voltage remains constant. At 60 usec, the applied voltage is equal
to zero, and EL and ER are equal but opposite in polarity. After
this time, ER and EL decay to zero at a rate determined by the
universal time constant chart.
Section VII. RC PULSESHAPING CIRCUITS
30.
GENERAL.
In radar systems, it is often necessary to change or reshape
an input waveform. Sawtooth and triangular waveforms are required
for deflection circuits, and sharp pulses are required to trigger the
modulating and transmitting circuits. As seen previously, RC and RL
circuits may be used to obtain various output waveforms from
different inputs by varying the circuits' time constant and taking
the output waveforms from different components. Differentiators and
integrators are the two most common types of RC and RL shaping
circuits. Each shapes the waveform in a different way.
31.
DIFFERENTIATION.
a. A waveform is differentiated when the amplitude of the output
waveform is proportional to the rate of change of voltage in the
input waveform. Any highpass RC or RL circuit with a shorttime
constant, as compared to the reference periods of the applied
waveform, acts as a differentiator. In a series RL circuit, the
differentiated output is always taken across the inductor; while in a
series RC circuit, it is always taken across the resistor. The RC
differentiator (Figure 41A) is the most widely used.
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