Feedback error control arrangement

Claim 2

An improved error control system including a source of information messages, a transmitting terminal comprising means for generating a first set of parity check digits for each of said information messages, and transmission means for applying said information messages to one end of a communication channel, and a receiving terminal connected to the other end of said communication channel comprising means for registering messages applied to said communication channel by said transmitting terminal, means for generating a second set of parity check digits for each message registered, and means for transmitting said second sets of parity check digits to said transmitting terminal, said transmitting terminal further comprising means for comparing each corresponding first and second set of parity check digits, and retransmission means for reapplying to said channel that information message whose first and second set of parity check digits do not match, said transmission means including said retransmission means, wherein the improvement comprises means at said transmitting terminal for generating and registering indication messages identifying those information messages whose first and second set of parity check digits do not match, and means at said transmitting terminal for applying said indication messages to said communication channel following the application of all of said information messages to said channel and said receiving terminal further comprises means connected to said channel for processing said indication messages and for removing from said receiving terminal registering means those information messages identified by said indication messages.

Claim 3

The system of claim 1, wherein said receiving terminal-registering means comprises magnetic tape apparatus for storing received messages on a magnetic tape reel and for rewinding said tape reel at the termination of transmission of messages, and wherein said processing and removing means comprises apparatus for signaling said tape unit to erase those information messages identified by said indication messages as said tape reel is rewound.

Claim 4

In an error control system including a source of data messages, an encoder comprising storage means for temporarily storing data messages, means for transmitting Data messages to a receiving terminal, means for generating parity check digits for data messages, means for applying data messages from said source to said storage means, said transmitting means, and said generating means, comparing means for comparing parity check digits generated for a data message by said generating means with parity check digits generated for said data message at the receiving terminal and received therefrom by the comparing means, means responsive to said comparing means for signaling said storage means to reregister said data message and to apply said data message to said transmitting means and said generating means upon the occurrence of a mismatch between the parity check digits generated by said generating means and the parity check digits generated at the receiving terminal, means responsive to said comparing means for generating and registering an identification signal for each data message upon the occurrence of said mismatch, and means for applying said identification signals to said storage means, said transmitting means, and said generating means after all information messages have been transmitted.

Claim 5

In an error control system including a source of data messages, an encoder comprising storage means for temporarily storing data messages, means for transmitting Data messages to a receiving terminal, means for generating parity check digits for data messages, means for applying data messages from said source to said storage means, said transmitting means, and said generating means, comparing means for comparing parity check digits generated for a data message by said generating means with parity check digits generated for said data message at the receiving terminal and received therefrom by the comparing means, means responsive to said comparing means for signaling said storage means to reregister said data message and to apply said data message to said transmitting means and said generating means upon the occurrence of a mismatch between the parity check digits generated by said generating means and the parity check digits generated at the receiving terminal, means responsive to said comparing means for generating and registering an identification signal for each data message upon the occurrence of said mismatch, and means for applying said identification signals to said storage means, said transmitting means, and said generating means after all information messages have been transmitted.

Claim 6

The encoder of claim 3, wherein said identification registering means comprises a clock for generating a signal each time an information message or identification message is applied to said storage means, said transmitting means, and said generating means, a counter for counting said clock signals and for generating a signal representative of the count registered upon the occurrence of said mismatch, wherein the counter is reset after said representative signal is generated, and representative signal registering means for registering each of said representative signals.

Claim 7

The system of claim 3, further including a receiving terminal comprising means for generating parity check digits for information messages and identification messages received from said encoder and for applying such check digits to said channel for transmission to said encoder, means for storing information messages and identification messages received from said encoder, and means for removing the information messages specified by said identification messages from said receiving terminal storing means.

Claim 8

A system as in claim 5, wherein said receiving terminal storage means comprises a magnetic tape unit in which received information and identification messages are stored on a tape reel and wherein said processing and removing means comprises apparatus for signaling said storage unit to erase information messages specified by said identification messages from said tape reel as said reel is rewound after termination of transmission.

Claim 9

A system as in claim 5 wherein said receiving terminal storage means comprises a magnetic tape storage unit including a tape reel for storing information messages and identification messages, apparatus for rewinding said tape reel upon the termination of transmission and for generating a signal as each message passes under the erase mechanism of said storage unit, and apparatus for reading messages from said tape reel as said reel is rewound, identification message storage means for storing the identification messages read from said tape reel as said tape reel is rewound, a translator for translating said identification messages into counter-actuating signals, and a counter responsive to said translator for registering a count indicated by said counter-actuating signals, for decrementing the registered count by one in response to the signals generated by the tape unit, and for signaling said tape unit to erase the information message passing under the erase mechanism upon the counter reaching a count of one.

Claim 10

An improved method for controlling errors in a data transmission system having both forward and reverse channels wherein parity check digits for an information message are generated at a transmitting terminal and there stored, the informaTion message is transmitted to a receiving terminal and there stored, parity check digits for the received information message are generated ta the receiving terminal and transmitted to the transmitting terminal, the received digits are compared with the stored digits at the transmitting terminal, and the said information message is retransmitted if the parity check digits do not agree and a next information message is transmitted if the parity check digits agree, wherein said improvement comprises the steps of storing an indication of the information message retransmitted, transmitting the stored indications after all information messages have been transmitted, and removing those information messages specified by said indications from the receiving terminal storage.

Claim 11

An improved method for controlling errors in a data transmission system having both forward and reverse channels wherein parity check digits for an information message are generated at a transmitting terminal and there stored, the informaTion message is transmitted to a receiving terminal and there stored, parity check digits for the received information message are generated ta the receiving terminal and transmitted to the transmitting terminal, the received digits are compared with the stored digits at the transmitting terminal, and the said information message is retransmitted if the parity check digits do not agree and a next information message is transmitted if the parity check digits agree, wherein said improvement comprises the steps of storing an indication of the information message retransmitted, transmitting the stored indications after all information messages have been transmitted, and removing those information messages specified by said indications from the receiving terminal storage.

Claim 12

The method of claim 8, wherein the messages received at the receiving terminal are stored in a magnetic tape unit on a tape reel, and wherein the removing step comprises the steps of rewinding said tape reel after all information messages and indications have been transmitted and erasing the information messages specified by said indications as said tape reel is rewound.

Claim 13

The method of claim 9 wherein said erasing step comprises the steps of reading said indications from said tape reel, translating said indications into counter-actuating signals, actuating a counter to register a count specified by an indication, decrementing the counter by one count each time a message passes under the erase mechanism of said tape unit, and signaling the tape units to erase a message when the counter reaches a count of one.

Claim 14

In an improved data transmission system including a transmitter, a receiver, and a channel interconnecting said transmitter and receiver comprising a source of information messages at said transmitter, control means at said transmitter for controlling said source of information messages, transmitter check signal generating and registering means responsive to said control means for generating and registering a first set of information message check signals for each information message, transmitting means responsive to said control means for applying said information messages to said channel for transmission to said receiver, receiver check generating means at said receiver for generating a second set of information message check signals for each information message received from said channel, means at said receiver for applying said second set of information message check signals to said channel for transmission to said transmitter, comparing means at said transmitter for comparing said second set of information message check signals received from said channel with said first set of information message check signals generated and registered at said transmitter and retransmitting means for reapplying said information messages to said transmitting means for transmission to said receiver in response to signals generated at said comparing means upon failure of said first and second sets of information message check signals to match, wherein said improvement comprises means responsive to said comparing means for generating and storing indication messages identifying those information messages whose first and second sets of information message check signals do not match.

Claim 15

In an improved data transmission system including a transmitter, a receiver, and a channel interconnecting said transmitter and receiver comprising a source of information messages at said transmitter, control means at said transmitter for controlling said source of information messages, transmitter check signal generating and registering means responsive to said control means for generating and registering a first set of information message check signals for each information message, transmitting means responsive to said control means for applying said information messages to said channel for transmission to said receiver, receiver check generating means at said receiver for generating a second set of information message check signals for each information message received from said channel, means at said receiver for applying said second set of information message check signals to said channel for transmission to said transmitter, comparing means at said transmitter for comparing said second set of information message check signals received from said channel with said first set of information message check signals generated and registered at said transmitter and retransmitting means for reapplying said information messages to said transmitting means for transmission to said receiver in response to signals generated at said comparing means upon failure of said first and second sets of information message check signals to match, wherein said improvement comprises means responsive to said comparing means for generating and storing indication messages identifying those information messages whose first and second sets of information message check signals do not match.

Claim 16

Apparatus according to claim 11 wherein said transmitter check signal generating and registering means includes means for generating a first set of indication message check signals for each indication message.

Claim 17

Apparatus according to claim 12 wherein said transmitting means further includes means for applying said indication messages to said channel for transmission to said receiver.

Claim 18

Apparatus according to claim 13 wherein said receiver check generating means includes means connected to said channel for generating a second set of indication message check signals for each indication message received from said channel.

Claim 19

Apparatus according to claim 14 wherein saId means at said receiver for applying said second set of information message check signals to said channel for transmission to said transmitter includes means for applying said second set of indication message check signals to said channel for transmission to said transmitter.

Claim 20

Apparatus according to claim 15 wherein, said comparing means further includes means for comparing said second set of indication message check signals with said registered first set of indication message check signals.

Claim 21

Apparatus according to claim 16 wherein said retransmitting means further includes means for reapplying said indication message to said transmitting means upon failure of said first and second sets of indication message check signals to match.

Claim 22

Apparatus according to claim 17 wherein said receiver further includes storage means connected to said channel for storing said information and indication messages received from said transmitter,

Claim 23

Apparatus according to claim 18 wherein said receiver further includes removing means for removing from said storage means those information and indication messages indicated by said indication messages to have produced first and second check sets which do not match.

Claim 24

The combination of claim 19 wherein said receiver storage means comprises a magnetic tape unit including a tape reel for storing said received messages and wherein said removing means comprises apparatus for signaling said tape unit to erase those information and indication messages identified by said indication messages as said tape reel is rewound following transmission of all messages.