No PRAVE messages received

So, you set up RavTrack PC and connected your base station to the computer running RavTrack PC.  And yet, nothing is happening. This article describes some common solutions to communication problems in a RavTrack GPS tracking system.

Connection/COM port issues

When the system is running, select View > Communication Statistics from the main screen.  This will show you how the various RavTrack PC communication channels are operating.  In the second column of the communication statistics is a message counter with two numbers AAA/BBB.  AAA is the number of NMEA messages from the local radio connected to RavTrack PC.  BBB is the number of PRAVE messages that came into RavTrack PC through this channel.  A PRAVE message occurs whenever the “base” radio receiver connected to RavTrack receives a GPS position report over-the-air.

If the message counter shows 0/0, then there is no communication with the base radio.  This is probably due to on of the following things, and will have to be remedied:

  1. The Base radio is off.
  2. The base radio is not connected to the PC running RavTrack PC.
  3. The COM port that the base radio is plugged into is not configured correctly (Program Properties > Congure I/O to repair it).
  4. The cable connecting the base to the PC is bad, or is a “Null modem”. For most computers, the connection will be a USB or a 9-pin serial cable wired 1:1.
  5. The COM port that the base is connected to is in use by another software program.

No Over-the-Air Reception

If the message counter in the Communication Statistics window shows  NNN/0 where NNN is some non-zero number, and the second number is 0, this means the base radio is communicating with RavTrack PC sending NMEA messages, but nothing is being received over the air.   The COM port and cables are fine, but there is a problem receiving the over-the-air messages.  The most common problems that will cause this and need to be corrected are:

  1. No antenna is connected to the base radio.
  2. The base antenna cable or connector is broken.
  3. The KEYPHRASE is not set.  The KEYPHRASE encryption code must be the same in all radios.  The factory default KEYPHRASE is “RAVEON”.
  4. The base receiver is not set to the correct frequency. Note: the base’s STAT LED will blink green each time it receives a message from a GPS transponder.
  5. The TOID (ATDT) in the mobile transponders are not set to the base station’s ID.  Note: you can set the base station address mask to ATMK 0000 to receive all messages regardless of TOID.
  6. The mobile transponders are not transmitting.  Reasons for them not transmitting may be:
    A. No power to the transponder.
    B. No GPS satellite lock.  The transponder’s GPS antenna must be able to see the sky.
    C. The transmit frequency is incorrect.
    D. The KEYPHRASE is wrong.
    E. Their antenna or coax cable is broken or disconnected.

Common Configuration Errors

From the factory, all Raveon GPS transponders and base stations are configured to work out of the box.  You will not need to set anything just to verify they work.  But, you may bave to modify some settings for your particular installation before you put them in the field. The following parameters within the base station and GPS transponders must all be set correctly and to the same settings on all units for your system to work:

  2. Over-the-air baud radio. Do not change without consulting the factory.
  3. TOID of the transponder must be the ID of the base.
  4. Group number (ATGP).  The factory  default is none, and is typically left at none (ATGP 0).
  5. TDMATIME and SLOTTIME parameters.