[time-nuts] ...Conexant (Rockwell) Jupiter behaving strangely

jmfranke jmfranke at cox.net
Thu Apr 6 16:25:39 EDT 2006

I have been experimenting with the Jupiter receiver.  Even without the 
backup battery, I can sometimes get a similar problem.  The receiver 
indicates a 3D lock, but the 10 kHz signal is not stabilized for another 45 
seconds.  Without the backup battery, 3D lock can take 15 minutes.  I 
experience the long delay even for a power supply interruption.  I believe 
the receiver has to do a cold search.  Once the 10 kHz is locked and I 
disconnect the antenna, the receiver does not report a loss of lock for 
twenty to thirty seconds.  During this time and for an undetermined time 
later, the 10 kHz signal stays close to 10.000000 kHz.  When I restore the 
antenna, relock takes only seconds and the 10 kHz is quickly relocked with a 
short glitch.  More work will be required to nail down these numbers.  With 
my receiver, the startup 10 kHz frequency is typically 0.030 to 0.070 Hz 
high.  I intend to divide down the 10 kHz output from a Jupiter receiver to 
drive a General Radio model 1103 Synchronometer (1 kHz) and a General Radio 
model 1109 comparison oscilloscope having a circular sweep (10 kHz, 1 kHz, 
and 100 Hz).

John  WA4WDL
Yorktown, VA

----- Original Message ----- 
From: "Normand Martel" <martelno at yahoo.com>
To: <time-nuts at febo.com>
Sent: Tuesday, March 07, 2006 8:44 AM
Subject: [time-nuts] ...Conexant (Rockwell) Jupiter behaving strangely

> Hi...
> I currently use a Conexant (Rockwell) Jupiter GPS
> receiver to calibrate a standalone Oscilloquartz B541
> OXCO as a local frequency standard, and, while being
> less accurate that a professionnal GPS slaved
> frequency standard, it far overmeets my needs.
> The beauty with the Conexant Jupiter is that it
> features a GPS precise 10kPPS (10kHz squarewave)
> signal, which is by far easier to work with than the
> well known 1PPS TIMEMARK found on most GPS receivers.
> My problem with the 10kPPS signal is that it doesn't
> lockup at each time the GPS receiver gets a fix if the
> backup battery is plugged-in. If i remove the backup
> battery, the 10kPPS signal locks-up everytime i cycle
> the receiver's power and get a fix. One more thing:
> The fix is good regardless of the 10kPPS lock
> condition... This screws me up!
> My temporary solution is to use the receiver without
> the battery backup, but this gives me a lenghty TTFF
> problem: The receiver takes a lot more time to get a
> fix if i don't plug-in the battery. Have you worked
> with this receiver and the 10 kPPS signal? Is there a
> way i could get sure this signal locks-up with the GPS
> clocks?
> When the receiver's 10kPPS doesn't lockup, it runs at
> 9998.8365 - 9998.8404 PPS, which is far more away than
> the initial (turn-on) out-of-lock (10000.02PPS)
> condition.
> Thanks for your attention...
> Normand Martel VE2UM
> Montreal, Canada
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