Transmitter Synchronization Using Global Time Reference
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Solution Overview
Problem
Existing terrestrial transmission systems face interference and coverage issues due to overlapping signals from multiple transmitters, which can result in reception difficulties for receivers, especially in areas with varying weather conditions and external blockages, and previous solutions do not ensure identical data transmission from primary and secondary transmitters.
Innovation Solution
A method and apparatus that synchronize the carriers and data transmission from multiple transmitters using a common time reference, adjusting the phase and delay of signals to minimize interference and ensure identical data reception, utilizing a master transmitter and secondary transmitters with time synchronization modules and delay mechanisms to align signals for optimal coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple transmitters are used to extend coverage area, then the coverage area is improved, but signal interference increases
Solution Approach 1:
The system performs preliminary synchronization of transmission timing before signals are broadcast. A master transmitter establishes a reference timing signal that secondary transmitters use to align their transmissions, preventing interference through pre-coordinated time slots and synchronization sequences before actual data transmission begins.
Solution Approach 2:
The system implements feedback mechanisms where transmitters monitor signal quality and timing alignment. Receivers provide feedback information about signal strength and interference levels, allowing the master transmitter to adjust timing parameters and power levels of secondary transmitters to optimize coverage while minimizing interference.
2Reliability
If transmitters are placed in overlapping coverage areas, then reception reliability is improved in shadowed areas, but interference with primary transmitter signals increases
Solution Approach 1:
The system assigns different transmission characteristics to different transmitters based on their local coverage requirements. Secondary transmitters in shadowed areas use different power levels, modulation schemes, or time slots compared to the primary transmitter, allowing them to reliably serve their specific local areas without causing harmful interference to the primary transmitter's broader coverage zone.
3Strength
If auxiliary transmitters are used to strengthen signals in some areas, then signal strength is improved, but interference in other areas increases
Solution Approach 1:
The system segments the overall coverage area into distinct zones, each served by specific transmitters. The master transmitter handles primary broad coverage while secondary auxiliary transmitters are assigned to specific segmented zones where signal enhancement is needed. This spatial segmentation allows signal strengthening in target areas while limiting interference propagation to other areas through careful zone definition and transmitter placement.
Data Source
AI summary
A method and apparatus for synchronizing multiple transmitters is disclosed. A global time reference is used to synchronize the arrival of data from a plurality of secondary transmitters in a receiver station. In one embodiment, the global time reference is provided by a GPS satellite, and may also be used to synchronize the carriers of the signals received at the receiver station from each of the plurality of transmitters. In one embodiment, a pilot signal used for ATSC applications is added by the secondary transmitters.