Measure LFXO precisely

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Measure LFXO precisely

Post by Anped » Fri Nov 17, 2017 8:36 am


I have a real time LFXO running at 32768 Hz. The specification is +/- 20 ppm tolerance which means the real frequency must be between 32767.34464 Hz and 32768.65536 Hz.
My problem is that the oscilloscope measurement program only gives me 4 digits where I need at least 6 digits.
Is there a way to get more digits out of the scope software?
I use a 5444B and I have a probe on an GPIO pin that shifts based on the crystal.
Next question, is the 5444B time stable enough to give me the precision I need?
BR Anped

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Re: Measure LFXO precisely

Post by alan » Sat Nov 18, 2017 7:43 am

Hi. As you have a PicoScope 5000 you have access to the DeepMeasure feature in the lastest software. This will give higher resolution / more digits for your frequency measurement. ... eepmeasure

Your PicoScope 5444B has a timebase accuracy of ±2 ppm (±1 ppm/year) so is an order of magnitude better than the crystal oscillator you are measuring.

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