| Products > Test Equipment |
| Bode Plot Computational Time for various DSOs |
| << < (7/10) > >> |
| BillyO:
--- Quote from: Someone on November 08, 2022, 01:35:28 am ---from people wanting to promote XXX brand and say YYY brand is no good by picking their favourite corner case --- End quote --- Of course! BTW, the best brand is the one I have. |
| Someone:
--- Quote from: 2N3055 on November 08, 2022, 01:20:59 am ---When at 100Hz, one period is 10ms. You need many of those for calculations.. 60 points in 9 seconds from 100Hz to 100kHz, not very likely.. --- End quote --- 61 points log spaced from 100Hz to 100kHz would need just under 100ms to capture a single cycle of each, of course with zero noise suppression. Compare to a chirp that could squeeze a flat (or shaped) 100-100k Hz spectrum into a single 10ms period, less energy so even more noise sensitive. This thread is not contributing much as the runtime of the measurement is presented without knowing how much of that time was actually spent capturing data, not comparable at all. Back to the numbers I do know, getting the measurements (not the raw data) to plot this sort of thing under the conditions here: https://www.eevblog.com/forum/testgear/faster-fra-from-scope-by-external-control-over-visa/ The actual data captured was less than 1% of the total time spent from pressing start to seeing the result, you can increase the averaging/noise rejection amount and barely affect the total run time. Offloading data captures for FFT or other frequency selective filtering can become more time efficient, entirely dependent on the specific measurement conditions/noise present. But to get those sorts of numbers people need to reverse engineer exactly what these onboard bode/FRA measurement tools are doing. |
| Someone:
--- Quote from: nctnico on November 08, 2022, 01:35:20 am --- --- Quote from: 2N3055 on November 08, 2022, 01:20:59 am ---When at 100Hz, one period is 10ms. You need many of those for calculations.. 60 points in 9 seconds from 100Hz to 100kHz, not very likely.. --- End quote --- A real network analyser does the same sweep in less than a second. The same network as used in the 'torture test' thread measured using an Anritsu MS4630B: --- End quote --- Gee, how much more confusion and distraction do you want to add to this thread? That's a sweep with 21 points (not 61 as compared to the other examples) and a RBW of 30Hz, how long was the actual capture? and sweep time? since they arent shown on the plot or mentioned by you. Log sweep? non-constant RBW? plenty of tricks to pull to make your one sided and misleading claims. |
| gf:
--- Quote from: Someone on November 08, 2022, 02:07:48 am ---61 points log spaced from 100Hz to 100kHz would need just under 100ms to capture a single cycle of each, of course with zero noise suppression. --- End quote --- Not with zero noise suppression. At 2GSa/s the processing gain at 100Hz can be up to 70dB, and at 100kHz up to 40dB, if one cycle is captured. |
| Someone:
--- Quote from: gf on November 08, 2022, 06:34:09 am --- --- Quote from: Someone on November 08, 2022, 02:07:48 am ---61 points log spaced from 100Hz to 100kHz would need just under 100ms to capture a single cycle of each, of course with zero noise suppression. --- End quote --- Not with zero noise suppression. At 2GSa/s the processing gain at 100Hz can be up to 70dB, and at 100kHz up to 40dB, if one cycle is captured. --- End quote --- in-band noise suppression is guaranteed to be zero for a single cycle capture. Yet some scopes are using nothing more than the cursor measurements, so even out of band suppression can be zero for a single capture! GSa/s have nothing to do with it, any frequency selective suppression is relative to the steepness of the filter + settling (and therefore total period of capture). It is an absolute constraint, more filtering and noise rejection requires more periods captured (one way or another). |
| Navigation |
| Message Index |
| Next page |
| Previous page |