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Chapter 7 Tutorial
Modulation
7
Modulation
Modulation is the process of modifying a high-frequency signal (called the
carrier signal) with low-frequency information (called the modulating
signal). The carrier and modulating signals can have any waveshape,
but the carrier is usually a sine waveform.
The two most common types of modulation are amplitude modulation
(AM) and frequency modulation (FM). These two forms of modulation
modify the carrier’s amplitude or frequency, respectively, according to
the instantaneous value of the modulating signal. Pulse width
modulation (PWM) is provided for pulse waveforms only. In PWM, the
pulse width or duty cycle of the pulse waveform is varied according to the
modulating signal.
The function generator will accept an internal or external modulation
source. If you select the internal source, the modulated waveform is
generated by a secondary DDS synthesizer. If you select the external
source, the modulated waveform is controlled by the signal level present
on the function generator’s rear-panel Modulation In connector.
The external signal is sampled and digitized by an analog-to-digital
converter (ADC). With either modulation source, the result is a stream of
digital samples representing the modulating waveform.
Amplitude Modulation (AM)
The function generator implements a form of AM called “double-
sideband transmitted carrier.” This is the type of modulation used by
most AM radio stations.
Amplitude Modulation
Modulating Signal
Modulated Carrier
(100% depth shown)
33210A users guide.book Page 326 Wednesday, July 16, 2008 11:16 AM
Summary of Contents for 33210A
Page 1: ...Keysight 33210A 10 MHz Function Arbitrary Waveform Generator User s Guide ...
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Page 14: ...12 Contents Contents 33210A users guide book Page 12 Wednesday July 16 2008 11 16 AM ...
Page 15: ...1 1 Quick Start 33210A users guide book Page 13 Wednesday July 16 2008 11 16 AM ...
Page 53: ...3 3 Features and Functions 33210A users guide book Page 51 Wednesday July 16 2008 11 16 AM ...
Page 273: ...5 5 Error Messages 33210A users guide book Page 271 Wednesday July 16 2008 11 16 AM ...
Page 301: ...6 6 Application Programs 33210A users guide book Page 299 Wednesday July 16 2008 11 16 AM ...
Page 311: ...7 7 Tutorial 33210A users guide book Page 309 Wednesday July 16 2008 11 16 AM ...
Page 335: ...8 8 Specifications 33210A users guide book Page 333 Wednesday July 16 2008 11 16 AM ...