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.

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,...
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...
"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 4 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 4 years ago (07/04/2016)
...

Re: Restorative Upsampling

Reply posted 4 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 4 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 4 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 4 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 4 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 4 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 4 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 4 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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