At the heart of one of our test facilities there is a large metal box, cut off from the outside world. Step inside and all outside noise disappears; your phone switches over to a new network, and the air you breathe will be filtered through a vent that repels radio waves. Lock the door behind you: you are now in the Faraday cage – an artificial world where every Vodafone handset, tablet, dongle and software update gets stressed to its limit, and is made to withstand up to 20 hours of rigorous network testing.
“We cherry pick the hardest situations to put the devices through,” says test engineer James Mortlock. As our mini-documentary shows, he sometimes spends hours at a time in the dimly-lit confines of the Faraday cage, measuring device readings as they flicker across the array of monitors.
“You can lose yourself in here. It’s like reading a different language…”
The Faraday cage itself is constructed from an aluminium compound designed to offer full electro magnetic shielding. No wavelengths can pass though, and once inside, a phone, or device, will pick up a signal from the Vodafone test network, which is designed to replicate the network our customers connect to every day. Even the terminator plugs on the network patch panel – which are used to channel in the radio waves to the cage – are sealed when surplus to requirements to avoid any stray signal. As Mortlock’s boss Paul Williamson explains in our exclusive video, it’s like sitting in a giant microwave.
“This is the Lossy box,” Mortlock points to a small terminal sitting against the back wall, “It’s a signal attenuator and we use it to control the Vodafone test network so that we can see how the device responds in different situations.”
Mortlock uses the Lossy box to tune in and out of different signals and resistance to see how the handset would cope moving from cell to cell, or how it would respond if the network was suddenly very busy. He can fill up the test network with users, or bring it crashing down.
“We test congestion, we force handovers from cell to cell, (or antenna to antenna), because that has to be seamless, we try sending data and calling at the same time, we move between 3G and 2G – everything we can think of to stress the device.”
Things don’t always go smoothly, “Sometimes there are a few issues with a handset, sometimes there are hundreds of issues,” Mortlock says. It can take six months of the phone going back and forth to the manufacturer before all the problems have been ironed out, “It used to be that we had a six week window with phones, now we support a device for up to two years with all the different software updates.” Even so, he adds, it’s only when a customer really starts using a phone; making calls, using Twitter and Facebook and sending emails at the same time that its true capacity is revealed.
Only one thing intrudes into the sealed off atmosphere of the Faraday cage – a loud alarm that rings every 25 minutes and has to be manually switched off. That’s incase engineers get too lost in their own world. Even after a few minutes Mortlock is slightly mesmerised by the signals that move across the screens like heartbeats: “I never feel claustrophobic in here. It’s as if you’re watching a whole new story unfolding.”