Automated Matrix for Communication Line Connections

The present invention relates to the field of communication and more particularly to those aspects of communication wherein the medium through which the communication is conducted are electrical conductors. More particularly the present invention relates to a communication system having a plurality of dedicated terminal devices which are connected to dedicated electrical conductors. In even greater particularity the present invention relates to apparatus for connecting each of the dedicated conductors to a selected transmission line for communication with a remote location.

The present system may be most easily understood by referring to the familiar commercial telephone system. As is well known, the telephone system is composed of a number of central offices, each of which is typically located in a city or other population center. Each central office services a number of remote terminals, each of which is located in another smaller population center which may be several miles from the central office. Each remote terminal services a number of subscriber lines and thus is sometimes referred to as a remote concentrator in as much as all of the subscriber lines are brought together for connection to lines running to the central station. For example, there may be 96 lines running from each remote terminal to the central station and there may be 125 subscriber lines (cable pairs) concentrated at the remote terminal. It should be understood that the remote terminal is installed with more lines and cable pairs than are initially needed to allow for growth upon installation. Also spare lines and cable pairs are needed to replace damaged or defective line or cable pairs. To provide service to a subscriber, a spare line from the remote terminal is connected to a spare cable pair going near the subscriber's residence or business.

Each connection of the cable pair to a line, whether for installation, repair, or disconnection, is typically made by hand by telephone personnel dispatched to the remote terminal. This is a very labor intensive operation which entails not only the labor on site but also the time and cost of transporting personnel to the remote terminals.

From the foregoing, it may be seen that considerable effort is required to simply make the proper connection, even when well known terminal equipment is being used. An analogous problem is presented in various applications wherein a number of terminal devices, such as sensors are distributed to provide data or information to a central unit. As in the telephone system, each unit must be individually connected at considerable expense.

It is the principal object of our invention to eliminate the need for service personnel to go to the remote terminals and the like to make line connections or disconnections.

Another object of the invention is to provide the ability to test lines and cable pairs remotely before connecting them or while they are in service.

Our invention advantageously permits the use of inexpensive technology to accomplish these objects and to provide other advantages by using a crossconnect matrix formed by an array of crosspoint contact pairs, with one contact of each pair connected to a line conductor and the other contact connected to one conductor in a cable pair oriented perpendicular thereto. A shorting contact assembly is provided for each line or each cable pair and is movable along the line or cable pair via a stepper motor to a selected crosspoint, whereupon the line and cable pair are connected together. The stepper motors are controlled and monitored by a microprocessor which receives instructions from and sends information to a remote location, for example, the central office.

Apparatus incorporating features of our invention are depicted in the accompanying drawings which form a portion of this disclosure and wherein:

FIG. 1 is a schematic block representation of a system wherein our invention may be utilized;

FIG. 2 is a schematic block representation of our invention in greater detail;

FIG. 3 is a plan view of the matrix portion of our invention;

FIG. 4 is a side elevational view of the matrix portion taken along line 4--4 of FIG. 3;

FIG. 5 is a sectional view of the matrix portion of our invention taken along line 5--5 of FIG. 3; and

FIG. 6 is a partial view of the carrier assembly and matrix portion taken along line 6--6 of FIG. 5.

Referring to the drawings for a better understanding of the invention, note that FIG. 1 is a representation of a system in which our invention can be used. Our invention is a crossconnect system 10 comprising a crossconnect matrix 11 and a matrix control unit 12. The crossconnect system 10 is physically located at a remote terminal 13 which is connected by a plurality of two wire communication lines 14 to a central office 16, which in turn is in communication with a dispatching and maintenance center 17. The remote terminal 13 serves to concentrate the subscriber cable pairs 18 which are dedicated to a specified end user or unit of terminal equipment. Our crossconnect system 10 provides the interface between the lines 14 and subscriber cable pairs 18. The actual interconnection of the line 14 and cable pairs 18 occurs on the crossconnect matrix 11 shown in FIG. 2 and in more detail in FIGS. 3-6.

As can be appreciated from FIG. 2 and FIG. 3, the lines 14 are connected to the matrix 11 at a set of co-planar parallel line pair elements 14a & 14b. The cable pairs are connected to the matrix at a set of co-planar parallel cable pair elements 18a & 18b with the plane of each set of conductors being parallel and spaced from the plane of the other set. The line pair elements 14a & 14b are oriented perpendicular to the cable pair elements 18a & 18b. Thus it may be seen that the line pair elements 14a & 14b may be formed on one side of a dielectric 19 such as a printed circuit board and the cable pair elements 18a & 18b formed on the opposite side of the dielectric 19, thus the sets of conductors form an ordered grid with identifiable crosspoints, even though the conductors remain separated at the crosspoints.

Interconnection between the conductors at the crosspoints may be accomplished by forming a plated through hole 21 from the conductor on one side of the dielectric 19 through the dielectric proximal each crosspoint and positioning a short conductor segment 22 in the plane of the conductor on the other side of the dielectric 19. Thus the short conductor segment 22 and each conductor of the cable pair element 18a & 18b in FIG. 6 form a set of contacts, which when closed connect line element 14a to cable pair element 18a & line element 14b to cable pair element 18b. Each set of contacts may be closed by a pair of shorting springs 23a & b which slide along one surface of the dielectric until the desired line elements 14a & b and cable pair elements 18a & b are in electrical contact through the shorting springs 23a & b. A pair of shorting springs 23a & b is provided for each pair of line elements 14a & b, and moves over the dielectric along a path parallel to the line elements 14a & 14b. Each pair of shorting springs 23a & b is attached to a non-conducting carrier 24 which threadedly engages a screw or worm 26 such that rotation of the worm 26 moves the carrier 24 axially along the line element 14a & b. The worms 26 for each pair of line elements are mounted for rotation in a frame member 27 and 28 at opposing ends of the dielectric 19. As may be seen in FIGS. 3 and 4, frame member 28 has a slot 29 formed longitudinally therein opening outwardly parallel to the dielectric 19. Also as may be seen in FIG. 4, each end of worm 26 mounted in frame member 28 has a slot 31 formed therein which can be aligned with the slot 29.

Mounted outwardly of frame member 28 is a stepper motor 32 having an output shaft 33 and a tip 34 adapted for sliding engagement within slots 29 and 31. The tip 34 acts like the blade of a screwdriver and has a width less than the diameter of the worm 26 so that it may rotate. The stepper motor 32 is mounted to a carriage 36 which is also threadedly engaged by a worm 37 mounted for rotation in frame member 38 and 39 which extend perpendicularly to frame member 27 and 28. A second stepper motor 41 drives this worm 37 thereby urging motor 32 axially along the worm and thus moving tip 34 along the length of slot 29. Frame member 42 stabilizes the frame members 38 and 39.

Stepper motors 32 and 41 are controlled via conventional stepper motor drivers which in turn receive instructional data from the matrix control unit 12.

The matrix control unit is shown in greater detail in FIG. 2 and includes a microprocessor 46 with an EPROM 47 for storage of software to enable the microprocessor 46 to control the cross connect matrix 11 and to communicate with a remote location such as the dispatching and maintenance center 17. A random access memory (RAM) 48 is provided in conjunction with microprocessor 46 and contains the data base concerning all of the crosspoints in the matrix 11. This information defines which line elements 14a & b are connected to which cable pair elements 18a & b. The RAM 48 must be provided with a battery back-up 49 or other device to prevent loss of this data base in the event of a power failure or the like. For example, a detector 51 for power failure is provided to detect the loss of power in sufficient time for the microprocessor 46 to store current conditions in RAM 48 before loss of power to the microprocessor 46, thus RAM 48 must remain unaffected to enable the microprocessor 46 to resume its operation upon restoration of power.

The microprocessor 46 communicates with the dispatching and maintenance center 17 over a line circuit using Dual Tone Multi-frequency (DTMF) protocol or by using the RS-232C communication protocol. In either event the remaining components of the matrix control unit 12 are described with reference to customary telephone nomenclature which is intended to apply to both telephone systems and other communication systems. The communications line circuit includes a TIP (T) and RING (R) pair which provide input from the remote control area via a surge protector 52, as is commonly known and used, to protect the cross connect system 10 from high voltage surges such as lightning. A full wave diode bridge 53 to maintain the proper polarity as is indicated by the (+) or (-) on the bridge outputs. A voltage detector 54, termed a ring current detector, detects ring voltage across the output of the full wave diode bridge 53 and signals the occurrence of the same to the microprocessor 46. A transformer 56 is used, as is conventional, to provide electrical isolation between the T and R lines and the remainder of the control circuitry. Serially connected to the transformer 56 is a seize switch 57 which is essentially a solid state switch which closes the circuit between the T and R lines. Closure of the seize switch 57 is initiated by the microprocessor 46 either upon receipt of a ring voltage detector signal from voltage detector 54 or to initiate an outgoing message from the cross connect system 10. To assure that the seize switch 57 is operational, a current detector 58 is serially connected therewith and provides a signal to the microprocessor 46 indicative of the presence of current in the circuit.

The secondary of transformer 56 is connected to a progress tone detector 59 which detects such signals as dial tones, busy tones and audible ringing which are signalled to the microprocessor 46 and are used to determine the status of the communication lines for outgoing messages. The microprocessor 46 is interfaced to the secondary of transformer 56 for communication purposes by a DTMF receiver 61 and a DTMF transmitter 62 or a modem 63 depending on whether the DTMF communication protocol or the RS-232C communication protocol is used.

In operation, it is to be understood that the EPROM 47 is programmed in accordance with the needs of the user and the size of the matrix 11. Upon energization, the microprocessor 46 is placed in an idle state and awaits a signal from the voltage detector 54 indicating that a communication from the dispatching and maintenance center 17 is to be received. The microprocessor 46 thereupon signals the seize switch 57 to close the circuit and monitors the current detector 58 for a signal indicating that the circuit has been closed. To initiate a call, the microprocessor 46 sends a seize command to the seize switch 57 and monitors the current detector 58. The progress tone detector 59 then indicates to the microprocessor 46 the status of the communication line. The microprocessor 46 communicates via the DTMF transmitter 62 and receiver 61 or modem 63 in the conventional manner.

The control signals are received by the microprocessor 46 to cause connection of the individual line pair elements 14a & 14b to the selected cable pair elements 18a & 18b. The microprocessor 46 in turn sends signals to the stepper motor drivers 45 which in turn control the stepper motors 41 and 42. Motor 41 turns worm 37 to position motor 32 at the end of a selected worm 26 which runs parallel to the line pair elements 14a & 14b. Note that the tip 34 travels within slot 29 and is positioned within slot 31 at the end of worm 26. Motor 32 turns the selected worm 26 to move the shorting springs 23a & 23b to the selected crosspoint such that the cable pair elements 18a & 18b are electrically connected to the line segment 22 and thus to the line pair elements 14a & 14b. Note that with this arrangement the line pair elements may be connected with any cable pair elements selected. The cable pair elements are spaced apart such that an integral number of revolutions of the worm 26 are required to move the spring contacts 23a & b between adjacent crosspoints thus tip 34 will re-align with slot 29 and the motor 32 is free to move along the worm 37 to position each set of sliding springs 23 as required by the microprocessor 46.

It may thus be seen that if a cable pair is connected to a defective or damaged line pair, the cross connect system 10 can disconnect the cable pair and connect them to an alternate or spare line pair. Likewise if a cable pair becomes non-functional or unnecessary, it may be disconnected from the line pair which is then available for connection to any cable pair. All of which may be accomplished without ever sending a technician into the field, thus effecting a tremendous savings in labor, time and efficiency.

While we have shown our invention in one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit thereof.