Digital Broadcast Transmission with Known Sequences for VSB Equalization
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Solution Overview
Problem
The ATSC VSB digital broadcasting system experiences poor reception performance, especially in Doppler fading channels, due to the infrequent occurrence of known sequences like field syncs, which limits the capacity to remove multipath and equalize signals effectively.
Innovation Solution
A digital broadcasting transmission system is developed that inserts predefined known sequences, known as stuff bytes, at specific locations within the data stream, which are then encoded and modulated for transmission, allowing receivers to improve synchronization and equalization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If field sync and segment sync are used as known sequences for equalization, then equalization performance can be improved, but reception performance deteriorates in poor channels because these known sequences occur infrequently
Solution Approach 1:
The patent divides the data stream into segments and inserts known sequences (stuff bytes) at specific locations within each segment. This segmentation approach increases the frequency of known sequence occurrences from once every 312 segments to multiple times per segment, thereby improving reception performance in poor channels while maintaining equalization capability
Solution Approach 2:
The patent inserts known sequences (stuff bytes) in advance at predetermined locations within the data stream before transmission. This preliminary placement of known sequences allows the receiver to perform channel estimation and equalization more frequently, improving reliability in fading channels without requiring changes to the existing field sync or segment sync structure
2Reliability
If known sequences are inserted frequently to improve reception performance, then channel estimation capability improves, but data transmission efficiency deteriorates
Solution Approach 1:
The patent applies local quality by inserting known sequences (stuff bytes) only at specific predetermined locations within the data stream rather than uniformly throughout. This selective placement provides channel estimation capability where needed while minimizing the impact on overall data transmission efficiency
Solution Approach 2:
The patent changes the parameter of known sequence frequency by inserting stuff bytes at specific intervals within segments rather than relying solely on field sync and segment sync. This parameter change increases the availability of known sequences for channel estimation without requiring a complete restructuring of the data transmission format
Data Source
AI summary
A digital broadcast transmitting system and a signal processing method thereof that improves the receiving performance of the system. A digital broadcast transmitter includes a randomizer to receive and randomize a transport stream into a specified position of which stuff bytes are inserted, a replacement sequence generator to generate known data including a predefined sequence, a stuff-byte exchange unit to insert the known data into the specified position of the transport stream into which stuff bytes are inserted, an encoder to encode the transport stream output from the stuff-byte exchange unit for an error correction, and a transmission unit to modulate the encoded transport stream, RF-convert the modulated transport stream and transmit the RF-converted data. The digital broadcast receiving performance is improved even in an inferior multi-path channel by detecting the known data from the received transmission and using the known data for synchronization and equalization.