Page 396 - Fundamentals of Radar Signal Processing

FIGURE 5.28 Blind zone maps for two different PRIs. The maps are drawn to
the same velocity and range scales. Left: PRI = 100 μs. Right: PRI = 120 μs.

The left image of Fig. 5.29 results from overlaying the two blind zone maps
i n Fig. 5.28 on common intervals in range and velocity. Range-velocity
coordinates that are in the blind zone at both PRFs are shown as black; those in
only one of the two blind zones are shown in gray; and those in the clear on both

PRFs are shown in white. For example, the target at 300 m/s and 30 km
mentioned above falls in the gray area, suggesting that a radar collecting a CPI
of data at each of these two PRIs would detect the target on only one of them
(120 μs). The image on the right is the blind zone map that would result from the
use of these two PRIs and a “1 of 2” detection logic. This means that a detection
at particular range-velocity coordinates is accepted as being a true target if it is

detected on at least one of the CPIs; detection on both is not required. With this
logic, a target at any range-velocity pair in the white or gray area of the left
figure would be expected to be detectable (assuming adequate SIR). Only the
coordinate pairs in the black area of the left image would be considered blind,
leading to the blind zone map shown on the right.