BBC Media correspondent Nick Higham reports

ONdigital - owned by ITV companies Carlton and Granada - took centre stage on Monday.

Its unique selling point is that its programmes can be received through normal TV aerials as long as you have a £200 digital decoder.

The company announced a £7.99 per month basic package, comprising six paid-for channels, the five existing BBC and ITV channels, plus new free channels.

Customers will be asked to select their six paid-for options out of a total of 15 "primary channel" choices including UK Gold, UK Horizons, Sky One and channels run by Carlton and Granada.

New free channels include BBC News 24, BBC Choice and ITV2. Premium services, such as films and sport, will cost more.

ONdigital will begin broadcasting on 15 November and the company says 70% of the UK population will be able to receive at least part of the service, with 50-55% able to receive all of it. In a year's time, those numbers should be 90% and 70%.

On Thursday, Sky Digital will launch its own range of packages, to be beamed into homes via satellite.

On the same day thousands of new satellite decoders and free installation deals will hit the shops.

Sky's cheapest package, with 11 TV channels plus 10 audio channels, will cost £6.99 a month.

The new BBC Choice

Four "mid-range" packages with eight or nine more channels will cost £8.99 and £11.99 a month will buy a Family Pack of 40 non-premium channels.

Sky will be able to broadcast more than 100 channels - a larger number than ONdigital can provide - but 44 of the channels available will be audio-only non-stop music stations.

Another 48 channels will be used for showing pay per view feature films - the same film being shown at different times.

Sky digital customers will need a dish like this

It will begin broadcasting when it is launched, 45 days earlier than its rivals at ONdigital and at least three months before cable operators begin to offer digital cable channels.

Digital cable, which is due early next year, will also offer more than 100 channels, and should be able to provide more interactivity.

The BBC has been broadcasting digital programmes for several weeks already.

Digital viewers will need either a digital TV or a set-top decoder. Set top boxes will cost around £200 if you also sign up with ONdigital or Sky Digital.

Subscription not required

If a viewer does not want to pay any monthly fees at all, they will be able to buy a digital TV or an add-on decoder box without signing up with either company.

All five terrestrial channels will be available in wide screen with stereo sound and without interference, plus BBC Choice, BBC News 24 and ITV2 - other free BBC digital channels are promised in 1999.

But the decoder will cost an extra £150-£200 as the companies selling subscriptions are subsidising its price to attract customers.

Industry observers have expressed concern over the fact that different decoders are needed so far to receive ONdigital and Sky Digital's services.