Demodulator Channel Decoder Early Invocation for Faster TV Acquisition
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Solution Overview
Problem
Current digital demodulation systems, such as DVB-T/H, face delays in channel change times due to the time-consuming process of synchronizing channel decoders at super-frame boundaries, which increases video and audio rendering times for viewers.
Innovation Solution
The method involves detecting and de-interleaving even and odd OFDM symbols based on scattered pilot positions, synchronizing the demodulator at OFDM symbol boundaries, and performing Viterbi decoding and convolutional encoding to align with SYNC patterns, thereby reducing channel change times by initializing channel decoder modules at sub-super frame boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel decoder is synchronized at super-frame boundary, then decoding accuracy is ensured, but channel change time increases
Solution Approach 1:
The patent performs preliminary actions by initializing Viterbi decoder and RS decoder states earlier at frame boundaries and OFDM symbol boundaries, rather than waiting for super-frame boundaries. This preliminary initialization allows the decoders to be ready sooner, reducing channel change time while maintaining decoding accuracy through proper state management.
Solution Approach 2:
The patent segments the super-frame boundary synchronization into multiple smaller synchronization points: frame boundaries and OFDM symbol boundaries. By dividing the large super-frame interval into smaller segments, the system can initiate decoding operations earlier at these intermediate boundaries, reducing overall acquisition time while preserving decoding reliability through segmented state initialization.
2Manufacturing precision
If search for synchronisation boundary is performed, then proper decoding alignment is achieved, but acquisition time increases
Solution Approach 1:
The patent performs preliminary synchronization actions at frame boundaries and OFDM symbol boundaries before the final super-frame boundary is reached. By preliminarily aligning decoders at these intermediate points using known frame structures and pilot symbols, the system reduces the time needed for final synchronization without compromising alignment precision.
Solution Approach 2:
The patent uses frame boundaries and OFDM symbol boundaries as intermediary synchronization points between the coarse tuning stage and the final super-frame boundary alignment. These intermediaries provide structured reference points (using frame headers and pilot symbols) that facilitate gradual alignment, reducing overall acquisition time while maintaining precise decoding alignment at the final stage.
Data Source
AI summary
In one embodiment, a Television (TV) receiver to perform a method of synchronizing a demodulator at a Viterbi decode input in the TV receiver using one or more bit de-interleaved even and odd Orthogonal Frequency Division Multiplexing (OFDM) symbols is provided. The method includes (i) performing a Viterbi decoding on the bit de-interleaved even and odd OFDM symbols when a frame boundary does not exist for the bit de-interleaved even and odd OFDM symbols, (ii) performing a convolutional encoding on an decoded data output of the Viterbi decoding, (iii) determining whether an output of the convolutional encoding of the bit de-interleaved OFDM symbols matches an input at a Viterbi decode, and (iv) determining whether the output of the convolutional encoding of the bit de-interleaved even and odd OFDM symbols matches with a SYNC pattern or a SYNC′ pattern to obtain a RS packet align boundary.