Diagnostic parameter for GSM and GPS status

GSM Status

The field named “RSSI” (Received Signal Strength Indication) indicates to you the quality of the signal of the network.

We can split RSSI values into 4 levels:

  • 0-9: Marginal
  • 10-14: OK
  • 15-19: Good
  • 20-31: Excellent

The field name is RSSI (https://store.munic.io/documentations/Fields_OBDV6&V8) and it stores the modem RSSI. Range is 0-32, the more the better. A special value of 99 indicates the value is not known yet.

GPS Status

We have 3 fields that can five you a GDOP value (Geometric dilution of precision). (https://store.munic.io/documentations/Fields_OBDV6&V8)

  • GPS_HDOP: Horizontal dilution of the precision of the GPS.
  • GPS_PDOP: Positional dilution of the precision of the GPS.
  • GPS_VDOP: Vertical dilution of the precision of the GPS.

GPS_PDOP is the field that we use per default and gives you a good confidence level about the GPS signal quality.
GPS_FIXED_SAT_NUM: Number of satellites used for the GPS fix.

That being said, a PDOP value of 2 or a good RSSI may not be transmitted if the vehicle goes in a no coverage zone a few seconds after being recorded as the emission strategy per default is 2 minutes and even if it can be changed, the minimum period is 30 seconds.

A development could be made to lower the emission period to a minimum but it would be around 5/10 seconds, thus this corner case could still exist.

The more satellites we have the more accurate the position is, and the less time is required to have a GNSS fix.

At least 4 satellites are required to have a 3D fix.

Please find below the meaning of DOP Values

DOP Value Rating Description
1 Ideal Highest possible confidence level to be used for applications demanding the highest possible precision at all times.
1-2 Excellent At this confidence level, positional measurements are considered accurate enough to meet all but the most sensitive applications.
2-5 Good Represents a level that marks the minimum appropriate for making accurate decisions. Positional measurements could be used to make reliable in-route navigation suggestions to the user.
5-10 Moderate Positional measurements could be used for calculations, but the fix quality could still be improved. A more open view of the sky is recommended.
10-20 Fair Represents a low confidence level. Positional measurements should be discarded or used only to indicate a very rough estimate of the current location.
>20 Poor At this level, measurements are inaccurate and should be discarded.