MULTIPLE-TARGET FREQUENCY-MODULATED CONTINUOUS-WAVE RANGING BY EVALUATION OF THE IMPULSE-RESPONSE PHASE

A microwave frequency-modulated continuous wave (FMCW) radar for preci sion ranging of multiple targets is described. The evaluation of the F MCW raw data is based on a fast Fourier transform (FFT), In contrast t o costumary techniques, we additionally evaluate its phase, The phase ambiguity is resolved on the basis of the more approximate envelope ev aluation. The FMCW system does not need separate phase measurements, h owever, the phase information is extracted from the FMCW data. In comp arison with conventional FFT techniques the evaluation Of ''response p hase'' enhances measurement accuracy or, which is equivalent, allows o ne to reduce the sweeping bandwidth while maintaining accuracy, The ph ase processing implies a Hilbert transform, which leads to small phase errors, The algorithm can be extended. such that the phase measuremen t is essentially error-free, One makes use of the virtual range finder , where measurement data are compared with synthetically prepared data to achieve the best fit.