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Jerry Avins (@jya)

I've been retired for 17 years. I haven't been active a comp.sdp lately, but I will try to change that. ((I miss the many friends I made.) I worked for 25 years at RCA's David Sarnoff Labs until it closed, and then at a few other places. I retired from Siemens Research.

Re: how to apply Laplace filter value to FFT Nyquist bin?

Reply posted 10 years ago (08/10/2016)
There is an acquisition time. The closer you get to DC or Fs/2, the longer you have to squint at the signal to understand it. The relation is essentially reciprocal,...

Re: how to apply Laplace filter value to FFT Nyquist bin?

Reply posted 10 years ago (08/09/2016)
We often get sloppy about limits when thinking in terms of continuous variables. Remember, we count frequencies with an FFT, we don't measure them as such. Fs/2...

Re: how to apply Laplace filter value to FFT Nyquist bin?

Reply posted 10 years ago (08/08/2016)
"The sampling rate is fixed by the system, which uses the rising and falling edge of a clock signal. It cannot be changed. If the clock signal is 100 MHz,...
Stitching successive frames must account for inevitable* perspective distortion, but deals only with the edges of the frames. NTSC resolution is effectively 640...

Re: Adding 45 degrees phase shift to a FIR bandpass

Reply posted 10 years ago (07/12/2016)
Wolf,In a digital implementation, there is no reason to avoid putting all the phase shift into one of the channels. (Back when we did this with analog circuits,...

Re: A digital filter question

Reply posted 10 years ago (07/04/2016)
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Re: Restorative Upsampling

Reply posted 10 years ago (07/03/2016)
I learned from Einstein to value gedanken experiments. Suppose that a pure 15 KHz signal is sampled at 20 KHz. (I like to keep to round numbers.) Normally, the sampler...

Re: A digital filter question

Reply posted 10 years ago (07/03/2016)
Yes. Rick, I'm the very Jerry you once had a beer with out in California. This isn't a social medium, so I'll keep it short. I'm in reasonably good health. but my...

Re: A digital filter question

Reply posted 10 years ago (07/03/2016)
Sure I have. I first encountered something like it when I was trying to educate myself about analog techniques, back in the 1950s. For now, forget the math. When certain...

Re: IQ frequency shifting (software radio tuning)

Reply posted 10 years ago (06/08/2016)
There is only one subcarrier. That is the AM, suppressed-carrier difference signal. Don't forget the 19 Khz pilot tone that you need to extract and frequency double...

Re: Newbie with questions about decimation for SDR

Reply posted 10 years ago (05/16/2016)
In the spirit of "First make it work, then make it pretty" I'll point out that you needn't actually calculate the samples that you intend to discard.Jerry

Re: IQ frequency shifting (software radio tuning)

Reply posted 10 years ago (05/04/2016)
For FM audio, there is only one subcarrier. (There may be others for ancillary services. Look up SCA) The main signal, that which would be recovered by a simple...

Re: IQ frequency shifting (software radio tuning)

Reply posted 10 years ago (05/04/2016)
Since you already have I and Q, you can do FM demod with the function arctan(Q/I). That's a teaser; you don't want to compute arctan at the sample rate. Rick Lyons...

Re: 90 Degrees Shift of Digital Signal

Reply posted 10 years ago (04/28/2016)
If you do go the Hilbert route, There are some simplifications you should keep in mind.* Use an odd number of FIR taps. That way, you can get the delayed unshifted...

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