The Motion Sensor is a gadget utilized in the Battlefield Series. It is an integral tool for scouting and collecting real-time intelligence, this portable high-tech device is designed for sensing even the slightest twitch of movement, alerting the owner when an enemy has breached the premises on foot or by vehicle. They can be thrown much like a grenade to help spot enemy infantry and vehicles in its radius. They operate for a short period of time, after which it will no longer detect enemies.
In Battlefield: Bad Company's singleplayer, on the single player level, Crash and Grab, the player starts with motion sensors, along with an MP-443 Grach and HG-2s.
In multiplayer, the MTN-55 is issued to the Recon kit. A kit can carry 3 of them at a time. When thrown, any enemies within the area of effect will appear as a red dot in the game or of a certain icon if they are in a vehicle, like when an enemy player is spotted, as well as inside the mini-map. There is no limit to how many can be thrown at a time; it is common for them to be spammed, as they can be replenished at ammo crates.
"An integral tool for scouting and collecting real time intelligence, this portable high tech device is designed for sensing even the slightest twitch of movement alerting an owner when an enemy has breached the premises on foot, or by vehicle."
— In-game description
The Motion Sensor returns in Battlefield: Bad Company 2 with many changes. It is still only available to the Recon class and the user can carry 3 of them at a time. The motion sensor displays enemies within its detection radius of 25 meters on the mini-map as red triangles, and has a shorter active time of twenty seconds. Only one of them can be used by a player at any given time; if another is used while the first one is still active it will be replaced by the second one. However the sensors now also send out a beeping noise whenever an enemy is detected, alerting the user in addition to their target. They can also be replenished by ammo boxes from Assault players, and resupplied very quickly. Motion sensors, as their name implies, can only detect motion. If a player remains still, the motion sensor will be unable to track the player. Paradoxically, motion sensors will detect enemy explosives that are planted (i.e. mines) by placing an icon on the tacmap, but this icon will disappear once the motion sensor has expired.
Enemies killed within the range of a motion sensor give the player a 'motion mine assist' worth 20 points, with 10 extra points if the kill was by a squadmate.
The Motion Sensor is a gadget available for the Recon kit. It works exactly in the same way as it does in the Bad Company series, but has a smaller range and a long recharge time. However, you can both increase range and reduce the time needed to throw a new motion sensor with the Motion Sensortraining option. It lasts on the ground for about 30 seconds.
After 2011/09/01 game update players get points for enemies that had been killed while their position was revealed on the mini-map by the Motion Sensor.
When a motion sensor is thrown, it makes a sound when it hits the ground. Hearing the tell-tale 'clink' will tell players that they have been spotted and should take some sort of action.
Standing still will not alert the player of their presence (looking around, aiming, using weapons and crouching are not detectable either). This may throw the enemy off, thinking that the player has left the area or been killed.
The motion sensor's design resembles that of Battlefield 2142's Motion Mine, though it lacks the arming switch.
Any enemies picked up by the motion sensor only appear on the map. Pips will not appear above an enemy's head. This makes the sensor less useful in Hardcore gamemodes as the distinctive bleep is the only giveaway of nearby enemies.