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What is bluetooth?

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This is, at least sometimes, a science for dummies blog, because I’m a dummy about science and I’m here to educate myself, in a way that I’m hoping might be of interest to others.

So here’s something I’m truly ignorant of. Let me start with a definition from ignorance, then see how I can transmogrify it with a bit of research. Bluetooth is a technology used in mobile phones, computers and such, which assists in processing and communicating information more efficiently.

I don’t even know if this is a true definition, apart from its vagueness, but I expect it will have nothing to do with the colour blue or with teeth. So, it’s to Wikipedia I go, for starters:

Bluetooth is a wireless technology standard for exchanging data over short distances (using short-wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security.(I’ve removed the links – don’t want to make things too easy).

So now I’m slightly wiser. The short-wavelength ISM radio bands (Industrial, Scientific, Medical) are internationally reserved for the aforementioned purposes. That’s to say, to the exclusion of telecommunications.

But hang on, bluetooth is a telecommunications technology that apparently works within the reserved band. How does that work? I don’t know.

Anyhow, having read most of the Wikipedia article on bluetooth (I just couldn’t finish it), I definitely have a better understanding of the technology than I did before, despite only comprehending about 5% of the article. Still, I’m not in a position to explain it, even to myself. So now it’s time for How Stuff Works, for a less geeky guide to bluetooth. The following owes a lot to the HSW article “How Bluetooth Works”, but I’ve put it in my own words to wrap my head more tightly around the concept.

Bluetooth is a way of connecting electronic devices to each other, sans wire. You may be thinking Wifi here, but bluetooth is a quite different, though in many ways complementary, technology. It was first developed in the mid-nineties at the labs of the telecommunications company Ericsson, and has developed rapidly since then. It’s greatest advantage over other wireless systems such as the infrared technology used in most TV remotes is that it is more versatile, low-energy and low-cost – but versatility is the key. For example, infrared technology works with ‘line of sight’ – you have to point the remote at the device – and it’s essentially one-way.

Finding a way of connecting devices requires a protocol, a set of commands and responses which essentially make sense of the messages being sent between them. This protocol in Bluetooth technology requires very little transmission power, about a milliwatt of power for each transmission signal. The weakness of the signals are a key in avoiding interference in the all-important ISM band within which Bluetooth networking operates, but they limit the range to distances of about 10 metres. However, Bluetooth is not line-of-sight technology, and can be used effectively, for example, in a small house. Bluetooth can connect as many as eight devices simultaneously, but they don’t interfere with each other because of a technique called spread-spectrum frequency hopping, which means they change frequencies regularly, 1600 times per second, using 79 randomly chosen individual frequencies within a designated range. They make full use of a limited spectrum, and as each transmitting device uses this technique automatically, no two transmitters are likely to be using the same frequency at the same time. They’re also unlikely to disrupt other devices in the ISM range because of the fractional time-periods occupying particular frequencies.

Bluetooth-capable devices come within range of each other and automatically create networks known as piconets. This network may be as simple as one between a mobile phone and its headset, but these piconets, once established, frequency-hop in unison so that they can be in constant contact and can be differentiated from piconets in the vicinity.

Anyway, that’s basically as much as I need to know about Bluetooth. There are other issues around security, which can be interesting and problematic, but not too much of a concern for the average user. The automaticity of Bluetooth is one of its many pain-free advantages, and that’s apparently a help with security too. You can switch your Bluetooth mode to ‘undiscoverable’ so as to avoid contact with other Bluetooth devices, and there are other more elaborate security options.

So, with this knowledge, how do I change my world? I think the answer is – only connect.

Written by stewart henderson

December 27, 2013 at 7:57 am

Posted in magic, science, technology

Tagged with ,

One Response

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  1. It is reserved to the exclusion of teleccommunication in that your cell phone and tv stations etc. cannot use that band. That band is open only to short range communications whether that is for cell phones or music players or garage door openers… the big regional and nationwide carriers cannot use that band of frequencies. This means that your headset doesn’t have to compete with a radio station or phone calls etc. for space to exchange data. BTW it also means your bluetooth won’t interfere with the operation of an airplane… wehhhhhhheeeeeeeee


    December 27, 2013 at 12:21 pm

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