SNR of a pulse

[zappedagain]

I have a system where I'm receiving pulses and I'd like to quantify the signal to noise ratio for the pulse.

Are there any standards calculations for determining the signal to noise ratio of a pulse? In a CW (continuous wave) system I'll take the ratio of the RMS (root mean square) voltage of the signal and divide it by the noise (also in RMS).

If I do this for a pulse, I have to throw some assumption in for the repetition of the pulse; a pulse with a slower repeition rate will have a lower RMS value than a pulse with a faster repetition rate. That make sense for a continuous time system, but not for an aquisition system with a fixed time window.

For example, i have two systems that measure the pulse. One collects data for 10 times the duration of the pulse and the other system collects data for 40 times the duration of the pulse. They both measure the same pulse, but one reports a RMS value 4x what the other reports.

I could measure the RMS is a fixed window around the pulse to eliminate this variation but that gets a bit too application specific and could introduce error if my fall time slows down. Is there a standard technique that I'm missing?

Another technique would be to divide the rms value by the acquisition window width. That will give me a constant value in Vrms/sec; strange units though and a quick test didn't give me the results I expected...


Can anyone recommend any good books on pulse analysis?

 

[zappedagain]

Thanks IR. Can you recommend any good reference books on radar signal processing?

Z

 

[IRstuff]

Sure, Barton has written a TON of books on radar:

http://www.amazon.com/System-Analys...0675235?ie=UTF8&s=books&qid=1187806986&sr=1-1

I think the following is an update to his original text:

http://www.amazon.com/Modern-System...0675235?ie=UTF8&s=books&qid=1187806986&sr=1-5

TTFN

FAQ731-376

 

[Warpspeed]

I guess one solution to this is to decide by how much the pulse amplitude can be reduced, or the noise floor increased, before whatever this pulse does, stops functioning.

The whole question is so application dependent, that a simple concise answer is not really possible.

But some sort of test specification could probably be devised to give a measurement of "db above not working" threshold that may be a useful yardstick ?

 

[zappedagain]

Warp,

You are correct that this is very application specific. Even in my system we have different applications on how the pulse is processed. Some applications are mainly concerned about the jitter and distortion on the pulse; other applications are more interested in the frequency content of the pulse.

At least now with this 'pulse peak vs. noise peak ratio (PPNPR) I have a tool that I can use to compare the effect of changes in/to the system (if we do that it will cost us x dB).

Z

 

[IRstuff]

Just remember that Pd and Pfa are usually calculated with peak signal and rms noise

TTFN

FAQ731-376

 

[SamuraiMike]

microwaves101.com has a section on spectrum analyzer measurements and that has a section on pulses, though I didn't notice SNR in particular.