Carrier concentrator system and method

Claim 2

A multi-channel carrier system interconnecting a plurality of communication lines at a control terminal with corresponding communication lines at one or more remote terminals by means of transmission channels in which said terminals include means forming sequential frames of message time slots, each message time slot constituting a transmission channel for a communications line, and means responsive to the active or idle status of communication lines for controlling the number of message time slots in each frame so that message time slots are provided only for active communication lines and the frame rate varies in accordance with the number of message time slots in each frame.

Claim 3

A multi-channel carrier system as in claim 1 in which said terminals include means for adding or deleting message time slots in said frames as communication lines become active or idle respectively.

Claim 4

A multi-channel carrier system as in claim 1 in which said terminals include means for adding a framing time slot to each frame.

Claim 5

A multi-channel carrier system as in claim 2 in which said means for adding or deleting message time slots is responsive to the active or idle status of communication lines at the control terminal or at the remote terminals to add a message time slot whenever either the control end or remote end of a communications line becomes active, or to delete a message time slot whenever both the control end and the remote end of a communications line become idle.

Claim 6

A multi-channel carrier system as in claim 2 in which said means for adding or deleting message time slots includes means at the control terminal for sensing the active or idle state of communication lines at the control terminal and providing information relative thereto, means at the remote terminals for sensing the active or idle state of communication lines at the remote terminals to transmit information relative thereto to the control terminal, means at the control terminal responsive to said information from the remote and control terminals for adding a message time slot to the system whenever either the control end or remote end of a communications line becomes ative, or for deleting a message time slot from the system whenever both the control end and the remote end of a communications line becomes idle.

Claim 7

A multi-channel carrier system as in claim 1 in which said terminals include means for sensing when the message time slots do not interconnect corresponding communication lines at the control and remote terminals and generating a misframe signal and means responsive to said misframe signal for reframing the system whereby the message time slots interconnect corresponding communication lines at the control and remote terminals.

Claim 8

A multi-channel carrier system as in claim 5 in which the active or idle state of each communication line at the control and remote terminals is sensed sequentially by a scanning system which advances one line every two frames of time slots.

Claim 9

A multi-channel carrier system comprising a control terminal, one or more remote terminals, and an interconnecting transmission medium providing transmission between a plurality of communication lines connected to the control terminal and a corresponding number of communication lines connected to the remote terminal, said transmission being provided by transmission channels in transmission frames in which said control terminal includes means for sensing when a communication line requires a transmission channel, means responsive to the sensing of a requirement for a transmission channel to form transmission channels in said frame only for those communication lines requiring transmission channels whereby said transmission frames include only channels corresponding to communication lines requiring transmission channels with a frame rate corresponding thereto.

Claim 10

A multi-channel carrier system comprising a control terminal, one or more remote terminals, and an interconnecting transmission medium providing transmission between a plurality of communication lines connected to the control terminal and a corresponding number of communication lines connected to the remote terminal, said transmission being provided by transmission channels in transmission frames in which said control terminal includes means for sensing when a communication line requires a transmission channel, means responsive to the sensing of a requirement for a transmission channel to form transmission channels in said frame only for those communication lines requiring transmission channels whereby said transmission frames include only channels corresponding to communication lines requiring transmission channels with a frame rate corresponding thereto.

Claim 11

A multi-channel carrier system as in claim 8 in which said control terminal includes means for adding or deleting transmission channels as communication lines become active or idle respectively.

Claim 12

A multi-channel carrier system as in claim 8 in which said means for sensing when a communication line requires a transmission channel includes means for sensing a requirement either by a communication line at the control terminal or a communication line at the remote terminal.

Claim 13

A multi-channel carrier system as in claim 8 in which said terminals include means for sensing when assigned transmission channels do not interconnect corresponding active communication lines at the control and remote terminals and means responsive to said sensing means for reassigning the transmission channels so that corresponding communication lines at the control and remote terminals are interconnected.

Claim 14

A transmission system providing transmission channels between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals including a transmission medium between the communication lines at said control terminal and the communication lines at said one or more remote terminals and means forming sequential frames of message time slots constituting transmission channels and applying said frames of message time slots to said transmission medium, said last named means responsive only to active communication lines for providing message time slots whereby the number of message time slots per frame is equal to the number of active communication lines and the frame rate varies in accordance with the number of message time slots.

Claim 15

A transmission system providing transmission channels between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals including a transmission medium between the communication lines at said control terminal and the communication lines at said one or more remote terminals and means forming sequential frames of message time slots constituting transmission channels and applying said frames of message time slots to said transmission medium, said last named means responsive only to active communication lines for providing message time slots whereby the number of message time slots per frame is equal to the number of active communication lines and the frame rate varies in accordance with the number of message time slots.

Claim 16

A transmission system as in claim 12 wherein said means for forming sequential frames of message time slots constituting transmission channels includes means for adding to each frame a frame time slot for delineating the frame and a control time slot for transmitting control signals.

Claim 17

A transmission system as in claim 12 including means at the remote terminal for sensing whether a communication line is active or idle and transmitting information relative thereto over the control time slot to the control terminal, means at said control terminal for sensing whether communication lines connected to said control terminal are active or idle and providing information relative thereto and means at the control terminal responsive to the control and remote terminals information serving to add a transmission channel to the system whenever either the control end or the remote end of a communications line becomes active, or to delete a transmission channel from the system whenever both the control end and the remote end of a communication line becomes idle.

Claim 18

A transmission system as in claim 12 including means at the terminals for limiting the minimum number of time slots in any frame.

Claim 19

A transmission system as in claim 15 in which said control terminal includes means for limiting the maximum number of time slots in any frame.

Claim 20

A transmission system as in claim 12 including means for detecting when the message time slots do not interconnect corresponding communication lines at the control and remote terminals to form a misframe signal, said means responsive to said misframe signal for reframing the system whereby the message time slots interconnect corresponding communication lines at the control and remote terminals.

Claim 21

A transmission system as in claim 17 wherein during reframing the system reverts to a two time-slot frame to reframe the system in said two time-slot mode.

Claim 22

A multi-channel carrier system interconnecting a plurality of communication lines at a control terminal with corresponding communication lines at one or more remote terminals by means of transmission channels in which each of said terminals includes means forming sequential frames of message time slots, each message time slot constituting a transmission channel for a communications line, and means at the control terminal responsive to the active or idle status of communication lines at the control terminal or at the remote terminals for controlling the number of message time slots in each frame so that message time slots are provided only for active communication lines and the frame rate varies in accordance with the number of time slots.

Claim 23

A multi-channel carrier system interconnecting a plurality of communication lines at a control terminal with corresponding communication lines at one or more remote terminals by means of transmission channels in which each of said terminals includes means forming sequential frames of message time slots, each message time slot constituting a transmission channel for a communications line, and means at the control terminal responsive to the active or idle status of communication lines at the control terminal or at the remote terminals for controlling the number of message time slots in each frame so that message time slots are provided only for active communication lines and the frame rate varies in accordance with the number of time slots.

Claim 24

A multi-channel carrier system as in claim 19 in which said terminals include means for adding a message time slot whenever either the control end or remote end of a communications line becomes active, or to removing a message time slot whenever both the control end and the remote end of a communications line becomes idle.

Claim 25

A multi-channel subscriber carrier system for connecting a plurality of subscriber line appearances at a central office to corresponding remote subscriber lines comprising a control terminal connected to said central office line appearances, one or more remote terminals connected to said subscriber lines and a transmission medium interconnecting said control terminal and said one or more remote terminals, means in said control terminal for sensing when a subscriber line is active, means responsive to sensing of an active subscriber line to provide transmission channels only for active subscriber lines which occupy one time slot in sequential frames of time slots transmitted over said transmission medium to complete transmission channels between the subscriber lines at the remote terminal and the corresponding line appearances at the central office, said frame length and rate being dependent upon the number of active lines.

Claim 26

A multi-channel subscriber carrier system for connecting a plurality of subscriber line appearances at a central office to corresponding remote subscriber lines comprising a control terminal connected to said central office line appearances, one or more remote terminals connected to said subscriber lines and a transmission medium interconnecting said control terminal and said one or more remote terminals, means in said control terminal for sensing when a subscriber line is active, means responsive to sensing of an active subscriber line to provide transmission channels only for active subscriber lines which occupy one time slot in sequential frames of time slots transmitted over said transmission medium to complete transmission channels between the subscriber lines at the remote terminal and the corresponding line appearances at the central office, said frame length and rate being dependent upon the number of active lines.

Claim 27

A subscriber carrier system as in claim 21 wherein said control terminal includes means providing a framing time slot at the beginning of said frame for identifying frames of time slots and a control time slot at the end of said frames for transmitting control information between the control and remote terminals.

Claim 28

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including a plurality of control terminal line interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line units including an encoder serving to encode said received information for transmission to said remote terminal and a decoder for decoding encoded information received from said remote terminal, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission medium, a transmit memory having a plurality of memory cells, one for each communication line, each of said cells adapted to be marked active or idle corresponding to the current state of the associated communication line, a transmitting message time base having a plurality of inputs one connected to each of said memory cells and a plurality of corresponding outputs one connected to each of said encoders and corresponding transmission gates, said message time base serving to generate recurring frames of sequential clock pulses of one time slot duration on the outputs corresponding to the active memory cells only, each clock pulse serving to clock the encoder and transmission gate of the associated line interface unit, said sequential clock pulses serving to multiplex the encoded information onto said transmission medium a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the remote terminals, a receive memory having a plurality of memory cells one for each line, each of said cells adapted to be marked identical to the cells of the transmit memory, a receiving message time base having a plurality of inputs one connected to each of said receive memory cells and a plurality of corresponding outputs one connected to each corresponding receiving gate, said receiving time base serving to generate recurring frames of sequential clock pulses on the outputs corresponding to the active memory cells only, each clock pulse serving to clock an associated recurring gate, said sequential clock pulses serving to demultiplex incoming coded information on said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding communication line; said one or more remote terminals each including: a plurality of remote terminal line interface units connected to each communication line of said remote terminals to receive information therefrom and supply information thereto, each of said line units including an encoder serving to encode received information for transmission over said transmission medium to the control terminal and a decoder for decoding information received from said transmission medium, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission medium, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the transmission medium, a memory having a plurality of memory cells one for each line, each of said cells adapted to be marked identical to the cells of the transmit memory, a message time base having a plurality of inputs one for each memory cell of the communication lines associated with said terminal and a plurality of corresponding outputs one connected to the encoder and the transmission and receiving gates of the corresponding line units, said message time base serving to sequentially generate recurring frames of sequential clock pulses of one time slot duration on the outputs corresponding to an active memory cell only, each clock pulse serving to clock the encoder and transmission gate of an associated line unit, said sequential clock pulses serving to multiplex the encoded information onto said transmission medium, said clock pulses also serving to clock associated receiving gates, said sequetial clock pulses serving to demultiplex incoming information from said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding communication line at the remote terminal.

Claim 29

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including a plurality of control terminal line interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line units including an encoder serving to encode said received information for transmission to said remote terminal and a decoder for decoding encoded information received from said remote terminal, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission medium, a transmit memory having a plurality of memory cells, one for each communication line, each of said cells adapted to be marked active or idle corresponding to the current state of the associated communication line, a transmitting message time base having a plurality of inputs one connected to each of said memory cells and a plurality of corresponding outputs one connected to each of said encoders and corresponding transmission gates, said message time base serving to generate recurring frames of sequential clock pulses of one time slot duration on the outputs corresponding to the active memory cells only, each clock pulse serving to clock the encoder and transmission gate of the associated line interface unit, said sequential clock pulses serving to multiplex the encoded information onto said transmission medium a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the remote terminals, a receive memory having a plurality of memory cells one for each line, each of said cells adapted to be marked identical to the cells of the transmit memory, a receiving message time base having a plurality of inputs one connected to each of said receive memory cells and a plurality of corresponding outputs one connected to each corresponding receiving gate, said receiving time base serving to generate recurring frames of sequential clock pulses on the outputs corresponding to the active memory cells only, each clock pulse serving to clock an associated recurring gate, said sequential clock pulses serving to demultiplex incoming coded information on said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding communication line; said one or more remote terminals each including: a plurality of remote terminal line interface units connected to each communication line of said remote terminals to receive information therefrom and supply information thereto, each of said line units including an encoder serving to encode received information for transmission over said transmission medium to the control terminal and a decoder for decoding information received from said transmission medium, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission medium, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the transmission medium, a memory having a plurality of memory cells one for each line, each of said cells adapted to be marked identical to the cells of the transmit memory, a message time base having a plurality of inputs one for each memory cell of the communication lines associated with said terminal and a plurality of corresponding outputs one connected to the encoder and the transmission and receiving gates of the corresponding line units, said message time base serving to sequentially generate recurring frames of sequential clock pulses of one time slot duration on the outputs corresponding to an active memory cell only, each clock pulse serving to clock the encoder and transmission gate of an associated line unit, said sequential clock pulses serving to multiplex the encoded information onto said transmission medium, said clock pulses also serving to clock associated receiving gates, said sequetial clock pulses serving to demultiplex incoming information from said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding communication line at the remote terminal.

Claim 30

A multi-channel system as in claim 22 in which said plurality of communication lines connected to the control terminal comprise subscriber line appearances at a central office and the corresponding communication lines connected to the one or more remote terminals correspond to subscriber lines.

Claim 31

A multi-channel system as in claim 23 including traffic control means, means in said time base for generating a framing clock pulse of one time slot duration to the beginning of each of said recurring frames of sequential clock pulses, a transmission gate connected to said traffic control means serving to multiplex framing information onto said transmission medium, and means in said time base for generating a control clock pulse of one time slot duration at the end of each of said recurring frames of sequential clock pulses and a transmission gate connected to said traffic control means serving to multiplex control information onto said transmission medium responsive to said control clock pulse.

Claim 32

A multi-channel system as in claim 25 in which the remote terminal line units include means indicating the status of the associated communication lines, means at the remote terminal for sequentially scanning the line units to generate a status signal corresponding to the status of the associated communication line, means at the remote terminal responsive to said control clock pulses to multiplex the status information onto said transmission medium, means at the control terminal for demultiplexing the incoming status information from the remote terminals on said transmission medium, means at the control terminal for sequentially scanning the status of each communication line at the control terminal, means for combining said remote line status information and control terminal line status information and providing an active line scan signal if one or both line status information is active and an idle line scan signal if both are idle, means for scanning the control terminal transmit memory and forming a transmit memory signal indicating the idle or active status of the corresponding memory cell, means for comparing said line scan signal with the transmit memory signal forming a traffic change signal when only one is active or idle, and means responsive to the traffic change signal for adding a message time slot if the line scan signal is active and the memory scan is idle and means for deleting a time slot if the line scan signal is idle and the memory scan is active.

Claim 33

A communication system as in claim 26 in which said sequential scanning means includes a line counter and decoder.

Claim 34

A communication system as in claim 27 in which said traffic change signal stops the control terminal line counter at the count of the line requiring change, generates a change instruction and multiplex the change instruction in the frame and control message time slots for transmission to the remote terminals, said change instructions identifying the subscriber line and the required change.

Claim 35

A communication system as in claim 28 in which said remote terminals include means for receiving the change instruction, means responsive to receipt of complete change instruction for resetting the remote terminal line counter to the corresponding count, and means for conforming the corresponding remote terminal memory cell to the instruction to mark the memory cell idle or active.

Claim 36

A communication system as in claim 28 wherein said means for instructing the remote terminals comprises sending the binary code identifying the memory cell to be changed in successive control time slots.

Claim 37

A communication system as in claim 23 in which said control and remote terminals each include means for sensing when the incoming framing pulses do not coincide with the local framing pulses whereby to generate a misframe signal.

Claim 38

A communication system as in claim 31 including means responsive to the misframe signal for forcing the time base into a two-bit frame mode and emitting a sequence of logic bits of one type, means at each of the other terminals responsive to said logic bits of one type for forcing each of said terminals in turn into a two-bit frame mode and emitting said one logic state, means at the control terminal for generating two-bit frame with alternating logic after a predetermined time, and means at the remote terminals responsive to said two-bit mode for framing said remote terminals and transmitting a two-bit frame with alternating logic, and means at the control terminal responsive to the two-bit alternating logic frame pattern for transmitting a roll call consisting of a plurality of two-bit frames one frame for each of the communication lines associated with the carrier system to address and conform the memory cells at each of the remote terminals and at the receiving portion of the control terminal.

Claim 39

A transmission system as in claim 23 in which said control terminal transmitting message time base includes means for limiting the minimum number of time slots in any frame.

Claim 40

A transmission system as in claim 23 in which said control terminal transmitting message time base includes means for limiting the maximum number of time slots in any frame.

Claim 41

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including: a plurality of control terminal interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line interface units including a delta modulation encoder serving to encode said received information for transmission to said remote terminal and a delta modulation decoder for decoding encoded information received from said remote terminal, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission line, means for generating recurring frames of sequential transmitting clock pulses of one time slot duration for each active communication line with the frame rate dependent upon the number of time slots, each clock pulse serving to clock the encoder and transmission gate of an associated line interface unit to multiplex the encoded information onto said transmission medium as frames of encoded information, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the remote terminal, means for generating recurring frames of sequential receiving clock pulses for each active line, each clock pulse serving to clock an associated receiving gate to demultiplex incoming coded information on said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding line; said one or more remote terminals including: a plurality of remote terminal line interface units connected to each communication line of said remote terminal to receive information therefrom and supply information thereto, each of said line units including a delta modulation encoder serving to encode received information for transmission to the control terminal over said transmission medium and a delta modulation decoder for decoding information received from the control terminal over said transmission medium, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission line medium, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information on the transmission medium, means for generating recurring frames of sequential clock pulses of one time slot duration on the output corresponding to an active communication line with the frame rate dependent upon the number of time slots, each clock pulse serving to clock the encoder and transmission gate of an associated line interface unit to multiplex the encoded information onto said transmission medium as frames of encoded information, said clock pulses also serving to clock associated receiving gates to demultiplex incoming information on said transmission medium and apply the same to an associated decoder which decodes the information and applies it to the corresponding communication line at the remote terminal.

Claim 42

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including: a plurality of control terminal interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line interface units including a delta modulation encoder serving to encode said received information for transmission to said remote terminal and a delta modulation decoder for decoding encoded information received from said remote terminal, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission line, means for generating recurring frames of sequential transmitting clock pulses of one time slot duration for each active communication line with the frame rate dependent upon the number of time slots, each clock pulse serving to clock the encoder and transmission gate of an associated line interface unit to multiplex the encoded information onto said transmission medium as frames of encoded information, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information from the remote terminal, means for generating recurring frames of sequential receiving clock pulses for each active line, each clock pulse serving to clock an associated receiving gate to demultiplex incoming coded information on said transmission medium and apply the same to an associated decoder which decodes the information and applies its output to the corresponding line; said one or more remote terminals including: a plurality of remote terminal line interface units connected to each communication line of said remote terminal to receive information therefrom and supply information thereto, each of said line units including a delta modulation encoder serving to encode received information for transmission to the control terminal over said transmission medium and a delta modulation decoder for decoding information received from the control terminal over said transmission medium, a plurality of transmission gates one connected to the output of each encoder for multiplexing the encoded information onto said transmission line medium, a plurality of receiving gates one for each communication line connected to the transmission medium to receive information on the transmission medium, means for generating recurring frames of sequential clock pulses of one time slot duration on the output corresponding to an active communication line with the frame rate dependent upon the number of time slots, each clock pulse serving to clock the encoder and transmission gate of an associated line interface unit to multiplex the encoded information onto said transmission medium as frames of encoded information, said clock pulses also serving to clock associated receiving gates to demultiplex incoming information on said transmission medium and apply the same to an associated decoder which decodes the information and applies it to the corresponding communication line at the remote terminal.

Claim 43

A multi-channel system as in claim 35 including means at the control terminal for sensing the active or idle state of communication lines connected to the control terminal and providing information relative thereto, means at the remote terminals for sensing the active or idle state of communication lines connected to the remote terminals to transmit information relative thereto to the control terminal, means at the control terminal responsive to said information from the remote and control terminals for adding a message time slot to the system whenever either the control end or remote end of a communications line becomes active, or deleting a message time slot from the system whenever both the control end and the remote end of a communications line becomes idle.

Claim 44

A multi-channel system as in claim 35 in which said terminals include means for sensing when the message time slots do not interconnect corresponding communication lines at the control and remote terminals and generating a misframe signal and means responsive to said misframe signal for reframing the system whereby the message time slots interconnect corresponding communication lines at the control and remote terminals.

Claim 45

A multi-channel system as in cliam 36 in which the active or idle state of each communication line at the control and remote terminals is sensed sequentially by a scanning system which advances one line every two frames of time slots.

Claim 46

A multi-channel system as in cliam 36 in which the active or idle state of each communication line at the control and remote terminals is sensed sequentially by a scanning system which advances one line every two frames of time slots.

Claim 47

A multi-channel system as in claim 35 in which said means for generating transmitting clock pulses includes means for limiting the minimum number of clock pulses in any frame.

Claim 48

A multi-channel system as in claim 35 in which said means for generating transmitting clock pulses includes means for limiting the maximum number of clock pulses in any frame.

Claim 49

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including; a plurality of control terminal line interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line interface units including a delta modulation encoder serving to encode said receive information for transmission to said remote terminal and a delta modulation decoder for decoding information received from said remote terminal, multiplexing means serving to multiplex the encoded information of active communication lines onto said transmission medium as sequential frames of sequential message time slots, said frames including one time slot for each active line and said sequential frames having a frame rate which varies with the number of time slots in each frame, means for demultiplexing incoming sequential frames of sequential message time slots and applying the same to the respective decoders connected to the communication lines for providing messages to the respective communication line, said one or more remote terminals each including: a plurality of remote terminal line interface units connected to each communication line of said one or more remote terminals to receive information therefrom and supply information thereto, each of said line units including a delta modulation encoder serving to encode received information for transmission over said transmission medium to the control terminal and a delta modulation decoder for decoding information received from said transmission medium, multiplexing means serving to multiplex the encoded information of active communication lines onto said transmission mediums as sequential frames of sequential message time slots, said frames including one time slot for each active line and said sequential frames having a frame rate which varies with the number of time slots in each frame, and demultiplexing means for demultiplexing incoming sequential frames of sequential message time slots and applying same to the respective decoders connected to the associated active communication line.

Claim 50

A multi-channel system of the type described for providing transmission between a plurality of communication lines connected to a control terminal and corresponding communication lines connected to one or more remote terminals over a transmission medium interconnecting said control and remote terminals, said control terminal including; a plurality of control terminal line interface units, one connected to each communication line to receive information therefrom and supply information thereto, each of said line interface units including a delta modulation encoder serving to encode said receive information for transmission to said remote terminal and a delta modulation decoder for decoding information received from said remote terminal, multiplexing means serving to multiplex the encoded information of active communication lines onto said transmission medium as sequential frames of sequential message time slots, said frames including one time slot for each active line and said sequential frames having a frame rate which varies with the number of time slots in each frame, means for demultiplexing incoming sequential frames of sequential message time slots and applying the same to the respective decoders connected to the communication lines for providing messages to the respective communication line, said one or more remote terminals each including: a plurality of remote terminal line interface units connected to each communication line of said one or more remote terminals to receive information therefrom and supply information thereto, each of said line units including a delta modulation encoder serving to encode received information for transmission over said transmission medium to the control terminal and a delta modulation decoder for decoding information received from said transmission medium, multiplexing means serving to multiplex the encoded information of active communication lines onto said transmission mediums as sequential frames of sequential message time slots, said frames including one time slot for each active line and said sequential frames having a frame rate which varies with the number of time slots in each frame, and demultiplexing means for demultiplexing incoming sequential frames of sequential message time slots and applying same to the respective decoders connected to the associated active communication line.

Claim 51

A multi-channel carrier system as in claim 41 in which said system includes means for adding or deleting message time slots as communication lines become active or idle respectively.

Claim 52

A multi-channel carrier system as in claim 41 in which said multiplexing means includes means for adding a framing time slot for each frame.

Claim 53

A multi-channel carrier system as in claim 41 in which said terminals include means for sensing when the message time slots do not interconnect the corresponding communication lines at the control and remote terminals to generate a misframe signal, and means responsive to said misframe signal for reframing the system whereby the message time slots interconnect corresponding communication lines at the control and the remote terminals.

Claim 56

The method of transmitting information as in claim 45 including the step of sensing when communication lines become active or idle and adding or deleting message time slots from said frames of sequential message time slots whereby the number of message time slots corresponds to the number of active lines.

Claim 57

The method of transmitting information as in claim 46 including the step of sensing when there is a misframe and reframing the system.