modem: Correctly calculate signal strength

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/src/functions/functions.modem b/src/functions/functions.modem
index fd4ea17f1512491bcad0c0757cd1b4c86a6aa3ff..0f7cdee9c0b690f1b635e681c3545c43a5bde2c5 100644 (file)
--- a/src/functions/functions.modem
+++ b/src/functions/functions.modem
@@ -557,7 +557,7 @@ __modem_get_signal_quality() {
 
        case "${output}" in
                *,*)
-                       local rssi=${output%,*}
+                       local asu=${output%,*}
                        local ber=${output#*,}
 
                        print "${!argument}"
@@ -571,24 +571,86 @@ __modem_get_signal_quality() {
        return ${EXIT_ERROR}
 }
 
+__modem_rssi_to_dbm() {
+       local rssi="${1}"
+
+       # 99 indicates unknown signal strength
+       [ ${rssi} -eq 99 ] && return ${EXIT_UNKNOWN}
+
+       print "$(( ${rssi} * 2 - 113 ))"
+       return ${EXIT_OK}
+}
+
+__modem_rscp_to_dbm() {
+       local rscp="${1}"
+
+       # 255 indicates unknown signal strength
+       [ ${rscp} -eq 255 ] && return ${EXIT_UNKNOWN}
+
+       print "$(( ${rscp} - 116 ))"
+       return ${EXIT_OK}
+}
+
+__modem_rsrp_to_dbm() {
+       local rsrp="${1}"
+
+       case "${rsrp}" in
+               0)
+                       print "< -140"
+                       ;;
+               97)
+                       print "> -44"
+                       ;;
+               *)
+                       # This is only an approximation since RSRP references
+                       # to a range of +/-1dbm
+                       print "$(( ${rsrp} - 141 ))"
+                       ;;
+       esac
+
+       return ${EXIT_OK}
+}
+
 modem_get_signal_quality() {
        local device=${1}
        assert isset device
 
-       local rssi
-       rssi=$(__modem_get_signal_quality ${device} rssi)
+       # Arbritrary Strength Unit
+       local asu
+       asu=$(__modem_get_signal_quality ${device} asu)
        assert_check_retval $?
 
-       isset rssi || return ${EXIT_ERROR}
+       isset asu || return ${EXIT_ERROR}
 
-       # 99 indicates an unknown signal strength.
-       [ ${rssi} -eq 99 ] && return ${EXIT_UNKNOWN}
+       local network_mode="$(modem_get_network_mode ${device} &>/dev/null; echo $?)"
 
-       local dbm=$(( ${rssi} * 2 ))
-       dbm=$(( ${dbm} - 113 ))
+       local ret
+       case "${network_mode}" in
+               # GSM
+               ${EXIT_OPMODE_GSM}|${EXIT_OPMODE_COMPACTGSM}|${GSM_WITH_EGPRS})
+                       __modem_rssi_to_dbm "${asu}"
+                       ret=${?}
+                       ;;
 
-       print "%d" "${dbm}"
-       return ${EXIT_OK}
+               # UMTS
+               ${EXIT_OPMODE_UMTS}|${EXIT_OPMODE_UMTS_WITH_HSDPA}|${EXIT_OPMODE_UMTS_WITH_HSUPA}|${EXIT_OPMODE_UMTS_WITH_HSDPA_AND_HSUPA})
+                       __modem_rscp_to_dbm "${asu}"
+                       ret=${?}
+                       ;;
+
+               # LTE
+               ${EXIT_OPMODE_LTE})
+                       __modem_rsrp_to_dbm "${asu}"
+                       ret=${?}
+                       ;;
+
+               # unknown
+               *)
+                       ret=${EXIT_ERROR}
+                       ;;
+       esac
+
+       return ${ret}
 }
 
 modem_get_bit_error_rate() {