5-22
Figure 5-22.—Pulsed radar output.
Figure 5-23.—Pulsed radar changes caused by modulating signal changes.
ANALYZING THE SPECTRUM PATTERN
The leading and trailing edges of the radiated pulse-modulated signal must have a sharp rise time and
decay time and a constant amplitude between them. Incorrect pulse shape will cause frequency spread and
pulling, which results in less available energy at the frequency to which the receiver is tuned. The primary
reason for analyzing the spectrum is to determine the exact amount of amplitude and frequency
modulation present. The amount of amplitude modulation determines the increase in the number of
sidebands within the applied pulse spectrum; an increase in frequency modulation increases the amplitude
of the side-lobe frequencies. In either case, the energy available to the main spectrum lobe is decreased.
