VSB Broadcast Reception Using SRS for Multipath Equalization
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Solution Overview
Problem
The existing ATSC VSB digital broadcast system faces challenges in receiving performance, particularly in multi-path fading channel environments with Doppler effects, due to the low frequency of the field sync signal, which hampers equalization and results in deteriorated reception quality.
Innovation Solution
A digital broadcast transmitter/receiver system is enhanced by inserting a known supplementary reference sequence (SRS) into the VSB data stream, allowing for improved synchronization and equalization through the use of stuff bytes in the adaptation field of the MPEG-2 transport stream, which are replaced with specified known data for better channel estimation and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If field sync signal is used for synchronization in ATSC VSB system, then system compatibility is maintained, but receiving performance deteriorates in multi-path fading channel environments
Solution Approach 1:
The patent divides the synchronization function into two parts: field sync signal for basic system compatibility and supplementary reference sequence (SRS) for enhanced equalization performance. The SRS is inserted periodically in the data stream to provide additional reference points for channel estimation, while maintaining the original field sync signal structure for backward compatibility.
Solution Approach 2:
The supplementary reference sequence acts as an intermediary element between the transmitter and receiver, providing a known reference pattern that facilitates channel estimation and equalization in adverse channel conditions without interfering with the standard ATSC signal structure.
2Measurement precision
If known sequence is inserted into data stream, then equalization performance improves, but device complexity increases
Solution Approach 1:
The known supplementary reference sequence is inserted in advance at predetermined positions in the data stream before transmission. This allows the receiver to perform channel estimation and equalization using the pre-positioned reference, avoiding the need for complex adaptive algorithms during real-time reception.
Solution Approach 2:
The patent modifies the data stream by inserting specific known patterns (SRS) at regular intervals defined by a period parameter. This parameter-based approach allows flexible control of reference sequence density to balance performance improvement against complexity and bandwidth overhead.
Data Source
AI summary
A digital broadcast transmitting/receiving system, and a signal processing method thereof, includes a randomizer for randomizing a transport stream into a specified position of which stuff bytes are inserted, a stuff-byte exchanger for replacing the stuff bytes included in data output from the randomizer with specified known data, an RS encoder for performing an RS-encoding of data output from the stuff-byte exchanger, an interleaver for interleaving data output from the RS encoder, a trellis encoder for performing a trellis encoding of data output from the interleaver, an RS parity generator for generating a parity by performing an RS encoding of data output from the RS encoder, and outputting the generated parity to the trellis encoder, and a modulator/RF converter for modulating data output from the trellis encoder and performing an RF up-converting of the modulated data. The digital broadcast receiving performance can be improved even in an inferior multi-path channel by detecting the known data from the received signal and using the known data for synchronization and equalization in a digital broadcast receiver.