DTV Receiver Sync Signal Detection Using Phase Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
DTV receivers face challenges in accurately determining the main path in multipath environments due to phase offsets, leading to difficulties in synchronization and reduced equalizer performance.
Innovation Solution
The use of both Real (RD) and Imaginary (ID) parts of equalizer training signals to detect the frame sync segment and output a phase-corrected Real part signal, allowing for reliable synchronization with the main path, even when the Real part signal is small, by calculating and compensating for phase offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only the Real part signal is used for synchronization detection, then the detection process is simple, but the ability to determine the main path in multipath environments is compromised due to phase offsets
Solution Approach 1:
The patent transitions from using only the Real part signal to utilizing both Real and Imaginary parts of the equalizer training signals. This dimensional expansion allows the system to capture phase offset information that would otherwise be lost, enabling reliable main path determination even in multipath environments while maintaining computational feasibility through structured processing of the additional dimension.
Solution Approach 2:
The patent introduces an intermediary processing stage that separately handles the Real and Imaginary parts of the training signals. By processing these components through distinct correlators and then combining their results, the system creates an intermediate representation that preserves phase information while maintaining the simplicity of the overall detection process.
2Reliability
If phase offset compensation is implemented, then synchronization reliability is improved, but the device complexity increases due to additional processing stages
Solution Approach 1:
The patent segments the signal processing into distinct functional blocks: separate correlators for Real and Imaginary parts, a phase offset calculation unit, and a compensation stage. This segmentation allows each component to perform its specific function efficiently while the modular structure keeps the overall complexity manageable and systematic.
Solution Approach 2:
The patent changes the parameter space by introducing phase offset as a measurable and adjustable parameter. By calculating the phase offset from the Imaginary part correlation and using it to adjust the Real part signal, the system transforms a potentially unreliable synchronization process into a robust one that can adapt to varying channel conditions.
3Reliability
If both Real and Imaginary parts are processed for synchronization, then main path detection reliability is improved, but the processing time and computational load increase
Solution Approach 1:
The patent performs preliminary correlation processing on both Real and Imaginary parts separately before combining the results. This preliminary action allows the system to identify strong correlation peaks in each dimension independently, then use these pre-processed results to quickly determine the main path without requiring exhaustive search of the entire signal space.
Data Source
AI summary
A digital television (DTV) receiver is provided, comprising: a demodulator that demodulates television signals and outputs equalizer training signals in the form of real (I) and imaginary (Q) data; a sync signal detector, and a phase compensator that offsets the phase of the I and Q data based on the phase offset signal and outputs phase adjusted I data under control of the lock control signal. The sync signal detector comprises: a correlator that correlates the equalizer training signals including the I and Q data; a power calculator that calculates the sum of the power of the correlated I and Q data; a comparator that compares (the sum) against a preset threshold and outputs a compare indication signal; a sync lock controller that monitors the compare indication signal and outputs a lock control signal; and a phase calculator that calculates a phase of the equalizer training signals based on the I and Q data and outputs a phase offset signal based on the compare indication signal.