9
Troubleshooting
Nothing is working and my GPS receiver does not acquire lock
Complete the following steps, in order:
•
Check that there are no obstructions (e.g. buildings, tunnels) around or above the installation; move to
another location as necessary.
•
Isolate any internal jamming sources; switch off all other electronic devices.
•
Check all cable connections for damage, excessive bending and that they are correctly secured.
•
Check the GPS receiver functions correctly when connected directly to ONE antenna, without
GPSdome connected. Repeat with the other antenna. If both antennas are confirmed as OK, then
reconnect GPSdome.
•
Check that the antennas are connected to GPSdome ‘P’ and ‘A’ connectors, and that the SMA
connectors are tightened.
•
Check that the GPSdome ‘R’ connector is connected to the GPS receiver, and that the SMA
connectors are tightened at both ends.
•
Check that 3.3VDC - 32VDC external power is connected from the GPSdome to an applicable power
source.
•
Check that the green LED is ON when an active GPS receiver is connected.
Interference indication
The custom integrated circuit at the core of GPSdome has an open drain output to indicate the presence of
jamming or spoofing events. Its switch point is a function of external antenna LNA gain and so cannot be
precisely specified.
Please note that this connection is optional
Please read the following information:
The open drain circuit inside GPSdome (left hand side of Figure 1) connects to the “brown” wire. In case of
reception without jamming or spoofing, the Control FET is off, and the jamming detect wire is open circuit
for DC voltages applied up to wire. When jamming is detected, the Control FET connects the internal 1k
resistor to ground.
In order to translate the interference indication (brown wire) to logic level signal, connect the brown wire to
DC voltage in the customer equipment via pullup resistor.
Jamming Detect Output Circuit
Australia
:
info@vicom.com.au
|
www.vicom.com.au
New Zealand
:
info@vicom.co.
nz
|
www.vicom.co.
nz
