CERN & TETRA, the full story.

“CERN is a bit particular,” begins Frédéric Chapron, as we pull away from the visitor centre for a tour of the main site. It sounds like a well-loved CERN quip, but it encapsulates the place perfectly: at CERN, Europe’s collaborative subatomic physics laboratory near Geneva, they have particles and they have bits of data in almost unimaginable numbers.

In July 2012, CERN hit the headlines with its achievement of confirming the existence of the elusive, long sought-after Higgs Boson. In finding this, it located one more piece in the cosmic jigsaw puzzle of what composes all the matter in our universe. CERN’s Large Hadron Collider (LHC), a giant particle accelerator built in a circular underground tunnel 27 km around, is shut down for more than a year for an upgrade that will double the energy of its beam. But deeper mysteries remain to be explored when it reopens - such as why no-one has found the so-called dark matter which is thought to account for most of the mass of the universe, and why the matter in our universe has not been annihilated by colliding with the antimatter which ought to exist somewhere. Amid all this effort, a new TETRA radio system, installed a year ago, will play an important behind-the scenes role.

At CERN’s IT department, where Chapron works in the Communications Services group, he offers an introduction to this remarkable institution and its activities. “CERN is an acronym which stands for the European Centre for Nuclear Research”, he explains. But he emphasizes: “You will see the word nuclear, but we don’t do nuclear weapons and there is no link with nuclear power plants. What we do is fundamental research in particle physics.”

Founded in 1954, CERN was established by 12 European nations as a centre of excellence in this branch of science, with a secondary aim of stemming the loss of European scientific brainpower to the US. Since then its achievements have included two Nobel prizes (its Higgs Boson discovery has yet to be saluted in this way) and today it is supported by 20 member states with others waiting to join.

“What we can say also about CERN is that it’s an amazing example of international collaboration”, continues Chapron.”We don’t keep secret the data that we produce at CERN, we share it with all physicists. They can be US, Japan, no matter the nationality of the physicists. Here we talk about pure science.”

If this sounds a little rarefied, it’s worth remembering another of CERN’s gifts to humanity - the World Wide Web, conceived there by the British computer scientist Sir Tim Berners-Lee. “There was a challenge to share the data when he came up with this idea,” Chapron says. “He made this discovery to meet the needs of CERN and then we had his discovery shared with all people of the world.”

Some 2,400 people staff the site, but many contractors are usually at work there too, especially during shutdown periods. In addition there is a floating population of around 7,000 scientists from all over the world, from senior researchers to students - as many as 12,000 in all. And over 80,000 visitors spend time at CERN each year.

Communications for Safety
An important function of the TETRA network is to ensure the safety of all these people. The radios, from Sepura, are equipped with embedded GPS modules, enabling staff to be located on CERN’s various above-ground sites, when necessary; the network covers some 60 square kilometres, extending into both France and Switzerland. But to monitor people working below ground - such as in the LHC ring - a special indoor location package based on radio beacons has been contributed by Sepura’s partner Sysoco. A trial installation yielded excellent results and a full deployment is about to begin.

Humans are not allowed in the tunnels while the beam is running - various safety systems make sure of this. But although the radiation disappears within a minute or two after it stops, other risks may remain, including strong magnetic fields, electrical hazards and helium escapes (the helium can drive out oxygen), and so it is important to be able to identify the location of any individuals at work there with sufficient accuracy.

“The LHC is not the only accelerator that we have,” Chapron adds. “If we want to speed up a particle, we have to inject a particle with an energy of 450?GeV already, so before that we need a chain of accelerators. We can’t run the LHC without the other accelerators. It’s about 50 kilometres of tunnels. And our objective with TETRA is to be able to the cover all these underground galleries with TETRA services.”


An embassy in red
The collaborative spirit pervades everything CERN does, and is symbolized even by the centre’s location near Geneva, straddling a frontier line. At its headquarters in Meyrin, the visitors’ entrance lies in Switzerland and the staff entrance in France. The European Union border cuts right through the site, creating certain challenges because of the different legislation applying on each side. For example, CERN must comply with the radio regulations of both countries.

One organ of CERN especially affected by this unusual situation is its private fire brigade, which is the main user of the TETRA radio network. Uniquely, the brigade’s vehicles carry diplomatic plates. “We are not Swiss and we are not French - we are just between”, explains Yann Léchevin, the brigade’s operational chief. “It’s a kind of embassy, in fact. It’s unique in the world!”

But the brigade is unusual for many other reasons. With some 60 staff on duty day and night, it performs not only traditional firefighting roles but also provides guards on the gates, security patrols, policing functions, ambulances, customs control, and even an out-of-hours legal service to support the customs functions. 

Another unique aspect is the wide range of physical and chemical hazards its firefighters may face, including gas risks and intense magnetic fields. “We have a lot of tunnels, very deep; we work inside the particle accelerator and we have a lot of technical tunnels”, continues Léchevin. “We have some classic buildings like a hostel, offices, we have a power plant. We have banks, a travel agency, a restaurant, a small supermarket, we have our own shuttle buses for public transport - it’s a small city! And our job is to try to protect life, property and goods at CERN - and the environment, because we have very strict rules for the impact of CERN on the environment.” 

Because of the gas risk, the brigade selected an ATEX-rated hand-portable radio for its firefighters, the Sepura STP8X. “When we chose equipment, one requirement was to find a more robust hand-portable able to work with a very high magnetic field,” Léchevin says. “We can go up to 4 tesla. If you imagine this room with four Tesla coils inside, and you put your hand-portable on the floor, it will move across the floor! it’s very strange! So we tested many different hand-portables to know which one is the best, the least sensitive to this.”


TETRA’s added value
Replacing an old VHF radio system, CERN’s TETRA system has introduced not only automatic personnel location but some other new capabilities too. Especially useful for the fire service is the ability to reconfigure talkgroups, for collaborating with other services while handling an incident. “For us it’s very interesting to be able to interconnect many, many different services”, says Léchevin. “It could be electricity, it could be cryogenic, it could be radio protection. For us, what is very interesting is to be able to link people and to work all together on this event - and afterwards, everybody can go back to their previous configuration, and not disturb the other people.

“For the user it’s crystal-clear, because he doesn’t have to change anything. We can do it remotely. It’s a very, very good tool because you can do your intervention, and at the end of the intervention you can delete this and everything comes back to the previous situation.

“And we really like to be able to configure for each user a different template for their specific use. As you can imagine, in this fire brigade a single firefighter doesn’t need the same functionality as me. For me, I really appreciate to be able to establish a phone call through the PABX to contact somebody with a phone and to have a phone book inside. For management that is very useful. But for a firefighter, the radio is inside the pocket, so you just need to turn it on and after that you just use your microphone.”

Each firefighter is assigned a personal radio; this encourages them to take care of it because their life may depend on it, but also it enables the control room to locate and contact specific individuals when necessary.

In CERN’s complex environment there are inevitably a few radio coverage gaps, and for these Léchevin values TETRA’s Direct Mode operation (DMO) feature. “If you are in a very strange place without network and you have to do your intervention, you can switch and create this local network just to handle your work - and then you can come back on the trunked network. For us it’s useful and we like it.”


Switching to digital
Before the TETRA project began some two years ago, CERN was already well equipped with on-site voice networks. It runs an IP-based PABX with 12,000 users and, since 1994, a private GSM network which now supports 40 base stations interconnected by an SDH ring. Recently, 3G services have been added. Mobile phone coverage is provided even underground, through an extensive ‘leaky feeder’ distribution infrastructure in the tunnels. CERN issues its own SIM cards and mobile numbers, offering automatic least-cost call routing to users.

But for radio users such as the fire brigade, a new solution was needed because support for the old VHF system (which also used the leaky feeder system) had been discontinued. “We didn’t want to go again for VHF because we thought it was not relevant any more in terms of technology for us”, Chapron says. “Of course, GSM was eliminated very fast - it is not a safety network.

“We had two alternatives - Tetrapol or TETRA - and obviously there was more chance to get a competitive tender with TETRA, and hopefully we would have many European manufacturers. Since the main contributors to CERN are European countries, we try in return to invest in European companies.”

Following a tender process, it was with the Austrian TETRA infrastructure manufacturer 3T that the project began, but soon afterwards 3T was acquired by Sepura and became Sepura Systems.

“When I knew that Sepura was buying 3T, I was really happy”, comments Chapron. “We knew that Sepura was a big contributor to the TETRA market and we felt reassured that Sepura invested in 3T. For other reasons, it’s one of those win-win situations because when we started this project on indoor localization, 3T didn’t have this solution in their portfolio. On the other side we got in touch with Sysoco, who presented their solution. We put 3T and Sysoco in contact together, and then Sepura came to make the marriage.

“It was just big luck! We met the objectives of CERN and also of several companies at once. It’s an excellent example of collaboration for us, I’d say. 

When the contract was awarded, it came in two phases: for the TETRA infrastructure itself, to be supplied by 3T, and then an option for the deployment of an indoor localization system. Initially, the Sysoco system was intended for tracking just a few radio terminals, but CERN needed to be able to locate as many as 500, and there were concerns that a flood of location messages might overload the TETRA network. However, after a study of several of several months with Sysoco and 3T, CERN felt confident enough to go ahead with the full deployment.

During the bidding process, the CERN team was deeply impressed by the 3T representative, who drew everyone’s attention to some technical errors he had spotted in the call for tender. “We felt it was really honest and open, sharing this information, because he did it in front of the other bidders,” Chapron adds. “3T could have kept this information for itself and made a bid which was compliant with the system and TETRA technology, and the other companies who hadn’t noticed this error would have made a bid which was not compliant at the end. But from the beginning, we’ve seen that 3T was really open to share, in the same spirit that we try to do.”

For the indoor localization function, simplicity of use was a main requirement: it should be fully automatic, not requiring any action by users. However, while safety workers such as firemen are very willing to be monitored by their control room, it was found that other radio users were less happy about being tracked all the time, even if it was purely for safety reasons. So a solution was found: tracking information would still be collected, but would not be displayed on screen. Ordinary users will not be shown unless a ‘safety event’ occurs - a man-down alarm, an emergency call or a known incident in the area. Then the fire brigade operator will be able to activate the localization of the TETRA terminals. 

A new dispatcher terminal now being developed by Sepura Systems will operate in this way by default. But already the TETRA system is credited with saving life - that of a security guard who suffered a heart attack a few months ago while patrolling alone at night. “Thanks to the outdoor localization system, the GPS embedded in the TETRA system, we could rescue him much faster,” Chapron explains. “We could detect that the man-down alarm was indicated, and the Fire Brigade could rescue this person.”