Synchronization loss detection in a V.34 receiver
AssigneeTelogy Networks, Inc.
InventorAdrian Zakrzewski
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Abstract
A method for detecting synchronization loss of the trellis minimum path metric in V.34 modem communications. The invention detects synchronization loss due to bit inversions in trellis decoding in transmitted digital frames due to a periodic inversion pattern that is used for superframe synchronization. The method provides synchronization loss detection by finding the ratio of moving averages for a series of data blocks to the average of a series of inverted 4D symbols located periodically in the beginning and center of received data frames.
Claims16
A method for determining synchronization loss of digital communications signals in a V.34 receiver, comprising the steps of:
- averaging the minimum path metric for a first periodic series of data blocks containing bit inversions;
- averaging the minimum path metric for a second periodic series of data blocks containing said bit inversions and comprising fewer symbols than said first periodic data blocks;
- calculating a ratio of the average of the minimum path metric for said first data blocks with the average of the minimum path metric for said second data blocks;
- detecting an increase in the minimum path metric by comparing the deviation of said ratio from a synchronization standard.
A method for detecting synchronization loss of digital communications signals in a receiver, comprising the steps of:
- sampling a plurality of a first series of data blocks within said digital signals containing periodic symbol inversions;
- sampling a plurality of a second series of data blocks within said digital signals that contain said periodic symbol inversions and are a subset of said first set of data blocks;
- calculating an average of minimum path metrics of a plurality of said first series of data blocks;
- calculating an average of the minimum path metric of a plurality of said second series of data blocks;
- calculating a ratio by dividing the average of said first series of data blocks by the average of said second series of data blocks;
- comparing said ratio of averages with a synchronization standard to detect synchronization of said digital communication signals in said receiver.
A method for detecting synchronization loss of digital communications signals in a receiver, comprising the steps of:
- sampling a plurality of a first series of mapping frames within a plurality of data frames containing periodic inverted symbols used for superframe synchronization;
- sampling a second series of mapping frames within a plurality of said data frames that are a subset of said first series of data frames contain said periodic inverted symbols used for superframe synchronization;
- calculating an average of minimum path metrics of a plurality of said first set of mapping frames;
- calculating an average of the minimum path metric of a plurality of said second series of mapping frames;
- obtaining a ratio by dividing the average of said first set of data blocks by the moving average of said second set of data blocks;
- comparing said ratio with a standard synchronized ratio to detect said synchronization loss.
Dependencies are inferred from the claim text.