Where do we go from here?
3 November 1995
Norman J McLeod
Recently I have been studying the latest, quite extraordinary, proposals from the Radio Authority concerning very low powered, freely radiating but permanent licences on the FM band.
For a long time now, I and many others have been arguing for some intermediate level of licences - something between the 28 day RSL and the eight-year permanent licences. There is a yawning chasm between the two in both financial and technical terms, and a lot of frustration from RSL operators who wish dearly to be able to carry on after the 28-day deadline expires.
What we have been offered is pretty damn close to the right answer on the face of it. After the DTI Radiocommunications Agency has assessed the technical feasibility of the proposed system a frequency (usually 87.7 MHz) will be assigned to the service and the licensee-designate given authority to operate the station for a twelve month period.
Following confirmation from the Radio Authority that continued operation of the service is OK and the station has complied with all the rules, a five-year licence will then be offered to the station. The Radio Authority will have the discretion to renew the licence at five-yearly intervals thereafter.
So far so good. But when I look at the other strings attached to this offer, I begin to wonder if the person drafting the regulations lives in the real world or some sort of 'Alice in Wonderland' fantasy. For a start, licences are only available in certain remote parts of the country, notwithstanding that frequencies in the 107 - 108 MHz band have all been specifically set aside for them. The map showing the areas privileged enough to have this offer made to them is supplied. It includes most of Scotland outwith the central belt, the Lake District, much of rural Wales, and the south- west of England. There is also a tiny patch around Scarborough in Yorkshire.
A phrase familiar to those of us who have wrestled with the inductive loop specification crops up in section 5 of the notes. "Emissions (it says) shall be restricted to ensure that they cannot be effectively received beyond the limit of the curtilage of the establishment or premises to which the licence relates." Under section 4, however, it admits that with just 50 mW "it is unlikely that a good or even adequate signal will be received throughout the establishment is concerned."
Both assertions are ridiculous. It is impossible to restrict VHF radiation to the "curtilage" of any set of premises. Sensitive tuners are available which will give solid mono copy with about three microvolts of signal, and so a 50 mW transmission can be heard - admittedly only with good quality receivers - more than a mile away under line-of-sight conditions. I should know because I've tried it and so have Wireless Workshop in their tests on leaky feeders. Confining VHF/FM transmissions to a specific set of premises is impossible.
Furthermore, 50 mW is not going to be enough to cover a set of premises such as a hospital where there are more and more computers and other RF-noisy equipment in use. To permit stereo operation at this power level is just asking for trouble. Alan Brown of Wireless Workshop (who have considerable experience with AM inductive loop systems) says that the low power and lack of interference protection is going to cause any would-be contractor no end of hassle.
When people pay money for a radio transmission system they expect it to work 24 hours a day 7 days a week 52 weeks a year. Induction loop AM systems such as the one sold by Wireless Workshop deliver this and can be effectively confined to a specific set of premises.
I would allow FOUR watt licences to be issued in the 107 - 108 MHz band and planned on the basis of MONO operation. They should be forbidden to run stereo because it makes planning criteria much more stringent. But licences should be available on the same basis and on the same terms as the current option.
All I am asking for is the power of a legal Citizen's Band (CB) radio rig- a mere four watts, because I believe that this level of power would be unlikely to cause interference to other services any more than legal CB rigs do.
There should be restrictions on the maximum EHAAT (effective height above average terrain) and the aerial height should be no more than 15m above ground level using a vertically polarised omnidirectional dipole aerial. Any student, hospital or other organisation should be able to apply for a four watt licence and this should be available on a nationwide basis.
Stations should be protected from each other by a simple rule-of- thumb separation and they should be encouraged to use aerials at the foot of valleys (thereby covering the slopes of the valley but not much more) in order to minimise the 'impact area' around the transmitter where the frequency in use is effectively 'sterilised'.
After all, we were told after the consultation sham that 107 - 108 MHz was going to be available for small stations. Well then. Where are these small stations? Shall we just leave 107 - 108 for the pirates?
Any readers wishing to comment on what I have said are welcome to call me on 01 273 684 172 or send e-mail to normac@fastnet.co.uk
Copyright NJ McLeod 1995