03-06-2013, 04:42 PM
AM, FM, and Digital Modulated Systems
Digital Modulated.ppt (Size: 2.01 MB / Downloads: 74)
Amplitude Modulation (AM)
Double Sideband Suppressed carrier (DSSC)
Assymetric Sideband Signals
Single sideband signals (SSB)
Frequency Division Multiplexing (FDM)
Generation of SSB
SSB Can be generated using two techniques
Phasing method
Filter Method
Phasing method
This method is a special modulation type of IQ canonical form
of Generalized transmitters discussed in Chapter 4 ( Fig 4.28)
Filter Method
The filtering method is a special case in which RF processing (with a
sideband filter) is used to form the equivalent g(t), instead of using
baseband processing to generate g(m) directly. The filter method is the
most popular method because excellent sideband suppression can be
obtained when a crystal oscillator is used for the sideband filter.
Crystal filters are relatively inexpensive when produced in quantity at
standard IF frequencies.