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A Bandpass Sampling Receiver for Wide-Bandwidth, Spectrally-Sparse Waveforms for High-Accuracy Range Measurements

Measuring range to millimeter accuracy using microwave wireless systems is challenging due to the need for wide-bandwidth waveforms. This work presents a Sparse Ranging Receiver (SpaRR) that utilizes spectrally-sparse waveforms and bandpass sampling to achieve high range accuracy measurements without the need for expensive wideband digitizers. The accuracy of a ranging system varies inversely with the RMS bandwidth of the waveform, and the optimal ranging waveform is one that concentrates its frequency content at the edges of its bandwidth. The SpaRR utilizes widely separate two-tone waveforms from L to X band to achieve high range accuracy with a low-speed digitizer. The theory, architecture, and signal processing associated with the SpaRR are presented, and measurements are shown demonstrating accuracies on the order of 100 μm for tone separations on the order of 2 GHz.