By Nick Higham BBC media correspondent

When Britain's digital terrestrial television network first launched almost exactly four years ago the occasion was marked in spectacular style.

Ulrika Jonsson, in evening gown, pressed the plunger to illuminate the giant Crystal Palace transmitter tower in south London and herald the start of what was then called Ondigital.

Fourteen months ago Ondigital, rebranded as ITV Digital, relaunched in equally high-profile style with woolly monkey and Johnny Vegas in a multi-million pound television advertising campaign.

This week Ulrika Jonsson has her mind on other things, ITV Digital is remembered only as one of the biggest broadcasting fiascos of recent times, the remaining woolly monkeys have been auctioned off for �150 apiece, and digital terrestrial television, now renamed Freeview, is making its third debut with a notable lack of fanfare.

Not even Monkey's new look could save Ondigital

The BBC, Sky and the transmitter company Crown Castle, the three partners behind Freeview, are launching their new service at 0600 GMT on Wednesday - but you could be forgiven for not having noticed.

Little publicity

There has been little publicity, and even on Wednesday itself nothing in the way of a press conference or launch party is planned, even though the partners are promising a �3.5 million advertising campaign - plus a website and information line telling people where they can - and can't - receive the programmes.

If the Freeview partners seem almost apologetic, that may be because the new service, licensed by the Independent Television Commission after ITV Digital went bust earlier this year, has a lot to prove.

Unlike ITV Digital (or indeed Sky Digital) Freeview is, as its name suggests, entirely free. There are no sport or movie channels, no subscriptions, no monthly direct debits - and no rooftop dishes.

In theory all it takes to tune in is your existing rooftop aerial and a plug-in adapter costing around �100 - or your old Ondigital or ITV Digital set-top box, if you still have it.

The old kit should work for the new service

Once tuned in you can choose from around 30 channels. There are eight from the BBC, including One to Four, the two children's channels (CBBC and CBeebies), News 24 and BBC Parliament.

Sky channels

There'll be ITV1, ITV2 and the ITV News Channel, Channel 4 and Five, the new factual channel UK History plus two others launching in January - UK Home Style, and an evening entertainment channel aimed at 13-44 year olds (just like BBC Three) called F tn.

Sky - which sees Freeview as a kind of insurance policy, a way to get the Sky brand into the 20 or 30 per cent of homes which are never likely to sign up for pay-TV - is contributing Sky News, Sky Sports News and Sky Travel.

Most of these channels are broadcasting already. The only ones actually launching this week are two music channels, The Hits and The Music Factory. F tn launches in January.

One channel has still to be allocated.

The consortium, the government and the ITC are gambling that enough people want extra television channels without having to pay for them to make the venture worthwhile - although Andy Duncan, the BBC's director of marketing, is careful not to put a figure on the numbers likely to be watching.

All he will say is that many of the 1.2 million former ITV Digital boxes are still thought to be in people's homes, and that sales of the �100 converters are going "quite well" at the rate of "tens of thousands a month".

Sky News gets the Sky name into more homes

In fact numbers are much less important to Freeview than they were to ITV Digital. The new consortium does not have to sell subscriptions to recoup the cost of premium programmes like ITV Digital's ultimately crippling �315 million deal with the Nationwide League.

Nonetheless it would be embarrassing for the BBC if Freeview flopped: strong uptake would help to silence critics who ask why the corporation is spending so much money on digital channels which only around a third (so far) of people can watch.

It would also be embarrassing for the government - which is still presumably hoping to reach its target of 100 per cent digital penetration by 2010 so it can switch off the existing analogue television transmissions.

Reception problems

But Freeview alone won't help the government to achieve that target. Reception is still far from universal.

BBC Three will replace BBC Choice on digital soon

ITV Digital's reception problems became legendary: in some households, it was said, opening the fridge door could knock out the signal.

Since then transmitter power has been doubled at many sites and the number of channels transmitted has been greatly reduced.

That has extended the number of homes that can receive all the channels from 65 per cent to 75 per cent of the population - but it still leaves a quarter of homes unable to get the service at all, or able to receive only some channels, and 25 per cent of us may need a new aerial.