Patrol speed uses which type of Doppler frequency?

The correct answer is low frequency. Patrol speed using Doppler radar typically refers to the frequency at which the radar device operates to measure the speed of moving vehicles. Doppler radar works by sending out a signal and measuring the frequency shift of the reflected signal from a moving object.

Low frequencies are commonly utilized in applications involving longer distances and better penetration capabilities, which is ideal for patrol operations. This is particularly suitable for measuring speed in various conditions, including when vehicles are at considerable distances from the radar device. Low frequencies help mitigate the effects of obstacles and allow for more reliable speed detection.

In contrast, high frequencies might provide better resolution and detail but can be less effective over long ranges, making them less suitable for patrol speed detection. Medium frequencies, while useful for certain applications, do not align with the specific needs of speed measurement in this context. Ultra high frequency equipment tends to have limitations with range and obstruction, which do not cater to the typical requirements of patrol speed detection. Thus, low frequency is the optimal choice for effective and reliable speed detection in patrol scenarios.