User guide

Aries Reference Manual Section 4 – Probes
Radio Systems Information Ltd. Page 73
5.4.1 Operation
The probe will start automatically when power is applied to the TETRA radio.
The probe will send back data to the server after every monitor event or test call. If there is no GPRS
coverage in an area, or the server is unavailable for any reason, then the probe will store the data to
internal memory instead until it has GPRS coverage again when it will send all of the stored data to the
server. The probe will store up to about 9000 data messages, which is equivalent to about 6 days
operation (assuming 60 second updates). For periods without GPRS longer than this the probe will store
the most recent data and drop the oldest data.
The probe sends back an error message if communication is lost with the TETRA radio or external power
is lost. Error messages are only sent once.
The probe logs the basic parameters in a monitor event typically every 60 seconds. This is a non-intrusive
action which does not cause the TETRA radio to transmit.
If enabled at the server then the probe will perform a test call typically every 5 minutes. The probe will
request a group call on the specified TETRA group. If the group call is granted then the probe maintains
the PTT for the period specified (typically 5 seconds) and then releases the PTT and lets the group call
time out. The test call can result in a call setup failure event if the call was never granted or a call dropped
event if the call failed during the call.
It is usual to assign a single TETRA group for all Aries probes and then configure the parameters at the
server so that each probe performs the test call in a different time slot so that there is no overlap of test
calls.
If at any time the TETRA radio hands over from one base site to another a handover event is produced.
Similarly if the TETRA radio has no service due to bad coverage then a no service event is produced.
The probe logs the following parameters:
Time
Latitude & Longitude
Vehicle Speed (km/h)
Current Base LAC
Current RSSI (dBm)
Current Base Site Frequency (MHz)
Current C1 (dB)
Best Neighbour Base LAC
Best Neighbour RSSI (DBM)
Best Neighbour C2 (dB)
Call Setup Time
Packet Data Download Time
GSM Signal Quality dBm
Event Type – one of the following:
Monitor
Call Setup Success
Call Setup Failure
Call Dropped
Handover
Failed Handover
No Service
TETRA Radio Communications Error
Running on Battery
Battery is too low (probe shuts down automatically)
External Power Applied
TETRA Radio Initialisation Failure (specified group is not available on the radio)
DMO (TETRA radio is in Direct Mode)