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17 - LabSat 2 Troubleshooting

USB Installation failure

Due to the nature of USB communications, the installation of the USB drivers may occasionally fail at various stages.

Should this happen the procedure should be repeated three or four times if necessary, prior to requesting technical support.

 

Trouble Locking onto Satellites

If the GNSS engine under test is having trouble locking onto satellites when replaying recorded data then please follow the checklist below for typical solutions:

 

  • During recording of LabSat data, ensure that the antenna is placed in a position where it has an unobstructed view of the sky. (See ‘GNSS Antenna Placement’ below)
  • Check the antenna connection with the LabSat; only small amounts of dirt in the socket can cause a significant reduction in signal strength.
    Also check the cable at the plug and along its length for any damage.
  • Check that the power supply is connected and free from damage.
  • If possible try another known working antenna, to confirm antenna functionality.
  • Perform a Cold Start of the device under test after starting the replay of data. This is because a GNSS receiver will normally download and store almanac information to help it re-acquire satellite signals from power up. Therefore, when a recorded GNSS test signal is replayed, it is possible that any almanac data previously stored in the GNSS engine will cause it to look for the wrong satellite signals.

 

No Communication with PC

  • If the power LED on the front of the LabSat is not illuminated then there is no power to the unit; check that battery is fresh or, if using a cigar lighter, check internal cigar lighter fuse.
  • Check that the USB cable (RLCAB042) is plugged into the ‘USB’ socket on the front panel of the LabSat.
  • Try disconnecting then reconnecting the USB cable with the LabSat powered.
  • Check that the USB cable is plugged into the COM port of the PC.
  • Check that no other programs are using the same COM port.
  • Disconnect the power to the LabSat then reconnect it.

COM Port Unavailable

Another software package installed on your computer may have reserved the COM port.  For example if VBOX Tools is open it may be using the COM port, preventing the LabSat from using it.

Optimising USB Connection Speed

  • LabSat 2 uses a high speed USB 2.0 connection to stream digitised GNSS data from LabSat 2 to the PC during replay and record
  • To ensure optimal USB connection speed and to ensure reliable operation of both the GPS + GLONASS replay and record functions it is important to ensure that other programs and devices are not accessing the USB Bus at the same time as Labsat 2.
  • During replay and record it is recommended that other programs running on the PC are shut down so that Windows does not attempt to service other applications, or utilise the USB Bus at the same time as LabSat 2.
  • The buffer loading display on the LabSat software should be used to display buffer loading on the PC. During normal replay and record operation the buffer loading display will be close to 0%
  • If buffer overloading is a problem try shutting down other applications on the PC and ensure that devices other than LabSat are not also connected to USB ports on the PC.
  • If buffer underflow occurs try replaying scenarios from the PC’s own hard disk drive, rather that the external 500 GB USB-HDD supplied with LabSat 2.  The 500 GB USB-HDD is useful for storing scenarios but it will help to limit the risk of buffer underflow if scenarios are first saved to the PC’s HDD before replay.  In a similar way, whilst recording new scenarios, it is best to record to the PC’s HDD, and then back up to the external 500 GB USB-HDD afterwards.
  • When recording or replaying large scenarios it is advisable to use a separate internal hard drive to the drive that the windows system is installed. Windows OS can use the system drive in an irregular manner and may interrupt smooth data flow.
  • If recording to a laptop that is running from an internal battery, make sure that the power manager settings in windows are configured such that the processor is running at full-power. In some cases, the standard settings will reduce the processor speed after one or two minutes of inactivity.

 

Buffer Overflow / Buffer Underflow

  • Buffer Overflow messages can occur in Record mode if the PC is not managing the data correctly. Please refer to the previous section Optimising UBS Connection Speed.
  • Buffer Underflow messages can occur in Replay mode if the PC is not managing the data correctly. Please refer to the previous section Optimising UBS Connection Speed.
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Last modified
17:36, 20 May 2015

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