Untangling police wires

Friday, 03 August, 2007


To communicate while on the move, many police officers use shoulder-mounted speaker-microphones, connected to their two-way radio by a long 'curly cord' cable which is both heavy and bulky.

The result is often uncomfortable and can increase their vulnerability. Shoulder-mounted speaker-mics can also be a pain in the neck - literally!

It's hard to cock your head towards the microphone while running after an offender.

Add to this the prospect of getting tangled in the cable, trying to hit the PTT button and you have a recipe for serious injury.

With the latest advances in wireless technology for two-way radios, these problems are now becoming a thing of the past.

Following successful trials in the US, wireless speaker-mics are now making their way onto police shoulders.

The lack of wires removes one risk factor for officers on the move and makes more convenient placement possible.

Traditional short-range wireless links have problems of their own, such as interference, which can prevent a wireless mic from connecting to an officer's radio, leaving him isolated.

To solve these problems, a US wireless headset company has developed a novel solution. Using low frequency magnetic fields instead of radio waves, it has created a wireless link to the radio which is both reliable and immune to RF interference.

FreeLinc's Near-Field Magnetic Communications technology uses low-frequency magnetic fields rather than RF to establish a communications link between the two-way radio and its accessories.

The magnetic fields create a 'personal communications bubble' around the user and are no larger than 1.5 m wide. Voice data is transmitted by modulating the magnetic field at a primary frequency of 13.56 MHz.

Because communications occurs by modulating a magnetic field, it is immune to interference from radio waves.

This means that RF transmitting devices such as radios, cordless phones, Bluetooth devices, etc will have no effect, resulting in a reliable wireless link over very short ranges.

As an added bonus, because nothing propagates beyond the 1.5 m 'bubble', the FreeLinc wireless transmission is inherently secure.

Anyone contemplating eavesdropping on an NFMC communications link would need a suite of magnetic field measuring equipment sensitive enough to decode minute fluctuations that represent the voice communications component.

They would also need to do all this within the 'personal space' of the user!

The Michigan State Police Radio Unit used the 'FreeMotion' headsets during the Detroit Super Bowl XL. Before this test, their sheriff's office field-tested products during a major league baseball all-star game.

"Any officer will tell you how frustrating it can be to have to fumble with radio controls, handsets and cords when trying to do a job," Wayne County Sheriff Warren Evans said.

"The devices we tested allowed our team to communicate totally hands free, so we worked with increased safety and security - without interruption."

"Everything relies on wires, which are the problem. They are not only uncomfortable, but also dangerous because you can get tangled in them," added Andre Simenaur, IT director of Wayne County.

(Based on an article in Law and Order journal Vol 54 No.8. By James Careless. Used with permission.)

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