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Measuring Burst Frequency

Posted: May 28th, 2020, 3:33 am
by c3mdc1
Hello,

I am generating a sine wave burst. The carrier frequency of the burst is around 10kHz and it runs for 10 cycles. There is then no signal until the next burst is generated. The frequency of the bursts is 50Hz.

How do I accurately measure the carrier frequency (10kHz) and the burst frequency (50Hz). Since it is not a continuous sine wave I have been using cursors which is not accurate.

I am using an MSO 2024B

Thanks

Re: Measuring Burst Frequency

Posted: May 28th, 2020, 5:52 am
by w2aew
Setup the scope with the Trigger Mode set to Normal, adjust the Holdoff to 10ms. This will ensure that the scope triggers on the beginning of the 10-cycle 10kHz burst.

Set the scope to 200us/div and adjust the horizontal position so that you see your complete burst.

To measure the 10kHz carrier - turn on the Frequency measurement, and then add Gating to the measurement. Use Gating with Cursors, and move the cursors to within just within the burst. Now you'll get an automatic measurement of your carrier frequency.

Re: Measuring Burst Frequency

Posted: May 28th, 2020, 9:38 am
by c3mdc1
Thanks,

This is getting close. It seems like the frequency (the 10kHz) bounces around depending where I put the cursors even though it is contained within the waveform. Maybe noise or jitter in the signal. Is there a way to smooth the measurement?

Let me know if there is a way to capture the waveform to share it if that helps.


Thanks

Craig

Re: Measuring Burst Frequency

Posted: May 28th, 2020, 9:44 am
by w2aew
You can turn on averaging in the Acquire menu, that will help. Also, make sure that the sample rate is sufficiently high (increase record length if necessary under the Acquire menu). Also, make sure the peak-peak of the signal occupies 80% or more of the vertical display.