3-10
Figure 3-9.—Trace rotation.
To synchronize sweep rotation with antenna rotation, you must convert antenna azimuth (bearing)
information into electrical signals. These signals, usually provided by synchros, control the amplitudes
and polarities of the sawtooth sweep currents applied to the deflection coils.
Figure 3-10 illustrates the waveforms of current required to produce a rotating range sweep. The
amplitudes of the sawtooth sweep currents are varied sinusoidally (like a sine wave), corresponding to the
rotation of the antenna. Notice that there is a 90 degree phase difference between the amplitude variations
of the horizontal and vertical waveforms.
