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Communications receiver arrangement
| Details |
Inventors: Barker, Andrew J.;
Assignee: Marconi Communications Limited (Coventry, GB)
Primary Examiner: Tu; Christine T.
Assistant Examiner:
Attorney, Agent or Firm: Kirschstein, et al.
A receiver in a digital communications system, in which the digital data occupy a number of levels, equalises the erroneous-count rates for the various data levels by deriving the count rates for the levels, comparing these count rates with each other and using the comparison result to adjust the threshold level which is used to detect the received data train. The error-counts are preferably derived as a byproduct of a Forward Error Correction system already available for performing normal error correction on the received data. The receiver arrangement is envisaged to find predominant application in a two-level system involving logical "1"'s and "0"'s, though it is applicable also to systems with three or more levels. |
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DETAILED DESCRIPTION In accordance with a first aspect of the invention, there is provided a communications receiver arrangement for the receipt of digital data, comprising: means for receiving digital data encoded in accordance with multiple encoding levels, means for establishing one or more thresholds for detecting the multiple encoding levels, and means for determining the error rate associated with each individual encoding level, the threshold-establishing means comprising a threshold-optimisation means for optimising the one or more thresholds on the basis of the determined error rates.
The threshold-optimisation means may comprise means for comparing the various error rates and means for changing the one or more thresholds on the basis of the comparison result.
The comparing means may form a ratio between the various error rates, in which case the threshold-changing means will vary the one or more thresholds until respective predetermined ratios are established between the error rates; alternatively, the comparing means may form a difference between the various error rates, in which case the threshold-changing means will vary the one or more thresholds until respective predetermined differences are established between the error rates.
The predetermined ratios may be approximately unity and the differences approximately zero.
The number of encoding levels may be two.
There may be a single threshold discriminating between the two levels.
A hysteresis is preferably provided in the threshold in order to provide stability of control.
Preferably the error rates are provided as a by-product of an error-correction system, e.
g.
a Forward Error Correction system.
In a second aspect of the invention, a method for equalising the spurious-count rates for each of multiple data-encoding levels in a communications receiver comprises: receiving data encoded in accordance with the multiple encoding levels, determining the spurious-count rates, and optimising, on the basis of the determined spurious-count rates, one or more thresholds for detecting the multiple encoding levels
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Radio 
