Figure 1: Procedure of “Sliding Window”
The most common method of correlating hits to form a plot report is known as the sliding window process.
The detected hits for each pulse repetition period are inserted as „1”s in the stored range cell dimension. For ATC radars, the range cells are typically 1/16 of a nautical mile (ca 0.8 microseconds).
A number of results for previous pulse intervals are stored - typically results from 8 - 16 PRTs may be stored (depending upon the Dwell Time) - this represents the window size (N).
A window is applied at each range cell, to count the number of hits that are present in the window at the same range. Due to a degree of uncertainty regarding the precise range cell in which a hit will be declared, it is normal practice to include hits in adjacent range cells. The number of hits found in the window is used as the target detection criterium.