Diagnostic Parameters: GSM & GPS Status
This guide details how to interpret signal quality for both cellular (GSM) and satellite (GPS/GNSS) communications on Munic devices.
1. GSM Status (Signal Strength)
The network quality is determined by the RSSI (Received Signal Strength Indication) field. This value represents the modem's signal strength on a scale of 0 to 31.
RSSI Reference Table
| RSSI Value | Signal Level | Quality Description |
| 0 – 9 | Marginal | High risk of disconnection or data loss. |
| 10 – 14 | OK | Stable connection, suitable for standard tasks. |
| 15 – 19 | Good | Reliable high-speed data transfer. |
| 20 – 31 | Excellent | Optimal network conditions. |
| 99 | Unknown | The value is not yet available or the modem is initializing. |
Note: For more details on data mapping, see the Field Documentation (OBD V6/V8).
2. GPS / GNSS Status (Precision & Satellites)
To determine the reliability of a location fix, we monitor DOP (Dilution of Precision) and satellite counts.
Key Data Fields
GPS_PDOP: Positional Dilution of Precision. This is our primary field for assessing overall fix confidence.
GPS_HDOP / GPS_VDOP: Horizontal and Vertical precision, respectively.
GPS_FIX_SAT_NUM: The number of satellites used for the fix.
Minimum for 3D Fix: 4 satellites.
Rule of thumb: More satellites = higher accuracy and faster initial fix.
PDOP Interpretation Guide
| DOP Value | Rating | Application Suitability |
| < 1 | Ideal | Highest precision; used for demanding professional apps. |
| 1 – 2 | Excellent | Accurate enough for almost all sensitive applications. |
| 2 – 5 | Good | Minimum threshold for reliable in-route navigation. |
| 5 – 10 | Moderate | Fairly reliable, but a more open view of the sky is recommended. |
| 10 – 20 | Fair | Low confidence; should only be used for rough estimates. |
| > 20 | Poor | Inaccurate data; measurements should be discarded. |
3. Important Limitations (Latency & Coverage)
It is important to understand that reported diagnostics reflect the status at the time of recording, not necessarily the time of transmission.
No Coverage Zones: A device may record a "Good" RSSI or a PDOP of 2, but if the vehicle enters a tunnel or dead zone immediately after, that data cannot be transmitted until coverage is regained.
Emission Strategy: By default, the device transmits data every 2 minutes. While this can be configured, the absolute minimum period is 30 seconds.
Custom Firmware: Specialized developments can lower the emission period to roughly 5–10 seconds, but "corner cases" (short signal drops between transmissions) will still exist due to the physics of cellular handovers.