The following information comprises details of the technical parameters of all analogue VHF and MF, and DAB transmitters (including services on multiplex) currently on-air. In-use parameters are included for interest, mainly for listeners and the receiver/aerial trade who wish to understand why the signals they receive are of a particular strength, and to give hints as to how they might improve reception. The maximum allowed parameters (within the terms of each licence) for analogue services are also included, for the benefit of those, principally in the industry, who wish to make calculations, particularly about interference, for coverage-planning purposes. 

·        Download the entire set of data values as a compressed zip Excel 5.0 workbook - 110 kB (click here - last updated 14/11/2003)

·        If you do not have a zip file extractor see www.winzip.com or  http://www.zipitfast.com

The information will normally include transmitters that have come on-air within the last month. Listeners are welcome to raise observations (to nick.astley-cooper@radioauthority.org.uk) on perceived accuracy of any of the technical information made available here. Please, however, do not bother to contact us with minor discrepancies in, for example, site heights or OS grid references. Nor is advice available from the Authority as to how this data might be used for coverage planning/assessment purposes: this requires specialist knowledge and, usually, computer software. Maps of the coverage of each of our FM and AM licences (as used for administrative purposes only) are available from the Engineering Department at £1 per copy (per licence).

And now an explanation of the parameters for Analogue services:  

Date of Transmission: This is the date on which the transmitter started radiating, and for a new service, would normally precede the official launch date by a few weeks. Where no date is given, the station will have come on-air before January 1991.

 

Name of station: Don’t be surprised if this changes mid-licence, and watch out for stations that use the band they are in rather than the actual frequency, in their name. Eg Music107 might actually be on 107.4 MHz.

 

Area of Coverage: This is a general indicator, and in the case of some smaller relays, might on occasions be described by the wider station coverage.

 

Site Name: It is not uncommon to find sites called different names by different organisations, or for one site name to cover a number of masts.

 

Frequency: This will either be in MHz for VHF stations or kHz for MF stations.

 

OS Grid Reference: These give the location of the transmitter, and normally refer to the bottom left-hand corner of the 100m square within which the mast lies.


RDS: This data refers only to VHF stations:

Programme Service Name: This is the name that should appear on an RDS radio when tuned to the station concerned. These are not rigidly controlled and obviously change when a station name changes. We do not wish to be advised of anomolies here, thanks.

PI Code: This is a geographically unique code that is hidden in the RDS datastream. It is an important factor in the way that an RDS radio switches between alternative frequencies, but you need to be well acquainted with your RDS instruction manual before assuming that the information here is incorrect!

TP/TA: a ‘Y’ indicates that, not only does this station produce traffic information, but it has dynamic control of its TA flag, with the benefits that that can provide, depending on the design of your RDS radio. Don’t expect to be switched between commercial radio stations via Enhanced Other Networks (EON), but vectoring between services simulcast on VHF and DAB is very much on the cards – once you buy a suitable DAB radio, of course!

Site Height: The height of the base of the mast/building in metres, above sea level.

  Aerial Height: The height of the transmitting aerial above ground level. For VHF aerials this will often be part-way up a mast, but for MF stations it normally refers to the whole length of the mast.

 

In-Use ERP/HP and ERP/VP: For VHF transmitters, this shows the Effective Radiated Power (the power that would be radiated normal to a half-wave dipole when connected to a power source of this amount) in the horizontal then the vertical plane of polarisation. These reflect the maximum levels achieved around the points of the compass, and are normally, but not always, on the same bearing in each polarisation.

In-Use EMRP: In the case of Medium Wave transmitters, this is the maximum Effective (Monopole) Radiated Power.

In-Use Direction of Maximum Signal: This gives an approximate direction, where an aerial radiates significantly more on any particular bearing. It takes reasonable account of differences between polarisations (see above) and multiple lobes.

In-Use Horizontal Radiation Patterns: These show the reductions in dB, in 10° steps in azimuth, starting with 0 and ending with 350, for each polarisation plane in the case of VHF and  normalised to the In-Use ERP/HP and In-Use ERP/VP respectively. Only one set of reductions is included for MF transmitter, normalised to the In-Use EMRP.

   

Licensed ERP/HP and ERP/VP: These are the maximum allowable values and may exceed the in-use figures.

Licensed EMRP: These are the maximum allowable values and may exceed the in-use figures.

Licensed Horizontal Radiation Patterns: These are the maximum allowable values and may be less restrictive than the in-use figures.

   
And for DAB:  

 

Only In-Use technical parameters are currently provided for DAB transmitters.  Their RF parameters are organised in the same way as for analogue, although note  that DAB transmissions are vertically polarised only.  The main differences from analogue are in the make–up of the programme content, and the network structure.  A DAB Ensemble (or multiplex) will carry an identical set of audio (and possibly data) services across its coverage area, and the spreadsheet has columns for up to 12 Service Labels, which are filled from the left.  The Ensemble will normally be broadcast from a number of transmitters on the one frequency; this is known as a Single Frequency Network (SFN).  Certain makes of radio enable the listener to identify which particular transmitter within an SFN is the dominant one in a given area, which can be useful in locating and orientating receive aerials.  Each transmitter carries its own Transmitter Identification (TII) codes and these 4 digit ‘main’ and ‘sub’ codes are now also included in the spreadsheet, but be warned that they are stored in ‘hexadecimal’ form, so you may need to convert them if your radio presents them in ‘decimal’.

Nick Astley-Cooper is the Deputy Director of Engineering at the Radio Authority

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Revised: November 14, 2003 .