Decoder Buffer Depth Control for Predictable SFN Signal Delay
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Solution Overview
Problem
Single frequency networks (SFNs) face reception problems due to signal overlap and delay uncertainties, leading to inconsistent signal reception and potential 'capture effects' in overlap areas, where listeners may receive signals from only one transmitter, and experience serious reception issues in fringe areas.
Innovation Solution
A decoder with a controllable buffer, such as a first-in first-out (FIFO) circuit, is used to introduce a predictable delay in synchronous data streams by adjusting the buffer depth based on average depth measurements, allowing for precise control of delay through feedback mechanisms, ensuring consistent signal arrival times across the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple RF transmitters broadcast the same signal on the same frequency in an SFN, then spectrum utilization efficiency and coverage area increase, but reception problems occur in overlap areas due to delay uncertainties and signal synchronization issues
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-adjusting the delay parameters for each transmitter based on their geographic locations and signal propagation characteristics. The control system determines the required delay compensation in advance before signal transmission, allowing each transmitter to apply the appropriate delay to its signal so that all signals arrive at receivers synchronized, thereby preventing reception problems in overlap areas while maintaining SFN benefits
2Area of stationary object
If transmitters are located farther apart to increase coverage area, then network coverage improves, but delay differences and synchronization difficulties increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the delay parameter (a time parameter) for each transmitter based on its location and the desired synchronization target. The control system calculates the appropriate delay compensation needed for signals from transmitters at various distances, transforming the time delay parameter to ensure synchronized arrival at receivers regardless of transmitter distance, thus enabling expanded coverage without synchronization loss
3Device complexity
If delay compensation is not applied in SFN, then system complexity is reduced, but reception quality deteriorates in fringe areas and overlap zones
Solution Approach 1:
The patent applies feedback by implementing a control system that monitors signal propagation conditions and adjusts delay parameters accordingly. The system receives information about transmitter locations, receiver positions, and signal characteristics, then feeds this information back to calculate and apply appropriate delay compensations, creating a closed-loop control mechanism that maintains reception quality without requiring overly complex hardware modifications at each transmitter
Data Source
AI summary
A decoder includes a buffer configured to incrementally transport a synchronous data stream through a path of the decoder. A control circuit is configured to control a depth parameter associated with the buffer and to provide a substantially predictable delay of the synchronous data stream through the path of the decoder.