Digital telephone switching system

Claim 2

In a telephone system of the type in which dialing or other control signals are used to determine the connection to be made between any one of a plurality of telephone lines calling another line selected from the same or other plurality of telephone lines, a switching matrix at one site interfacing with standard two or four-wire telephone transmission lines for switching from one line to another communication signal of the form produced by the user independently of the switching matrix, said switching matrix comprising means responsive to a calling line initiating a call for generating a digital code, XM, uniquely identifying said calling line, means responsive to control signals received from said calling line for generating a digital code, XN, uniquely identifying another line called, a plurality of converting means, one for each of said plurality of lines which may be calling, each converting means serving to convert communication signals received from its associated line to digital form, a plurality of reconverting means, one for each of said plurality of lines which may be called, each reconverting means serving to convert communication signals received to analog form for transmission through its associated line, and switching means resposive to said digital codes XM and XN for routing communication signals in digital form from a converting means associated with a calling line to a reconverting means associated with a called line, all of said converting, switching and reconverting means being at said one site, whereby all transmission to and from said switching matrix is in digital form.

Claim 3

The combination defined by claim 1 including a second similar switching matrix at said one site and responsive to said digital codes for switching communication signals from said called line to said calling line.

Claim 4

The combination of claim 2 wherein each of said switching matrices comprises a plurality of incoming bus bars, one for each incoming line, and a plurality of outgoing bus bars, one for each outgoing line, where an incoming line is a calling line in one switching matrix and a called line in the other, and an outgoing line is a called line in said one switching matrix and a calling line in the other, separate gating means for separately connecting each incoming bus bar to each outgoing bus bar such that for any outgoing bus bar selected at random, each one of the incoming bus bars is connected to it by a separate gating means, each gating means being responsive to a switching control signal to enable it to translate digital signals from an incoming bus bar to an outgoing bus bar, and means responsive to said digital codes XM and XN for generating a control signal SMN at a gating means uniquely identified by said digital codes for enabling said uniquely identified gating means to connect an incoming line to an outgoing line.

Claim 5

The combination of claim 3 wherein each gating means is comprised of an AND gate having two input terminals and one output terminal, one input terminal being connected to an incoming bus bar and the other being connected to receive a control signal from said control signal generating means, and said output terminal being connected to an outgoing bus bar.

Claim 6

The combination of claim 2 wherein each of said switching matrices comprises a common transmission channel, a code counter for repeatedly generating a plurality of unique digital codes in a predetermined sequence, said codes including all codes of incoming and outgoing lines, where an incoming line is a calling line in one switching system and the called line in the other, and an outgoing line is the called line in the one switching system and the calling line in the other, a source of clock pulses for driving said counter, a separate decoding means associated with each incoming line for detecting means associated with each incoming line for detecting when said counter has advanced to the code of the incoming line, means responsive to output signals from said decoding means for synchronizing said converting means on said incoming lines to operate in sequence, means responsive to output signals from said decoding means, for gating out in sequence digital signals from said converting means to said common channel, thereby effecting time-division multiplexing of digital signals from incoming lines onto said common channel, a separate register associated with each outgoing line adapted to receive and store the digital code of an incoming line involved in a telephone call, separate means associated with each register for decoding the digital code of an outgoing line involved in a telephone call, separate means associated with each outgoing line for comparing the output of said code counter with the digital code of an incoming line stored in the associated register, and a separate means responsive to the output of each comparator for synchronizing separate operation of one of said reconverting means connected to an outgoing line associated with the one of said registers being compared, thereby demultiplexing and reconverting to analog form digital signals time-division multiplexed onto said common channel in digital form.

Claim 7

The combination of claim 5 wherein said converting means and reconverting means transmit and receive respectively, digital signals in parallel, and said common channel transmits digital signals in parallel.