Radar and ARPA Manual

TARGET DETECTION

129

the transmitted pulse will clear the aerial after the start of

the timebase by an elapsed time equal to the duration of

one pulse length. This instant will coincide with the

arrival of an echo from any reflecting surface which lies

at a distance of one-half pulse length from the aerial (see

Figure 3.1(a)). The theoretical minimum detection

range can thus be determined by calculating the distance

travelled by radar energy in one-half the duration of the

transmitted pulse.

Example

3.

i Calculate the theoretical minimum detec-

tion range for a radar which has three pulse lengths, the

durations of which are 1.0, 0.5 and 0.1