Carrier recovery processor for a QAM television signal

Claim 2

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of an offset exhibited by a constellation associated with said processed carrier relative to a constellation associated with said television signal; and means for coupling said control signal to said signal processing path for reducing said offset; wherein said means for generating said control signal is a time multiplexed processor with plural operating modes providing a product-type output signal in at least one of said plural operating modes representative of said offset.

Claim 3

Apparatus according to claim 1, wherein said multiplexed processor exhibits a complete multiplex operating cycle within said symbol period.

Claim 4

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of an offset exhibited by a constellation associated with said processed carrier relative to a constellation associated with said television signal; and means for coupling said control signal to said signal processing path for reducing said offset; wherein said means for generating said control signal is a time multiplexed processor with plural operating modes providing a product-type output signal in at least one of said plural operating modes representative of said offset, said multiplexed processor being responsive to a first signal containing a constellation of symbols at received locations, and to a second signal containing a constellation of symbols at expected locations, said output signal of said multiplexed means representing a difference between said received and expected locations.

Claim 5

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of an offset exhibited by a constellation associated with said processed carrier relative to a constellation associated with said television signal; and means for coupling said control signal to said signal processing path for reducing said offset; wherein said means for generating said control signal is a time multiplexed processor with plural operating modes providing a product-type output signal in at least one of said plural operating modes representative of said offset, said multiplexed processor being responsive to a first signal containing a constellation of symbols at received locations, and to a second signal containing a constellation of symbols at expected locations, said output signal of said multiplexed means representing a difference between said received and expected locations.

Claim 6

Apparatus according to claim 1, wherein said television signal exhibits a spectrum wherein said quadrature amplitude modulated carrier is modulated with high priority information relative to information modulating an additional carrier in said spectrum.

Claim 7

Apparatus according to claim 1, wherein said multiplexer processor comprises a signal multiplier.

Claim 8

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of an offset exhibited by a constellation associated with said processed carrier relative to a constellation associated with said television signal; and means for coupling said control signal to said signal processing path for reducing said offset; wherein said means for generating said control signal is a time multiplexed processor with plural operating modes providing a product-type output signal in at least one of said plural operating modes representative of said offset; and said multiplexed processor comprises a signal multiplier which is multiplexed with latch means to successively perform multiplying and accumulating functions.

Claim 9

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of an offset exhibited by a constellation associated with said processed carrier relative to a constellation associated with said television signal; and means for coupling said control signal to said signal processing path for reducing said offset; wherein said means for generating said control signal is a time multiplexed processor with plural operating modes providing a product-type output signal in at least one of said plural operating modes representative of said offset; and said multiplexed processor comprises a signal multiplier which is multiplexed with latch means to successively perform multiplying and accumulating functions.

Claim 10

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier but subject to exhibiting a phase or frequency offset with respect to said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of said offset, said means for generating said control signal including a phase locked loop comprising multiplier means providing an output signal as a function of said offset in response to a first signal with symbols at received locations and to a second signal with symbols at expected locations; means for providing timing signals to said phase locked loop for causing said phase locked loop including said multiplier means to exhibit time-multiplexed operation; and means for coupling said control signal to said signal processing path for reducing said offset.

Claim 11

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier but subject to exhibiting a phase or frequency offset with respect to said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of said offset, said means for generating said control signal including a phase locked loop comprising multiplier means providing an output signal as a function of said offset in response to a first signal with symbols at received locations and to a second signal with symbols at expected locations; means for providing timing signals to said phase locked loop for causing said phase locked loop including said multiplier means to exhibit time-multiplexed operation; and means for coupling said control signal to said signal processing path for reducing said offset.

Claim 12

Apparatus according to claim 7, wherein said phase locked loop including said multiplier means exhibits a complete multiplex operating cycle within said symbol period.

Claim 13

Apparatus according to claim 7, wherein said control signal adjusts the phase of said reference signal.

Claim 14

Apparatus according to claim 7, wherein said television signal exhibits a spectrum including said quadrature amplitude modulated carrier modulated with high priority information relative to information modulating an additional carrier in said spectrum; and said phase locked loop including said multiplier means exhibits a complete multiplex operating cycle within said symbol period.

Claim 15

Apparatus according to claim 10, wherein said input means comprises an adaptive equalizer.

Claim 16

Apparatus according to claim 7, wherein said phase locked loop is a second order phase locked loop.

Claim 17

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier but subject to exhibiting a phase of frequency offset with respect to said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of said offset, said generating means including a second order phase locked loop comprising multiplier means providing an output signal as a function of said offset in response to a first signal with symbols at received locations and to a second signal with symbols at expected locations; means for providing timing signal to said phase locked loop for causing said phase locked loop including said multiplier means to exhibit time-multiplexed operation; and means for coupling said control signal to said signal processing path for reducing said offset, wherein said phase locked loop includes means responsive to said processed modulated carrier for selecting said symbols, said selecting means exhibiting a first signal gain factor and including memory means for generating said second signal with said symbols at expected locations.

Claim 18

In a television signal receiver including a signal processing path for processing a television signal containing a carrier quadrature amplitude modulated (QAM) with symbols exhibiting a given symbol period and mapped into prescribed locations of a grid-like constellation, apparatus comprising: means for generating a reference signal nominally at the frequency of said carrier but subject to exhibiting a phase of frequency offset with respect to said carrier; input means responsive to said modulated carrier and to said reference signal for producing a processed modulated carrier; means for generating a control signal as a function of said offset, said generating means including a second order phase locked loop comprising multiplier means providing an output signal as a function of said offset in response to a first signal with symbols at received locations and to a second signal with symbols at expected locations; means for providing timing signal to said phase locked loop for causing said phase locked loop including said multiplier means to exhibit time-multiplexed operation; and means for coupling said control signal to said signal processing path for reducing said offset, wherein said phase locked loop includes means responsive to said processed modulated carrier for selecting said symbols, said selecting means exhibiting a first signal gain factor and including memory means for generating said second signal with said symbols at expected locations.

Claim 19

Apparatus according to claim 13 and further including means in said phase locked loop exhibiting a second signal gain factor.