FM 400 kHz - Revised FM Licensing criteria for VHF-FM broadcasting stations

Revised FM Licensing criteria for VHF-FM broadcasting stations

VHF-FM broadcasting usage in New Zealand, and in many overseas countries, is based on a minimum frequency separation of 800 kHz between licences at the same transmitting site. This is known as an "800 kHz raster" and is consistent with ITU-R technical standards. It recognises the typical quality of receivers in use, and the efficient practice of multiplexing transmitters to a common antenna. In some circumstances, particularly where several sites might be used to cover the same general area, or when infill coverage licences might reduce licence availability at a main site, frequency separations as narrow as 600 kHz have been trialled and generally found to be satisfactory for long term use in that situation. This approach has allowed some additional services to be provided without detriment to wider use of the VHF-FM Broadcast Band.

In recent months two trials of even narrower separations have been conducted. A separation of 400 kHz has been in use at Skytower, Auckland, to proved a similar coverage from the same site, while a separation of 400 kHz has been used in Wellington between licences at two different sites (Kaukau and Towai) which have a degree of coverage overlap. These trials have been used to test specific planning characteristics in order to determine if a change in technical standards could be implemented. To date the trials have confirmed there are technical possibilities for use of narrower frequency separations than the present standard of 800 kHz, however in some areas the use of licences separated by 400 kHz may be limited by "co-channel" use of the same frequency in nearby areas. Further, presently available sub-carrier technologies, such as SCA and RDS, may be difficult to apply with narrower separation of frequencies, and future technologies such as digital IBOC may be impractical. Considering these wider implications, the full extent of new licences that might be available with rasters of less than 800 kHz has not yet been quantified.

The Ministry wishes to maximise the utility of the VHF-FM band and therefore intends, as a first step, to confirm the extent that rasters less than 800 kHz can be applied at major transmission sites, given present licences. It is therefore inappropriate to grant licences which might prejudice an optimal long term outcome until this work is completed, and subsequent policies on allocation of any new licences are finalised.

Therefore the Ministry will:

• Resolve licensing issues arising from the two identified trials with the parties concerned;
• Not create further licences at an established site if the resultant frequency separations do not comply with the established 800 kHz raster at that site;
• Not create further licences at an established site which has overlapping coverage with another site if the new licence would have a narrower frequency separation from a licence at the other site, than exists at present between the two sites;
• Only consider further trials of co-sited licences at separations of less than 800 kHz where the trial will, in the Ministry's opinion, provide new technical information that will assist further policy development;
• Consider applications for temporary new licences at new sites (i.e. locations without existing FM licences) intended to cover portions of the coverage area from an existing site, provided that
  • the new licence covers a minor part (less than 25% of the population) of the main coverage site;
  • the new licence does not directly preclude a "on raster" licence at the main site;
  • ITU-R protection ratios in Rec 412-9 are met;
  • the licence is agreed as temporary until issues related to narrower (less than 800 kHz) separation are resolved;
  • there is no expectation of the licence being made available on long term basis.
    

RSM Licensing will apply the above criteria to all new applications received from 15 November 2004.

Further work, including discussions with industry, is planned during 2005 to finalise technical and policy issues for the longer term. Following that work the above criteria will be reviewed and amended, or superseded, as appropriate.