Design Of The Traffic Speed-measured Radar System

Traffic-radar (Police used radar) is a direct application of continuous waved (CW) radar. It is well known that CW radar is able to measure Doppler effect as well as distance if a special code is used. It has many advantages, first, the facilities are simple and the transmit bandwidth is narrow. The narrow transmit bandwidth reduced wireless interference and simplified microwave preelection and filtering, so, it is easier to deal with the received waveform, because the bandwidth required by the intermediate frequency circuit is rather narrow. Second, no matter how fast and how far the target is, the CW radar can handle it without speed bluring.This dissertation proposed a new scheme of traffic radar based on CW radar. In this scheme, the working frequency of the microwave source is 24.15GHz, which means 100km/h equals 4374Hz, a frequency that is easy to be amplified. The microwave resource use a leakage controllable method to feed the echos to the crystal mixer, the output intermediate frequency signal, which schleps Doppler information is delivered to an orthogonal bi-channel noise amplifier, then through an A/D circuit to convert the analog signal to digital, finally, the digital signal is transmitted to the digital signal processor (DSP), through the software programming of DSP to complete digital filtering, FFT, and pick up target information in frequency, thereby realize the measurement of traffic speed.