The M314 Motion Tracker (also known as the motion scanner) is an iconic handheld ultrasound doppler surveillance device from the Alien franchise. Originally appearing in James Cameron's 1985 script for Aliens, it was standard-issue equipment for the US Colonial Marine Corps to track moving targets through contours, range, and bearing up to 1,000 meters.
Key Features & Lore
- Original Prop Design: The movie prop built by Terry Reed was famously crafted using a Kango 426 hammer drill casing and a Hama slide viewer.
- Functionality: It detects movement and displays proximity via a small radar/video screen accompanied by its signature, suspense-building "beep" that speeds up as targets get closer.
- Limitations: In-universe, it cannot differentiate between different types of movement, is vulnerable to jamming, and its active ultrasound pings can give away the user's location.
Replicas, Kits, and Apps
Official Prop Replicas: Collectors can find museum-quality, life-size props like the Hollywood Collectibles Group M314 Motion Tracker, which features working electronics and movie-accurate audio.
DIY & 3D Printed Kits: Fans often assemble or 3D-print their own functional or display props using kits found on Etsy or custom microcontroller builds using Raspberry Pi or ESP32 radar modules.
Mobile & Tabletop Apps: Interactive digital versions and companion apps exist for tabletop Alien RPG campaigns and mobile devices on iOS and Android to simulate live radar pings and tension.