the bandwidth must be 1 MHz in order to reproduce the leading edge of
the pulse. This formula also applies to the trailing edge by
substituting decay time tf for rise time tr.
d. Effects of harmonics on pulseduration time.
(1) The duration time (td) of a pulse depends on the low
frequency response of a circuit for good reproduction. Figure 7 is a
square wave that was passed through a circuit having poor, low
frequency response. Notice that the waveform is not flat on top
during the duration time. To obtain good reproduction of the
as good, highfrequency response.
Figure 7. Effect of a poor lowfrequency response on a
square wave
(2) The lowest frequency (fL) that a circuit must pass to
reproduce a pulse can be obtained from the formula fL = 1/prt, where
prt represents the pulse recurrence time in seconds. Notice that
this is the same as saying FL equals prf since the pulse recurrence
time is the reciprocal of the pulse repetition frequency. When the
lower frequency limit of the circuit equals the prf, satisfactory
reproduction results. A pulse having a repetition frequency of 1 kHz
requires that the lower limit of the bandwidth be 1 kHz.
8.
BANDWIDTH REQUIREMENTS FOR A SAWTOOTH WAVE.
a. The squarewave principles for high and lowfrequency
response can be applied to all nonsinusoidal waveforms. It can be
stated that the highfrequency response of a circuit affects any
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