[time-nuts] FE-5680A arrived
smither at c-c-i.com
Thu Jan 12 01:03:11 UTC 2012
Bob Smither wrote:
> I have noticed the the 1pps pulse goes away when I make a large change to the
> offset count through the RS232 connection. The pulse comes back after the unit
> has settled for a while.
More observations. My unit is S/N 0316 61953, UN 63983. If I try to change the
offset count (using RS232) by more than about 131,000 counts (0x20000) at a time
it sometimes loses the 1PPS and the lock signal goes high.
By bringing the offset count up slowly (increments of 0x10000) I recorded the
following drift rates versus offset count:
0 usec / sec at 0
1 usec / sec at 1441792 (0x160000)
2 usec / sec at 2949120 (0x2D0000)
3 usec / sec at 4390912 (0x430000)
4 usec / sec at 5898240 (0x5A0000)
The offset count was incremented in units of 0x10000 (65,536) counts so the
drifts are approximate.
A plot of these results is here:
My unit appears to have an adjustment resolution of about 6.8E-13 / count -
close to what has been reported here before.
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