Receiver for robust data extension for 8VSB signaling

Abstract

A robust data extension added to a standard 8VSB digital television signal is used to improve the performance of a digital television receiver. The robust data extension is added to a standard 8VSB digital television transmission system by encoding high priority data packets in a rate 1/2 trellis encoder. The high priority data 1/2 trellis encoded packets are then multiplexed with normal data packets and input into the normal data service of an 8VSB system, which further contains a rate 2/3 trellis encoder. The combined trellis encoding results in a rate 1/3 trellis encoding for robust data packets and a rate 2/3 trellis encoding for normal packets. Backward compatibility with existing receivers is maintained for 1) 8VSB signaling, 2) trellis encoding and decoding, 3) Reed Solomon encoding and decoding, and 4) MPEG compatibility. In addition to delivery of robust data for mobile applications, the redundant robust data packets also improve the performance of the receiver in the normal tier of service. In particular, the robust data packets improve the performance of the receiver equalizer filter in the presence of rapidly changing transient channel conditions such as dynamic multipath for both robust data packets and normal data packets. The robust data packets improve the performance of the carrier recovery loop and the symbol timing recovery loop.

1 . (canceled)  
     
     
         2 . In a communication system having a transmitter providing trellis encoded symbols, and a receiver having a trellis decoder for decoding said trellis encoded symbols, wherein said receiver includes stored path metrics for a plurality of state transition paths through said trellis decoder, and a receiver method including selecting the minimum path metric of said stored path metrics corresponding to the most likely path for each particular state of said trellis decoder, and selecting a survivor path corresponding to said selected minimum path metric and generating a Path Metric Minimum function, an improved method comprising: 
 computing a Path Metric Minimum Average as an average of said Path Metric Minimum function wherein said Path Metric Minimum Average is an indication of the reliability of the survivor paths being selected by said trellis decoder.    
     
     
         3 . In a communication system having a transmitter providing trellis encoded symbols, and a receiver having a trellis decoder for decoding said trellis encoded symbols, wherein said receiver includes stored path metrics for a plurality of state transition paths through said trellis decoder, and a receiver method including selecting the minimum path metric of said stored path metrics corresponding to the most likely path for each particular state of said trellis decoder, and selecting a survivor path corresponding to said selected minimum path metric and generating a Path Metric Minimum function, an improved method comprising: 
 computing a Path Metric Minimum Average as an average of said Path Metric Minimum function wherein said Path Metric Minimum Average is an indication of the reliability of the survivor paths being selected by said trellis decoder.    
     
     
         4 . In a communication system having a transmitter and a receiver, wherein said receiver includes a decision feedback equalizer having a plurality of filter coefficients and a tapped delay line for controlling the coefficient updating of the coefficients of said decision feedback equalizer on a coefficient by coefficient basis and an equalizer control unit, a method comprising: 
 generating a Tap Control signal in said equalizer control unit for use in said decision feedback equalizer wherein said Tap Control signal at each tap position of said tapped delay line is a first value if the symbol at that tap is a symbol with a high reliability of being correct and a second value if the symbol at that tap is a symbol that could not be reliably predicted; and    updating said coefficients if said Tap control signal is at said first value; and    holding said coefficients at its current values if said Tap control signal is at said second value.    
     
     
         5 . In a receiver method in accordance with  claim 4 , wherein said decision feedback equalizer includes a decision directed (DD) mode and an IIR mode, and a decision feedback equalizer error term, a method for updating said plurality of filter coefficients in decision directed mode, said method comprising: 
 updating corresponding ones of said plurality of filter coefficients at each tap position of said tapped delay line using said decision feedback equalizer error term when said Tap Control signal is said first value; and    not updating corresponding ones of each of said plurality of filter coefficients at each tap position of said tapped delay line when said Tap Control signal is said second value.    
     
     
         6 . In a communication system having a transmitter and a receiver, wherein said receiver includes a decision feedback equalizer having a plurality of filter coefficients and a tapped delay line for controlling the coefficient updating of the coefficients of said decision feedback equalizer on a coefficient by coefficient basis and an equalizer control unit, an apparatus comprising: 
 said equalizer control unit further including a Tap Control signal generator in said equalizer control unit coupled to said decision feedback equalizer wherein said Tap Control signal at each tap position of said tapped delay line is a first value if the symbol at that tap is a symbol with a high reliability of being correct and a second value if the symbol at that tap is a symbol that could not be reliably predicted; and    a coefficient updating circuit responsive to said Tap Control signal to update said coefficients if said Tap Control signal is at said first value, and to hold said coefficients at its current values if said Tap Control signal is at said second value.    
     
     
         7 . In a receiver apparatus in accordance with  claim 6 , wherein said decision feedback equalizer includes a decision directed (DD) mode and an IIR mode, and a decision feedback equalizer error term, an apparatus for updating said plurality of filter coefficients in decision directed mode, said apparatus comprising: 
 a coefficient updating circuit responsive to said Tap Control signal to update said corresponding ones of said plurality of filter coefficients at each tap position of said tapped delay line using said decision feedback equalizer error term when said Tap Control signal is said first value, and not updating corresponding ones of each of said plurality of filter coefficients at each tap position of said tapped delay line when said Tap Control signal is said second value.