It is one of the development directions of passive radar to expand the number of illuminators and increase the available signal power to improve the system performance.Aimed at the FM broadcasting passive radar

this paper researched the coherent processing technique based on multi-frequency signals.Starting from signal model

it deduced the expression of each matching-filter output

and analyzed the phase relationship of each signal and various factors infecting coherent integration of multi-signals.The differentia phase item of each signal was compensated during signal processing to realize coherent integration.At last

the performance improvements of range distinguishing

clutter restraint and detection SNR were discussed.Simulation results proved the valid of the theory analysis

and it was important to improve the system performance of passive radar.