[time-nuts] Re: Seeking info on Ericsson NCD 901 56/1 devices

[Peter Bell]

I've been playing with some of the GPS 03 01 modules and here's a quick
hack to get them working with
Lady Heather.

Unfortunately, it does require opening the module up and some soldering,
but it's not very complex.  Start by
removing the 33R series termination resistor on pin 42 of the STM32F105,
then solder a wire between the pad
for the far end of the resistor (I.E. the one not connected to the STM32)
and pin 17 on the Trimble module.

This results in RJ11 port #1 operating as before (I.E. Ericsson flavored
NMEA), but RJ11 port #2 now outputs
TSIP at 38400 baud.  The downside is you have no control over the receiver
, since it's still being driven by the
STM32.



On Wed, Aug 17, 2022 at 8:03 PM Bill Notfaded via time-nuts <
time-nuts at lists.febo.com> wrote:

> If we could figure out the protocol Lady Heather could be configured to
> work with it.  That would be neat.  I found some ATT documentation showing
> a picture of multiple (maybe 8-10) of these mounted in the bottom of the
> rack all getting GNSS signal off a splitter connected to one antenna and
> each unit fed to different ground base station radios.  I tried searching
> but Ericson seems to really hide it's documentation.  Some of the few
> references were companies charging for training classes and test quizzes
> for techs studying to work on base stations.  Ericson has a website with
> all the docs behind a customer/technician login... reminds me of how
> Symmetricom always was.
>
> Bill E.
>
> On Tue, Aug 16, 2022, 1:55 PM John Miller via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> > My units came in yesterday and I have had good luck with them, so far.
> > Very fast lock.
> > Interfacing with them is easy enough. The pinout on the osmocom site is
> > correct indeed,
> > and RS422<->UART devices are actually not required - the voltage levels
> > are 3v3, so
> > standard USB-UART devices connected to the "+" sides of Rx and Tx work
> > just fine.
> >
> > If you connect a standard T-568B ethernet cable to the jack, the pinout
> is:
> >
> > (2) Solid Orange - PPS
> > (4) Solid Blue - Tx (Data from GPS)
> > (6) Solid Green - Rx (Data to GPS)
> > (7) Brown White - 12v
> > (8) Solid Brown - GND
> >
> > Each RJ45 connector outputs identical signals and has identical pinouts.
> >
> > The default UART data is sent 9600 baud, 8n1. The data sent is a curious
> > Ericsson
> > protocol, and I have not been able to find complete documentation on it
> as
> > of yet.
> > I believe that the document that may contain the specs for this protocol
> > is titled
> > "IWD L2 L3 GPS Digital Interface" but I have not been able to find
> > reference to it other
> > than in a thesis written in 2012.
> >
> > Every second, two sentences are sent. $PERC,GPsts which is alleged to be
> > the GPS
> > status, specifically if it's in acquisition mode, surveying,
> > position-hold, or surveyed in. I have
> > had one unit running for over 12 hours continuously and it has not left
> > "position-hold"
> > mode. The second sentence sent is $PERC,GPppr, a "periodic PPS report"
> > which
> > includes GPS TOW, GPS Week, number of satellites used to compute the fix,
> > and
> > maybe more - the documentation is incomplete.
> >
> > Every 60 seconds it sends a handful of standard NMEA sentences: GNGSA,
> > GPGSA,
> > GLGSA, GPLSV, GPGSV, and GPGGA. A few other Ericsson PERC sentences are
> > sent as well. an "averaged position" sentence, and a sentence with date &
> > time.
> >
> > I don't yet know if there are any commands we can send to the unit to
> > enable it to
> > begin a survey or alter the strings transmitted. I imagine that there are
> > but we need
> > to get our hands on the protocol documentation first.
> >
> > At this point, my suspicion is that to get the best value for money out
> of
> > these things,
> > one should tap the UART & PPS signals directly off of the RES SMT 360
> > module itself and
> > bypass the SMT32 entirely.
> >
> >
> > Regards,
> > John
> > KC1QLN
> >
> >
> >
> > > On Aug 15, 2022, at 8:53:16 PM, Peter Bell via time-nuts <
> > time-nuts at lists.febo.com> wrote:
> > >
> > >  There is also another version of these Ericsson GPS receivers floating
> > > around - this one is marked "GRU 04 01" - physical construction is very
> > > similar, but this one appears to be manufactured by Trimble.
> > >
> > >
> > >
> > > Operationally, it's almost identical to the GPS 0301 described earlier,
> > and
> > > produces mostly the same output, except that it has an extra
> > > $PERC,GPpps sentence that the earlier model didn't.  From the look of
> the
> > > board, it's using the same (or very similar) GPS module, but
> > > with modified internal firmware so that it directly outputs the
> Ericsson
> > > messages rather than having to have the STM32 to translate the output.
> > >
> > > https://i.ibb.co/VmSLFSP/IMG-3625.jpg
> > > https://i.ibb.co/gg86jQw/IMG-3626.jpg
> > > https://i.ibb.co/7R1TBR0/IMG-3627.jpg
> > >
> > > From a hackability point of view, the GPS 0301 looks like a better bet.
> > >
> > > Regards,
> > >
> > > Pete Bell
> > >
> > >
> > > On Wed, Aug 10, 2022 at 9:39 AM John Miller via time-nuts <
> > > time-nuts at lists.febo.com> wrote:
> > >
> > >> Hey all,
> > >> Does anyone know anything about these "Ericsson NCD 901 56/1 GPS 03
> 01"
> > >> devices? They are all over ebay and are fairly cheap.
> > >>
> > >> https://www.ebay.com/itm/185337146688
> > >>
> > >> https://www.ebay.com/itm/294113323964
> > >>
> > >> https://www.ebay.com/itm/194342806640
> > >>
> > >> They have one SMA connector and two RJ45, probably RS485? I haven't
> been
> > >> able to unearth any documentation on them at all. A few pictures of
> > boxes
> > >> suggests they were made in 2016-2017 in Poland.
> > >>
> > >> Any insights?
> > >>
> > >> Thanks!
> > >> John
> > >> KC1QLN
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