Come the end of 2012, the Programme Makers and Special Events (PMSE) industry won't be restricted to spectrum white spaces in using their wireless microphones; Ofcom reckons wireless mikes and television signals can happily share the same frequencies.
The belief, laid out in the regulator's latest statement (19-page PDF/233KB, gets harder as it progresses), is based on testing that Ofcom has been doing since 1998, and assumes that wireless microphones won't go outdoors and that all TV aerials are more than 10 metres from the ground. With those caveats, Ofcom reckons wireless microphones can happily use the whole range of digital television frequencies without preventing anyone from watching Dr Who.
Outside things get a little more difficult, with interference in both directions being more of a problem. So the regulator has gotten together with the JMFG (who manages spectrum for the PMSE industry) to create an online database showing which bands are being used and where.
The database asks for log-on details, but can be accessed just by hitting "cancel" every now and then.
That shows which bands should offer least interference. The idea is to guide PMSE users into buying kit which will operate in their local unused (white) bands rather than relying on grey spaces where TV transmissions exist – even if Ofcom says that shouldn't matter. Many of those PMSE users are still clutching the Ofcom cheques they received for any Channel 69 kit they could scare up from the back of the cupboard, so knowing what to buy now is important.
Luvvies with Ofcom money burning a hole in their pocket might like to hold off though; the regulator admits that the spectrum plan might change if the government decides to chuck more resources into local TV or similar. There is also the question of how much white space is going to be consumed by the unlicensed devices that Ofcom plans to allow into the band.
These "white-fi" devices will use a database very similar to that put up by the JMFG, only read by a machine rather than a person. White space devices will provide local area networking as well as point-to-point connections, unrestricted by a licence or registration fee. Such devices should be required to avoid interfering with PMSE users, but how they'll manage that isn't yet clear.
In America, various white space channels have had to be reserved for wireless microphone use, in addition to the channels which have already been handed over (in the UK that's just channel 38, at 606MHz). Ofcom might decide to do something similar, though the small size of the UK means there's already a lot less white space available, and sharing frequencies with TV transmissions might not be acceptable to the noise boys no matter what Ofcom thinks. ®