The Design of Radar Signals Having Both High Range Resolution and High Velocity Resolution

The very large power requirements of present-day radars clearly demand full utilization of the potential of existing equipment. Unfortunately, an efficient equipment use does not always lead directly to a signal possessing desired high resolution characteristics. The "Chirp" scheme, which employs linear frequency modulation and is discussed in detail in the accompanying paper, 1 represents one method by which the desirable high resolution properties may be secured with an optimum equipment utilization. However, in Section 3.5 of the accompanying paper it was pointed out that the Chirp scheme, like ordinary radar techniques, possesses an inherent ambiguity in a simultaneous determination of both the range and velocity of a moving target. Ambiguity diagrams, 2 which are representations of joint response functions in both time and Doppler frequency, provide a pictorial representation of the uncertainty in determining range (time) and velocity (Doppler frequency). Fig. 1, (which is a duplicate of Fig. 38 of the accompanying paper) schematically illustrates the ambiguity diagrams corresponding to three different transmitted signals: (a) a long constant-frequency sig809