Ultra Basic GPS Tester – NEO8M + ESP32 Wroom with CoG

This is a really quick and basic GPS tester which evaluates a GPS module (in this case a Ublox-Neo8M and ESP32-Wroom. It has 3 core functions, evaluate the signal and reliability of the incoming signals, map the CoG or Course over Ground and establish what satellite is being used e.g.: GPS, BeiDou (BDS), Galileo or GLONASS. As the Neo8M has everything but GLONASS the messages are focused on Galileo and GPS. A sky Plot and other iterations from the basic acquisition are included to aid diagnosis and testing.

The code is light, basic, but allows a user to quickly get up and running.

Simply upload the code, look for “G5STO HUD-Setup” on your network or mobile phone. Apple IOS will connect to 192.168.4.1 initally and then open an web portal to assign a network. Just in case you get asked a password? it’s simply “12345678”.

Just a heads up….pun intended…..here is v 1.70 and update that parses BeiDou correctly and adds a Geiget counter sound, allows direct data entry to inject commands, spoofing and jamming detection which adds a basic heuristic engine, (Checking SNR and looking for exact matching SNR’s basically), object mapping, HDOP heatmap and lastly the SkyLine mapper shows a shadow to identify objects blocking the signal. For now the GLONASS detection is purged from the code as I am only using a Neo8M where a Neo8MN is required.

Click here to download the latest update. Click Here >>> HUD_Display_Neo8M_N

Copy all the code between the astrix:

****************************************************************************************************************

// G5STO – HuD style GPS tester for Neo8M

#include <WiFi.h>

#include <WiFiManager.h>

#include <AsyncTCP.h>

#include <ESPAsyncWebServer.h>

#include <TinyGPSPlus.h>

#include <vector>

TinyGPSPlus gps;

HardwareSerial GPSserial(2);

AsyncWebServer server(80);

AsyncWebSocket ws(“/ws”);

struct SatInfo {

int prn;

int snr;

int elevation;

int azimuth;

String system;

unsigned long lastActive;

unsigned long lastView;

};

std::vector<SatInfo> sats;

// ———- HUD HTML (PROGMEM) ———-

const char index_html[] PROGMEM = R”rawliteral(

<!DOCTYPE html>

<html>

<head>

<style>

body { margin:0; background:#000; color:#0f0; font-family:Consolas, monospace; }

.grid { display:grid; grid-template-columns:2fr 1fr; gap:10px; padding:10px; }

.panel { border:1px solid #0f0; padding:10px; box-shadow:0 0 10px #0f0; }

.title { font-size:18px; margin-bottom:5px; text-transform:uppercase; letter-spacing:2px; }

#compass-container {

position:relative; width:250px; height:250px; margin:0 auto;

border:1px solid #0f0; border-radius:50%; box-shadow:0 0 15px #0f0;

}

#compass-ring { position:absolute; width:100%; height:100%; border-radius:50%; border:2px solid #0f0; }

#compass-needle {

position:absolute; width:2px; height:45%; background:#0f0;

top:5%; left:50%; transform-origin:50% 90%; box-shadow:0 0 10px #0f0;

}

#compass-center {

position:absolute; width:12px; height:12px; background:#000;

border:2px solid #0f0; border-radius:50%; top:50%; left:50%;

transform:translate(-50%, -50%);

}

#compass-label { position:absolute; bottom:10px; width:100%; text-align:center; font-size:16px; }

.hud-row { display:flex; justify-content:space-between; margin-bottom:5px; }

.hud-label { text-transform:uppercase; letter-spacing:1px; }

.hud-value { font-weight:bold; }

#console, #satbox {

background:#010; padding:5px; font-size:12px; border:1px solid #0f0;

overflow-y:auto;

}

#console { height:200px; }

#satbox { height:150px; margin-top:5px; }

#console::-webkit-scrollbar, #satbox::-webkit-scrollbar { width:6px; }

#console::-webkit-scrollbar-thumb, #satbox::-webkit-scrollbar-thumb { background:#0f0; }

</style>

</head>

<body>

<div class=”title”>G5STO – Navigation style HuD GPS – tester</div>

</div>

</div>

<input type=”checkbox” id=”unitToggle” onchange=”toggleUnits()”> MPH

</label>

</div>

<div class=”hud-row”><div class=”hud-label” id=”speedLabel”>Speed (km/h)</div><div class=”hud-value” id=”speed”>—</div></div>

<div class=”hud-row”><div class=”hud-label”>Altitude (m)</div><div class=”hud-value” id=”alt”>—</div></div>

<div class=”hud-row”><div class=”hud-label”>Satellites</div><div class=”hud-value” id=”sats”>—</div></div>

</div>

<div class=”title”>Packet Console</div>

<div class=”title” style=”margin-top:10px;”>Satellite Status</div>

</div>

let socket;

function connectWS() {

socket = new WebSocket(“ws://” + location.host + “/ws”);

socket.onopen = () => logLine(“[WS] Connected”);

socket.onclose = () => {

logLine(“[WS] Disconnected, retrying…”);

setTimeout(connectWS, 2000);

};

socket.onmessage = event => {

const data = event.data;

if (data.startsWith(“{“)) {

try {

const j = JSON.parse(data);

updateHUD(j);

} catch (e) {

logLine(“[JSON ERROR] ” + e);

}

} else if (data.startsWith(“[“)) {

try {

const list = JSON.parse(data);

updateSatellites(list);

drawSkyPlot(list);

} catch (e) {

logLine(“[SAT JSON ERROR] ” + e);

}

} else {

logLine(data);

}

};

}

function logLine(t) {

const c = document.getElementById(“console”);

c.innerHTML += t.replace(/</g, “<”) + “<br>”;

c.scrollTop = c.scrollHeight;

}

function updateHUD(j) {

let spd = j.speed;

if (document.getElementById(“unitToggle”).checked) {

spd *= 0.621371;

}

document.getElementById(“speed”).textContent = spd.toFixed(1);

document.getElementById(“alt”).textContent = j.alt.toFixed(1);

document.getElementById(“sats”).textContent = j.sats;

document.getElementById(“hdop”).textContent = j.hdop.toFixed(1);

document.getElementById(“lat”).textContent = j.lat.toFixed(6);

document.getElementById(“lng”).textContent = j.lng.toFixed(6);

const needle = document.getElementById(“compass-needle”);

const label = document.getElementById(“compass-label”);

needle.style.transform = “rotate(” + j.cog + “deg)”;

label.textContent = “COG: ” + j.cog.toFixed(1) + “°”;

}

function toggleUnits() {

const chk = document.getElementById(“unitToggle”).checked;

document.getElementById(“speedLabel”).innerText = chk ? “Speed (mph)” : “Speed (km/h)”;

localStorage.setItem(“useMPH”, chk);

}

function updateSatellites(list) {

const box = document.getElementById(“satbox”);

box.innerHTML = “”;

list.forEach(s => {

// Satellites active in the last 3.5 seconds will be marked as ‘Used’ and dark Green

const isUsed = s.used;

const color = isUsed ? “#0f0” : “#078007”;

const usedText = isUsed ? ” (U)” : “”;

box.innerHTML += `<span style=”color:${color}; white-space: pre;”>${s.system.padEnd(7)} PRN ${String(s.prn).padStart(3)} | El: ${String(s.elev).padStart(2)}° Az: ${String(s.azim).padStart(3)}° | SNR: ${String(s.snr).padStart(2)} ${usedText}</span><br>`;

});

box.scrollTop = box.scrollHeight;

}

function drawSkyPlot(satellites) {

const canvas = document.getElementById(‘skyplot’);

const ctx = canvas.getContext(‘2d’);

const w = canvas.width;

const h = canvas.height;

const cx = w / 2;

const cy = h / 2;

const radius = w / 2 – 10;

const sysColors = {

“GPS”: “#00f”, “GLONASS”: “#f00”, “Galileo”: “#0f0”, “BeiDou”: “#f90”, “GNSS”: “#fff”

};

ctx.clearRect(0, 0, w, h);

// Draw rings and lines

ctx.strokeStyle = ‘#030’;

ctx.beginPath(); ctx.arc(cx, cy, radius / 2, 0, 2 * Math.PI); ctx.stroke(); // 45 deg elevation

ctx.beginPath(); ctx.arc(cx, cy, radius, 0, 2 * Math.PI); ctx.stroke(); // Horizon

ctx.beginPath(); ctx.moveTo(cx – radius, cy); ctx.lineTo(cx + radius, cy); ctx.stroke();

ctx.beginPath(); ctx.moveTo(cx, cy – radius); ctx.lineTo(cx, cy + radius); ctx.stroke();

ctx.fillStyle = ‘#070’;

ctx.font = ’10px Consolas’;

ctx.textAlign = ‘center’;

ctx.fillText(‘N’, cx, cy – radius – 2);

// Plot satellites

satellites.forEach(s => {

if (s.elev === null || s.azim === null) return;

const r = radius * (90 – s.elev) / 90;

const angle = (s.azim – 90) * Math.PI / 180; // Azimuth 0=N, rotate for canvas

const x = cx + r * Math.cos(angle);

const y = cy + r * Math.sin(angle);

ctx.fillStyle = sysColors[s.system] || ‘#fff’;

ctx.beginPath();

ctx.arc(x, y, 5, 0, 2 * Math.PI);

ctx.fill();

if (s.used) {

ctx.strokeStyle = ‘#ff0’;

ctx.lineWidth = 2;

ctx.stroke();

}

});

}

window.onload = () => {

if (localStorage.getItem(“useMPH”) === “true”) {

document.getElementById(“unitToggle”).checked = true;

toggleUnits();

}

connectWS();

};

</script>

</body>

</html>

)rawliteral”;

// ———- WiFi ———-

void setupWiFi() {

WiFi.mode(WIFI_STA);

WiFiManager wm;

wm.setAPCallback([](WiFiManager *wm) {

Serial.println(“Entering config portal…”);

});

if (!wm.autoConnect(“G5STO HUD-Setup”, “12345678”)) {

Serial.println(“WiFi failed, rebooting…”);

delay(3000);

ESP.restart();

}

Serial.print(“WiFi connected. IP: “);

Serial.println(WiFi.localIP());

}

// ———- WebSocket Events ———-

void onWsEvent(AsyncWebSocket *server, AsyncWebSocketClient *client,

AwsEventType type, void *arg, uint8_t *data, size_t len) {

if (type == WS_EVT_CONNECT)

Serial.printf(“WS client %u connected\n”, client->id());

else if (type == WS_EVT_DISCONNECT)

Serial.printf(“WS client %u disconnected\n”, client->id());

}

// ———- GSV Parsing ———-

void parseGSV(const String &line) {

String sys;

String talker = line.substring(1, 3);

if (talker == “GP”) sys = “GPS”;

else if (talker == “GL”) sys = “GLONASS”;

else if (talker == “GA”) sys = “Galileo”;

else if (talker == “BD” || talker == “GB”) sys = “BeiDou”;

else if (talker == “GN”) sys = “GNSS”;

else return; // Ignore unknown GSV talkers

int idx = 0;

int pStart = 0;

int prn = 0, elev = 0, azim = 0; // Temp variables

for (int i = 0; i < line.length(); i++) {

if (line[i] == ‘,’ || line[i] == ‘*’) {

String val = line.substring(pStart, i);

// Satellite data starts at field 4, repeating every 4 fields

if (idx >= 4) {

int subField = (idx – 4) % 4;

if (subField == 0) prn = val.toInt();

else if (subField == 1) elev = val.toInt();

else if (subField == 2) azim = val.toInt();

else if (subField == 3) {

int snr = val.toInt();

if (prn > 0) {

bool found = false;

for (auto &s : sats) {

if (s.prn == prn && s.system == sys) {

s.elevation = elev; s.azimuth = azim; s.snr = snr;

s.lastView = millis();

found = true; break;

}

if (!found) {

SatInfo s;

s.prn = prn; s.elevation = elev; s.azimuth = azim; s.snr = snr;

s.system = sys; s.lastActive = 0; s.lastView = millis();

sats.push_back(s);

}

idx++;

pStart = i + 1;

}

// ———- GSA Parsing ———-

void parseGSA(const String &line) {

String sys;

String talker = line.substring(1, 3);

if (talker == “GP”) sys = “GPS”;

else if (talker == “GL”) sys = “GLONASS”;

else if (talker == “GA”) sys = “Galileo”;

else if (talker == “BD” || talker == “GB”) sys = “BeiDou”;

else if (talker == “GN”) sys = “GNSS”; // Mixed message

else return;

int idx = 0;

int pStart = 0;

int activePRNs[12];

int prnCount = 0;

int systemId = 0;

for (int i = 0; i < line.length(); i++) {

if (line[i] == ‘,’ || line[i] == ‘*’) {

String val = line.substring(pStart, i);

// PRNs are in fields 3 to 14

if (idx >= 3 && idx <= 14 && val.length() > 0) {

if (prnCount < 12) activePRNs[prnCount++] = val.toInt();

}

// System ID in field 18 (NMEA 4.10)

if (idx == 18 && val.length() > 0) {

systemId = val.toInt();

}

idx++;

pStart = i + 1;

}

if (systemId == 1) sys = “GPS”;

else if (systemId == 2) sys = “GLONASS”;

else if (systemId == 3) sys = “Galileo”;

else if (systemId == 4) sys = “BeiDou”;

for (int i = 0; i < prnCount; i++) {

int prn = activePRNs[i];

for (auto &s : sats) {

bool sysMatch = (sys == “GNSS”) ? true : (s.system == sys);

if (s.prn == prn && sysMatch) {

s.lastActive = millis();

break; // Found satellite, move to next PRN in GSA message

}

// ———- Setup ———-

void setup() {

Serial.begin(115200);

GPSserial.begin(9600, SERIAL_8N1, 16, 17); //adjust this if using soemthing other than Wroom

// Increase buffer to prevent overflow during heavy parsing

GPSserial.setRxBufferSize(1024);

setupWiFi();

ws.onEvent(onWsEvent);

server.addHandler(&ws);

server.on(“/”, HTTP_GET, [](AsyncWebServerRequest *request) {

request->send_P(200, “text/html”, index_html);

});

server.begin();

Serial.println(“Server started”);

}

// ———- Loop ———-

void loop() {

static String nmeaLine = “”;

static unsigned long lastNMEASend = 0;

static unsigned long lastJsonSend = 0;

static unsigned long lastSatSend = 0;

static unsigned long lastPing = 0;

// Pass commands from u-center (PC) to GPS module

while (Serial.available()) {

GPSserial.write(Serial.read());

}

while (GPSserial.available()) {

char c = GPSserial.read();

Serial.write(c); // Pass GPS data to u-center (PC)

gps.encode(c);

if (c == ‘\n’) {

if (nmeaLine.startsWith(“$GPGSV”) ||

nmeaLine.startsWith(“$GLGSV”) ||

nmeaLine.startsWith(“$GAGSV”) ||

nmeaLine.startsWith(“$BDGSV”) ||

nmeaLine.startsWith(“$GNGSV”)) {

parseGSV(nmeaLine);

}

if (nmeaLine.startsWith(“$GNGSA”) ||

nmeaLine.startsWith(“$GPGSA”) ||

nmeaLine.startsWith(“$GLGSA”) ||

nmeaLine.startsWith(“$GAGSA”) ||

nmeaLine.startsWith(“$BDGSA”)) {

parseGSA(nmeaLine);

}

if (millis() – lastNMEASend > 250) {

ws.textAll(nmeaLine);

lastNMEASend = millis();

}

nmeaLine = “”;

} else if (c != ‘\r’) {

nmeaLine += c;

}

if (millis() – lastJsonSend > 1000) {

lastJsonSend = millis();

if (gps.location.isValid()) {

String json = “{“;

json += “\”lat\”:” + String(gps.location.lat(), 6) + “,”;

json += “\”lng\”:” + String(gps.location.lng(), 6) + “,”;

json += “\”speed\”:” + String(gps.speed.kmph(), 1) + “,”;

json += “\”alt\”:” + String(gps.altitude.meters(), 1) + “,”;

json += “\”cog\”:” + String(gps.course.deg(), 1) + “,”;

json += “\”sats\”:” + String(gps.satellites.value()) + “,”;

json += “\”hdop\”:” + String(gps.hdop.hdop(), 1);

json += “}”;

ws.textAll(json);

}

if (millis() – lastSatSend > 2000) {

lastSatSend = millis();

// Prune old satellites (not seen in 10 seconds)

for (int i = sats.size() – 1; i >= 0; i–) {

if (millis() – sats[i].lastView > 10000) sats.erase(sats.begin() + i);

}

if (!sats.empty()) {

String satJson = “[“;

for (size_t i = 0; i < sats.size(); i++) {

satJson += “{“;

satJson += “\”prn\”:” + String(sats[i].prn) + “,”;

satJson += “\”elev\”:” + String(sats[i].elevation) + “,”;

satJson += “\”azim\”:” + String(sats[i].azimuth) + “,”;

satJson += “\”snr\”:” + String(sats[i].snr) + “,”;

satJson += “\”system\”:\”” + sats[i].system + “\”,”;

// Mark used if active in the last 3.5 seconds

satJson += “\”used\”:” + String((millis() – sats[i].lastActive < 3500) ? “true” : “false”);

satJson += “}”;

if (i < sats.size() – 1) satJson += “,”;

}

satJson += “]”;

ws.textAll(satJson);

}

if (millis() – lastPing > 15000) {

ws.pingAll();

lastPing = millis();

}

***********************************************************************************************************************