Frequency Comb OFDM Radar System With High Range Resolution and Low Sampling Rate

Abstract

Common orthogonal frequency-division multiplexing (OFDM)-based radar waveforms normally require high sampling rates if a good range resolution shall be achieved. In contrast, this article proposes a scheme that keeps the necessary sampling rates at the transmitter (Tx) and receiver (Rx) constant while simultaneously increasing the instantaneous signal bandwidth in the radar channel. In addition, not only a high range resolution but also a high unambiguous velocity can be achieved with the waveform. The scheme is based on the upconversion and downconversion of a thinned out OFDM signal with two different frequency combs at the Tx and Rx. In the downconversion process, the orthogonal subcarriers of the several subbands in the RF channel are interleaved in a way that they can be sampled by an analog-to-digital converter with a lower sampling rate than the overall signal bandwidth. The theoretical model of the waveform and the necessary signal processing steps are explained in detail and the proof of concept measurements are provided, which verifies the practical functionality of the proposed scheme.