[time-nuts] Lucent KS-24361, curious observation
doug at dougronald.com
Mon Dec 1 16:20:44 EST 2014
I have also received mine, and powered them with my GPS antenna indoors. After a 20 minute wait, I had full lock, and proceeded to compare the 15 MHz to WWVB. I saw a 20 degree shift in 4 hours which was pretty linear. I don't know if that is WWVB's propagation variation, or the Lucent "warming-up", but I'm a happy camper as I have never had a decent reference here before. I have not yet tapped into the diagnostic information available on the "Diagnostic" port.
I have a couple questions which someone may have an answer for:
1) Every once-in-a-while, REF-1's "NO GPS" LED will flash. It flashes twice, three times, or four times, then back to extinguished for a long time. Anyone also see that on theirs, and what might the unit be trying to tell me?
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?
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Paul
Sent: Monday, December 01, 2014 8:48 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent KS-24361, curious observation
On Mon, Dec 1, 2014 at 11:15 AM, Graham <planophore at aei.ca> wrote:
> It has been less than 18 hours since I powered them up so I am not yet
> wondering why the the REF-0 LED's are in the state they are as I have
> seen reports of others having to wait 24 hours or so before every "locks in".
There are differing states. My pair went OK+Standby in about 10 minutes but they're not "stable" at that point.
Here's a log snippet:
Log 019:20141128.00:00:00: Power on
Log 020:20141128.00:00:26: Power settings ok, Int: 17 dBm, Ext: 17 dBm Log 021:20141128.00:52:21: Position hold mode started Log 022:20141128.01:28:32: GPS reference valid at 20141128.20:34:00 Log 023:20141128.20:35:04: Locked mode entered Log 024:20141129.10:35:03: Ready for 4 hour flywheel Log 025:20141129.16:35:03: Ready for 8 hour flywheel
The first timestamp after power-on is 00:00 of the last valid date prior to power-off. I assume the deltas are correct. So 1:29 to Locked and 20 more hours to "stable". Holdover uncertainty continues to decrease for many more hours. It decreased from hundreds of microseconds to 3 at the time of that log and is now at 900 nanoseconds.
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