Initial attempt at decoding Kenwood GPS data.

NXDNGateway/GPSHandler.cpp

@@ -1,5 +1,5 @@
 /*
-*   Copyright (C) 2018 by Jonathan Naylor G4KLX
+*   Copyright (C) 2018,2020 by Jonathan Naylor G4KLX
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
@@ -64,7 +64,9 @@ void CGPSHandler::processData(const unsigned char* data)
 	m_length += NXDN_DATA_LENGTH;
 
 	if (data[0U] == 0x00U) {
-		processNMEA();
+		bool ret = processIcom();
+		if (!ret)
+			processKenwood();
 		reset();
 	}
 }
@@ -81,23 +83,25 @@ void CGPSHandler::reset()
 	m_source.clear();
 }
 
-void CGPSHandler::processNMEA()
+bool CGPSHandler::processIcom()
 {
 	if (m_data[0U] != NXDN_DATA_TYPE_GPS)
-		return;
+		return false;
 
 	if (::memcmp(m_data + 1U, "$G", 2U) != 0)
-		return;
+		return false;
 
 	if (::strchr((char*)(m_data + 1U), '*') == NULL)
-		return;
+		return false;
+
+	// From here onwards we have something that looks like Icom GPS data
 
 	if (!checkXOR())
-		return;
+		return true;
 
 	if (::memcmp(m_data + 4U, "RMC", 3U) != 0) {
 		CUtils::dump("Unhandled NMEA sentence", (unsigned char*)(m_data + 1U), m_length - 1U);
-		return;
+		return true;
 	}
 
 	// Parse the $GxRMC string into tokens
@@ -114,11 +118,11 @@ void CGPSHandler::processNMEA()
 
 	// Is there any position data?
 	if (pRMC[3U] == NULL || pRMC[4U] == NULL || pRMC[5U] == NULL || pRMC[6U] == NULL || ::strlen(pRMC[3U]) == 0U || ::strlen(pRMC[4U]) == 0U || ::strlen(pRMC[5U]) == 0 || ::strlen(pRMC[6U]) == 0)
-		return;
+		return true;
 
 	// Is it a valid GPS fix?
 	if (::strcmp(pRMC[2U], "A") != 0)
-		return;
+		return true;
 
 	double latitude  = ::atof(pRMC[3U]);
 	double longitude = ::atof(pRMC[5U]);
@@ -142,6 +146,8 @@ void CGPSHandler::processNMEA()
 	}
 
 	m_writer->write(output);
+
+	return true;
 }
 
 bool CGPSHandler::checkXOR() const
@@ -158,3 +164,95 @@ bool CGPSHandler::checkXOR() const
 
 	return ::memcmp(buffer, p2 + 1U, 2U) == 0;
 }
+
+void CGPSHandler::processKenwood()
+{
+	enum {
+		GPS_FULL,
+		GPS_SHORT,
+		GPS_VERY_SHORT
+	} type;
+
+	switch (m_data[0U]) {
+	case 0x00U:
+		type = GPS_FULL;
+		break;
+	case 0x01U:
+		type = GPS_SHORT;
+		break;
+	case 0x02U:
+		type = GPS_VERY_SHORT;
+		break;
+	default:
+		return;
+	}
+
+	unsigned char UTCss = m_data[1U] & 0x3FU;
+	unsigned char UTCmm = ((m_data[1U] & 0xC0U) >> 2) | (m_data[2U] & 0x0FU);
+	unsigned char UTChh = ((m_data[3U] & 0x01U) << 4) | (m_data[2U] & 0xF0U) >> 4;
+
+	unsigned char UTCday   = 0x1FU;
+	unsigned char UTCmonth = 0x0FU;
+	unsigned char UTCyear  = 0x7FU;
+	if (type == GPS_FULL) {
+		UTCday   = m_data[15U] & 0x1FU;
+		UTCmonth = ((m_data[15U] & 0xE0U) >> 3) | (m_data[16] & 0x01U);
+		UTCyear  = (m_data[16U] & 0xFEU) >> 1;
+	}
+
+	unsigned char north     = 'N';
+	unsigned int latAfter   = 0x7FFFU;
+	unsigned int latBefore  = 0xFFFFU;
+	unsigned char east      = 'E';
+	unsigned int longAfter  = 0x7FFFU;
+	unsigned int longBefore = 0xFFFFU;
+	if (type == GPS_VERY_SHORT) {
+		north     = (m_data[5U] & 0x01U) == 0x00U ? 'N' : 'S';
+		latAfter  = ((m_data[5U] & 0xFEU) >> 1) | (m_data[6U] << 7);
+		latBefore = (m_data[8U] << 8) | m_data[7U];
+
+		east       = (m_data[9U] & 0x01U) == 0x00U ? 'E' : 'W';
+		longAfter  = ((m_data[9U] & 0xFEU) >> 1) | (m_data[10U] << 7);
+		longBefore = (m_data[12U] << 8) | m_data[11U];
+	} else {
+		north     = (m_data[7U] & 0x01U) == 0x00U ? 'N' : 'S';
+		latAfter  = ((m_data[7U] & 0xFEU) >> 1) | (m_data[8U] << 7);
+		latBefore = (m_data[10U] << 8) | m_data[9U];
+
+		east       = (m_data[11U] & 0x01U) == 0x00U ? 'E' : 'W';
+		longAfter  = ((m_data[11U] & 0xFEU) >> 1) | (m_data[12U] << 7);
+		longBefore = (m_data[14U] << 8) | m_data[13U];
+	}
+
+	if (latAfter == 0x7FFFU || latBefore == 0xFFFFU || longAfter == 0x7FFFU || longBefore == 0xFFFFU)
+		return;
+
+	unsigned int course      = 0xFFFFU;
+	unsigned int speedBefore = 0x3FFU;
+	unsigned int speedAfter  = 0x0FU;
+	if (type == GPS_FULL) {
+		course      = (m_data[21U] << 4) | (m_data[22U] & 0x0FU);
+		speedBefore = ((m_data[23U] & 0xF0U) << 2) | (m_data[24U] & 0x3FU);
+		speedAfter  = m_data[23U] & 0x0FU;
+	}
+
+	std::string source = m_source;
+	if (!m_suffix.empty()) {
+		source.append("-");
+		source.append(m_suffix.substr(0U, 1U));
+	}
+
+	char output[300U];
+	if (course != 0xFFFFU && speedBefore != 0x3FFU && speedAfter != 0x0FU) {
+		::sprintf(output, "%s>APDPRS,NXDN*,qAR,%s:!%07u.%02lu%c/%08u.%02u%cr%03d/%03d via MMDVM",
+			source.c_str(), m_callsign.c_str(), latBefore, latAfter, north, longBefore, longAfter, east, course / 10U, speedBefore);
+	}
+	else {
+		::sprintf(output, "%s>APDPRS,NXDN*,qAR,%s:!%07u.%02u%c/%08u.%02u%cr via MMDVM",
+			source.c_str(), m_callsign.c_str(), latBefore, latAfter, north, longBefore, longAfter, east);
+	}
+
+	LogMessage("Kenwood APRS message = %s", output);
+
+	// m_writer->write(output);
+}

NXDNGateway/GPSHandler.h

@@ -1,5 +1,5 @@
 /*
-*   Copyright (C) 2018 by Jonathan Naylor G4KLX
+*   Copyright (C) 2018,2020 by Jonathan Naylor G4KLX
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
@@ -42,7 +42,8 @@ private:
 	std::string    m_source;
 	std::string    m_suffix;
 
-	void processNMEA();
+	bool processIcom();
+	void processKenwood();
 	bool checkXOR() const;
 	void reset();
 };

NXDNGateway/Version.h

@@ -19,6 +19,6 @@
 #if !defined(VERSION_H)
 #define	VERSION_H
 
-const char* VERSION = "20200409";
+const char* VERSION = "20200429";
 
 #endif