Conducted Comb Generator model CGC-255E & CGC-510E
Page 12 of 15
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Rev. 022020
Theory
The conducted Comb Generators use an impulse to generate its step frequency output. It uses
a stable power supply and signal shaping circuit to obtain relatively stable signal output with
frequency components extending up to 115 MHz.
The Comb Generators operates on battery power. The battery output is controlled by a voltage
the regulator circuit to provide stable power output to the signal generating circuit. The signal
generating circuit consists of a clock generator, impulse generator, wave shaping circuit and
output matching. The signal frequency is generated by a crystal oscillator. An impulse in time
domain corresponds to a flat output across the entire frequency spectrum in frequency
domain. An ideal impulse, by definition is an infinite magnitude pulse with zero rise and fall
time with no duration. Such a pulse is not practical; however, the models CGC-255E and CGC-
510E conducted Comb generators use this principle to get an output across a wide band. The
highly stable frequency output from the oscillator is used to generate an impulse with very
short duration and sharp rise and fall times. The shaping circuit was designed for improved
stability, extended frequency response, and output impedance matching to 50 ohms. Since the
circuit cannot generate an ideal impulse with zero rise and fall times.
This theory describes the general behavior of the field, but each Comb Generator may behave
slightly different than the other due to circuit variation. Since the Comb Generators were
designed to provide a reference reading at a given frequency, this limitation is not a problem.
