The active sonar is a device that uses sound propagation to detect nearby objects.
The active sonar functions by emitting a special sonic wave and detecting the resulting echoes. The waves' angle of reflection and reflection interval is then used to calculate and display the position of nearby objects.
During the CIA's Virtuous Mission and Operation Snake Eater of 1964, Naked Snake utilized an active sonar device, created by FOX's technology expert Sigint. The sound of the sonic wave carried the risk of revealing Snake's position to enemies and animals, necessitating caution when used, and could also be rendered inoperable by electronic jamming. Though the sonar's use was limited by batteries, its detection of stationary objects gave it an advantage over the motion sensor.
In 1984, Venom Snake's bionic arm was equipped with an active sonar, which he activates when pounding the ground with his fist, causing a minor shockwave.
Behind the scenes
The Active Sonar is featured in Metal Gear Solid 3: Snake Eater as one of several devices that can be used to locate the positions of enemy guards and animals. A sound wave is emitted by pressing the L3 button and the positions are displayed in the top right of the screen. It is very precise, though it is rendered inoperable by radio disruption during the Alert Phase. The item has a weight of 3.2 kg in the Backpack. The Active Sonar, as well as the Anti-Personnel Sensor and the Motion Detector, are not available in the European Extreme difficulty.
The Active Sonar also makes an appearance in the minigame Snake vs. Monkey.