Distributed network synchronization system
First Claim
1. A digital transmission system comprising a central station and a plurality of remote stations, each station including means for transmitting and receiving digital data in a sequence of frames, transmission means arranged between said central station and each of said remote stations and causing a variable inherent delay therebetween dependent upon the location of the respective remote station, the central station including means for transmitting a first signal to each of said remote stations chosen in turn and for receiving a signal therefrom dependent on the first signal and means for producing from said first signal and said received signal a delay signal representative of the inherent delay relative to the chosen remote station and for transmitting said delay signal to said remote station, and each remote station including means for receiving and storing said delay signal and means for changing the time of transmission of the transmission means of said remote station in dependence upon said stored delay.
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Accused Products
Abstract
A synchronization system is provided for a tree-type transmission system comprising a central station connected to a plurality of remote stations in an effectively sequential manner, each station including transmitting and receiving means for digital data in a sequence of frames. Each remote station is instructed regularly by the central station of the time delay between the remote station and the central station. The remote station stores the time delay and arranges to advance information transmitted by the remote station so as to be received by the central station within the proper position in the frame. The time delay is measured by the central station by sensing a pattern of bits repetitively transmitted by the remote station and comparing the received pattern with a stored pattern and counting the number of shifts of the received pattern necessary to match the stored pattern. The delay stored by the remote station is tuned to one quarter of a bit to ensure accurate synchronization.
82 Citations
26 Claims
- 1. A digital transmission system comprising a central station and a plurality of remote stations, each station including means for transmitting and receiving digital data in a sequence of frames, transmission means arranged between said central station and each of said remote stations and causing a variable inherent delay therebetween dependent upon the location of the respective remote station, the central station including means for transmitting a first signal to each of said remote stations chosen in turn and for receiving a signal therefrom dependent on the first signal and means for producing from said first signal and said received signal a delay signal representative of the inherent delay relative to the chosen remote station and for transmitting said delay signal to said remote station, and each remote station including means for receiving and storing said delay signal and means for changing the time of transmission of the transmission means of said remote station in dependence upon said stored delay.
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25. A digital transmission system comprising a central station and a plurality of remote stations, each station including means for transmitting and receiving digital data signal in a sequence of frames, transmission means arranged between said central station and each of said remote stations and causing a variable inherent delay therebetween dependent upon the location of the respective remote station, the central station including means for transmitting a first signal to a chosen one of said remote stations and for receiving a signal therefrom dependent on the first signal and means for producing from said first signal and said received signal a delay signal representative of the inherent delay relative to the chosen remote station and for transmitting said delay signal to said remote station, and each remote station including means for receiving and storing said delay signal, means for synchronizing a nominal time of transmission of the transmission means of said remote station with data signals received from said central station and means for advancing the actual time of transmission of the transmission means relative to said nominal time in dependence upon said stored delay.
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26. A digital transmission system comprising a central station and a plurality of remote stations, each station including means for transmitting and receiving digital data in a sequence of frames, tree-type transmission means arranged from said central station to each of said remote stations effectively sequentially and causing a variable inherent delay between the central station and each of the remote stations dependent upon the location of the respective remote station on the transmission means, the central station including means for transmitting a first signal to each of said remote stations chosen in turn and for receiving a signal therefrom dependent on the first signal and means for producing from said first signal and said received signal a delay signal respresentative of the inherent delay relative to the chosen remote station and for transmitting said delay signal to said remote station, and each remote station including means for receiving and storing said delay signal, means for synchronizing a nominal time of transmission of the transmission means of said remote station with data signals received from said central station and means for advancing the actual time of transmission of the transmission means relative to said nominal time in dependence upon said stored delay.
Specification