SciMux DVB-T Stream Synchronization via Adaptation Fields
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Solution Overview
Problem
Satellite delivery of DVB-T transport streams faces challenges with packet jitter and data loss due to RF noise, weather conditions, and positional drift, leading to interference and transmitter outages in Single Frequency Networks (SFN) systems.
Innovation Solution
The SciMux system combines multiple DVB-T transport streams into a single carrier using Digital Transport Formatters (DTFs) and Multiple Transport Receivers (MTRs), employing Adaptation Fields to coordinate timestamps and correct packet jitter, while adding data security and system control through an In-Band Controller (IBC).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If satellite delivery is used to transmit DVB-T transport streams, then installation cost is reduced and deployment time is shortened, but packet jitter and data loss occur due to RF noise, weather conditions, and positional drift
Solution Approach 1:
The patent applies preliminary action by inserting adaptation fields with timing information and packet counters into the transport stream before satellite transmission. These fields are prepared in advance to enable the receiving modulator to compensate for packet jitter and maintain synchronization, thus preventing transmission errors before they occur
Solution Approach 2:
The patent implements feedback mechanisms by using packet counters and timing information in adaptation fields to monitor and adjust packet delivery. The system continuously compares expected versus actual packet arrival times and uses this feedback to correct synchronization drift and maintain reliable transmission despite satellite channel variations
2Productivity
If multiple DVB-T transport streams are combined into a single carrier, then system efficiency is improved, but packet jitter increases making timing synchronization difficult
Solution Approach 1:
The patent applies segmentation by dividing the combined transport stream into individually addressable packets, each containing timing information and packet counters in adaptation fields. This allows the receiving modulator to process and synchronize each packet independently, maintaining precise timing synchronization even when multiple streams are combined into a single carrier
Solution Approach 2:
The patent uses adaptation fields as intermediaries between the combined transport stream and the receiving modulator. These fields carry timing information and packet counters that mediate the synchronization process, enabling the receiving modulator to reconstruct accurate timing information from the combined stream without direct access to original source timing
3Reliability
If Dropped packets or substituted packets occur in SFN networks, then resynchronization is initiated, but transmitter contributions are reduced and regional signal strength is weakened
Solution Approach 1:
The patent applies beforehand cushioning by incorporating redundant timing information and packet counters in adaptation fields that provide a buffer against packet loss. This cushioning allows the receiving modulator to detect and correct synchronization issues without initiating full resynchronization, thereby maintaining transmitter contributions and signal strength
Data Source
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AI summary
A method for correcting packet errors in a combined stream including steps of receiving a combined and re-packetized transport stream comprising program information for at least two transport streams (A and B), wherein each transport stream (A and B) comprises program information associated with respective distinctive packet IDs (PIDs), detecting an invader packet associated with the combined and re-packetized transport stream A does not belong in the combined and re-packetized transport stream A, offering the invader packet to combined and re- packetized transport stream B in which a gap is detected, and de-combining combined and re-packetized transport stream B such that information from a de-combined version of the invader packet fills a gap in a de-combined version of combined and re- packetized transport stream B.