PORTABLE CALL GENERATOR

Abstract: A portable call generator 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. The test apparatus comprises an ''A'' line interface (5) and a ''B'' line interface (8) for coupling first and second test numbers to a programmable processor (1) in which a plurality of test parameters can be selectively stored in an associated memory (2). The A line interface is activated by signals from the processor to seize the first test number, establish a connexion between the first and second test numbers, and perform selected tests on the interconnect circuit.

Description: Portable Call Generator Technical Field 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 ser¬ vice and to trace network faults. Background Art 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 num¬ ber to a second 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 improved test apparatus of the above type which avoids the aforementioned disadvantages. Summary of the Invention According to the invention there is provided a testing apparatus for generating repetitive telephone traffic test signals for testing the per¬ formance 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 coupl¬ ing 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, es¬ tablish 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 read-out means. Brief Description of Drawings In order that the invention may be readily carried into effect, an em¬ bodiment thereof will now be described in relation to the drawing. Best Mode of Carrying out the Invention Re erring to the drawing there is shown a block schematic circuit of the test apparatus which comprises a microprocessor 1 having an associated non-volatile memory 2, an associated keypad and liquid crystal display 3 coupled thereto by an inpu /output means (I/O) ; an "A" line interface circuit 5 incorporating a controllable relay arrangement (not shown) con¬ trolled by dialling information produced by driver means la as a result of information keyed into the processor. Connection to the 'A' line interface circuit 5 is via teπninals "a", "b" and "m" for connection to the voice transmission pair ("a", "b") and the meter wire ("m") of the "originating" test number. Also coupled to "A" line interface circuit 5 is a tone re¬ ceiver 6 which comprises a bandpass filter (BPF) for attenuating all fre¬ quencies 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 in¬ jection, 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 cir¬ cuits, 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 DUMP chip. All operations of the test unit are controlled by the microprocessor 1 in conjunction with memory 2. Test parameters 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 - or decadic. 5. 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 un¬ manned exchange from a central location. 10. An answer mode in which the test apparatus is used as a TCARS in a re¬ mote exchange. In operation, information from the keypad 3 is polled by the micro¬ processor by a known repetitive scanning process. Each key operation is detected as a connection between a matrix horizontal and vertical con¬ nection. A translation is made by software to produce the required func ¬ tion. All of the parameters have default settings which enables the test apparatus to revert to standard parameters after power up. Once the param¬ eters are set, a start key may be activated, and under the control of the microprocessor the following sequence of events occurs: A loop signal is applied to "A" line interface circuit 5 whose "a", "b" and " " 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 "originating" line. After a programπed delay to await dial tone, the terminating number is automatically dialled using DTMP 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 detected 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 "3" interface circuits via the exchange interconnect circuit. A test tone gen¬ erated in tone sender 9 is then injected into "B" line interface circuit 8. This test tone is then detected in tone receiver 6. Ωie BPF in tone re¬ ceiver 6 excludes spurious 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 partic¬ ular exchange type selected during set-up. If a fault in the transmission of the test 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 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 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 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 de¬ vices 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: AMENDED CLAIMS [received by the International Bureau on 9 October 1989 (09.10.89) original claim 7 cancelled; claim 1 amended; other claims unchanged (2 pages)] The claims defining the invention are 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 appa¬ ratus 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 con¬ dition Is encountered for locating said fault condition, and when in a sec¬ ond programmable test mode store the results of said tests in said memory means for presentation in read-out means, stored 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 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 inter¬ face means is coupled to a test tone receiver means for detecting the pres ¬ ence 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 me¬ tering parameters. 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 re ¬ lay set. 10. A test apparatus as claimed in any one of the preceding claims, further including audio monitor means for monitoring progress of said se¬ lected tests. 11. A test apparatus substantially as herein described with reference to the figure of the drawing. STATEMENTUNDERARTICLE19 Claim 1 has been amended in order to distinguish the invention defined therein from prior art disclosed in documents cited in the International Search Report. This has been done by incorporating the feature defined in old claim 7 into claim 1. A consequential amendment to the text of the "Summary of Invention" on page 1 of the description is required.

Applicants: STANDARD TELEPHONES CABLES LTD, STANDARD TELEPHONES AND CABLES PTY. LIMITED
Application year: 1989
Main classification: H04M1
IPC codes: H04M3