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Neets Module 18-Radar Principles | Next
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2-3
Figure 2-1.—Time relationship of waveforms.
This energy is conducted along a transmission line to the radar antenna. It is radiated by the antenna
into space. When this transmitter energy strikes one or more reflecting objects in its path, some of the
transmitted energy is reflected back to the antenna as echo pulses. Echo pulses from three reflecting
targets at different ranges are illustrated in figure 2-1. These echoes are converted to the corresponding
receiver output signals as shown in the figure. The larger initial and final pulses in the receiver output
signal are caused by the energy that leaks through the duplexer when a pulse is being transmitted.
The indicator sweep voltage shown in figure 2-1 is initiated at the same time the transmitter is
triggered. In other applications, it may be more desirable to delay the timing trigger pulse that is to be fed
to the indicator sweep circuit. Delaying the trigger pulse will initiate the indicator sweep after a pulse is
transmitted.
Note in figure 2-1 that the positive portion of the indicator intensity gate pulse (applied to the
cathode-ray tube control grid) occurs only during the indicator sweep time. As a result, the visible
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