Hi > On Aug 6, 2015, at 1:43 PM, Jim Lux <[email protected]> wrote: > > On 8/5/15 8:27 PM, Donald wrote: >> On 8/5/2015 7:55 PM, Bob Camp wrote: >>> Hi >>> >>> Analog Devices has some very nice ADC’s that are directly targeted at >>> doing this general sort of thing. They do not have any “odd” filtering >>> approach >>> that creates issues. Some of the early 192 KHz audio parts did not do >>> very well >>> past 1/4 the clock rate. >> What type of FFT horse power would be needed at 192 Khz ? >> > > not very much.. > > It's a fairly narrow band signal, It might be more computationally efficient > to do a Bandpass FIR and decimate.
If you have an FPGA to do the “lots of bits” add(s), a higher order decimator followed by a filter probably will do just fine. With some care you can get a few hundred db of filtering that way (math wise). Even without much thought, you can get past 150 db. You likely will hit IMD issues on your ADC *long* before that. The decimator (which is computationally simple) does all the high speed heavy lifting. The filter(s) run(s) at a much slower rate so it’s not terribly MIPS intensive. Bob > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
