Sub-Nyquist Ultra-Wideband Sparse Signal Reception via Variable Frequency Comb

We demonstrate a new class of ultra-wideband (UWB) sparse radio frequency (RF) signal receiver relying on direct sub-sampling in frequency domain and compressive sensing (CS) techniques. The sampling process is realized with a hybrid RF-photonic architecture for discrete Fourier transform (DFT) on broadband RF signals using a variable-pitch frequency comb. Sub-sampled DFT coefficients are used to recover the input RF signal which is sparse in a chosen domain. Instead of digitizing signals with a full-rate analog to digital converter (ADC), the new approach requires sub-rate quantization, reducing hardware complexity via sub-sampling in frequency domain. Both simulated and experimental verifications were achieved by high-fidelity reception of various sparse signals within 3 GHz to 7.9 GHz band.