This invention relates to a communication system wherein a plurality of stations can communicate with each other, without going through a central switchboard; and more particularly to such a communication system that is as private as possible -- the commmunication system having, in addition, the capability of conference calls and a command-override.

A loop circuit interface module enabling a plurality of data terminals remote from each other and from a central controller to communicate with each other and the central controller over a plurality of data channels interconnecting same is disclosed. The loop circuit interface module comprises a plurality of data ports for inputting data from either the loop controller or another loop circuit interface module. The data ports also output data to the loop controller or another loop circuit interfa...

A communication device is disclosed. The device comprises keyboard means having a plurality of keys. The keys are operable to enable the user to create a message to be communicated, or to select one of a plurality of predetermined messages to be communicated. User operable feedback switch means including a sequential display means presents each key from the keyboard means to the user. The feedback switch means is further operable during the time a key is presented to duplicate the operability of...

1. In combination: a signal source for producing a signal having characteristic variations representative of intelligence, a first code source for producing a first code signal having apparently random characteristic variations but actually having characteristic variations conforming to a first particular code sequence which repeats after a relatively short time interval, a second code source for producing a second code signal likewise having apparently random characteristic variations but actua...

A communication system for combining telephone service with hands-free talk-back intercom service is disclosed. The telephone service includes a telephone exchange network having an outside trunk, an internal trunk, and a device for switching the telephones within the system between either the outside trunk or the internal trunk in response to appropriate signals from the telephones. The intercom network generally includes a main distribution station associated with various telephones and transd...

A communication aid comprising an assembly of illustrations individually mounted on a ring to provide a basic means of communication for individuals who have difficulty expressing their needs, or who cannot be understood by others. Each illustration or picture represents a necessity of living and is contained within the pocket of a transparent plastic envelope. Each envelope is mounted for free sliding movement on a ring. By sliding the envelopes along the ring, the individual can point to the i...

2. A method by which a submarine while deeply submerged in the sea may receive a message from a remote station without disclosing to others the position of the submarine, which comprises transmitting from said remote station into the atmosphere message information modulated on electromagnetic radiant energy, intercepting said radiant energy at a plurality of separated and widely dispersed relay stations on the surface of the sea, extracting the message information from the electromagnetic energy...

Data and speech are transmitted along an elongate member from a transmitter to a receiver. Toroids are used to effect a low frequency coupling between the transceivers and the elongate member. The toroids are segmented and their windings are such as to form part of a resonant circuit as well as being arranged around the segments such that external fields are cancelled. Protective shrouds are arranged around at least part of the toroids.

A pulse modulation system in which both ends of the pulses of a train can be modulated in time relative to time marker signals, permits establishment of a four-channel, time division, duplex communication system on a single radio frequency carrier. The modulation technique permits pulse width modulation of signals whose band width exceeds the pulse repetition rate. Such a system can provide relatively narrow band, low noise, communication, and it is applicable to transmission and reception of hi...

A method and apparatus for code communication is disclosed in order to achieve band-width compression. Successive portions of information are derived and the next portion of information is predicted from at least one preceding portion, an error signal is then generated corresponding to the difference between the predicted portion and the next actual portion of information, whereafter the error signal is coded for transmission to a receiving device. The system is particularly described for coding...