Add signal strength and timestamp parsing.

main/lowpower_uat.go

@@ -66,7 +66,7 @@ func radioSerialPortReader() {
 		for i := 0; i < bufLen-6; i++ {
 			if (buf[i] == radioMagic[0]) && (buf[i+1] == radioMagic[1]) && (buf[i+2] == radioMagic[2]) && (buf[i+3] == radioMagic[3]) {
 				// Found the magic sequence. Get the length.
-				msgLen := int(uint16(buf[i+4]) + (uint16(buf[i+5]) << 8))
+				msgLen := int(uint16(buf[i+4])+(uint16(buf[i+5])<<8)) + 5 // 5 bytes for RSSI and TS.
 				// Check if we've read enough to finish this message.
 				if bufLen < i+6+msgLen {
 					break // Wait for more of the message to come in.
@@ -91,13 +91,25 @@ func radioSerialPortReader() {
 
 func processRadioMessage(msg []byte) {
 	log.Printf("processRadioMessage(): %d %s\n", len(msg), hex.EncodeToString(msg))
+
+	// RSSI and message timestamp are prepended to the actual packet.
+
+	// RSSI
+	rssiRaw := int8(msg[0])
+	rssiAdjusted := int16(rssiRaw) - 132 // -132 dBm, calculated minimum RSSI.
+	rssiDump978 := int16(1000 * (10 ^ (float64(rssiAdjusted) / 20)))
+
+	_ := uint32(msg[1]) + (uint32(msg[2]) << 8) + (uint32(msg[3]) << 16) + (uint32(msg[4]) << 24) // Timestamp. Currently unused.
+
+	msg = msg[5:]
+
 	var toRelay string
 	switch len(msg) {
 	case 552:
 		to := make([]byte, 552)
 		var rs_errors int
 		i := int(C.correct_uplink_frame((*C.uint8_t)(unsafe.Pointer(&msg[0])), (*C.uint8_t)(unsafe.Pointer(&to[0])), (*C.int)(unsafe.Pointer(&rs_errors))))
-		toRelay = "+" + hex.EncodeToString(to[:432]) + ";"
+		toRelay = fmt.Sprintf("+%s;ss=%d;", hex.EncodeToString(to[:432]), rssiDump978)
 		log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
 	case 48:
 		to := make([]byte, 48)
@@ -106,11 +118,11 @@ func processRadioMessage(msg []byte) {
 		i := int(C.correct_adsb_frame((*C.uint8_t)(unsafe.Pointer(&to[0])), (*C.int)(unsafe.Pointer(&rs_errors))))
 		if i == 1 {
 			// Short ADS-B frame.
-			toRelay = "-" + hex.EncodeToString(to[:18]) + ";"
+			toRelay = fmt.Sprintf("-%s;ss=%d;", hex.EncodeToString(to[:18]), rssiDump978)
 			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
 		} else if i == 2 {
 			// Long ADS-B frame.
-			toRelay = "-" + hex.EncodeToString(to[:34]) + ";"
+			toRelay = fmt.Sprintf("-%s;ss=%d;", hex.EncodeToString(to[:34]), rssiDump978)
 			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, toRelay)
 		} else {
 			log.Printf("i=%d, rs_errors=%d, msg=%s\n", i, rs_errors, hex.EncodeToString(to))