Kaiser,
I can give you estimate numbers for configuration switch times for I/Q streaming and segmented I/Q for the SM200B.
– I/Q streaming reconfiguration times are going to be between 15-60ms (which includes a small I/Q acquisition at each configuration) depending on decimation (longer for higher sample rates) and the I/Q queue size (see smSetIQUSBQueueSize). I achieve 15ms switch times with decimation 8 (bandwidth = 5MHz) and queue size of 5ms, and 60ms with decimation 1 (bandwidth = 40MHz) and default queue size (41ms). Smaller queue sizes are less resistant to USB data loss, but for short acquisitions, this is probably not a problem.
– Segmented I/Q reconfiguration times are ~20ms (which includes a small acquisition at each configuration). Segmented I/Q captures are limited to 160MHz bandwidth, so if you are trying to reduce noise and measure specific signals, you will need to further tune, filter, and decimate the I/Q data.
I’m not entirely sure I understand the noise issues you are having. If the SNR is low, and you need to know amplitude variation over short time intervals, consider decreasing ref level to -20 or below (if you haven’t already), performing I/Q streaming using a bandwidth that only includes your signal of interest, and performing overlapping FFTs with very high overlap rates. This can get you microsecond level resolution on your spectrums. You can play with this idea in our Spike software in zero-span mode with the waterfall plot.
If you just need to know the power of these signals over time, and SNR is low, you could measure channel power from the sweeps (which would help with noisy signals), or use I/Q and do an AM vs Time approach, and calculate power over a duration of time domain samples.
Some customers use a search/handoff approach. One receiver scanning and another measuring signals of interest reported by the search receiver. This way there is no blind time on the search receiver.
I hope you get some other feedback.
Regards,
Andrew