GPS Module + Arduino: Does a Cheap Sensor Actually Work?

I connected a budget GPS module to my Arduino Mega to find out whether a cheap sensor can actually lock onto satellites. The short answer: it depends heavily on where you test it.

Wiring the GPS module to Arduino Mega

The GPS module needed soldering before I could connect the wires. The connections are straightforward:

VCC → 5V
GND → GND
TX → RX1 (pin 19)
RX → TX1 (pin 18)

Reading raw NMEA data

Upload this basic sketch and open the Serial Monitor at 9600 baud. The output looks like gibberish at first â€” that is actually NMEA data, a standard format that encodes position, time, and satellite info.

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);
}

void loop() {
  while (Serial1.available()) {
    Serial.write(Serial1.read());
  }
}

Parsing coordinates with TinyGPS++

Install the TinyGPS++ library via the Arduino Library Manager, then upload this sketch. It translates the raw NMEA stream into readable coordinates:

#include <TinyGPS++.h>

TinyGPSPlus gps;

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);
}

void loop() {
  while (Serial1.available()) {
    gps.encode(Serial1.read());
  }

  if (gps.location.isUpdated()) {
    Serial.print("Satellites: ");
    Serial.println(gps.satellites.value());
    Serial.print("Latitude:   ");
    Serial.println(gps.location.lat(), 6);
    Serial.print("Longitude:  ");
    Serial.println(gps.location.lng(), 6);
    Serial.print("Altitude:   ");
    Serial.println(gps.altitude.meters());
  }
}

Signal testing: indoors, window, and outside

I tested the module in three environments:

Indoors: No satellites detected. Walls block the signal completely.
Through a window: After waiting a couple of minutes, the module picked up 3 satellites and returned coordinates — but the altitude was wrong and the location pointed to France (I am not in France).
Outside in an open field: I waited 10 minutes per attempt, moved away from concrete to a grass area with no buildings within 50 metres — still no satellite lock.

Conclusion

A cheap GPS module has real limitations. It cannot get a signal indoors and struggled significantly even outside. Building a larger antenna might help improve reception. If you have experience improving GPS signal quality with cheap modules, leave a comment — I would love to revisit this in a future video.

Wiring the GPS module to Arduino Mega

Reading raw NMEA data

Parsing coordinates with TinyGPS++

Signal testing: indoors, window, and outside

Conclusion

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