Re: AW: Bessel-filter problems

[Chipmuenk]

Hello Bernd,

given a sampling rate of 5 GHz (or 1 GHz as well), you can only use the
simplest of DSP in the fastest available technology, i.e. you would have to
design your own ASIC (on which hardware do you plan to do your number
crunching?)

Even with a custom-specific IC, you would have to use very short wordlengths
to perform multiplications and additions in the given time frame.

Even with a cascaded filter implementation (much more robust to coefficient
and data quantization than direct form filters), I would guess you probably
need coefficients with at least 12 ... 14 bit wordlength and about the same
for your data. 

If your coefficients are too short, your filter may easily become unstable
(poles outside unit circle) or you may end up with massive errors in your
filter characteristic. Oppenheim / Schafer, "Discrete-time signal
processing" gives a good desription of these effects in fixpoint filters.

What about an analog solution? You're way up in the RF domain.

Good luck,

Christian

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