Modulation scheme: Difference between revisions

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The [[Modulator]] converts an input signal into a form suitable for RF transmission. The [[Demodulator]] recovers the original signal. Since the RF signal is a based sine wave oscillating around the transmission frequency, the [[Modulator]] has to modulate this sine wave in a way so that all information is transmitted and well-recoverable but only as little [[Bandwidth]] as allowed is allocated.
The [[modulator]] converts an input signal into a form suitable for RF transmission. The [[demodulator]] recovers the original signal. Since the RF signal is a based sine wave oscillating around the transmission frequency, the modulator has to modulate this sine wave in a way so that all transmitted information is recoverable, but only as little [[bandwidth]] as allowed is allocated.


The more the Modulation Scheme modifies the original sine wave the more the [[Frequency]] of the RF sine wave will vary -- the higher the [[Bandwidth]] will be.
The more the '''modulation scheme''' modifies the original sine wave, the more the [[frequency]] of the RF sine wave will vary, and the higher the bandwidth will be.


{| class="wikitable"

|+ Analog modulation schemes
{| border="1" cellpadding="5" cellspacing="0" align="center"
|+'''Analog Modulation Schemes'''
|-
|-
! Shortform !! Name
! style="background:#ffdead;" | Shortform
! style="background:#ffdead;" | Name
|-
|-
! style="background:#efefef;" | [[Amplitude Modulation|AM]]
| AM || [[Amplitude modulation]]
! [[Amplitude Modulation]]
|-
|-
! style="background:#efefef;" | [[Frequency Modulation|FM]]
| FM || [[Frequency modulation]]
! [[Frequency Modulation]]
|-
|-
! style="background:#efefef;" | [[Wikipedia:Phase_modulation|PM]]
| PM || [[Wikipedia:Phase modulation|Phase modulation]]
! [[Wikipedia:Phase_modulation|Phase Modulation]]
|-
|-
|}
|}


{| class="wikitable"

|+ Digital modulation schemes
{| border="1" cellpadding="5" cellspacing="0" align="center"
! Shortform !! Name
|+'''Digital Modulation Schemes'''
|-
|-
| ASK || Amplitude shift keying
! style="background:#ffdead;" | Shortform
! style="background:#ffdead;" | Name
|-
|-
| FSK || Frequency shift keying
! style="background:#efefef;" | [[Binary Phase Shift Keying|BPSK]]
! [[Binary Phase Shift Keying]]
|-
|-
! style="background:#efefef;" | [[Quadrature Phase Shift Keying|QPSK]]
| BPSK || [[Binary Phase Shift Keying]]
! [[Quadrature Phase Shift Keying]]
|-
|-
! style="background:#efefef;" | [[Quadrature Amplitude Modulation|QAM-16]]
| QPSK || [[Quadrature Phase Shift Keying]]
! 16-state [[Quadrature Amplitude Modulation]]
|-
|-
| QAM-16 || 16-state [[quadrature amplitude modulation]]
! style="background:#efefef;" | [[Quadrature Amplitude Modulation|QAM-32]]
! 32-state [[Quadrature Amplitude Modulation]]
|-
|-
| QAM-32 || 32-state quadrature amplitude modulation
! style="background:#efefef;" | [[Quadrature Amplitude Modulation|QAM-64]]
! 64-state [[Quadrature Amplitude Modulation]]
|-
|-
| QAM-64 || 64-state quadrature amplitude modulation
! style="background:#efefef;" | [[Quadrature Amplitude Modulation|QAM-128]]
! 128-state [[Quadrature Amplitude Modulation]]
|-
|-
| QAM-128 || 128-state quadrature amplitude modulation
! style="background:#efefef;" | [[Quadrature Amplitude Modulation|QAM-256]]
! 256-state [[Quadrature Amplitude Modulation]]
|-
|-
| QAM-256 || 256-state quadrature amplitude modulation
! style="background:#efefef;" | [[8VSB]]
! 8-state [[Vestigial Side Band Modulation]]
|-
|-
! style="background:#efefef;" | [[Orthogonal frequency division modulation|OFDM<br>DMT]]
| [[8VSB]] || 8-state [[vestigial side band modulation]]
|-
! [[Orthogonal frequency division modulation|Orthogonal frequency division modulation<br>Discrete multitone modulation]]
| OFDM<br>DMT || [[Orthogonal frequency division modulation]]<br>Discrete multitone modulation
|}
|}



If you interested in the inner workings and the theory behind demodulators
for digital TV, there are some signal processing tutorials
at http://www.complextoreal.com/.


[[Category:Technology]]
[[Category:Technology]]

Latest revision as of 19:48, 28 December 2016

The modulator converts an input signal into a form suitable for RF transmission. The demodulator recovers the original signal. Since the RF signal is a based sine wave oscillating around the transmission frequency, the modulator has to modulate this sine wave in a way so that all transmitted information is recoverable, but only as little bandwidth as allowed is allocated.

The more the modulation scheme modifies the original sine wave, the more the frequency of the RF sine wave will vary, and the higher the bandwidth will be.

Analog modulation schemes
Shortform Name
AM Amplitude modulation
FM Frequency modulation
PM Phase modulation
Digital modulation schemes
Shortform Name
ASK Amplitude shift keying
FSK Frequency shift keying
BPSK Binary Phase Shift Keying
QPSK Quadrature Phase Shift Keying
QAM-16 16-state quadrature amplitude modulation
QAM-32 32-state quadrature amplitude modulation
QAM-64 64-state quadrature amplitude modulation
QAM-128 128-state quadrature amplitude modulation
QAM-256 256-state quadrature amplitude modulation
8VSB 8-state vestigial side band modulation
OFDM
DMT		 Orthogonal frequency division modulation
Discrete multitone modulation
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