Complex sentence: When used within a moving vehicle the device measures the relative speed of the police and target vehicle, police are required to follow the offending vehicle for 200 metres and have a certified speedometer, largely negating advantages of the device.
Split into simpler sentences: When used within a moving vehicle the device measures the relative speed of the police and target vehicle. Police are required to follow the offending vehicle for 200 metres and have a certified speedometer, largely negating advantages of the device.