[time-nuts] Lucent KS-24361, curious observation

Hal Murray hmurray at megapathdsl.net
Mon Dec 1 20:22:37 EST 2014


doug at dougronald.com said:
> 2) What is the 5 MHz crystal oscillator locked to? If it the L1 or L2
> carrier - cool, or the PRN code clock - okay, but if it is the 1 PPS - ugh.
> Since the sync signal must go through the jumper cable, I suspect it is the
> 1 PPS. Anyone know, and if it is the 1 PPS, is that as ugly as I believe? 

All the GPS work is done in a small low-cost module, the type typical used in 
consumer gear with a firmware tweak to work in position hold mode.  
Generally, that gear is L1 only, and the only signals that come out of the 
module are a serial port and the PPS signal.

Why do you think the PPS is "ugly"?  It's generally derived from the crystal 
that drives the CPU on the module.  It's normally within 1/2 cycle (10s of 
nano seconds) within the desired time.  Some modules will tell you how far 
off it is - the sawtooth correction.


-- 
These are my opinions.  I hate spam.






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