Radar Sweep Protocol Initiated
The tremors started three days ago. Subtle at first, barely registering on the seismic sensors scattered around the Phoenix compound. But today, the ground shakes with purpose. Something massive is moving out there in the wasteland, and it's getting closer.
Commander Chen's voice crackles through the intercom as you work in the electronics bay. "Phoenix team, we need eyes on the perimeter. The motion sensors are picking up multiple contacts, but they're not giving us range or bearing. We're flying blind out here."
You glance at the salvaged ultrasonic sensor on your workbench. Next to it sits a servo motor, liberated from a damaged security drone last week. The LCD display shield catches the emergency lighting, its dark surface reflecting the red glow that bathes the compound during threat conditions.
This is it. The moment when theory becomes survival. You're about to build a 180-degree sweep radar system that could mean the difference between early warning and catastrophic surprise. The servo will rotate the ultrasonic sensor back and forth like a lighthouse beacon, while the sensor measures distances to anything that moves in the wasteland. The LCD will paint a picture of the approaching threats, each contact appearing as a cyan dot on a dark radar screen.
Outside, the tremors intensify. Whatever is coming, it's bringing friends. Time to give the Phoenix resistance the eyes they desperately need.
Mission Objectives
When you complete this radar upgrade, you'll be able to:
- Build an automatic sweeping radar system that rotates 180 degrees
- Control a servo motor to precisely position your ultrasonic sensor
- Display real-time distance measurements on a graphical radar screen
- Create visual range indicators showing how far threats can approach
- Understand how radar sweep patterns provide comprehensive area coverage
This system will automatically scan a 180-degree arc, measuring distances to objects and plotting them on a circular radar display. Each sweep reveals the position and range of anything in your detection zone.
Understanding Sweep Radar Technology
Think of how a lighthouse works. The beacon rotates in a steady circle, sending out light in all directions over time. When that beam hits a ship, the light reflects back, revealing the vessel's position. Our radar system works exactly the same way, but with sound instead of light.
The servo motor acts as our lighthouse mechanism, slowly rotating the ultrasonic sensor back and forth across a 180-degree arc. At each position, the sensor sends out a sound pulse and listens for the echo. The time between the pulse and echo tells us how far away any object is at that specific angle.
Real radar systems use radio waves that travel at the speed of light, but our ultrasonic version uses sound waves traveling at about 343 meters per second. This makes the math simpler and the components cheaper, while still providing excellent detection capability for close-range surveillance.
The magic happens when we combine position data with distance data. The servo tells us which direction we're pointing, and the ultrasonic sensor tells us how far the nearest object is in that direction. Plot those coordinates on a screen, and suddenly you have a complete picture of everything within your detection range.
This sweeping approach covers much more territory than a fixed sensor. A stationary ultrasonic sensor can only detect objects directly in front of it. But a rotating sensor can monitor an entire semicircle, tracking multiple targets and showing their relative positions on a single display.
Wiring the Radar Array
This wiring creates three separate communication channels between your HERO Board and the radar components:
- Ultrasonic Sensor (HC-SR04): Trigger pin to digital 22, Echo pin to digital 23. The trigger pin sends the "ping" command, while the echo pin listens for the return signal and measures timing.
- Servo Motor (SG90): Signal wire to digital pin 24, power to 5V, ground to GND. The servo needs the 5V supply because it contains both a motor and control circuitry.
- LCD Display Shield: Mounts directly onto the HERO Board pins. This shield uses multiple pins for communication but manages them automatically through the graphics library.
Make sure the servo's power wire connects to 5V, not 3.3V. Servos draw significant current during movement, and insufficient voltage will cause erratic positioning.