A raised cosine filter is a low-pass filter which is commonly used for pulse shaping in data transmission systems (e.g. modems). The frequency response |H(f)| of a perfect raised cosine filter is symmetrical about 0 Hz, and is divided into three parts (just like Gallia): it is flat (constant) in the pass-band; it sinks in a graceful cosine curve to zero through the transition region; and it is zero outside the pass-band. The response of a real filter is an approximation to this behaviour.
The equations which defined the filter contain a parameter ``beta'', which is known as the roll-off factor or the excess bandwidth. ``beta'' lies between 0 and 1.
I'd like to show you the equations which define the frequency-domain and time-domain response, but HTML is not up to it. If you can view PostScript, you can see the equations here, or consult Proakis.
The filter is designed as a finite-impulse-response (FIR) filter. You specify the length of the impulse response; that is equal to the number (n, say) of x coefficients in the ``C'' code. The filter will have:
Here we go:
file: /Techref/uk/ac/york/cs/www-users/http/~fisher/mkfilter/racos.htm, 4KB, , updated: 2000/6/29 18:32, local time: 2024/4/20 12:26, |
©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://techref.massmind.org/techref/uk/ac/york/cs/www-users/http/~fisher/mkfilter/racos.htm"> Raised Cosine Filters </A> |
Did you find what you needed? |
Welcome to massmind.org! |
Welcome to techref.massmind.org! |
.