How does radar determine a vehicle's speed?

Radar determines a vehicle's speed by using the principle of Doppler effect, which involves bouncing radio waves off a moving target (in this case, the vehicle) and analyzing the frequency shift of the returned signals. When a radar signal is emitted, it travels to the moving vehicle and reflects back to the radar unit. If the vehicle is moving towards the radar, the frequency of the reflected signal increases, and if it is moving away, the frequency decreases. The radar system calculates the speed of the vehicle by measuring this frequency shift, allowing it to accurately determine how fast the vehicle is moving.

Other methods, while they may appear relevant, do not align with the functionality of radar systems. For example, measuring distance over time does not account for the specific dynamics of moving objects and is more typical of other types of measurements. Similarly, estimating based on acceleration patterns is not applicable in real-time speed measurement. Lastly, calculating the time taken to travel a specific distance is more basic and requires knowledge of initial and final positions, which is not how radar operates. The radar's method, focusing on the frequency changes of returned signals, is precise and effective for traffic enforcement.