History of Single sideband modulation

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	Revision 9 . . (edit) December 6, 2001 1:21 am by The Anome [wikied 'Donald Duck']
	Revision 8 . . (edit) December 4, 2001 8:30 am by The Anome [linked 'intermediate frequency\|IF']
	Revision 7 . . (edit) December 4, 2001 8:29 am by The Anome [linked encryption, relinked bandwidth]
	Revision 6 . . (edit) December 4, 2001 7:40 am by The Anome [better link to QAM]
	Revision 5 . . December 4, 2001 7:27 am by The Anome [reworded a bit]
	Revision 4 . . December 4, 2001 7:23 am by The Anome [mentioned VSB]
	Revision 3 . . December 3, 2001 2:27 am by The Anome [mentioned SSB is a special case of QAM]
	Revision 2 . . (edit) December 3, 2001 2:18 am by The Anome [added see also]
	Revision 1 . . December 3, 2001 2:18 am by The Anome [created initial SSB article]

Difference (from prior major revision) (minor diff, author diff)

Changed: 1c1

Single sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of power and bandwidth.

Single sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of power and bandwidth. It is closely related to vestigial sideband modulation (VSB) (see below).

Changed: 3c3

Amplitude modulation typically produces a modulated output signal that has twice the bandwidth of the modulating signal, with a significant power component at the original carrier frequency. Single sideband modulation improves this, at the cost of extra complexity.

Changed: 9c9

To recover the original signal, the carrier must be replaced with an extra 'false carrier' signal, prior to sending the signal to a standard envelope detector.

When the 'wrong' subcarrier is only partially suppressed, the resulting modulation technique is known as vestigial sideband modulation (VSB).

Added: 10a11

To recover the original signal from an SSB signal, the carrier must be replaced with an extra 'false carrier' signal, prior to sending the signal to a standard envelope detector.

Added: 11a13

Changed: 13,16c15

For this to work, the false carrier must be accurately adjusted to match the frequency of the original carrier. If the false carrier is mis-adjusted, the output signal will be frequency-shifted, making speech sound strange and 'Donald Duck'-like.

If the wrong subcarrier is selected at IF conversion time, the audio signal will also be frequency inverted. This effect was used, in conjunction with other filtering techniques, during World War II as a method for speech encryption.

If the wrong subcarrier is selected at IF? conversion time, the audio signal will also be frequency inverted. This effect was used, in conjunction with other filtering techniques, during World War II as a method for speech encryption.

Removed: 19d17

When the 'wrong' subcarrier is only partially suppressed, this moudulation technique is known as vestigial sideband modulation (VSB).

Changed: 21c19,20

Note: SSB and VSB can also be regarded mathematically as special cases of [Quadrature Amplitude Modulation]?.

Note: SSB and VSB can also be regarded mathematically as special cases of quadrature amplitude modulation.