Patent ID: 6225943
Filing Date: 2001-05-01
Classification: G01S

Abstract:
In the operation of a pulse radar transmitting a constant PRF waveform, such waveform being divided into successive sets of ""N"" pulses of radio frequency energy, each one of such pulses being at a predetermined frequency, the method of increasing the ambiguous range due to the constant PRF waveform, such method comprising the steps of:(a) shifting, relative to the phase of the radio frequency energy in the first one of the ""N"" pulses in each successive set, the phase of the radio frequency energy in each successive transmitted pulse, the amount, in degrees, of such shift in phase for any given pulse being proportional to the square of the number, ""n"", of pulse intervals in the constant PRF waveform between the first pulse and the given pulse in each set of ""N"" pulses;(b) correlating a delayed replica of each transmitted one of each one of the ""N"" pulses with simultaneously received echo signals from a desired range and from ambiguous ranges finally to produce ""N"" correlation signals, each one of such signals having an autocorrelated portion indicative of echo signals from the desired range and a cross-correlated portion indicative of echo signals from ambiguous ranges; and(c) integrating the ""N"" correlation signals to produce an output signal corresponding only to the sum of the autocorrelated portions in the ""N"" correlation signals.