Signal Quality
Execution command returns the received signal strength indication from the ISU. Response is
in the form:
+CSQ: <rssi>
where <rssi> is:
| Value | Result |
|---|---|
| 0 | Equivalent to 0 bars displayed on the ISU signal strength indicator. |
| 1 | Equivalent to 1 bars displayed on the ISU signal strength indicator. |
| 2 | Equivalent to 2 bars displayed on the ISU signal strength indicator. |
| 3 | Equivalent to 3 bars displayed on the ISU signal strength indicator. |
| 4 | Equivalent to 4 bars displayed on the ISU signal strength indicator. |
| 5 | Equivalent to 5 bars displayed on the ISU signal strength indicator. |
These commands return the Relative Signal Strength Indicator value to the application. The commands return a value between 0 and 5. The value indicates strength of the signal relative to the noise floor. A value of 0 indicates no discernable signal and the communications will not work. A value of 1 is the minimum signal strength required to transmit. Every incremental value is an additional 2 dB of margin. For example; 2 is + 2 dB, 3 +4 dB, 5 +8 dB.
The +CSQ results are not ‘instantaneous’ and the calculation may take seconds. The +CSQF command immediately returns the results of the last RSSI calculation to the user. The user must keep in mind this value may be ‘old’, perhaps 15 seconds.
The
+CSQform of the command waits for an updated signal strength reading to become available. This will usually be within two seconds of issuing the command. If the ISU is in the process of acquiring the system, or in a satellite handoff, a delay in response of up to 10 seconds may be experienced.
The
+CSQFform of the command returns immediately, reporting the last known signal strength.