Coherent Process for Random Frequency-Coded Chirp-Subpulse Stepped Frequency Signals

Random frequency-coded chirp-subpulse stepped frequency signals combine the advantages of frequency-coded signals and chirp signals. Positive characteristics of these signals include low probability of intercept (LPI), electromagnetic compatibility (EMC) and anti-ratio frequency interference (APFI). Due to inter-pulse frequency hopping, non-coherent accumulation techniques have traditionally been used in signal processing which has led to the deterioration of target detection performance in low signal-to-noise ratio (SNR) as well as clutter environments and limited anti-interference. To combat this problem, a phase cancellation based coherent process for random frequency-coded chirp-subpulse stepped frequency signals is proposed. This method combines the Doppler coherent process and range synthesis in the condition of interpulse frequency hopping. The effectiveness is tested and verified by simulation experiments.