In traffic RADAR, speed measurements are determined by changes in which signal property?

In traffic RADAR systems, speed measurements are primarily determined by changes in frequency, which is based on the Doppler effect. When a moving vehicle approaches or recedes from the RADAR unit, there is a shift in the frequency of the reflected signal relative to the transmitted signal. This frequency shift is directly proportional to the speed of the vehicle, allowing the RADAR to calculate its speed accurately.

The Doppler effect explains that the frequency of the waves changes depending on the relative motion between the source of the waves and the observer. As the vehicle moves towards the RADAR unit, the frequency increases (positive shift), and as it moves away, the frequency decreases (negative shift). By measuring this frequency change, traffic RADAR can effectively determine the speed of the vehicle in real-time.

While amplitude, velocity, and phase are important properties in different contexts, they do not directly relate to how traffic RADAR computes speed. Amplitude pertains to the strength of the signal rather than speed, velocity is the term for the speed vector of the moving object but isn’t measured directly, and phase changes can provide information about distance rather than speed in the case of RADAR. Thus, frequency is the key property used to ascertain speed in traffic RADAR applications