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Digital Signal Analysis
What is a QAM Signal
Quadrature Amplitude Modulation (QAM) uses many different
phases known as states: 16, 32, 64, and 256. Each state is defined
by a specific amplitude and phase. This means the generation
and detection of symbols is more complex than a simple phase or
amplitude device. Each time the number of states per symbol is
increased the total data and bandwidth increases. The modulation
schemes shown occupy the same bandwidth (after filtering), but
have varying efficiencies (in theory at least).
QAM — Constellation Diagrams
Constellation diagrams are used to graphically represent the
quality and distortion of a digital signal. In practice, there is
always a combination of modulation errors that may be difficult
to separate and identify, as such, it is recommended to evaluate
the measured constellation diagrams using mathematical and
statistically methods. The following section will provide application
and interpretation information of constellation diagrams of digital
modulated signals.
Summary of Contents for AMM-806
Page 86: ...79 TVCB PC Installation ...
Page 93: ...86 SMI Installation Torque Patterns 1 Start Here 2 3 4 5 6 1 Start Here 2 3 4 4 PORT 8 PORT ...
Page 125: ...118 Fiber Optics Fiber Loss vs Path Length Single Mode 1550 nm ...
Page 156: ...149 Cable TV Channel Format NTSC NTSC Composite Video Waveform ...
Page 157: ...150 US Frequency Spectrum ...
Page 158: ...151 FCC Aeronautical Band Frequencies Used for Communication and Navigation ...
Page 175: ...168 Common CATV Symbols ...
Page 176: ...169 Common CATV Symbols ...
Page 177: ...170 Digital L Band Distribution Symbols ...
Page 178: ...171 Digital L Band Distribution Symbols ...
Page 183: ...176 Typical Cable Attenuation Chart in dB 100 Feet 68 F 20 C ...
Page 187: ...180 Echo Rating Graph ...
Page 188: ...181 Signal to Interference Limits Non Coherent Carriers ...
Page 190: ...183 Heterodyne Modulator Analog ...
Page 191: ...184 Heterodyne Processor Analog ...
Page 213: ...206 Multiplexers ...
Page 285: ...Rev 8 0 ...