Signal independent pulse code modulation data enhancer and associated method
AssigneeTRW Inc.
InventorKenneth C. Smith
Life of this patent
Estimating the term…
Abstract
A pulse code modulation (PCM) data enhancer which corrects bit errors using correlations between two particular PCM words received by a receiving unit separated by a predetermined time interval and a method therefor. A primary and a number of secondary pulse codes are stored in a first-in-first-out (FIFO) memory. The primary pulse code is modified, and the modified and secondary pulse codes provide addresses to a memory storing the probability of a transition between the modified pulse code and each of the secondary pulse codes. The probabilities are then accumulated, and the modified pulse code resulting in the greatest accumulated probability is output as an error-corrected data word.
Claims27
Apparatus for correcting potential bit errors in a series of received pulse codes including a primary pulse code and a plurality of secondary pulse codes, comprising:
- means for storing the primary pulse code and a plurality of secondary pulse codes, each of said secondary pulse codes being associated with a transition probability that is the likelihood of transition between said primary pulse code and a particular one of said secondary pulse codes;
- means for modifying said primary pulse code to correct a potential error;
- means for accumulating for said modified and primary pulse codes the transition probabilities between said modified and primary pulse codes and each of said secondary pulse codes and calculating a weight for each modified and primary pulse code;
- and
- means for correcting potential errors in said primary pulse code in accordance with said weights, said weights defining whether to substitute one of said modified pulse codes for said primary pulse code when said primary pulse code was received with error.
A method for correcting bit errors in a series of received pulse codes, comprising the steps of:
- storing a primary pulse code and a plurality of secondary pulse codes, each of said secondary pulse codes being associated with a transition probability that defines the likelihood of transition between said primary pulse code and a particular one of said secondary pulse codes;
- modifying said primary pulse code to correct a potential error;
- accumulating for said modified and primary pulse codes the transition probabilities between said modified and primary pulse codes and each of said secondary pulse codes to define a weight for each modified and primary pulse codes, said weights defining whether to substitute one of said modified pulse codes for said primary pulse code when said primary pulse code was received with an error;
- and
- correcting potential errors in said primary pulse code in accordance with said weights.
An apparatus for correcting potential errors in a series of received pulse codes, comprising:
- a data receiver for receiving a data signal represented by a series of pulse codes, said pulse codes varying in a correlative manner such that a transition probability defines a likelihood of transition between a first and a second pulse code over a predetermined time interval;
- means for storing a plurality of transition probabilities between each said first pulse code and each of said second pulse codes for each of a number of said predetermined time intervals;
- means for storing a primary pulse code and a plurality of secondary pulse codes received by said data receiver, each of said secondary pulse codes being separated from said primary pulse code by different predetermined time intervals;
- means for modifying said primary pulse code and for determining a transition probability between said modified pulse code and each of said plurality of secondary pulse codes;
- means for accumulating for each of a plurality of modified pulse codes and said primary pulse code a cumulative transition probability between said modified pulse code and each of said secondary pulse codes, said accumulating means providing information in accordance with one of the modified and primary pulse codes and said cumulative transition probability;
- and
- error correction means for modifying said primary pulse code in accordance with said cumulative transition probability such that the modified and primary pulse codes yielding a maximum cumulative transition probability replaces the primary pulse code.
Dependencies are inferred from the claim text.