GW Instek GRF-1300, Руководство пользователя

Страница: 63 / 110

RF Communication and Signals Experiments
Figure 5-3.
Spectrum of an
AM wave
U
cm
1/ 2 m
a
U
cm
1/ 2 m
a
U
cm
c
−
ω Ω
c
ω
c
ω + Ω
From the above analysis, we can understand that amplitude
modulation is a process of shifting a low frequency modulating
signal into the sideband of a high frequency carrier. Obviously,
in AM waves, the carrier does not contain any useful
information. Information is only included in the sidebands.
Experiment
contents
1. Measure the waveform and spectrum of an AM wave.
2. Measure the spectrum of the AM wave with different carrier
frequencies and with modulating signals with different
amplitudes.
1. Turn on the power to the GRF-1300 and GSP-730.
2. Set the GRF-1300 as follows:
•
Set the GRF-1300 to the default power-on state.
•
Connect the output port on the Baseband module to the AM
in port on the AM module with an RF cable.
•
Connect the RF/FM output port on the RF Synthesizer/FM
to the RF in port on the AM module with an RF cable.
•
Turn the potentiometer clockwise to the end.
Experiment
steps
3. Connect the AM output port to the input port of the spectrum
analyzer with the 800mm RF cable.
61