Digital Broadcast Receiver Synchronization Using Known Data Sequences
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Solution Overview
Problem
The Vestigial Sideband (VSB) transmission mode used in digital broadcasting in North America and Korea is prone to performance deterioration in poor channel environments, especially when using portable or mobile receivers, due to insufficient resistance to channel changes and noise.
Innovation Solution
A digital broadcasting system that enhances receiving performance by performing additional encoding on mobile service data, inserting known data sequences, and using these sequences for demodulation and channel equalization in a digital broadcast receiving system, thereby improving resistance to channel changes and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VSB transmission mode is used for digital broadcasting, then the system can maintain compatibility with existing infrastructure, but receiving performance deteriorates in poor channel environments and mobile conditions
Solution Approach 1:
The patent applies preliminary action by inserting known data sequences (pilot signals) before actual data transmission. These known sequences are pre-placed at specific positions in the transmitted signal, allowing the receiver to perform frequency offset estimation and channel equalization before decoding the actual data, thereby improving receiving performance in mobile and noisy environments
Solution Approach 2:
The patent uses an intermediary approach by introducing auxiliary known data sequences as mediators between the transmitted signal and the receiver processing. These sequences serve as reference signals that facilitate frequency offset compensation and channel equalization, acting as an intermediary element that improves the overall transmission reliability without changing the core VSB modulation scheme
2Reliability
If additional encoding is performed on mobile service data, then error correction capability is enhanced, but data transmission efficiency decreases
Solution Approach 1:
The patent applies local quality by selectively applying additional encoding only to mobile service data portions, while maintaining standard encoding for other data. The known data sequences are inserted at specific local positions within the data stream, providing enhanced error correction and frequency offset compensation only where needed for mobile reception, thereby balancing reliability improvement with transmission efficiency
Data Source
AI summary
A digital broadcast receiving system includes a known data detector, a carrier recovery unit, and a timing recovery unit. The known data detector may detect known data information inserted and transmitted from a digital broadcast transmitting system and using the known data information to estimate initial frequency offset. The carrier recovery unit may obtain initial synchronization by using the initial frequency offset, and may detect frequency offset from the received data by using the known sequence position indicator so as to perform carrier recovery. The timing recovery unit may detect timing error information from the received signal by using the known sequence position indicator so as to perform timing recovery.