Mr Cox thinks the switch-over target is still attainable
With the first government deadline for an analogue switch-off less than five years away, Mr Cox has called on the government to do more to increase digital coverage for TV viewers across the UK.
"The government has got to produce a plan for the digital terrestrial TV frequencies," he told BBC News Online.
Chosen by the government to chair the Digital Stakeholders Group, Mr Cox has been charged with clearing a path for the new TV medium.
He must also clear the analogue frequencies for what the government hopes will be a big sell-off.
Although he called the analogue switch-off - planned to take place between 2006 and 2010 - "a realistic possibility" he said it "depended what happened over the next 12 months".
But despite some high-profile announcements from the BBC and others about digital delights to come, take-up has been slow.
A veteran of LWT and currently deputy chairman of Channel 4, Mr Cox said he can see where some of the problem lies.
"People regard digital TV as a paid medium, and for those who are not already interested there's no reason to go and get this equipment," he told BBC News Online.
"There is also genuine confusion over what you get, and how much you have to pay.
"Then the digital TV set price is not comparable to the price of an analogue set," he added.
Mr Cox said the government must move fast on increasing digital coverage for the UK.
"What has not been sorted out is what further frequencies will be allocated for reaching beyond the 80% of the country which can presently be reached by the digital signal.
"Do the government want 90%, 95%? That's what we need to know, as do manufacturers who need to know exactly what to build."
But Mr Cox said he was optimistic about the Pace digital adaptor - a set-top box set to come on to the market for £99 in April.
Inertia
"It will begin to fill an empty whole in the market," said Mr Cox.
And he refused to countenance the possibility that the digital switch-over could actually fail, in the face of public inertia.
"No, I don't think that will happen," he said.
"The switch may not happen within the government deadline, but I'm sure the country will go digital at some point."