VSB Sync Detection Using Partial Noncoherent Correlation
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Solution Overview
Problem
Conventional VSB receivers face challenges in accurately detecting sync signals due to phase noise and carrier frequency offset, which affect the accuracy of sync signal detection, especially when phase is twisted at ±90° or carrier frequency offset exists.
Innovation Solution
The proposed solution involves using a plurality of partial noncoherent correlators to calculate correlation values between sub sequences of a training sequence and both the 'I' and 'Q' signals of the received signal, squaring and adding these values to exclude the influence of carrier frequency offset, and detecting the sync signal based on the maximum correlation value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correlation methods are used to detect sync signals, then the detection process is simple, but the detection accuracy deteriorates due to phase noise and carrier frequency offset
Solution Approach 1:
The training sequence is divided into multiple sub-sequences, and the correlator is segmented into multiple partial correlators that process each sub-sequence independently. This segmentation allows the system to detect sync signals accurately by combining results from multiple smaller correlation operations, reducing the impact of phase noise and carrier frequency offset while maintaining manageable complexity
Solution Approach 2:
The invention transitions from single-dimension correlation (using only I or only Q signal) to two-dimension noncoherent correlation by combining both I and Q signal correlations. The noncoherent correlation computes the sum of squared correlations from both dimensions, effectively eliminating phase dependency and improving detection accuracy in the presence of phase noise
2Measurement precision
If noncoherent correlation is used to eliminate phase noise influence, then detection accuracy improves, but computational complexity increases
Solution Approach 1:
By segmenting the training sequence into sub-sequences and using multiple partial correlators, the computational workload is distributed across parallel processing units. Each partial correlator performs simpler correlation operations on smaller data segments, and the results are combined through noncoherent integration, reducing overall computational energy consumption while maintaining detection accuracy
Solution Approach 2:
The system performs correlation operations on multiple sub-sequences rather than the entire training sequence at once. This partial action approach allows incremental computation and combination of results, reducing the energy burden of any single computational step while achieving the same overall detection accuracy through cumulative evidence
3Reliability
If the training sequence is divided into sub-sequences for partial correlation, then the influence of carrier frequency offset is reduced, but the device complexity increases
Solution Approach 1:
The training sequence is divided into multiple sub-sequences that are processed by separate partial correlators. This segmentation reduces the time span of each correlation operation, thereby minimizing the accumulation of carrier frequency offset effects within each sub-sequence. The overall detection reliability is improved by combining results from multiple shorter, more reliable partial correlations
Solution Approach 2:
Multiple partial correlation results from different sub-sequences are merged through noncoherent integration (summing squared magnitudes). This merging process combines the reliable information from each sub-sequence while canceling out the effects of carrier frequency offset, achieving enhanced detection reliability without requiring each individual correlator to be overly complex
Data Source
AI summary
An apparatus to detect a sync signal, a VSB receiver using the same, and a method thereof. The apparatus includes a plurality of partial correlators to calculate a first partial correlation value between a sub sequence of a training sequence and an “I” signal of a received signal and a second partial correlation value between the sub sequence of the training sequence and a “Q” signal of the received signal, a plurality of squarers to square the first and second partial correlation values for each sub sequence, respectively, a plurality of adders to add the partial correlation values and to provide a correlation signal, a maximum value detection unit to detect a maximum one of the added partial correlation values, and a position detection unit to detect a position of the detected maximum value as the sync signal of the received signal.