[time-nuts] Any Spectracom hackers out there?
brooke at pacific.net
Sun Oct 24 14:03:20 EDT 2004
Is the idea to be able to decode the WWVB time signal by using a known
Do you have docs on the 8170?
Brooke Clarke, N6GCE
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
John Ackermann N8UR wrote:
> I'm planning to try some experimental mods on a Spectracom 8170 WWVB
> clock and wonder if anyone out there has done (or considered)
> something similar. Please contact me off-list so we don't bore
> everyone else...
> My hope is to remove the several millisecond jump and consequent long
> recovery time when the receiver momentarily loses lock, which seems to
> happen every couple of days.
> The 8170 phase locks a 10MHz crystal to the WWVB signal, dividing that
> down to 1pps for the on-time signal. It then decodes the WWVB
> timecode, and shifts (delays or advances) the 1pps in 100us steps in a
> slow PLL to stay on the mark.
> My thought is to replace the phaselocked 10MHz signal with an external
> oscillator (in my case, an Rb standard that's monitored against
> LORAN-C) to avoid the bump that happens when the cheap 10MHz crystal
> in the 8170 loses lock and free runs for a few minutes.
> Spectracom had an option to automatically switch to an external
> reference when the WWVB signal was lost, but I'm wondering if it would
> work to use the external clock all the time, since the Rb is kept
> within a few parts in 10e-12 of LORAN (and is also checked against GPS
> every so often).
> Just curious if anyone else has looked into this.
> John N8UR
> jra at febo.com
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> time-nuts at febo.com
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