2004 Motorola Oncore M12+ timing GPS receiver - setup problem

[JBeale]

Is anyone familiar with the Oncore M12?

I have an Motorola Oncore M12+ timing GPS receiver board I got from ebay, and a 3V external antenna with MMCX connector.
I built an interface board with linear regulator to provide +3.0V to the board and antenna, and convert the board's TTL serial to USB.
I downloaded Motorola WinOncore12 v1.2 from http://www.synergy-gps.com/index.php?option=com_content&task=view&id=163&Itemid=115 and used the "Setup Receiver" wizard to start at my known GPS location and current UTC time. The antenna is up on the roof with a clear sky view. The "receiver ID" button tells me this:

Code: [Select]

COPYRIGHT 1991-2004 MOTOROLA INC.
SFTW P/N #     61-G10268A 
SOFTWARE VER # 2          
SOFTWARE REV # 0.1        
SOFTWARE DATE  JUN 09 2004
MODEL #    P273T12T18     
HWDR P/N # 2              
SERIAL #   P0BQE7         
MANUFACTUR DATE 4M21     

I know the M12+ receiver is seeing satellites, as the "Azimuth & Elevation Window" "Satellite Info" tab shows "Visible Satellites: 10" and lists ten PRNs with slowly changing Doppler, Azimuth, Elevation values for each, and "Status OK". However "C/No" is 00 for all of them.  In the "Azimuth and Elevation" tab I see the satellite positions and green trails behind them. In "Navigation Window" I see "Receiver Status  12 Channel (6004) Acquiring Satellites  Antenna Sense: Under Current". The self-test button shows everything OK except for the antenna undercurrent.

The board has no backup battery and this was a cold start. I assume it takes about half an hour to download the almanac & ephemeris from a cold start. However it's been running for more than an hour with no position fixes yet, even though there should be no signal level problems in this location (other GPS units have had no trouble here). Is there anything obvious I'm doing wrong?

[JBeale]

Got it working. I misunderstood "satellites visible" to mean that the receiver was receiving signals from satellites, but just didn't know the exact orbits yet. That seems to be incorrect; apparently it just means that the satellites "should" be visible based on the rough coordinates and time of day that I entered, but implies nothing about actual signal reception. Apparently it really wasn't getting any signals at all. I changed to a different antenna, and it immediately saw a few satellites and acquired a 3D lock after a few minutes.