Demonstration of Real-time Cognitive Radar using Spectrally-Notched Random FM Waveforms

With the reality of increasing radio frequency (RF) spectral congestion, radar systems capable of dynamic spectrum sharing are needed. Recent work has demonstrated a real-time cognitive capability on a software defined radio (SDR) by generating pulse-agile LFM chirps that vary their center frequency and bandwidth to avoid dynamic interference on a per-pulse basis. Separately, spectral notching of random FM waveforms was developed and experimentally evaluated as another means with which to mitigate emulated interference, though real-time operation had not yet been demonstrated. Here the operational framework of the former is combined with the waveform agility of the latter to facilitate real-time generation of notched, random FM waveforms as part of an integrated cognitive SDR architecture. This implementation supports pulse repetition frequencies up to 2.2 kHz for on-the-fly waveform synthesis, can incorporate multiple spectral notches per waveform, and can achieve notch depths of 25 dB relative to peak power (with greater depth possible given greater computational resources). Performance examples are illustrated along with implementation decisions and design trade-offs.