Searching \ for '[EE] ELF radio wave data logger' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/mems.htm?key=data
Search entire site for: 'ELF radio wave data logger'.

Exact match. Not showing close matches.
PICList Thread
'[EE] ELF radio wave data logger'
2006\01\09@151942 by lucid

flavicon
face
Can anyone guide me towards a relatively budgetary solution (ideally
PC based) for logging a broad spectrum or multiple narrower spectrums
of Extra Low Frequency electro-magnetic radiation in the .01-2000 Hz
range? Something like a simple card for PC with external antenna of
some sort would be great.

Thanks, TC

2006\01\09@153549 by David VanHorn

picon face
On 1/9/06, spam_OUTlucidTakeThisOuTspammagnet.ca <.....lucidKILLspamspam@spam@magnet.ca> wrote:
>
> Can anyone guide me towards a relatively budgetary solution (ideally
> PC based) for logging a broad spectrum or multiple narrower spectrums
> of Extra Low Frequency electro-magnetic radiation in the .01-2000 Hz
> range? Something like a simple card for PC with external antenna of
> some sort would be great.


Things get pretty interesting down there.  The PC itself is a loud noise
source.

Look at what's done for "Whistlers" and ELF reception, should give you some
ideas.

2006\01\09@205405 by Sergey Dryga

face picon face
<lucid <at> magnet.ca> writes:

>
> Can anyone guide me towards a relatively budgetary solution (ideally
> PC based) for logging a broad spectrum or multiple narrower spectrums
> of Extra Low Frequency electro-magnetic radiation in the .01-2000 Hz
> range? Something like a simple card for PC with external antenna of
> some sort would be great.

I think SETI people use this tipe of equipment.  I remember seeing couple
amateur groups with home-brew radiotelescopes some-time ago.  They record
signal in this range after downconversion.  

Another option is to use PC sound card.  All you need is sample at >4Khz in
order to do spectrum analysis.

Sergey


2006\01\10@152121 by Jesse Lackey

flavicon
face
One possible issue with sound cards is that most, if not all, are
AC-coupled; so low frequencies are rolled off.  This should be specified
on the sound card somewhere, but 20Hz is typical.  I looked into DIY EKG
stuff once for a project my brother was interested in, and this
effectively prevents sound cards as input devices in that application.
(most brainwave stuff is in the 30hz and below range).

An external A/D that isn't AC-coupled (or has the -3db point at 1Hz or
somesuch) and sends samples digitally to a digital-in soundcard would
solve this.  I've heard of this technique being used for various
non-audio data acquisition projects.

Good luck, sounds fun!
J


Sergey Dryga wrote:

{Quote hidden}

2006\01\10@180505 by Peter

picon face

On Mon, 9 Jan 2006, David VanHorn wrote:

> On 1/9/06, lucidspamKILLspammagnet.ca <.....lucidKILLspamspam.....magnet.ca> wrote:
>>
>> Can anyone guide me towards a relatively budgetary solution (ideally
>> PC based) for logging a broad spectrum or multiple narrower spectrums
>> of Extra Low Frequency electro-magnetic radiation in the .01-2000 Hz
>> range? Something like a simple card for PC with external antenna of
>> some sort would be great.
>
> Things get pretty interesting down there.  The PC itself is a loud noise
> source.
>
> Look at what's done for "Whistlers" and ELF reception, should give you some
> ideas.

Hehe. I just restored an old valved radio to life. I can use it next to
the computer just fine (can't do that with a SONY ICF-SW11). Totally
imprevious to RFI from the computer. With about 75V headroom I can
understand that ... it's a nice portable from the 1950's with instant on
(direct heated filaments). I am listening to it now (DX on AM). It is
more sensitive with its 4 valves (some are double) than the ICF-SW11 and
sounds better too. Just one problem: I don't think it has an AGC ...

As to logging with a PC, it should be no problem as long as the receiver
is coupled with optical fiber to the PC. I have been trying to get to do
this using inexpensive 'miniplug' (SPDIF) fiber cable but it is still on
the to-be-done list. Some day soon ... in fact this thread may bring it
closer.

thanks,
Peter

2006\01\11@053829 by Alan B. Pearce

face picon face
>Hehe. I just restored an old valved radio to life.
...
>It is more sensitive with its 4 valves (some are
>double) than the ICF-SW11

Is it actually more sensitive, or just appears so because of lower
selectivity?

I do remember a ham guy deriding other ham guys who were claiming the "band
was alive tonight" because they could sense all sorts of signals due to lack
of bandwidth selectivity and low image rejection.

2006\01\11@190658 by Peter

picon face

On Wed, 11 Jan 2006, Alan B. Pearce wrote:

>> Hehe. I just restored an old valved radio to life.
> ...
>> It is more sensitive with its 4 valves (some are
>> double) than the ICF-SW11
>
> Is it actually more sensitive, or just appears so because of lower
> selectivity?

It has very good selectivity. It uses a heptode oscillator-mixer, a
pentode IF stage and two twin-tuned IF transformers. IF+RF gain for such
a system can be >70dB with 30-40dB more added in the audio stage (2x
pentodes). Image rejection is very good (the ferrite rod wound antenna
coil has a high Q) and the air variable has specially crafted (different
sized) moving plates for osc and rf, for perfect tracking. This radio is
from ~1955 so it represents the sum of the lessons of the previous years
probably. After that transistors quickly took over the market. (and all
this happened a long time before I was born ...)

Peter

More... (looser matching)
- Last day of these posts
- In 2006 , 2007 only
- Today
- New search...