Samsung GPSDO 

So the next project is a Samsung GPSDO I bought from ebay for about $30 + Shipping.
It's quite similar to the Trimble and Symmetricom GPS devices, but also very different.
For now I have it running with good results but that was not so easy, and not Plug&Play.

 

Unlike the buyer would like you to believe, not every unit is usable when plugging it in.

For me the unit did not lock even after have it running for 3 day's in a row, so that was not good.
I did not have the break-out board with the 50pin flat cable with it,and the used SMD devices are to small to attach a wire to it.

So I ordered this board from China. 

 

Now it was easy to attach the serial port to it, and check with the PC what the status is.
       - UCCM Slot STATE -

1-1 #Now UCCM STATUS ----------------------------[Alarm]
1-2 #Before UCCM STATUS -------------------------[OCXO Warm]
2-1 #Reference Clock Operation ------------------[Not Used]
2-2 #Current Reference Type ---------------------[Ext Clock]
2-3 #Current Select Reference -------------------[NOT SELECT][Ext ?]
2-4 #Current Reference Status -------------------[Unavailable]
    #GPS STATUS ---------------------------------[Unavailable]
    #Priority Level -----------------------------[EXT->GPS]
    #ALARM STATUS
    #H/W FAIL -----------------------------------[NONE]
    #OPERATION ALARM ----------------------------[EXTREF]
    PLL STATUS ----------------------------------[Disable]
    Current PLL MODE ----------------------------[OFFSET OBSERVATION MODE]
"Command Complete"
So it as warm, but programmed to use it with an external signal as reference (why?) .

Searching the internet just did not gave me much solutions, but did find out that many other had similar problems. one of the solutions was to use a external programmer to send the needed commands to the board. later more about this solution.


Edit 2020-02-11: I got a message from Jan SM4UKU, with the hint that the board should have a bridge from pin 39 to GND.
In that way you enable the settings for internal GPS reference.

More information also on this very useful website:
 https://time-nuts.febo.narkive.com/Tm2BCk3v/samsung-gpsdo-chinese-surplus  

 

Now for lady Heather, not very high-tech looking program, but useful so we need this.
Google it and you will find version 5.0 from KE5FX, but not working on our device... :-( 

After logging into the EEVBLOG i found out that there is a 6.14 beta version which is available as download (Will put it on my site).
Link: https://www.eevblog.com/forum/metrology/lady-heather-v6-beta-for-windows-exe/

So, now it was useful.:

 

This is my status after running half a day.
My horizon for the GPS satellites starts at about 35-45 degree so there is room for improvement. But we have a lock and the first survey was done and the signal is stabilizing. 
I do have a antenna error, despite the fact there is 5V and about 20mA.

maybe it expects more power drain, I will test this soon.

Updates will follow.