RF over Fiber Required in the World s Longest, Deepest Railway Tunnel

Gotthard Base Tunnel 2016' train image (source: Federal Office of Transports (FOT))

The Gotthard Base Tunnel is the world's longest and deepest railway tunnel at 57km (35.5 miles), with up to 2,300 metres of rock cover. Taking over 17 years to construct, there were numerous challenges involved, including how to get PMR (Private Mobile Radio), GSM-R (Global System for Mobile Communications - Railway) and UMTS (Universal Mobile Telecommunications System) in the tunnel.

The communications services are needed for workers, train operatives and passengers to use their mobile phones for cellular phone calls/text messaging and 3G/4G mobile data.

In order for the GSM-R, PMR and UMTS base stations to operate they need to be provided with timing synchronisation. Digital services provider, ATOS AG needed to get GPS signals from an outside, clear sky location into the tunnel to the base stations. ATOS solved the challenge by using specialists ViaLite Communications' RF over fiber GPS links.

The high sensitivity links allow the signal, which is very low at -110 to -130dBm, to be accurately transported over considerable distances; connecting high-gain ViaLite GPS antennas - located on the mountainside - to the base stations within the tunnel.

The ViaLite system used incorporates 3U rack chassis units and multiple levels of 1:1 redundancy to ensure 5 nines reliability; this is very similar to the ViaLite system in the London Underground which was installed in 2001/2. Gotthard Base Tunnel's system also incorporates ViaLite ODE-A outdoor enclosures, which are used to house the GPS links above the tunnel; protecting them from the elements.

ViaLite Communications provided full on-site training to ATOS to allow them to install and service the GPS links in Switzerland, where the tunnel connects Ersfeld (UR) and Bodio (TI).

Neil Seager, Head of Sales at ViaLite Communications, said: This was a complex and challenging project and we were honoured to be involved with ATOS in its delivery.

The Gotthard Tunnel opens for full service on 11 December 2016.

About ViaLite Communications

ViaLite Communications is a division of Pulse Power and Measurement Ltd (PPM). PPM was founded in 1994 and has three further divisions: PPM Power, PPM Test and PPM Systems. PPM's hub website: www.ppm.co.uk.

ViaLite designs and manufactures RF over fiber links/systems, support modules (including an SNMP Monitor & Control module), rack chassis and outdoor enclosures (the ODE range).

This year (2016), ViaLite celebrated 20 years of RF over fiber links and the shipment of its 10,000th RF link.

Customers include: Intelsat, Eutelsat, HMGCC, Motorola, Thales Defence & Communications, UK MOD, European Broadcasting Corporation, BT, BAE Systems, Astrium.

ViaLite products are used in a variety of markets, including: Satcom, Broadcast, Cellular and Network Timing, Telemetry, Maritime, Government, Mining and Public Safety.

Website: www.vialite.com

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