Filter Design - Calculate and display the impulse response (kernel) and frequency response for a windowed-sinc FIR filter - firkernel.htm
Filters are basic to electronics, as bearings are to mechanical engineering. I created this page for several reasons:
- to better understand how filters work. Much of what I understand about filters I learned from The Scientist and Engineer's Guide to Digital Signal Processing. I recommend it.
- to create FIR (Finite Impulse Response) filter kernels that I can copy and paste
into BasicDSP (which has a FIR function),
"A program for experimenting with simple audio DSP algorithms".
I found BasicDSP by Googling PA3FWM, the author of WebSDR. PA3FWM (Pieter-Tjerk de Boer) is
also one of the two authors of BasicDSP.
(WebSDR is "a Software-Defined Radio receiver connected to the internet,
allowing many listeners to listen and tune it simultaneously." WebSDR illuminates the use of
a filter to extract a signal from the ether.
- I have a long-standing interest (dare I say obsession) with
DTMF - Dual-Tone Multi-Frequency signally. I've used
filters I designed with this page in BasicDSP to create a system that separates the low and high frequency bands used in DTMF.
- When you design a filter with this page you get (in addition to the kernel and frequency response) a URL that will get your design back.
source is available as a Google Docs document. (The browser on my Palm doesn't have View/Source.) - http://docs.google.com/Doc?id=accnfh3pfb3_361g77gvbdn&hl=en
- Other pages I've found helpful in understanding filters:
- I used FLOT to create the graphs. I found it made creating attractive graphs very easy. FLOT, in turn, uses jQuery.
- Comments or questions: firstname.lastname@example.org