Real-time 5.7 GHz Realization of Multidimensional 2D Hybrid Approximate DFT Spectrum Sensors for RF Situational Awareness

The measurement and perception of the RF spec-trum is key for managing the electromagnetic environment of the future. Multichannel spectrum sensors that measure the RF environment can provide situational awareness across dimensions of space and time, leading to information on modulation, bandwidth, and frequency use across multiple directions of propagation. This paper builds upon recent progress on efficient 32-channel 5.7 GHz spectrum sensing by using a multiplierless approximate DFT operating in the spatial domain. In this work, 32 parallel temporal FFTs of size 1024 bins are realized as a parallel processing systolic array on a Xilinx reconfigurable open architecture computing hardware (ROACH-2) FPGA system to enable fine grained spectrum monitoring at about 100 kHz resolution across 32 simultaneous digital RF beams.