LoRa_APRS_iGate/src/gps_utils.cpp

#include <TinyGPS++.h>
#include <WiFi.h>
#include "configuration.h"
#include "gps_utils.h"

extern Configuration  Config;
extern WiFiClient     espClient;
String                distance;


namespace GPS_Utils {

    String double2string(double n, int ndec) {
        String r = "";
        if (n>-1 && n<0) {
            r = "-";
        }   
        int v = n;
        r += v;
        r += '.';
        for (int i=0;i<ndec;i++) {
            n -= v;
            n = 10 * abs(n);
            v = n;
            r += v;
        }
        return r;
    }

    String processLatitudeAPRS(double lat) {
        String degrees = double2string(lat,6);
        String north_south, latitude, convDeg3;
        float convDeg, convDeg2;

        if (abs(degrees.toFloat()) < 10) {
            latitude += "0";
        }
        if (degrees.indexOf("-") == 0) {
            north_south = "S";
            latitude += degrees.substring(1,degrees.indexOf("."));
        } else {
            north_south = "N";
            latitude += degrees.substring(0,degrees.indexOf("."));
        }
        convDeg = abs(degrees.toFloat()) - abs(int(degrees.toFloat()));
        convDeg2 = (convDeg * 60)/100;
        convDeg3 = String(convDeg2,6);
        latitude += convDeg3.substring(convDeg3.indexOf(".")+1,convDeg3.indexOf(".")+3) + "." + convDeg3.substring(convDeg3.indexOf(".")+3,convDeg3.indexOf(".")+5);
        latitude += north_south;
        return latitude;
    }

    String processLongitudeAPRS(double lon) {
        String degrees = double2string(lon,6);
        String east_west, longitude, convDeg3;
        float convDeg, convDeg2;
        
        if (abs(degrees.toFloat()) < 100) {
            longitude += "0";
        }
        if (abs(degrees.toFloat()) < 10) {
            longitude += "0";
        }
        if (degrees.indexOf("-") == 0) {
            east_west = "W";
            longitude += degrees.substring(1,degrees.indexOf("."));
        } else {
            east_west = "E";
            longitude += degrees.substring(0,degrees.indexOf("."));
        }
        convDeg = abs(degrees.toFloat()) - abs(int(degrees.toFloat()));
        convDeg2 = (convDeg * 60)/100;
        convDeg3 = String(convDeg2,6);
        longitude += convDeg3.substring(convDeg3.indexOf(".")+1,convDeg3.indexOf(".")+3) + "." + convDeg3.substring(convDeg3.indexOf(".")+3,convDeg3.indexOf(".")+5);
        longitude += east_west;
        return longitude;
    }

    String generateBeacon() {
        String stationLatitude = processLatitudeAPRS(Config.beacon.latitude);
        String stationLongitude = processLongitudeAPRS(Config.beacon.longitude);

        String beaconPacket = Config.callsign + ">APLRG1," + Config.beacon.path;

        if (Config.aprs_is.active && Config.digi.mode == 0) { // If APRSIS enabled and Digi disabled
            beaconPacket += ",qAC";
        } else {}

        beaconPacket += ":=" + stationLatitude + Config.beacon.overlay + stationLongitude + Config.beacon.symbol;
        beaconPacket += Config.beacon.comment;

        return beaconPacket;
    }

    String generateiGateLoRaBeacon() {
        String stationLatitude = processLatitudeAPRS(Config.beacon.latitude);
        String stationLongitude = processLongitudeAPRS(Config.beacon.longitude);
        
        String beaconPacket = Config.callsign + ">APLRG1," + Config.beacon.path + ":=" + stationLatitude + Config.beacon.overlay + stationLongitude + Config.beacon.symbol;

        return beaconPacket;
    }

    double calculateDistanceTo(double latitude, double longitude) {
        return TinyGPSPlus::distanceBetween(Config.beacon.latitude,Config.beacon.longitude, latitude, longitude) / 1000.0;
    }

    String decodeEncodedGPS(String packet) {
        String GPSPacket = packet.substring(packet.indexOf(":!")+3);
        String encodedLatitude    = GPSPacket.substring(0,4);
        String encodedLongtitude  = GPSPacket.substring(4,8);

        int Y1 = int(encodedLatitude[0]);
        int Y2 = int(encodedLatitude[1]);
        int Y3 = int(encodedLatitude[2]);
        int Y4 = int(encodedLatitude[3]);
        float decodedLatitude = 90.0 - ((((Y1-33) * pow(91,3)) + ((Y2-33) * pow(91,2)) + ((Y3-33) * 91) + Y4-33) / 380926.0);
        
        int X1 = int(encodedLongtitude[0]);
        int X2 = int(encodedLongtitude[1]);
        int X3 = int(encodedLongtitude[2]);
        int X4 = int(encodedLongtitude[3]);
        float decodedLongitude = -180.0 + ((((X1-33) * pow(91,3)) + ((X2-33) * pow(91,2)) + ((X3-33) * 91) + X4-33) / 190463.0);
        distance = String(calculateDistanceTo(decodedLatitude, decodedLongitude),1);
        return String(decodedLatitude,5) + "N / " + String(decodedLongitude,5) + "E / " + distance + "km";
    }

    String getReceivedGPS(String packet) {
        String infoGPS;
        if (packet.indexOf(":!") > 10) {
            infoGPS = packet.substring(packet.indexOf(":!")+2);
        } else if (packet.indexOf(":=") > 10) {
            infoGPS = packet.substring(packet.indexOf(":=")+2);
        }
        String Latitude       = infoGPS.substring(0,8);
        String Longitude      = infoGPS.substring(9,18);

        float convertedLatitude, convertedLongitude;
        String firstLatPart   = Latitude.substring(0,2);
        String secondLatPart  = Latitude.substring(2,4);
        String thirdLatPart   = Latitude.substring(Latitude.indexOf(".")+1,Latitude.indexOf(".")+3);
        String firstLngPart   = Longitude.substring(0,3);
        String secondLngPart  = Longitude.substring(3,5);
        String thirdLngPart   = Longitude.substring(Longitude.indexOf(".")+1,Longitude.indexOf(".")+3);
        convertedLatitude     = firstLatPart.toFloat() + (secondLatPart.toFloat()/60) + (thirdLatPart.toFloat()/(60*100));
        convertedLongitude    = firstLngPart.toFloat() + (secondLngPart.toFloat()/60) + (thirdLngPart.toFloat()/(60*100));
        
        String LatSign = String(Latitude[7]);
        String LngSign = String(Longitude[8]);
        if (LatSign == "S") {
            convertedLatitude = -convertedLatitude;
        } 
        if (LngSign == "W") {
            convertedLongitude = -convertedLongitude;
        }
        distance = String(calculateDistanceTo(convertedLatitude, convertedLongitude),1);
        return String(convertedLatitude,5) + "N / " + String(convertedLongitude,5) + "E / " + distance + "km";
    }

    String getDistance(String packet) {
        int encodedBytePosition = 0;
        if (packet.indexOf(":!") > 10) {
            encodedBytePosition = packet.indexOf(":!") + 14;
        }
        if (packet.indexOf(":=") > 10) {
            encodedBytePosition = packet.indexOf(":=") + 14;
        }
        if (encodedBytePosition != 0) {
            if (String(packet[encodedBytePosition]) == "G" || String(packet[encodedBytePosition]) == "Q" || String(packet[encodedBytePosition]) == "[" || String(packet[encodedBytePosition]) == "H") {
                return decodeEncodedGPS(packet);
            } else {
                return getReceivedGPS(packet);
            }
        } else {
            return " _ / _ / _ ";
        }
    }

}