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 Title: |
US4063220:
Multipoint data communication system with collision detection
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Metcalfe, Robert M.; Woodside, CA
Boggs, David R.; Palo Alto, CA
Thacker, Charles P.; Palo Alto, CA
Lampson, Butler W.; Portola Valley, CA
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| Assignee: |
Xerox Corporation, Stamford, CT
other patents from XEROX CORPORATION (635240) (approx. 15,002)
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| Published / Filed: |
1977-12-13
/ 1975-03-31
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| Application Number: |
US1975000563741
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| IPC Code: |
Advanced:
G06F 13/00;
G06F 13/376;
H04L 12/413;
H04L 25/49;
Core:
G06F 13/36;
H04L 12/407;
more...
IPC-7:
H04Q 9/00;
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| ECLA Code: |
G06F13/376; H04L12/413; H04L25/49C;
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| U.S. Class: |
Current:
370/462;
Original:
340/147.LP;
178/058.A;
340/147.R;
340/163;
340/346;
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| Field of Search: |
340/147 R,147 LP,163,151,152 R,152 T,346
325/022,57
178/58 A
179/2 DP,15 AS,17 B,30
343/177,180
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| Priority Number: |
| 1975-03-31 |
US1975000563741 |
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| Abstract: |
Apparatus for enabling communications between two or more data processing stations comprising a communication cable arranged in branched segments including taps distributed thereover. Tied to each tap is a transceiver which on the other side connects to an associated interface stage. Each transceiver includes, in addition to the usual transmitter and receiver sections, a gate which compares the data from the interface stage with the data on the cable and indicates whether such are equal. Should such be unequal, an interference between the transceiver and the cable is indicated, disabling the associated transmitter section. Each interface stage tied to such transceiver also includes an input and an output buffer on the other end thereof interfacing with a using device, such input and output buffers storing both the incoming and outgoing data. The output buffer is connected to a clock-driven shift register which converts the buffered data to a serial stream, feeds such data to a phase encoder, which then connects to the transmitter or driver section of the transceiver. The input buffer is loaded by an input shift register which derives its clock from a phase decoder, the shift register and the phase decoder both connecting to the receiver section. When the station is to start transmitting, the phase decoder detects the presence of other transmissions on the cable and detains the output shift register until no other transmissions are sensed. Once a transmission has begun, if interference is detected and the transmitter section is disabled, a random number generator is used to select an interval of time at the completion of which the next attempted transmission will take place. Concurrently, a counter counts the number of interferences, or collisions, which recur in the attempted transmissions of one data packet and weights the mean of the random number generator accordingly. The input shift register is also connected to an address decoder which enables data transfer to the input buffer only during those times when the data is preceded by an appropriate address.
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| Attorney, Agent or Firm: |
Beck, J. E. ;
Anderson, T. J. ;
Smith, B. P. ;
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| Primary / Asst. Examiners: |
Caldwell, Sr., John W.; Groody, James J.
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| INPADOC Legal Status: |
None
Family Legal Status Report
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| Family: |
Show 15 known family members
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First Claim:
Show all 22 claims |
We claim:
1. A data communication system comprising:
- a communicating medium;
- a plurality of transceivers connected to said medium, each transceiver including transmitting means for transmitting a signal onto said medium, and receiving means for receiving a signal communicated on said medium by another transceiver;
- collision detecting means coupled to the transmitting means and the receiving means of each transceiver for generating a collision signal whenever a signal communicated on said medium by another transceiver is received by said receiving means during the time said transmitting means is transmitting a signal onto said communicating medium; and
- means connected to each transceiver and responsive to the presence of said collision signal for interrupting the transmission of a signal onto said medium by said transmitting means.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 254 U.S. patent(s) that reference this one
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