[time-nuts] tyco electronics A1025

[Brian Inglis]

On 2014-12-14 10:29, Francesco Messineo wrote:
> On Sun, Dec 14, 2014 at 6:12 PM, Bob Camp <kb8tq at n1k.org> wrote:
>>> that's not meant as a "time nut" stratum 1.
>>> It's just a free gps module I would like to recycle as a needed
>>> stratum 1 server for a small network.
>>> Of course if I can find informations on it.
>>> I know there're better options, but in this case anything would do.
>>
>> … and NTP is not a GPSDO or a Cs replacement.
>>
>> My guess is that there is no PPS out of the device. It would be very unusual if there was. Finding the NEMA output pin should be possible with an oscilloscope. At that point, a simple serial connection to the server is about all you need. Bring up the NEMA driver and it is running. It is unlikely that any further optimization would be possible, even with the (maybe) 290 page data sheet on the part. I would not let the lack of a data sheet stop you in this case. Hook up the output to a PC with a terminal program and see what you get. The main problem would be if you need to find the serial input pin to change what it puts out, hopefully you do not.

> The A1029, which is a newer model, has indeed a PPS output and I've
> been able to find a datasheet for it but the pinout isn't anything
> like the A1025.
> I planned to reverse engineer the pinout, but I'd like at least not to
> be forced to try to guess the power pins. Maybe someone still has the
> data for this older module.

One article mentions the A1029 as a drop in replacement for the A1025,
as an early auto receiver with gyro and dead reckoning nav "holdover",
but that may refer to the complete module, and you may have just the GPS.

The GPS could have provided PPS for DR nav, and some TE model specs offer
TCXOs, which may also have been required for DR timing holdover, but may
not have been part of the GPS.

Those GPS seem to have been standard STMicroelectronics parts with firmware
customization for functions and additions, and offered proprietary $PSTM
NMEA sentences. If you can read off the STM part STA 2... (perhaps under
a patch antenna) you may be able to search for more details.

-- 
Take care. Thanks, Brian Inglis