Air Defense System – DIY Arduino Project

Welcome back to another exciting and advanced IoT + Embedded Systems project by YaranaIoT Guru — the Air Defense System – DIY Arduino Project.
This is one of the most fascinating projects you can build at home to simulate how real-world radar and air defense systems detect incoming aerial threats — safely, educationally, and creatively using Arduino and sensors.

The goal of this project is not to create a real weapon, but to learn the core principles behind radar scanning, distance measurement, tracking, and automation.

🔹 What is an Air Defense System?

An Air Defense System is designed to detect, track, and respond to airborne objects like aircraft, drones, or missiles. In the military, these systems use radar, infrared, and tracking sensors to identify threats and automatically respond using countermeasures.

But in our DIY educational version, we will simulate this process using:

Ultrasonic sensor (HC-SR04) or LiDAR to detect objects,
Servo motor to rotate the sensor,
Arduino to process and control data,
Buzzer/LED to simulate an alarm or defensive action, and
Processing (PC Software) for radar-style visualization.

This gives you a realistic experience of how air surveillance systems work, while staying 100% safe and within learning limits.

🔹 Main Features of the Project

✅ Real-time radar scanning with live motion
✅ Detection of objects using ultrasonic or LiDAR sensors
✅ Automatic servo rotation for wide scanning range
✅ Visual radar display on a computer using Processing software
✅ Alarm activation when an object enters the detection zone
✅ Modular design – works with Arduino UNO, Nano, or ESP32
✅ Extendable to Wi-Fi alert, GPS, or GSM (4G) systems

🔹 Learning Objectives

By the end of this project, you’ll understand:

How ultrasonic or LiDAR sensors measure distance
How servo motors can simulate radar scanning
How to send serial data from Arduino to PC
How to visualize sensor readings in a radar-like display
How to trigger alarms or automatic responses

This project perfectly combines electronics, programming, and real-world logic, giving students and IoT enthusiasts a solid foundation in automation and defense-inspired systems.

🔹 Applications of This Project

While this is a simulation, the same concepts are used in:

Anti-drone systems
Border surveillance
Object detection robots
Autonomous security systems
Smart military training tools
IoT radar and tracking modules

🔹 System Working Principle

Servo Scanning: The servo motor rotates from 0° to 180°, carrying the ultrasonic sensor to scan its environment.
Object Detection: The ultrasonic sensor sends sound waves and calculates the distance by measuring the echo time.
Data Processing: The Arduino processes distance readings and determines if any object is within the threat range.
Alert Mechanism: If a target is detected, an LED and buzzer are triggered to simulate an air defense response.
Visualization: Data is sent to a PC using the Serial interface, where Processing software visualizes the detected object in real time.

🔹 How Real It Feels

When you finish the setup, you’ll actually see your sensor sweeping back and forth like a radar antenna — and when an object (like a hand, ball, or drone) enters its path, the buzzer and LED instantly respond. It’s a perfect demonstration of automation + defense logic in action.

🧩 Required Components

Before we dive into wiring and setup, let’s list everything you’ll need for the project. These components are easy to find and budget-friendly.

Component	Quantity	Description
Arduino UNO / Nano	1	The main microcontroller used for controlling all sensors and outputs
Ultrasonic Sensor (HC-SR04)	1	Detects objects by measuring distance using sound waves
Servo Motor (SG90 or MG90S)	1	Rotates the ultrasonic sensor to simulate radar scanning
Buzzer	1	Simulates alarm or alert tone when an object is detected
Red LED	1	Indicates detection of a nearby object
220Ω Resistor	1	Used to limit current for LED
Breadboard / PCB	1	For easy connections and prototyping
Jumper Wires (Male-Male)	Several	Used to connect components
USB Cable	1	To connect Arduino to PC for programming and Processing interface
5V Power Supply / USB	1	Powers the circuit
(Optional) ESP32 / A7670C 4G Module	1	For wireless IoT alert system (future upgrade)

🧠 Circuit Overview

The Air Defense Radar System consists of three main parts:

Sensor Module (HC-SR04): Measures distance by sending out an ultrasonic pulse and detecting the echo.
Servo Mechanism: Continuously rotates the sensor between 0° and 180° to scan the surroundings.
Alert & Processing System: Arduino calculates the distance and sends live data to the computer for visualization while triggering LED/Buzzer alerts when an object is detected within a critical range.

⚡ Pin Connections

Module	Arduino Pin	Description
Ultrasonic Sensor – VCC	5V	Power input
Ultrasonic Sensor – GND	GND	Ground
Ultrasonic Sensor – TRIG	D9	Trigger pin for sending pulses
Ultrasonic Sensor – ECHO	D10	Echo pin for receiving sound reflection
Servo Motor – Signal	D11	Controls the rotation of the servo
Buzzer – Positive	D7	Activates alarm on detection
LED – Positive	D6	Turns ON when object detected
Common GND	GND	Shared ground connection

🔌 Wiring Instructions

Mount the Ultrasonic Sensor on top of the servo motor using a small bracket or hot glue.
- The sensor will rotate left and right as the servo moves, simulating radar sweep.
Connect the Sensor:
- TRIG → Pin D9
- ECHO → Pin D10
- VCC → 5V
- GND → GND
Connect the Servo:
- Signal → D11
- VCC → 5V
- GND → GND
Connect LED and Buzzer:
- LED → D6 (through a 220Ω resistor)
- Buzzer → D7
- Both GNDs connected to Arduino GND
Connect Arduino to PC via USB for serial communication and power supply.

🧭 Circuit Diagram Description

When you visualize this circuit, the ultrasonic sensor sits on top of the servo motor, allowing rotational scanning. The servo is controlled via PWM from Arduino (pin D11). The ultrasonic module uses the trigger pin to send high-frequency sound waves, and the echo pin to receive the reflected signal.

Whenever an obstacle is detected within a specified range (say 20 cm), the buzzer and LED activate to simulate the defense system engaging.

Meanwhile, the Arduino continuously sends the current angle and distance via Serial communication to your Processing software, which displays the radar-like interface on the computer screen.

💡 Safety and Power Tips

Always power the servo motor with a stable 5V — if using USB, avoid overloading the Arduino’s onboard regulator.
If servo jitter occurs, use an external 5V supply shared with Arduino’s GND.
Double-check the connections before uploading the code. Incorrect servo wiring can cause high current draw or damage the board.
Avoid mechanical obstruction to the servo arm while scanning.

🧰 Mounting the Setup

To make your project look professional:

Use a cardboard or acrylic baseplate for stability.
Mount the Arduino and breadboard neatly.
Place the servo and sensor assembly at the center front for best scanning coverage.
You can even label sections like “RADAR SCANNER,” “DEFENSE ALERT,” etc., for a more finished look.

🔄 Working Recap So Far

Step 1: Servo rotates sensor → sweeping motion.
Step 2: Sensor measures distance.
Step 3: Arduino calculates range.
Step 4: Alerts trigger when object detected.
Step 5: Data sent to PC for radar display.

At this stage, your circuit is ready and tested for rotation and detection.

🧠 Overview

Now that the hardware setup is complete, it’s time to program your Arduino Air Defense System.
In this part, we’ll write and explain the complete Arduino sketch that:

Controls the servo motor for radar scanning
Measures distances using the ultrasonic sensor
Sends live angle–distance data to the PC for radar visualization
Activates buzzer and LED alerts when an object is within a defined threat zone

This program brings your system to life — making it move, sense, react, and communicate like a real radar-based defense system.

⚙️ Arduino Code

Below is the full Arduino sketch, fully commented and ready to upload.

/***************************************************
  Air Defense System – DIY Arduino Project
  Developed by YaranaIoT Guru
  Description: Simulates radar scanning & target detection
****************************************************/

#include <Servo.h>  // Servo motor control library

Servo radarServo;

// Pin definitions
const int trigPin = 9;
const int echoPin = 10;
const int buzzerPin = 7;
const int ledPin = 6;

// Variables
long duration;
int distance;

void setup() {
  Serial.begin(9600);
  radarServo.attach(11); // Servo connected to D11

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);

  Serial.println("Air Defense Radar System Initialized...");
}

void loop() {

  // Sweep servo from 0° to 180°
  for (int angle = 0; angle <= 180; angle++) {
    radarServo.write(angle);
    delay(20);
    distance = getDistance();

    // Send angle & distance to Processing
    Serial.print(angle);
    Serial.print(",");
    Serial.println(distance);

    // Activate alert if target detected
    if (distance < 25 && distance > 0) {
      digitalWrite(buzzerPin, HIGH);
      digitalWrite(ledPin, HIGH);
    } else {
      digitalWrite(buzzerPin, LOW);
      digitalWrite(ledPin, LOW);
    }
  }

  // Sweep back from 180° to 0°
  for (int angle = 180; angle >= 0; angle--) {
    radarServo.write(angle);
    delay(20);
    distance = getDistance();

    Serial.print(angle);
    Serial.print(",");
    Serial.println(distance);

    if (distance < 25 && distance > 0) {
      digitalWrite(buzzerPin, HIGH);
      digitalWrite(ledPin, HIGH);
    } else {
      digitalWrite(buzzerPin, LOW);
      digitalWrite(ledPin, LOW);
    }
  }
}

// Function to measure distance using ultrasonic sensor
int getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;  // Convert to cm
  return distance;
}

📜 Code Explanation

Let’s break it down step by step:

1️⃣ Servo Control

radarServo.attach(11);

This command attaches the servo motor to pin D11. The servo is rotated between 0°–180° in both directions to simulate radar motion.

2️⃣ Distance Measurement

duration = pulseIn(echoPin, HIGH);
distance = duration * 0.034 / 2;

The ultrasonic sensor emits a sound pulse via the TRIG pin.
It waits for the echo via the ECHO pin.
The time difference (duration) is converted to distance in centimeters.

3️⃣ Data Transmission

Serial.print(angle);
Serial.print(",");
Serial.println(distance);

This sends live scanning data to the PC over Serial communication, which is later visualized as a radar graph using the Processing IDE.
Each data line contains an angle and distance separated by a comma.

4️⃣ Alert Trigger

if (distance < 25 && distance > 0) {
  digitalWrite(buzzerPin, HIGH);
  digitalWrite(ledPin, HIGH);
}

If the detected object is within 25 cm, the buzzer and LED are activated — simulating the defense system engaging a target.

5️⃣ Bidirectional Scanning

The two for-loops (0° → 180° and 180° → 0°) ensure continuous sweeping in both directions — giving a real radar-like motion.

🔍 Testing the Setup

Once you’ve uploaded the code:

Open Serial Monitor (9600 baud).
You’ll see real-time angle–distance data.
Move your hand or an object in front of the sensor.
When it enters the defined range (under 25 cm), the LED and buzzer will activate.

This confirms that your hardware and logic are functioning correctly.

💡 Troubleshooting Tips

Issue	Possible Cause	Solution
Servo not moving	Wrong pin or low power	Check connection and use external 5V
Distance always shows 0	TRIG/ECHO swapped	Correct the wiring
Random false alerts	Electrical noise	Add capacitor across power lines
Serial data unreadable	Wrong baud rate	Set to 9600 in both code & Serial Monitor

🎯 Bringing the Radar to Life with Processing IDE

Your Arduino is now continuously sending angle + distance data via the serial port.
To see the scanning radar visually — just like a real defense console — we’ll use the Processing IDE, a powerful graphical programming environment.

🧩 Step 1: Install Processing IDE

Visit https://processing.org/download.
Choose the version for your OS (Windows/Mac/Linux).
Extract and install it.
Open a new sketch — this will be used to visualize radar data.

🧠 Step 2: Understanding How It Works

The Processing sketch will:

Read serial data sent by Arduino (angle,distance)
Draw a radar-like arc on the screen
Display detected objects as dots or red zones
Simulate a rotating sweep line

Essentially, it turns your Arduino’s numeric output into a live, graphical radar interface.

💻 Step 3: Processing Code

/***************************************************
 Air Defense Radar Visualization – Processing Sketch
 Developed by YaranaIoT Guru
****************************************************/

import processing.serial.*;
Serial myPort;
String data = "";
int angle, distance;

void setup() {
  size(1000, 600);
  myPort = new Serial(this, "COM5", 9600); // Change COM port as needed
  myPort.bufferUntil('\n');
  background(0);
}

void draw() {
  fill(0, 10);
  noStroke();
  rect(0, 0, width, height); // Slight fade effect

  // Draw radar circle
  stroke(0, 255, 0);
  noFill();
  ellipse(width/2, height, 400, 400);
  ellipse(width/2, height, 300, 300);
  ellipse(width/2, height, 200, 200);
  ellipse(width/2, height, 100, 100);

  // Draw angle line
  translate(width/2, height);
  stroke(0, 255, 0);
  line(0, 0, 400*cos(radians(angle)), -400*sin(radians(angle)));

  // Plot detected object
  if (distance < 40 && distance > 0) {
    float x = distance * cos(radians(angle));
    float y = -distance * sin(radians(angle));
    fill(255, 0, 0);
    noStroke();
    ellipse(x, y, 10, 10);
  }
}

void serialEvent(Serial p) {
  data = p.readStringUntil('\n');
  if (data != null) {
    data = trim(data);
    String[] values = split(data, ',');
    if (values.length == 2) {
      angle = int(values[0]);
      distance = int(values[1]);
    }
  }
}

⚙️ Step 4: Linking Arduino & Processing

Upload your Arduino sketch first.
Note the COM port (e.g., COM5).
Edit that line in the Processing code: myPort = new Serial(this, "COM5", 9600);
Run the Processing sketch.

You’ll now see a green sweeping radar line and red dots whenever an object appears in range — just like a mini defense console!

🚀 Real-World Testing

Here’s what to expect during live testing:

Test Action	Expected Response
Place an object 15 cm away	Red dot on radar, buzzer + LED on
Move object slowly	Dot moves accordingly on the screen
Object > 40 cm away	Dot disappears, silent state
Sweep line motion	Smooth left–right scanning with fade effect

You’ve now built a fully functional radar simulation system powered by Arduino + Processing!

🔧 Possible Improvements (Mk II Version)

Once you’ve mastered the basics, here are great upgrades for your next version:

Use ESP32 instead of Arduino UNO for Wi-Fi + IoT connectivity.
Send data to a cloud dashboard (like Ubidots / ThingsBoard / Blynk).
Add servo position feedback for more accuracy.
Use multiple ultrasonic sensors for a wider scan angle.
Integrate with a camera module to capture intruder images.
Display radar on an OLED screen without Processing.
Add GSM / 4G module (SIM A7670C) to send SMS alerts on detection.

These improvements can transform your DIY radar into a professional IoT-enabled Air Defense Simulator.

📊 Key Learnings

By completing this project, you learned how to:

✅ Interface and control a servo motor
✅ Measure distances with ultrasonic sensor (HC-SR04)
✅ Use Serial Communication for data transfer
✅ Visualize real-time sensor data with Processing IDE
✅ Build a responsive alert system with LED + buzzer
✅ Apply creative programming to simulate military radar systems

🧩 Project Summary

Component	Function
Arduino UNO	Central controller
Ultrasonic Sensor	Object detection
Servo Motor	Radar sweep movement
LED + Buzzer	Threat alerts
Processing IDE	Graphical radar display
Power Supply (5 V)	System power

🌐 IoT Integration Idea (Optional)

If you connect this setup to an ESP32, you can:

Publish radar data to Ubidots or ThingSpeak in real-time.
Create dashboards showing live sweep positions and target distances.
Control the radar remotely using a mobile app.

This turns your DIY project into a Smart IoT Air Defense System, merging hardware, networking, and cloud visualization.

🏁 Conclusion

Congratulations! 🎉
You’ve successfully built a DIY Air Defense Radar System using Arduino.
It scans, detects, alerts, and even visualizes intruding objects — just like an actual defense radar station.

This project is not only fun but also a perfect combination of electronics + programming + visualization + IoT concepts.

Keep experimenting — maybe the next version from Yarana IoT Guru will include AI object recognition or automated target tracking! 🔥

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