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

[Bob Camp]

Hi
> On Dec 1, 2014, at 4:20 PM, Doug Ronald <doug at dougronald.com> wrote:
> 
> 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?

If the light flashes, that’s saying the antenna current is over / under the limit the box is looking for. 

> 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. 

The 1 pps out of the GPS module is what they lock to . There is a lot of information in the archives explicating why Doppler on L1 or L2 make direct carrier lock less useful. 

> Anyone know, and if it is the 1 PPS, is that as ugly as I believe?

The PPS is s differential output. Run into a proper receiver it looks pretty good to me.

Bob

> 
> -Doug Ronald
> 
> -----Original Message-----
> 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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