Discussion:
Tbolt temperature sensitivity.
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John Green
2018-04-08 12:30:07 UTC
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I don't use what LH says about temperature. I compare the 10 MHz output to
something else. With two Tbolts sitting about 2 feet apart on my bench,
both fed from the same antenna, both with factory settings, when the heat
kicks on, I see a change in the difference between the two. Comparing a
Tbolt to another, different GPSDO, the effect is even greater. Next step is
to compare the Tbolt to a rubidium source that has been adjusted to match
the Tbolt as closely as possible at a stable temperature. I suppose you
could say the the Tbolt stays *locked* to GPS since the difference never
gets to 100 nS, meaning they are always within 1 Hz. What I usually see
when comparing the Tbolt to another, different model GPSDO is that the time
difference between the two 10 MHz signals slips at a fairly constant rate,
going from zero past 100 nS, and then through zero, over and over. I also
tried comparing the 1 PPS and the time jumped around quite a bit. Since I
plan to actually use 10 MHz instead of 1 PPS, I decided to quit looking at
1 PPS.
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Bob kb8tq
2018-04-08 14:53:51 UTC
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Hi

Back a while, I ran a fleet of TBolt’s and other GPSDO’s for quite a while.
They all ran into HP counters to monitor the PPS outputs. I never saw
any of them hit or slip at the 100 ns level. Indeed different GPSDO
firmware does the time / frequency tradeoff differently. I’ve also run them
against various Cs standards. The results there were pretty much the same.

None of the environments I was running in were very crazy. They all held a
couple degrees C and the cycles were in the one hour-ish range.

Bob
Post by John Green
I don't use what LH says about temperature. I compare the 10 MHz output to
something else. With two Tbolts sitting about 2 feet apart on my bench,
both fed from the same antenna, both with factory settings, when the heat
kicks on, I see a change in the difference between the two. Comparing a
Tbolt to another, different GPSDO, the effect is even greater. Next step is
to compare the Tbolt to a rubidium source that has been adjusted to match
the Tbolt as closely as possible at a stable temperature. I suppose you
could say the the Tbolt stays *locked* to GPS since the difference never
gets to 100 nS, meaning they are always within 1 Hz. What I usually see
when comparing the Tbolt to another, different model GPSDO is that the time
difference between the two 10 MHz signals slips at a fairly constant rate,
going from zero past 100 nS, and then through zero, over and over. I also
tried comparing the 1 PPS and the time jumped around quite a bit. Since I
plan to actually use 10 MHz instead of 1 PPS, I decided to quit looking at
1 PPS.
_______________________________________________
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- time-***@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

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