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Goodbye broadcast TV?

As regular readers will already know, I don't watch TV.

The old FreeView receiver sits in the spare room -- as does the satellite dish that it needs.

The UHF antenna that was on the roof toppled to the ground some time ago and now lies inert, resting peacefully in the garden -- offering slugs and snails a place to practice their uphill climbs and downhill braking.

I know I'm not alone in weaning myself off "the opiate of the masses" and have found that the more you look, the more you find others who are also enjoying the amount of time they've gained from doing likewise.

And now, in a rather surprising move, the UK House of Lords is considering shutting down that country's terrestrial TV broadcasting network.

What? Force the people to go cold-turkey without their regular dose of Corro Street, East Enders, Big Brother and other bits of vicarity?

Well not completely.

According to this story, consideration is being given to freeing up all terrestrial broadcast frequencies for use by more important services -- such as high-speed mobile phone networks.

Personally, I find this very interesting since, some time ago, I predicted problems with our increasingly wireless world.

When you compare RF based systems to those reliant on copper or fibre, things look very good for wireless -- until you start running out of space in the spectrum.

While it's great to have phone and data wherever you go, without the need to find a wired data connection -- the ever-increasing demand for ever-faster services means that more and more of the spectrum is required. Eventually you reach a point where you just can't squeeze any more than a pint into that pint-pot.

With copper and fibre, the answer is simple -- you just lay some more cable. Double the number of cables and you immediately double your bandwidth -- it's a simple and scales in a linear fashion.

With RF however, it's not as simple as adding more spectrum - because there may not be any more spectrum to add.

Take a look at the existing allocations of RF spectrum here in NZ and you'll see what I mean.

What's more, adding more spectrum to a service may involve a change of band (ie: a significantly different frequency). Whereas one piece of copper or fibre behaves much like another, the same simply isn't true when you're dealing with RF frequencies.

A transmission on very high frequencies in the GHz range have very different propagation characteristics to a transmission on far lower frequencies in the MHz range.

Higher frequencies need only very small antennas -- lower frequencies require much larger and more cumbersome aerials which may make them unsuited to portable equipment.

Of course researchers are always working on new ways to get more out of less and one of the latest initiatives in this area is an exploitation of the effects that polarization produces.

Normal radio transmissions are effectively two-dimensional - like a sheet of paper. By using different angles of polarization it becomes possible to use the same frequency for multiple signals, whilst reducing the chances of interference between them. Unfortunately, while this might work very well for links involving fixed antennas, as soon as you go mobile it becomes very difficult to control the angle of polarization due to the changing orientation of the mobile device.

So basically -- we have a finite resource that is already coming under significant demand-pressure.

The effects of this are already showing up overseas -- where LightSquared's mobile network was found to be interfering with GPS signals.

In the UK, the 4G mobile network is about to clash with that country's FreeView TV service, requiring millions of consumers to buy special filters to help mitigate the effect.

Here in NZ we've already seen that the government is decommissioning analog TV in favour of digital services because it allows them to claw back some of that valuable spectrum space. But what happens when that recovered space is also fully allocated?

Perhaps it won't be too long before terrestrial TV broadcasts become just a memory here in New Zealand too.

Unfortunately, when that happens, your UFB broadband connection will probably revert to dial-up speeds of an evening while every man and his dog starts watching Shortland Street via their IP connection.

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