Pulse or digital communications – Repeaters – Testing
Patent
1985-12-27
1988-10-04
Griffin, Robert L.
Pulse or digital communications
Repeaters
Testing
370108, 370118, 371 1, 375109, H04J 306
Patent
active
047759879
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to broadband digital transmission systems.
BACKGROUND AND SUMMARY OF THE INVENTION
Telephone systems are capable of transmitting digital information in a multiplicity of time division multiplexed channels, but the characteristics of such systems are such that the maximum rate at which digital data can be transmitted along any one channel is limited for example to 64 kbits per second.
It is an object of the present invention to provide a method of increasing the rate at which data can be transmitted by combining channels.
A public switched digital network cannot guarantee to provide from a multichannel source paths of equal delay to a multichannel destination. Additionally, crossovers may occur such that all the channels at the destination will not be connected to their corresponding channels at the source.
For effective data transmission at the increased rate, these delays need equalization and crossed connections need to be rearranged.
According to the invention, there is provided a digital data transmission system comprising a distributor for distributing the data in a data stream equally to N different outputs (where N is an integer), means for establishing N channels of communication between first and second locations, each channel for carrying the data from a corresponding one of said outputs from said first to said second location, and a reassembler at said second location to reassemble the distributed data received from said N channels into said data stream in its pre-distributed form.
According to the invention, there is further provided a method of transmitting a digital data stream comprising the steps of establishing N channels (where N is an integer) of communication from a first to a second location, transmitting synchronizing signals along each channel during an initial pre-data stream transmission period, reassembling the N streams received at the second location into a data stream, determining from said synchronizing signals in the reassembled data stream any differences in the transmission times along said channels, equalizing said transmission times, cyclically distributing the data into N streams, and transmitting each said stream along a corresponding one of said channels.
BRIEF DESCRIPTION OF THE DRAWINGS
Broadband digital data transmission systems embodying the invention will now be described with reference to the accompanying diagrammatic drawings in which:
FIGS. 1A and 1B are block diagrams of a first embodiment of a system;
FIG. 2 is a block diagram of a second embodiment of the system; and
FIGS. 3A and 3B are more detailed block diagrams of the second embodiment.
DETAILED DESCRIPTION
The digital system to be described is arranged to transmit data occurring at a rate of 384 kbits/second over a conventional telephone network. In a conventional telephone network a single channel of communication is usually capable of handling data occurring at a rate of up to 64 kbits/second.
In the present system, the data occurring at a rate of 384 kbits/second is first processed by cyclically distributing successive blocks of data into six streams so that in each stream data occurs at a rate of 64 kbits/second. Six channels of communication are then established over the telephone network and each stream is fed through a respective one of the six channels.
The data received at the other end of the six channels is then reassembled into its original form, that is into a single stream having a rate of 384 kbits/second.
Where a data stream to be transmitted has a bit rate other than that which forms an integral multiple of the desired individual channel transmission bit rate, then that stream is processed before distribution (for example by inserting additional redundant bits) to have a rate equal to an integral multiple of the desired transmission rate. The redundant bits are then subsequently removed after transmission.
Also, instead of distributing the data cyclically in blocks, it can more simply be distributed in individual bits.
The s
REFERENCES:
patent: 3304500 (1967-02-01), Likel
British Telecommunications PLC
Griffin Robert L.
Huseman Marianne
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