[time-nuts] Lucent KS-24361 REF 0 standalone

Thomas Petig thomas at petig.eu
Mon Feb 6 13:23:23 EST 2017


Hi everyone,
I am currently trying to repeat previous work of members of this list in
convincing the REF 0, to run standalone with a given 1PPS signal from a
gps. Similar to:
https://syncchannel.blogspot.se/2015/08/standalone-operation-of-lucent-ks-24361.html

I am using a skytraq gps with 100ms, 74AC04 for inverting and level
shifting and I added the jumper wires on J5. I simulate the Oncore
messages with a python script using a usb->uart cable and triggering on
the 1PPS pulse on the CTS line. I am sending @@Ea, @@En, @@Bb, @@Ap,
@@Aw, @@Ag, @@At, @@Az, @@Bj, @@Bo with a delay of 75 ms, as suggested
in the blog above:
https://github.com/thpe/oncore/blob/master/oncore_emu.py

Surprisingly, I have a constant delay of 0.8 ms, and only a jitter of
+/-0.1 ms for the oncore messages compared to the pulse on the CTS line.

Short everything is working and if I force external 1PPS usage it locks
to it (NO GPS light goes off). Using pForth:
1 force_ext_1pps
1 force_gps_1pps

But, it does not do it on its own, since it ignores the tracking mode
for the satellites and, I guess after reading the Z3801A manual,
therefore it claims the GPS 1PPS signal as invalid. E.g., for the entry
with @@Ea:
0x02, 0x08, 0xFF, 0x82
meaning satellite 2 in mode 8 (used for positioning) it assumes mode 0.
The other values, like signal strength 0xFF and channel status 0x82 are
taken, even if I change them to something else. The mode value is
ignored no matter what it says.

In the attached files on sees that "GPS 1PPS Invalid: not tracking", and
the mode of the is 0. I forced it to use the external 1PPS signal.

So, the question what tiny detail did I miss while reading the mailing
list archive and those blogs on how to set the REF 0 up for standalone
operation just using the Oncore messages?

Does someone has dump of the communication between REF 1 and
REF 0, until the REF 0 is happy (I don't have a REF 1)?

Regards,
   Thomas
   DK6KD
   SA6CID
-------------- next part --------------
--------------------------- Primary Receiver Status ---------------------------
SYNCHRONIZATION ............................................. [ Outputs Valid ]
SmartClock Mode ___________________________   Reference Outputs _______________
>> Locked to GPS                              TFOM     3             FFOM     0
   Recovery                                   1PPS TI +10.0 ns relative to GPS
   Holdover                                   HOLD THR 1.000 us
   Power-up                                   Holdover Uncertainty ____________
                                              Predict  2.0 us/initial 24 hrs
                                                
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 0 ____   Not Tracking: 10 _______   Time ____________________________
                   PRN  El  Az  PRN  El  Az   GPS      00:09:07     01 Jan 1998
                   * 2  80  16   17  32   5   GPS 1PPS Invalid: not tracking
                   * 4  48  32   18  48   0   ANT DLY  0 ns
                   * 6  64   0                Position ________________________
                   * 8  90   0                MODE     Hold
                   *10  90   1                
                   *12  90   2                LAT      N  23:18:06.080
                   *14  90   3                LON      E   8:59:34.784
                   *16  90   4                HGT                +2.56 m  (GPS)
                   *attempting to track       
HEALTH MONITOR ......................................................... [ OK ]
Self Test: OK    Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
-------------- next part --------------
TIME  0:00:15.000000000 DATE   1/01/1998
LAT  N  23:18:06.080
LON  E   8:59:34.784            VIS SATS   10
HGT (msl)              2.56     TRACK SATS   8
HGT (gps)              2.56     RX STATUS   20
PDOP                    0.0

CHN      SVID      MODE       SS      STATUS
 1         2         0       255        82
 2         4         0       255        82
 3         6         0       255        82
 4         8         0       255        82
 5        10         0       255        82
 6        12         0       255        82
 7        14         0       255        82
 8        16         0       255        82


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