Electronics > Metrology

Two GPSDO to get more accuracy?

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I now have two different GPSDO units and they agree with each other down to 1mhz.  This is good enough for me.

One is the BG7TBL type Chinese made GPSDO with the 2 line blue LCD screen which I bought about 3 years ago and the other is the Leo Bodnar made unit with the dual output which I have had for about 8 months.  I leave them on 24/7 and as stated previous, they agree with each other down to 1 milli hertz.

I only purchased the Leo Bodnar model for a sanity check and I'm glad I did.  :D

The Leo is also good as the output can be adjusted, it is not just 10Mhz it can be changed in software over a fairly wide range.



--- Quote from: FriedMule on June 15, 2022, 05:17:49 pm ---Long time is fairly precise, down to a few nanoseconds, but my biggest problem is when I am trying to measure a crystal and do not have days or weeks to measure.
How can I let say be more sure a crystal is accurate in 1-2 hours of measurement time?

--- End quote ---

A good GPSDO will be locked to the GPS - i.e. if it has a 10MHz output, it should *on average* produce 10,000,000 cycles per second. However, in any one second it may produce a bit less or a bit more. For argument sake, say it is lagging or leading the average by 2 cycles at the start of an hour, and is lagging or leading or leading by 2 cycles at the end. Then in the hour it has produced 36,000,000,000 cycles ±2 cycles. The maximum error in the number of cycles is 4, so the maximum error is a little more than 1 part in 10^10.

I don't know of any hobby application that would need to determine the accuracy of a standalone oscillator better than this. What did the OP have in mind?


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