NZ229272A - Telephone exchange interconnect testing circuit - Google Patents

Description

229 2 7 2 Priority Date(s): Complete Specification Filed:"^^ .

Class: A|t .DA \ .j.2,^r /.

VA».CvMS .feb.; Afei Publication Date: ?.?. .WX .!??! P.O. Journal, No: t « • • i TRUE COPY NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "PORTABLE CALL GENERATOR" WE, STANDARD TELEPHONES AND CABLES PTY. LIMITED, A Company of the State of New South Wales, of 252-280 Botany Road, Alexandria, New South Wales, 2015, Australia, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 1 229 2 This invention relates to test instruments used particularly, though not exclusively, in unstaffed telephone exchanges, and in particular to an instrument to generate repetitive telephone traffic to assess grade of service and 5 to trace network faults .

Such test instruments, generally referred to as call generators, are known. They basically test the performance of an exchange interconnect circuit connecting a first test number, referred to as an originating number to a second 10 test number or group of numbers referred to as terminating numbers. The known call generator suffers the disadvantage of having a limited number of test parameters which are, moreover, difficult to set up.

It is an object of the present invention to provide an 15 improved test apparatus of the above type which avoids the aforementioned disadvantages.

According to the invention there is provided a testing apparatus for generating repetitive telephone traffic test signals for testing the performance of a telephone exchange 20 interconnect circuit connecting a first test line number to at least one second test line number, said apparatus comprising a first interface means and a second interface means for coupling respective first and second line numbers to a 22 9 2 programmable processor means in which a plurality of test parameters can be selectively stored in an associated memory means, said first interface means being activated by signals from said processor means to seize said first test line num-5 ber, establish a connection between said first test line number and said second test line number and perform selected tests on said interconnect circuit, results of said tests being stored in said memory means for presentation in readout means.

In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the drawing.

Referring to the drawing there is shown a block schematic circuit of the test apparatus which comprises a micro-15 processor 1 having an associated non-volatile memory 2, an associated keypad and liquid crystal display 3 coupled thereto by an input/output means (I/O) 4; an "A" line interface circuit 5 incorporating a controllable relay arrangement (not shown) controlled by dialling information 20 produced by driver means la as a result of information keyed into the processor. Connection to the 'A' line interface circuit 5 is via terminals "a", "b" and "m" for connection to the voice transmission pair ("a", "b") and the meter wire 3 229 2 7 2 ("m") of the "originating" test number. Also coupled to "A" line interface circuit 5 Is a tone receiver 6 which comprises a bandpass filter (BPP) for attenuating all frequencies outside the test tone frequency band, and a level detector (not shown). The input means of an audio amplifier 7 is coupled to "A" line interface circuit 5 for monitoring the progress of tests being performed by the test apparatus. A "B" line interface circuit 8 is coupled to driver means la as well as to a tone sender 9 which generates test tone for injection, via "B" line interface circuit 8 into the voice transmission pair of the "terminating" test number connected to terminal "a" and "b" of the "B" line interface circuit. Two outputs of a trace tone generator 10, which is controlled by the microprocessor via a line coupled to the driver means la are respectively coupled to the "A" and "B" line interface circuits, for injecting characteristically different musical tones, generated in the trace tone generator, into the originating and terminating test lines to trace a detected fault. Preferably, these tones are generated in a DTMF chip.

All operations of the test unit are controlled by the microprocessor 1 in conjunction with memory 2. Test parame- 22 9 2 ters are entered via keypad 3 with detailed prompting displayed on the display. Parameters that may be set up are: 1. An internal call, that is the apparatus will call a terminating number or group of sequential numbers from an originating number. 2. An external call, that is the apparatus will call a test call answer relay set (TCARS) and receive answer signal from the TCARS. 3. Transmission and/or metering test. 4. Dialling mode - VP or decadic.

. Type of metering - depending on the type of exchange equipment. 6. Select number of test calls. 7. Log faults detected during test or, alternatively, stop the test when a test call fails. 8. Dial impulse parameters. 9. A remote start mode, used for testing interconnect circuits in an unmanned exchange from a central location.

. An answer mode in which the test apparatus is used as a TCARS in a remote exchange. 22 9 2 In operation, information from the keypad 3 is polled by the microprocessor by a known repetitive scanning process. Each key operation is detected as a connection between a matrix horizontal and vertical connection. A translation 5 is made by software to produce the required function. All of the parameters have default settings which enables the test apparatus to revert to standard parameters after power up. Once the parameters are set, a start key may be activated, and under the control of the microprocessor the fol-10 lowing sequence of events occurs: A loop signal is applied to "A" line interface circuit 5 whose "a", "b" and "m" terminals are connected to an originating line at the Main Distributing Frame (MDF) of the exchange. This causes an "off hook" condition which seizes the line circuit of the "origi-15 nating" line. After a programmed delay to await dial tone, the terminating number is automatically dialled using DTMF or decadic signalling as selected. As the "a" and "b" terminals of "B" line interface circuit 8 are connected to the "terminating" line on the MDF, a ring signal will be de-20 tected by the microprocessor and a signal applied to "B" line interface circuit 8 to apply a loop to "a" and "b", causing the ring to be tripped. A through connection is then established between the "A" and "B" interface circuits 6 229 2 via the exchange interconnect circuit. A test tone generated in tone sender 9 is then injected into "B" line interface circuit 8. This test tone is then detected in tone receiver 6. The BPP in tone receiver 6 excludes spurious 5 noise on signals.

If so programmed, the test apparatus tests for the arrival of a meter signal at "A" line Interface circuit 5 in the time required for the particular exchange type selected during set-up. If a fault in the transmission of the test 10 tone or the metering signal is detected, details of the fault and "terminating" number are stored in memory 2 for subsequent read-out. If the test call is successful the originating and terminating lines are restored to the idle condition by the removal of the loop signals from each line 15 interface circuit. After a predetermined delay the next test call is commenced and the above procedure repeated until the present number of test calls is completed. The test apparatus then stops.

Variations on this procedure may be selected, such as 20 setting up test calls to an automatic test call answering unit such as a TCARS, in a remote exchange. In this case the remote unit will answer the originating call and send 7 229 2 7 back a test tone, typically 820Hz. This tone is detected by "A" line interface circuit 5 as previously described.

During testing, audio amplifier 7 amplifies signals on the originating line allowing an operator to monitor the testing. This is particularly useful when the test apparatus is programmed to stop on a fault. In the event of a fault, the faulty connection may be held and two different trace tones respectively injected into each line interface circuit. This aids in the location of the fault.

Preferably, the test apparatus is provided with a plurality of LED devices on a front panel to indicate the state of the interface circuits and to indicate the operating mode.

While the present invention has been described with regard to many particulars, it is understood that equivalents may be readily substituted without departing from the scope of the invention.

Claims (11)

229272 What we claim is:-

1. A test apparatus for generating repetitive telephone traffic test signals for testing the performance of a telephone exchange interconnect circuit connecting a first test line number to at least one second test line number, said apparatus comprising a first interface means and a second interface means for coupling respective first and second line numbers to a programmable processor means in which a plurality of test parameters can be selectively stored in an associated memory means, said first interface means being activated by signals from said processor means to seize said first test line number, establish a connection between said first test line number and said second test line number and perform selected tests on said interconnect circuit, and when in a first programmable test mode stop on a fault condition being encountered in said interconnect circuit, said apparatus further Including a trace tone generator producing two distinct trace tones, each of which is coupled to respective first and second interface circuits by a control signal from said processor means when said fault condition is encountered for locating said fault condition, and when in a second programmable test mode store the results of said P K2. i ATcNT OFFICE 16 APR 1991 229272 tests in said memory means for presentation in read-out means.

2. A test apparatus as claimed in claim 1, wherein said processor means is operatively coupled to a keypad means such that contact operation of said keypad is polled by said processor means.

3« A test apparatus as claimed in claim 1 or 2, wherein said read-out means is a liquid crystal display means.

4. A test apparatus as claimed in any one of claims 1 to 3, wherein said second interface means is coupled to a test tone generator means, said processor means causing an injection of test tone produced in said test tone generator means upon the establishment of the connection between the first test line number and the second test line number.

5. A test apparatus as claimed in claim 4, wherein said first interface means is coupled to a test tone receiver means for detecting the presence of said injected test tone.

6. A test apparatus as claimed in claim 5, wherein said tone receiver means Includes a bandpass filter means for attenuating signals other than said test tone.

7- A test apparatus as claimed in any one of the preceding claims, wherein the plurality of test parameters includes transmission and/or metering parame 229272

8. A test apparatus as claimed in claim 7, wherein the test parameters include dial Impulse timing parameters.

9. A test apparatus as claimed in any one of claims 1 to 3, wherein said second interface circuit is replaced by a remote test call answer relay set.

10. A test apparatus as claimed in any one of the preceding claims, further including audio monitor means for monitoring progress of said selected tests.

11. A test apparatus substantially as herein described with reference to the figure of the drawing. STANDARD TELEPHONES AND CABLES PTY. LIMITED P.M. Conrick Authorized Agent P5/1/1703