Newbie question on SYMMETRICOM GPSDO 090-03861-03 #W561002488

[dl2sba]

Hi forum

I have a question regarding the SYMMETRICOM GPSDO. I bought one from ebay (http://r.ebay.com/bhR8rN) and have some questions, maybe someone can help me - I'm completely new to this topic.

The LOCK led flashes with about 2 Hz – this is the signal for full operational DO locked to GPS – right?

On the control panel unit I can see the values for HDOP, VDOP and PDOP - I cannot realy interpret these values correctly?!

• HDOP and VDOP where in range from 1 to 3 after the first powering up at my location.
• HDOP and VDOP are now since one day 0.0.
• PDOP is now more or less around 0.3 … 0, even when only one satellite is in view.
• During the first day, the HDOP, VDOP und PDOP values where dependent on the number of satellites and the LED right to the LCD lit up, when a PDOP value was display (> 4 satellites)
• The LED never lit up again, after the HDOP, VDOP values where 0.0 even with 5 or more satellites. Is this behavior (LED, 0 HDOP/VDOP values) correct?

This is the output of posstatus - here even the PDOP is displayed as 0.0 - bug?

UCCM-P > posstatus
-----------------------------------------------------------------------------
7/23/2016 10:50:22
-----------------------------------------------------------------------------
 Position : LAT(N 48:40:27.288) LON(E 9:14:31.206) H(361.60 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 9
   num of sats tracked > 5
   ------ Receiver Channel State ------
     CH 0 >  SateID(5) TrackMode(pos avail) SigValue(40)
     CH 1 >  SateID(14) TrackMode(pos avail) SigValue(33)
     CH 2 >  SateID(21) TrackMode(pos avail) SigValue(34)
     CH 3 >  SateID(25) TrackMode(pos avail) SigValue(42)
     CH 4 >  SateID(29) TrackMode(pos avail) SigValue(37)
     CH 5 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(2) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5647 mV,  Antenna Current: 24 mA
-----------------------------------------------------------------------------


Sorry for my dumb questions, but I didn't find anything in the forum on this topic.


73

Dietmar, DL2SBA

[SoundTech-LG]

According to the ebay listing, your "made with" Symmetricom GPSDO has a manual available by email request. Maybe a good place to start... how good/what/where is your antenna???

[Nuno_pt]

That look like another of the BG7??? GPSDO's.

You've here some topics about the SYMMETRICOM units inside, just search them.

For the meaning of HDOP/PDO/VDOP just search the web, HDOP GPS, you'll see it's definition.

[dl2sba]

Thanks a lot for the replies!

In the meantime I found the following behaviour:

The LED seems to show a 3D fix when the GPS is not in position HOLD mode.
After the survey is complete, the GPS switches to HOLD mode and the LED no more lights up.
When the GPS is in HOLD mode, only PDOP is shown. HDOP and VDOP then are zero.
The HOLD mode is retained even only one satellite is in view.