US5452009A — Digital transmission system with data rate optimi…

Claim 1

Independent Claim 69 words

A method of operating a cable system for transmitting a plurality of television signals over respective television channels comprising: defining a family of M level symbol data constellations; transmitting television signals on lower frequency ones of said television channels in data constellations of relatively higher values of M; and transmitting television signals on high frequency ones of said television channels in data constellations having relatively lower values of M.

Claim 2

Independent Claim 69 words

A method of operating a cable system for transmitting a plurality of television signals over respective television channels comprising: defining a family of M level symbol data constellations; transmitting television signals on lower frequency ones of said television channels in data constellations of relatively higher values of M; and transmitting television signals on high frequency ones of said television channels in data constellations having relatively lower values of M.

Claim 3

Dependent Claim 19 words

The method of claim 1 including modulating each of said television signals in the form of a VSB signal.

Claim 4

Dependent Claim 33 words

The method of claim 2 where M is high for low frequency ones of said vestigial sideband television signals and M is low for higher frequency ones of said vestigial sideband television signals.

Claim 5

Dependent Claim 16 words

The method of claim 3 where M may be equal to 2, 4, 8 or 16.

Claim 6

Dependent Claim 55 words

The method of claim 4 wherein the VSB modes of the television signals are defined by M and wherein the data rate corresponding to a VSB mode increases by one bit per symbol relative to the data rate corresponding to the immediately lower VSB mode while the signal to noise performance is reduced by 50%.

Claim 7

Dependent Claim 34 words

The method of claim 5 wherein the relative levels of the symbols of each VSB mode are evenly spaced and lie midway between the relative levels of selected symbols of all higher VSB modes.

Claim 8

Dependent Claim 11 words

The method of claim 1 wherein M is equal to 24.

Claim 9

Independent Claim 71 words

A method of operating a cable system for transmitting television signals on different television channels in the form of symbols having M levels comprising: transmitting said television signals with values of M that are inversely related to the signal to noise ratio of the cable system such that relatively high values of M are used for low frequency television channels and relatively low values are used for high frequency television channels.

Claim 10

Independent Claim 71 words

A method of operating a cable system for transmitting television signals on different television channels in the form of symbols having M levels comprising: transmitting said television signals with values of M that are inversely related to the signal to noise ratio of the cable system such that relatively high values of M are used for low frequency television channels and relatively low values are used for high frequency television channels.

Claim 11

Independent Claim 92 words

A method of operating a cable system for transmitting television signals of different channel frequency in the form of multilevel symbols having M levels comprising: transmitting television signals with values of M in a range of 2 to 16 that are inversely related to the overall signal to noise ratio of the transmission such that high values of M are used for low frequency television signals experiencing relatively good signal to noise transmissions and low values of M are used for high frequency television signals experiencing relatively poor signal to noise transmissions.

Claim 12

Independent Claim 92 words

A method of operating a cable system for transmitting television signals of different channel frequency in the form of multilevel symbols having M levels comprising: transmitting television signals with values of M in a range of 2 to 16 that are inversely related to the overall signal to noise ratio of the transmission such that high values of M are used for low frequency television signals experiencing relatively good signal to noise transmissions and low values of M are used for high frequency television signals experiencing relatively poor signal to noise transmissions.

Claim 13

Dependent Claim 68 words

A receiver for receiving television signals on a cable system, the television signals being encoded as M level symbols comprising: means for receiving said television signals; means for determining M for said received television signals; and means for processing said M level symbols, M being high for television signals experiencing a relatively low noise environment and M is low for television signals experiencing a relatively high noise environment.

Claim 14

Dependent Claim 68 words

A receiver for receiving television signals on a cable system, the television signals being encoded as M level symbols comprising: means for receiving said television signals; means for determining M for said received television signals; and means for processing said M level symbols, M being high for television signals experiencing a relatively low noise environment and M is low for television signals experiencing a relatively high noise environment.

Claim 15

Dependent Claim 43 words

The receiver of claim 10 wherein said television signals are vestigial sideband television signals and where M is high for low frequency ones of said vestigial sideband television signals and M is low for high frequency ones of said vestigial sideband television signals.

Claim 16

Dependent Claim 15 words

The receiver of claim 11 where M is in the range of 2 to 16.

Claim 17

Dependent Claim 55 words

The receiver of claim 12 wherein the VSB modes of the television signals are defined by M and wherein the data rate corresponding to a VSB mode increases by one bit per symbol relative to the data rate corresponding to the immediately lower VSB mode while the signal to noise performance is reduced by 50%.

Claim 18

Dependent Claim 34 words

The receiver of claim 13 wherein the relative levels of the symbols of each VSB mode are evenly spaced and lie midway between the relative levels of selected symbols of all higher VSB modes.

Claim 19

Independent Claim 80 words

A method of maximizing channel capacity in a cable system transmitting television signals as M level symbols over a distribution network characterized by a signal to noise ratio which decreases with increasing channel frequency, comprising: defining a family of data constellations for said television signals; and selecting one of said data constellations for each television signal such that for television signals transmitted on higher channel frequencies, the constellation assignments provide for increased signal to noise performance and reduced data rate.

Claim 20

Independent Claim 80 words

A method of maximizing channel capacity in a cable system transmitting television signals as M level symbols over a distribution network characterized by a signal to noise ratio which decreases with increasing channel frequency, comprising: defining a family of data constellations for said television signals; and selecting one of said data constellations for each television signal such that for television signals transmitted on higher channel frequencies, the constellation assignments provide for increased signal to noise performance and reduced data rate.

Claim 21

Dependent Claim 55 words

The method of claim 15 wherein the VSB modes of the television signals are defined by M and wherein the data rate corresponding to a VSB mode increases by one bit per symbol relative to the data rate corresponding to the immediately lower VSB mode while the signal to noise performance is reduced by 50%.

Claim 22

Dependent Claim 34 words

The method of claim 16 wherein the relative levels of the symbols of each VSB mode are evenly spaced and lie midway between the relative levels of selected symbols of all higher VSB modes.

Claim 23

Dependent Claim 29 words

The method of claim 15 wherein said television signals are encoded into frames of data with each frame including information about the data constellation used for the television signal.

Claim 24

Dependent Claim 15 words

The method of claim 15 wherein M is equal to 2, 4, 8 or 16.

Claim 25

Dependent Claim 11 words

The method of claim 15 wherein M is equal to 24.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-09-18	1999-03-20	1999-09-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-09-18	2003-03-20	2003-09-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-09-18	2007-03-20	2007-09-19	$7700.00	Window Closed / Lapsed

Digital transmission system with data rate optimized for noise in transmission medium

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