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| Trying to use frequency counter to read WFM/s from MSO5000. Need help. |
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| ballsystemlord:
I decided to do the recording again using the maximum amount of frames which I repeated 10 times for statistical accuracy. 1/(((3.53492443+3.53492619+3.53495844+3.53494414+3.53491179+3.53492468+3.53495636+3.53493569+3.53493560+3.53494433)/10)/458752) This gives me ~129,776 wfms/s. This is much closer to the counter's value of 164Khz. |
| ballsystemlord:
--- Quote from: Martin72 on September 25, 2024, 08:45:03 pm ---The best way is simply a second oscilloscope. When I wanted to capture the update rate of my MSO5074, I used a counter at home, but it didn't work properly. So I took the Rigol with me to work: https://www.eevblog.com/forum/blog/new-rigol-scope/msg2047141/#msg2047141 Almost 6 years ago again, time flies... --- End quote --- Well, first of all, I was trying to replicate what Dave did with the HD3 which was feeding it it's own trigger signal and then measuring the wfms/s. If it's not possible, I wanted to better understand why not. Second, as I mentioned above, "Unfortunately, I have only one oscilloscope at this time. Although I could go for one of those really cheap handheld scopes from china, I think I'm better off waiting till I could afford better equipment." |
| Sensorcat:
--- Quote from: Martin72 on September 25, 2024, 08:45:03 pm ---The best way is simply a second oscilloscope. --- End quote --- Yes of course, but he said he does not have a 2nd scope. I do not think that it is possible to get similar results from different ways to measure this, because the scope is essentially a computer with a non-real-time operating system. There are background tasks, and whenever the OS decides to do some housekeeping, the waveform rate will be temporarily reduced. So the result depends on the interval that is measured. Since the TRIG OUT signal is actually easy to measure (low output impedance, convenient amplitude, moderate frequency), I do not think that any of a counter, a decent DMM, another DSO will miss in counting the signal. So the rate goes up and down, even when measured with one instrument (verfied with a K2001: max rate results from 490k to 510k WFM/s). You have to decide whether you are interested in the maximum, the minimum, or an average; and which interval should be used to find this value. Regarding the use of the segmented memory method: The main difference between my results and the OP are likely the different settings in the number of segments (1,000 vs. 11), which corresponds to a different gate time in the measurement. When the outliers of the OPs results are removed (= housekeeping disregarded) there is a good match. I am surprised, though, about the results that exceed one second, as this means essentially that the instrument is completely stalled during the measurement. I have never observed such behaviour from my instrument. I have an non-hacked MSO5074, upgraded to 200MHz, with firmware 00.01.03.00.03. |
| Sensorcat:
--- Quote from: ballsystemlord on September 25, 2024, 09:19:01 pm ---I decided to do the recording again using the maximum amount of frames which I repeated 10 times for statistical accuracy. 1/(((3.53492443+3.53492619+3.53495844+3.53494414+3.53491179+3.53492468+3.53495636+3.53493569+3.53493560+3.53494433)/10)/458752) This gives me ~129,776 wfms/s. This is much closer to the counter's value of 164Khz. --- End quote --- As expected, with a much longer 'gate time', the results are much more stable now, all 3.5349... The extreme outliers from your first measurement remain a mystery. |
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