Yngve Rapp - The history of Ericsson

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Södertälje— the First AXE Exchange John Meurling The AXE system has been described in a number of articles in Ericsson Review No. 2, 1976^ 5 . The system exhibits a number of interesting technical innovations and properties. In particular the modular structure of both software and hardware has been highly acclaimed. This structure has made the system easier to handle as regards planning, production, installation and operation. The first AXE exchange has been installed in Södertälje. Experience from the installation and operation of this exchange has verified many of the system's properties. This experience is briefly recounted in this article. UDC621 395 34(485-3) Fig. 1 The AGF 500-switch exchange at Södertälje Fig. 2 Södertälje trunk code area — — - High usage route The Södertälje project Södertälje is a medium-sized industrial town some 40 kilometres south-west of Stockholm. Since 1940 the town has had an AGF 500-switch exchange, which today has slightly more than 31,000 installed subscriber lines. Södertälje is centre of a trunk code area (trunk code 0755). There are thus a 0755 SÖDERTÄLJE number of group centres and terminal exchanges (of the Swedish Telecommunications Administration's crossbar type) connected to the AGF exchange. There are also routes to Stockholm and other adjacent towns, but also to such distant places as Gothenburg and Malmö (see network configuration fig. 2). The AXE exchange in Södertälje consists of a 3000-line unit in the same building as the AGF exchange and constitutes the first step in its total replacement. Owing to the small size of the AXE unit in relation to the AGF exchange, all traffic is being preliminarily directed to and from the AXE unit via the AGF group selectors (see trunking diagram, fig. 4). The AXE exchange at present interworks with other exchanges on an AGF basis but will later be independent
JOHN MEURLING Telephone Exchange Division Telefonaktiebolagel LM Ericsson Fig. 3 The exchange building. The AXE exchange is on the ground floor. The remainder of the building accommodates offices and part of the AGF equipment Fig. 4 AXE, Södertälje Simplified trunking diagram AXE 10 LIC Line circuit SSN Subscriber stage switching network AJC Junctor circuit, A-subscriber BJC Junctor circuit, B-subscriber KRD Receiver for pushbutton signals GSNI Group selector stage switching network, incoming side GSNO Group selector stage switching network, outgoing side ITC Incoming trunk circuit OTC Outgoing trunk circuit CSD Code sender ASD Answering service device AGF S Finder LV Final selector SNR Cord circuit IGV First group selector IIGV Second group selector GIV Incoming group selector GUV Outgoing group selector FUR Outgoing trunk circuit of the AGF conditions. The new exchange does, however, afford an interesting example of the adaptibility of the AXE system. No additional interworking equipment has been introduced on the AGF side, but the characteristic revertive pulse signalling of the AGF system is entirely handled by AXE. The installation work took slightly longer one year. The reason for this extended period was that as Södertälje is the first AXE exchange in commercial service, the desire was to use it for verifying a number of new installation methods and aids. The handling of the software has, of course, been a matter of special interest. Since April 1976 a group of 20 trial subscribers has been connected. These were requested to generate as much traffic as possible. The test traffic has proceeded satisfactorily and has actively contributed to the testing of the exchange. During the first week of December 1976 the Administration made an operational test of the exchange. On this occasion an additional 20 subscriber lines were connected by special agreement, in this case high-traffic PBX lines. This test was the first phase in the Administration's acceptance of the exchange. 3 Installation and testing It has been very important to verify the principles for testing of functional units, i.e. the procedure by which the functional unit-the magazine-is equipped with PC boards, put through its final production test, and delivered to the installation site fully equipped and tested. This is of special value as regards the processors CP and RP, which are thus delivered equipped and tested. In a few days the hardware is fully tested (with a specially developed off-line test program AVS), including the I/O system with associated RP, after which the operative and maintenance system is loaded. This is run through in another few days. Thereafter APZ —the control system— constitutes the main instrument for the subsequent installation testing. APZ is accordingly kept in normal operation during the greater part of the installation testing period. As APZ hardware and operative systems have been tested in conjunction with their manufacture, APZ specialists are not normally needed on site during the installation stage. Three other important installation test aids have been used: — STG (Subscriber Traffic Generator) consisting chiefly of hardware. — SOLIT (Switch Operation and Link Tester), consisting mainly of off-line
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Page 12 and 13: 8 Yngve Rapp at his doctoral disser
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The Ericsson Group With associated
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Yngve Rapp - The history of Ericsson

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