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When read keysight 9913A manual,

Minimum signal duration with 100% probability of intercept (POI) at full amplitude accuracy 12 µs Minimum detectable signal 22 ns

What's the Minimum signal duration and Minimum detectable signal duraion of Ettus B210?

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A SDR peripheral like the Ettus USRP B210 continuously digitizes the incoming RF and sends it to the attached computer. There are no gaps in its coverage — anything that is within the bandwidth is captured in full.

If you use one to create a spectrum analyzer, the minimum duration of signal you will be able to observe will be determined by the algorithms used by the software that you use to process the signal; on a spectrum plot (power vs frequency) in particular, the windowing and degree of overlap between successive FFTs of the incoming signal. GNU Radio's “Frequency Sink” is very poor at visualizing short signals, since it does not overlap at all (so a pulse could land at the end of one FFT-window and the beginning of the next, or squarely in the middle of the window, and show up very differently or not at all), unless someone's improved that since the last time I checked.

On the other hand, you could write a program that looked for single samples with significantly higher amplitude, and then analyzed the region before and after it. This would consistently capture arbitrarily short pulse signals (up to the limit where a short pulse cannot be considered to be a narrow-band signal), and since it is analyzing a snapshot, it doesn't have to run in “real time”.

Again: It's all up to the software. That's the point of software-defined radio. Unfortunately, I don't have the math handy to tell you how to quantitatively measure the capabilities of a given sof, but I can assure you that the hardware is irrelevant — every SDR receiver works this way.

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  • $\begingroup$ Can I assume the value is much less than 9913A? $\endgroup$
    – kittygirl
    Sep 2, 2021 at 23:36
  • $\begingroup$ As my computer has only 2 cores with 2.5Ghz,will it become bottleneck when process full captured data from B210? $\endgroup$
    – kittygirl
    Sep 2, 2021 at 23:38
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    $\begingroup$ @kittygirl The value is not “much less” — it does not exist until you choose or write software. I've updated my answer to cover more of the possibilities. I can't give you an answer about particular processor performance other than “try it and see” — not my specialty. You might be interested in trying out gr-fosphor, if you haven't; it's a FFT/spectrum analyzer that uses GPU rather than CPU. $\endgroup$
    – Kevin Reid AG6YO
    Sep 3, 2021 at 0:03
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The bandwidth and thus the impulse response duration of any anti-aliasing filter(s) in front of the ADC affects the minimum duration of a signal that can pass the input filter(s) without (more than some specified amount of) attenuation.

The shorter the pulse of a given shape, the higher it’s spectral frequency content, and thus the less it might be able to pass unattenuated thtu an (anti-alias) filter with a roll off below that spectral frequency content.

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  • $\begingroup$ Even 0.0000000001 second pulse signal,I think it will arrive ADC through anti-aliasing filter..Is that right? $\endgroup$
    – kittygirl
    Feb 3 at 4:46

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