Tune division multiplex digital communication system employing delta modulation

Claim 1

A TELEPHONE SYSTEM FOR TRANSMITTING INFORMATION IN BINARY DIGITAL FORM IN WHICH EACH SUBSCRIBER TO THE TELEPHONE SYSTEM IS PREASSIGNED TO ONE GROUP OF SEVERAL GROUPS OF SUBSCRIBERS AND ALL INFORMATION SENT OR RECEIVED BY A GROUP OF SUBSCRIBERS IS TRANSMITTED ON A TIME SHARING BASIS BETWEEN PULSES OF A CONSTANT FREQUENCY SYNCHRONIZING PULSE TRAIN, EACH SUBSCRIBER BEING PREASSIGNED TO A TIME INTERVAL BETWEEN SUCCESSIVE SYNCHRONIZING PULSES COMPRISING A USER''S TELEPHONE SET FOR EACH SUBSCRIBER TO THE TELEPHONE SYSTEM, EACH USERS'' TELEPHONE SET INCLUDING MEANS FOR CONVERTING AUDIBLE INTO BINARY BITS OF INFORMATION AND MEANS FOR CONVERTING BINARY BITS OF INFORMATION INTO AUDIBLE SOUNDS, SEPARATE TRUNK LINE MEANS FOR CONNECTING EACH OF SAID GROUPS OF SUBSCRIBER''S TELEPHONE SETS TO A SWITCHING FACILITY WITH EACH OF SAID TRUNK LINE MEANS HAVING ORIGINATING AND TERMINATING ENDS IN THE SAID SWITCHING FACILITY, MEANS IN THE SAID SWITCHING FACILITY FOR PRODUCING THE SAID CONSTANT FREQUENCY SYNCHRONIZING PULSES AT THE SAID ORIGINATING ENDS OF THE SAID TRUNK LINE MEANS, MULTIPLEXING MEANS LOCATED OUTSIDE THE SWITCHING FACILITY FOR EACH OF SAID GROUPS OF SUBSCRIBER''S TELEPHONE SETS FOR INSERTING INTO SAID TRUNK LINE MEANS IN THE SAID PREASSIGNED TIME INTERVALS THE SAID BINARY BITS OF INFORMATION FROM SAID MEANS FOR CONVERTING AUDIBLE SOUNDS INTO BINARY BITS OF INFORMATION, DEMULTIPLEXING MEANS IN THE SAID SWITCHING FACILITY AT THE SAID TERMINATING ENDS OF SAID TRUNK LINE MEANS FOR REMOVING THE BINARY BITS OF INFORMATION FROM EACH OF SAID TIME INTERVALS AND SEPARATELY STORING THE BITS OF INFORMATION BY A STORAGE MEANS, MULTIPLEXING MEANS IN THE SAID SWITCHING FACILITY FOR INSERTING SELECTED ONES OF SAID STORED BITS OF INFORMATION INTO SAID TRUNK LINE MEANS NEAR THE SAID ORIGINATING ENDS, AND DEMULTIPLEXING MEANS CONNECTED TO THE SAID TRUNK LINE MEANS FOR SEPARATING THE SAID INSERTED STORED BITS OF INFORMATION AND APPLYING THEM TO THE SAID MEANS FOR CONVERTING BINARY BITS OF INFORMATION INTO AUDIBLE SOUNDS.