Tektronix TSG4102A, Руководство пользователя

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Operating basics
Output BNC which shows the 100 kHz modulating waveform. The middle trace
is the front panel BNC output, whose amplitude was set to 1 V
PP
. The bottom
trace is from the front panel Type N output, whose amplitude was set to 2 V
PP
.
Phase modulation Phase modulation can use either the internal modulation generator or an external
source. The internal modulator can generate sine, triangle, ramp, square, noise,
or user waveforms. The phase of the output traverses the speci
fi ed deviation at
the modulation rate. For example, with a frequency of 1000 MHz (1 GHz), and
modulation rate and deviation set to 10 kHz and 45°, respectively, the output will
be a
fi xed frequency with its phase traversing ±45 degrees at a 10 kHz rate.
Example.
The following image shows the frequency spectrum of a 0 dBm,
50 MHz carrier being phase modulated by a 10 kHz sine wave with a
deviation of 137.78°. Here, the modulation index,
β = phase deviation =
137.78° × 2 π / 360° = 2.40477 radians. For phase modulation by a sine,
the carrier amplitude is proportional to the Bessel function J0( β ), which
TSG4100A Series RF Signal Generators User Manual 35