GSM-Based Vehicle Tracking System: SIM800L & GPS Arduino

A GSM vehicle tracking system using SIM800L and GPS with Arduino is one of the most practical and satisfying projects an Indian maker can build. Whether you want to track a two-wheeler, monitor a delivery vehicle, or build a low-cost fleet management prototype, this combination of the SIM800L GSM module and the NEO-6M GPS module gives you real-time location data over India’s 2G network — which still has excellent coverage even in semi-urban areas. In this guide, you will get a complete hardware circuit, working Arduino code, and practical tips for using Indian SIM cards with SIM800L.

Components Required

• Arduino Uno or Nano
• SIM800L GSM/GPRS module
• NEO-6M GPS module
• Active GPS ceramic antenna (25×25mm, 28dB)
• 3.7V–4.2V LiPo battery or 3.4–4.4V regulated supply for SIM800L
• 1000µF / 6.3V capacitor (SIM800L power decoupling)
• Indian SIM card with 2G data/SMS plan (Jio does NOT work; use Airtel, Vi, or BSNL prepaid)
• Jumper wires, breadboard or PCB

GPS NEO-6M Satellite Positioning Module for Arduino

Widely used NEO-6M GPS module with UART interface, perfect for vehicle tracking projects. Includes onboard patch antenna.

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NEO-6M GPS Module with EPROM

NEO-6M GPS with onboard EPROM for faster cold start — reduces time to first fix (TTFF) significantly on power-up.

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SIM800L Module Overview & Indian SIM Compatibility

The SIM800L is a quad-band GSM/GPRS module that supports 850/900/1800/1900MHz. It communicates with Arduino via UART using AT commands and can send SMS, make calls, and send GPRS data packets. It is the go-to choice for IoT tracking projects due to its small size (24×24mm) and low cost.

Critical: SIM Card Compatibility in India

This is the most common issue Indian makers face. The SIM800L operates on 2G (GSM) networks. As of 2024:

• Jio: Does NOT work — Jio shut down its 2G network entirely. Jio SIMs will not register on SIM800L.
• Airtel: Works — Airtel still maintains 2G in most areas. Use an Airtel prepaid SIM. Activate it in a 2G-capable phone first.
• Vodafone-Idea (Vi): Works — Vi has 2G coverage in most cities and rural areas.
• BSNL: Works — Best rural coverage on 2G, ideal for vehicle tracking in remote areas.

SIM800L Power Requirements

The SIM800L requires 3.4V–4.4V DC, NOT 5V. It draws current spikes of up to 2A during GPRS transmission. Use a dedicated LiPo battery or a high-current 3.7V voltage regulator. Never power it from the Arduino’s 3.3V or 5V pins — this is the number one cause of "SIM800L not responding" issues.

NEO-6M GPS Module Overview

The u-blox NEO-6M is a compact GPS receiver with a UART interface (9600 baud default) that outputs NMEA sentences. Key specs:

• 50 channels, -161dBm tracking sensitivity
• Time to First Fix (cold start): ~27 seconds (with clear sky view)
• Horizontal accuracy: 2.5m CEP (with active antenna)
• Operating voltage: 3.3V–5V (most breakout boards have a regulator)
• Update rate: 1Hz default, configurable to 5Hz

25x25x8mm 28dB High Gain Active GPS Antenna for NEO-6M

External active ceramic GPS antenna with 28dB LNA gain — dramatically improves satellite fix in urban Indian environments with tall buildings.

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Circuit Diagram & Wiring

Use two separate SoftwareSerial ports on Arduino to communicate with both the SIM800L and NEO-6M simultaneously (Arduino Uno has only one hardware UART, used for USB/debug).

Arduino Code: GPS Coordinates via SMS

#include <SoftwareSerial.h>
#include <TinyGPS++.h>

SoftwareSerial sim800(2, 3); // SIM800L: RX=D2, TX=D3
SoftwareSerial gpsSerial(4, 5); // NEO-6M: RX=D4, TX=D5
TinyGPSPlus gps;

String phoneNumber = "+91XXXXXXXXXX"; // Your Indian mobile number

void setup() {
  Serial.begin(9600);
  sim800.begin(9600);
  gpsSerial.begin(9600);
  delay(3000);
  Serial.println("System ready");
  sim800.println("AT"); // Test SIM800L
  delay(1000);
  sim800.println("AT+CMGF=1"); // SMS text mode
  delay(500);
}

void sendSMS(float lat, float lng) {
  String mapLink = "https://maps.google.com/?q=" + String(lat, 6) + "," + String(lng, 6);
  sim800.println("AT+CMGS="" + phoneNumber + """);
  delay(500);
  sim800.print("Location: " + mapLink);
  sim800.write(26); // Ctrl+Z to send
  delay(3000);
  Serial.println("SMS sent: " + mapLink);
}

void loop() {
  // Read GPS data
  while (gpsSerial.available() > 0) {
    gps.encode(gpsSerial.read());
  }
  
  if (gps.location.isUpdated() && gps.location.isValid()) {
    float lat = gps.location.lat();
    float lng = gps.location.lng();
    Serial.print("Lat: "); Serial.print(lat, 6);
    Serial.print(" Lng: "); Serial.println(lng, 6);
    sendSMS(lat, lng);
    delay(60000); // Send location every 60 seconds
  }
}

Libraries needed: Install TinyGPS++ by Mikal Hart from the Arduino Library Manager. SoftwareSerial is built into the Arduino IDE.

Google Maps Integration

The SMS sent by the tracker contains a Google Maps link in the format https://maps.google.com/?q=LAT,LNG. When you receive this SMS on your smartphone, tapping the link opens Google Maps at the exact vehicle location. No server or app is needed for this basic setup.

Upgrading to GPRS Tracking (IoT Platform)

For continuous tracking with history, upgrade the code to use SIM800L’s GPRS to POST coordinates to a free IoT platform like:

• ThingSpeak: Free tier, supports up to 8 fields per channel, good for Indian students
• Ubidots: Has a map widget, free tier available
• Cayenne myDevices: Easy dashboard with GPS map out of the box

Adafruit FONA 808 – Mini Cellular GSM + GPS Breakout

All-in-one GSM + GPS module on a single breakout — simplifies wiring for vehicle tracking projects compared to using separate modules.

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Power Supply Tips for Vehicles

Deploying this tracker in an actual vehicle introduces power supply challenges that your bench setup never will.

12V Vehicle Battery to Arduino

Use a mini DC-DC buck converter module (LM2596-based) to step down the vehicle’s 12V to 5V for Arduino. Do NOT use a 7805 linear regulator — it will overheat and burn in an enclosed vehicle, especially in Indian summer conditions (cabin temps can exceed 65°C).

SIM800L Power

Power the SIM800L from a dedicated LiPo cell or use a high-current capable LDO/buck converter set to 3.9V. A 1000µF capacitor across the SIM800L power pins is mandatory to handle current spikes during GPRS bursts.

GPS Antenna Placement

Mount the active GPS antenna on the dashboard near the windscreen, or on the roof if you use an external magnetic mount antenna. Avoid placing it inside metal dashboards or under engine bonnets. In sedans, the antenna works well on the rear parcel shelf near the back window.

Ignition-Switched Power

Wire the tracker’s 12V input to the vehicle’s ignition-switched ACC line (not directly to the battery) so it powers on/off with the ignition. This prevents battery drain when the vehicle is parked for extended periods.

15cm 3dBi GSM/GPRS/3G PCB Antenna with IPEX Connector

Compact PCB antenna for SIM800L with IPEX/U.FL connector — improves GSM signal strength inside metal vehicle enclosures.

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Frequently Asked Questions