Acusonic sensors to pinpoint incoming threats to Ajax combat vehicles

The British Army’s new Ajax armoured combat vehicles are to be equipped with sensors designed to detect the direction of incoming enemy fire.


Thales has signed a £3.7m deal with General Dynamics Land Systems-UK to install its Acusonic sensor system on the army’s new fleet of armoured vehicles, which are due to come into service in 2020.

The sensors are designed to enhance the crew’s situational awareness, allowing them to respond more effectively to threats, according to Chris Wardman of the Acusonic team at Thales.

“When you are in large, highly protected military vehicles, it is difficult to see outside,” said Wardman. “So you may get shot at, but you may not know where the fire is coming from, and where your threat is.”

The Acusonic system uses sound to detect the source of enemy fire. It is based on Thales’ work on naval sonar, and uses the same principal to detect sound travelling through air as in water, said Wardman.

Sensitive microphones detect changes in pressure as a bullet or other type of ordnance flies through the air. Complex algorithms then process this data to determine the range and bearing of the bullet.

“You can determine range by the time of flight, [by comparing] the time the supersonic wave hits you, with the time it takes for the sound to reach you, because one is travelling faster than the other,” said Wardman.

Each vehicle will be fitted with three sensors, to give the crew a 360-degree threat detection capability.

Software processes information from the sensors and displays it on a screen within the vehicle.

In the future, the software could also be enhanced, to allow the technology to listen for different threats, for example.

The device is being manufactured at the company’s site at Templecombe in Somerset.