely the analyzer can discriminate between
two different power levels. This is because a narrower VBW removes
noise in the detector output.

I believe that the averaging/peak detection is somewhat redundant with
the VBW - in other words, they roughly have the same kind of effect on
the signal as decreasing or increasing the VBW, except that the
analyzer often allows you to average signals below some power level
and peak-detect those above that same threshold, whereas VBW is fixed
for an entire scan.

On Thu, May 24, 2012 at 11:38 PM, Herbert Graf <hkgrafspamspamgmail.com> wrote:
{Quote hidden}

>>> --

2012\05\27@055503 by cdb

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Of not much help (because I can't find mycopy), Electronics Australia (defunct) did a Spectrum Analyser project based on a TV tuner, I can't recall how the sweep component worked. I vaguely recall an early Elektor magazine (70's or 80's) also did one.

Colin
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cdb, RemoveMEcolinspamBeGonespamRemoveMEbtech-online.co.uk on 27/05/2012
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2012\05\27@055845 by cdb

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Found this webpage: http://www.nitehawk.com/rasmit/sa50.html

Colin
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cdb, KILLspamcolinspamBeGonespambtech-online.co.uk on 27/05/2012
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2012\05\28@131922 by Herbert Graf

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Wow, that would be awesome! Might someone here have a copy of one of
these projects they could scan and send to me?

Thanks! TTYL

On Sun, 2012-05-27 at 19:54 +1000, cdb wrote:
{Quote hidden}

>

2012\05\30@232308 by Eoin Ross

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>From what I recall of a kit using a tuner unit out of a vcr, the was a VCO that did the tuning, and a RSSI voltage out.

A sawtooth was fed to the VCO input, and X input of a scope. The RSSI was fed to the Y input of the scope.

This was a kit available from Dick Smith Electronics New Zealand in the late 90's

Herbert Graf <hkgrafspamBeGonespamspamBeGonegmail.com> wrote:


Wow, that would be awesome! Might someone here have a copy of one of
these projects they could scan and send to me?

Thanks! TTYL

On Sun, 2012-05-27 at 19:54 +1000, cdb wrote:
{Quote hidden}

2012\05\31@012803 by Manu Abraham

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On Thu, May 31, 2012 at 8:51 AM, Eoin Ross <spam_OUTERossSTOPspamspamchemstation.com> wrote:
> >From what I recall of a kit using a tuner unit out of a vcr, the was a VCO that did the tuning, and a RSSI voltage out.
>
> A sawtooth was fed to the VCO input, and X input of a scope. The RSSI was fed to the Y input of the scope.
>
> This was a kit available from Dick Smith Electronics New Zealand in the late 90's

Long gone are those PLL based tuners, these days what you get are
these Silcon tuners
which are a bit more slightly complex ones which uses NCO's
(Numerically controlled
Oscillators), Instead of a vanilla VCO. Not a very big deal though,
just some slight topology
differences.

In such a case, you can't feed a sawtooth directly to the
PLL/MOPLL/Silicon Tuner.
You would be very lucky, if you find a really old Tin can tuner which
uses a varactor

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