IE40682L - Testing of telephone exchange - Google Patents

Abstract

1477102 Automatic exchange systems COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS CIT-ALCATEL 24 Feb 1975 [25 Feb 1974] 7656/75 Heading H4K A traffic simulator comprises a number of electronically controlled test modules each adapted to simulate a calling and a called subscriber and mode selection means for operating the modules either asynchronously with the modules establishing independent connection or synchronously with all units co-operating to set up a plurality of calls all of which are at any one time in the same phase of establishment. Thus in the synchronous mode each module awaits the completion of a particular call phase by every other module before advancing to the next phase. If due to a fault one module fails to complete a phase, that module is or if in the synchronous mode all modules are prevented from advancing. The exchange equipment giving rise to the fault is thus held, an alarm sounds and a lamp characteristic of the fault is lit. The lamp to be lit is determined by the phase reached and the response achieved within a phase. The phases specified include onhook, off-hook awaiting PAX or PBX dial tone, awaiting public exchange dial tone, awaiting international dial tone, await ring back, check charge rate pulses and await a tone simulating speech returned by the simulated called subscriber upon answer, and await call clearing. The figure shows the analog circuitry of a module. It includes calling line terminals A1, B1 and called line terminals A2, B2 for connection to an exchange network represented by E1, L and E2. The calling line simulation components comprise line resistances R1, R2, line loop relay contacts dr impulsing contacts n and a speech circuit simulator comprising a transformer T1 and a tone detector ED the output of which conveys only the cadence of a received tone, the particular tone being received at any time being determined by counting during the makes and breaks in the cadence signal. Relay RTA responds to meter pulses on metering wire TA repeating these to a duration monitoring counting circuit via its contacts rta. The called subscriber simulation circuit includes a ringing signal detector S, line looping contacts de and a transformer T2 via which a continuous answering tone from a generator G may be coupled to the line. During a fault test changeover contacts im may be operated manually to couple the generator G- directly to the calling subscriber simulator. To enable service quality (i.e. the ratio between the number of communications initiated to the number of blockages that result from defects) to be monitored each module is provided with an extra counter for each type of defect to be recorded. [GB1477102A]