Re: Recommendation for high sample rate receiver?

[Kyeong Su Shin]

To whom it may concern:

It is already well-discussed, but I would like to add a few points:

-If you absolutely want to have a such receiver (it's pretty meaningless, as discussed already, but if you still want to), then you can grab a digital oscilloscope or a similar hardware and attach a RF frontend to it. You will end up losing some (actually, most of) samples, but you cannot run non-trivial data processing chains at 500MS/s in real-time with a generic desktop CPU anyway.

-Regarding on why this is pretty meaningless (not using the Nyquist criterion or maths, but using intuitions): consider two consecutive samples, sampled by your receiver. Since the sampling rate is way higher than the bandwidth of the signal, these values are going to be nearly identical. There could be a bit of differences in the amplitude and the phase, but the differences will be pretty small and will be easily washed out by the noise. You cannot expect to get reliable TDOA results from that. You will have to use more samples to get more reliable results.. or just use a slower receiver, anything that satisfies the Nyquist criterion.

-If you know the structure of the transmitted signal (like PRNs in GPS), and if you are dealing with CDMA-like signals, then maybe you want to review the GPS receiver design principles and apply that to your design. Not sure if that's the case, though..

-Please consider power difference of arrival or phase interferometry as alternative methods.

Regards,

Kyeong Su Shin

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보낸 사람: Qasim Chaudhari <address@hidden> 대신 Discuss-gnuradio <discuss-gnuradio-bounces+ksshin=address@hidden>
보낸 날짜: 2020년 1월 30일 목요일 오전 11:05
받는 사람: address@hidden <address@hidden>; address@hidden <address@hidden>
제목: Re: Recommendation for high sample rate receiver?

 

Hi

   A high sample rate for such ns times of arrival resolution is impractical. Same holds for high SNR and longer times of measurement. GPS and most other high resolution positioning systems stitch the information together from the signal time of arrival with the carrier phase of arrival. Since carrier frequencies are incredibly high, their phase can provide such ns accuracy because the phase information is preserved across the downconversion stages with sufficient linearity. For this purpose, the algorithms also need to determine the integer number of arriving wavelengths.

Cheers,

Qasim