[Lf] Re: lf digest, Vol 1 #146 - 1 msg

[Alberto di Bene]

Frank Gentges wrote:

> [snip]
> Any thoughts anyone?  Does this work?  Can we do it in background on a
> 486 "Dumpster Grade" Linux PC or should we build a dedicated filter?
> Can the sound card be run at 2000 samples per second under Linux or do
> we take every nth sample?
> [snip]

Frank,
               for longish FIR filter, a better solution is to implement them with
the FFT. In Hamview the bandpass filtering was done with a couple of
FFT / IFFT, with out-of-band rejection up to 60 dB, and it could also run
on a '486. And Hamview used 16-bit code for the FFT routines. Today
it is possible to find 32-bit FFT routines much more speedy than those.

As for the sampling rate, I'm afraid the lowest speed modern sound cards
can use is 5512.5  samples/sec. But decimation is always an option.

73,
Alberto    I2PHD