A radar detection system that estimates the received pulse frequency of a pulse in a received radar signal using a signal transmit frequency or one that uses frequency agility during a pulse duration. The radar detector system may include a radar detector that receives the radar signal from an antenna or antenna array. The receiver may be channelized, and each channel path may include Gaussian bandpass filter(s) centered at a different frequencies. The system includes an extended range radar detector that receives the signal in the channels and processing logic that processes the detected channel signals to identify the pulse frequency of emitters with or without frequency agility during a pulse duration. The frequency estimates of the pulse are based on calibrated amplitude differences in adjacent channels.