I stuck some old 12 V 7 A·h batteries in my homebrew power supply for the HP 3801A GPS Time / Frequency Standard, fired it up, put the antenna where it could see a good chunk of the sky, gave it a day to warm up / settle out, and it’s perfectly happy:
------------------------------- Receiver Status -------------------------------
SYNCHRONIZATION ............................................. [ Outputs Valid ]
SmartClock Mode ___________________________ Reference Outputs _______________
>> Locked to GPS TFOM 3 FFOM 0
Recovery 1PPS TI -38.3 ns relative to GPS
Holdover HOLD THR 1.000 us
Power-up Holdover Uncertainty ____________
Predict 366.2 us/initial 24 hrs
ACQUISITION ............................................ [ GPS 1PPS CLK Valid ]
Satellite Status __________________________ Time _____ +1 leap second pending
Tracking: 4 Not Tracking: 6 UTC 18:22:19 22 Jul 2016
PRN El Az SS PRN El Az 1PPS CLK Synchronized to UTC
3 34 104 48 * 1 36 48 ANT DLY 0 ns
17 62 308 103 6 27 220 Position ________________________
19 39 281 50 11 21 58 MODE Hold
28 80 133 64 *22 Acq .
24 12 319 LAT N 41:39:32.328
30 15 191 LON W 73:52:26.733
ELEV MASK 10 deg *attempting to track HGT +82.87 m (MSL)
HEALTH MONITOR ......................................................... [ OK ]
Self Test: OK Int Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK
scpi >
The FFOM 0 entry says the Frequency Figure Of Merit is “within specifications” of 10-9, averaged over one day. That means the actual frequency should be within 0.010 Hz of 10 MHz.
Feeding the 10 MHz frequency reference into the (equally warmed up) HP 8591E spectrum analyzer and selecting an absurdly narrow span produces a comforting sight:
Given the horizontal resolution, that’s dead on 10 MHz.
So, yeah, that signal at 57-ish kHz really isn’t at 60.000 kHz:
Which is good to know …
