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

Bob Camp kb8tq at n1k.org
Mon Feb 6 15:40:23 EST 2017


The only serial dialog between the two units is a repeat of the output of the
GPS module. My guess is that there is some subtle difference between
the Oncore data and they skytraq….


> On Feb 6, 2017, at 1:23 PM, Thomas Petig <thomas at petig.eu> wrote:
> 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
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