Signal LED

The Signal LED on the GPRS modem card is used to indicate the RSSI (received signal strength indicator) as reported by the “AT^SIND?” command (refer to the TC63 AT Command Set document). This command is sent periodically to the modem from the driver at a frequency determined by the configuration parameter “Monitor data poll cycle time”, and is thus dependant on “Enable poll for monitor data” being enabled (see Modem Configuration).

Table 2 shows the Signal LED patterns that are possible.

Table 2. Signal LED behavior on GPRS modem option card

Signal LED pattern	Pattern details	Meaning
On / Off continuous	1 sec On / 1 sec Off	Signal level not determined. Possible causes are: the AT^SIND? returned an error. the configuration parameter “Enable poll for monitor” is set to false.
Off, no flashes	always Off	RSSI is 0 (<-112 dbm) or modem driver failed or not started.
1 short flash	350ms On / 2 sec Off	RSSI is 1 (-112 dbm to -97 dbm).
2 short flashes	350ms On / 350ms Off / 350ms On / 2 sec Off	RSSI is 2 (-97 dbm to -82 dbm).
3 short flashes	350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 2 sec Off	RSSI is 3 (-82 dbm to -67 dbm).
4 short flashes	350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 2 sec Off	RSSI is 4 (-67 dbm to -52 dbm).
5 short flashes	350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 350ms Off / 350ms On / 2 sec Off	RSSI is 5 (> -52 dbm).