Measuring low frequencies with PicoScope/multimetre

Thread Starter

Jack Tranckle

Joined Jan 20, 2016
73
I have measured the frequency of a music synthesiser at different notes but seems to get slight error that the lower frequencies. the PicoScope seemed to take a while to settle to frequencies below 80Hz and sometimes crashed. is the picocope giving accurate readings at this low frequency? would a multimeter be better and measuring at lower frequencies ?
 

danadak

Joined Mar 10, 2018
4,057
What model Picoscope do you have ?

What does the manual say lower limit on freq counter is, if any ?

Regards, Dana.
 

Hymie

Joined Mar 30, 2018
1,091
Besides checking the instrument specification (as danadak says), in my experience audio signals (with their inherent harmonic content) can easily fool a frequency measurement.

If the picoscope is displaying the waveform, you could measure the period and check that it is displaying the correct frequency value.

Be aware that when using a scope to measure a waveform frequency, changing the time-base can alter the result – you need to ensure that the sweep rate is appropriate for the waveform to get a valid result.
 

Hymie

Joined Mar 30, 2018
1,091
One other piece of advice, make sure that you have a stable waveform displayed (triggering reliably); since you are only interested in frequency (and not voltages) try both ac and dc coupling of the signal, which may make a difference.
 

Janis59

Joined Aug 21, 2017
1,482
My picoscope is 6404C what is rather rich-endian. I never cached anything similar, but always I had been interested in rather high not low frequencies.
Thus, probably cheaper models may lie? Because generally, as more to give it time `to breath` as more exact ought be reading. If Your case says contrary, then SOMETHING may had went wrong.

By the way, try to use a time interval reading instead. Or use the ordinary frequency meter....
However, if the aim was musical instrument adjusting, may be warned that there exists a plenty of different note scales, the electronic, the absolute, the ralative, the string etc etc And all them diifers with +/- dozen of Hz.
And last idea, install the PC Zeitnitz scope, where You can use the built-in generator. To cach a interference betwen two frequencies You may with some few Hz exactness. And if generator is same exact as PC quartz, then such measurement will be rather precize.
 
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