Abstract: A radar transmitter in which a pseudo-random sequence of pulses are transmitted, each at a different frequency. Prior to the return of the first pulse, a receiver is retuned to the first transmit frequency, then the transmitter is retuned to the second transmit frequency and so on. The return pulses are integrated coherently across the sets at a each frequency to achieve the highest signal level. The pulses are integrated noncoherently within a set over all the frequencies transmitted to improve the signal-to-noise ratio.The technique of the present invention requires accurate knowledge of the range to the target. In a specific multi-line embodiment, the range calculation is provided by the centerline carrier frequency operating at a medium pulse repetition (prf) frequency. The retuning is then performed with the sidebands operating at a low prf.

Abstract: A system for transmitting a comb of radar signals. The invention includes a phase shifter for shifting the phase of an input carrier signal. A frequency modulation signal is adjusted in amplitude by an attenuator 16 and input to a balanced mixer 14. The balanced mixer 14 mixes the input carrier signal with the attenuated frequency modulation signal. A summer 20 combines the output of the phase shifter 12 with the output of the balanced mixer 14. The system 10 of the present invention provides an inexpensive means of generating and receiving a complex of illuminating signals having a spread spectrum consisting of lines (teeth) of carrier frequencies with controllable power. The system 10 is agile in that the power levels and the spectral positions of the teeth may be varied.