[time-nuts] Low-Cost Rubidium Performance
lists at rtty.us
Thu Feb 9 11:58:27 UTC 2012
Past 100 seconds I have seen some FE's that look better than your LPRO plot and some FE's that look worse than your FE plots. Running in a +/- 2C room apparently is not the best way to operate them for good long tau performance.
On Feb 8, 2012, at 9:36 PM, John Ackermann N8UR wrote:
> As threatened, I've measured stability (out to a trustworthy 10K seconds) and phase noise of the three popular telecom surplus Rb standards. I looked at two units of the FE-5680, two units of the Efratom FRS, and one Datum LPRO. (I have two more LPROs but don't have the mating connector on hand, and didn't want to solder on all three.)
> The Cliff Notes version:
> * The units had similar short term stability from 1 to 100 seconds.
> * Above 100 seconds, the LPRO was the clear winner. The FE and FRS split, with one of each being the worst two.
> * The FE-5680 phase noise loses big-time, both in noise floor and in the quantity and amplitude of spurs. That DDS comes with a price.
> * The LPRO has the best phase noise floor and cleanest spectrum.
> Pretty plots and the underlying data are at
> Important note: there's known to be a lot of variability among these units, so my sample size of one or two each isn't a guarantee that your unit will perform similarly.
> Next step is to do some longer-term stability measurements (out to 100K seconds). You may see that data in a month or so.
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