Mobile Phone Base Stations - Frequently Asked Questions

3) What if a radio site is not on the database?

4) Does Sitefinder cover all transmitter sites?

5) Why are the maps of Northern Ireland different than those of England, Scotland and Wales?

12) Why has TETRA been added to Sitefinder?

The - also known as the Stewart Group because it was chaired by Sir William Stewart - was established at the request made by the Minister for Public Health, Tessa Jowell, in April 1999, to examine the possible effects of mobile phones, base stations and transmitters on health.

The remit of the Group was :

to consider current concerns about the possible health effects from the use of mobile phones, base stations and transmitters;
to conduct a rigorous assessment of existing research and to give advice based on the present state of knowledge;
to make recommendations on further work that should be carried out to improve the basis for sound advice.

The has completed its work and its Report, published on 11 May 2000, presents its findings and recommendations.

The concluded that

"The balance of evidence to date suggests that exposures to radiation below and guidelines do not cause adverse health effects to the general population."

Furthermore, in relation to mobile phone base stations the concluded that:

"The balance of evidence indicates that there is no general risk to the health of people living near base stations, on the basis that exposures are expected to be small fractions of guidelines."

Overall, the Stewart Group recommended a precautionary approach to the use of mobile phones and base stations until more research results become available. Details of the main elements of this approach are outlined in two leaflets from the Department of Health entitled 'Mobile phones and health' and 'Mobile phone base stations and health'.

The report can be found on the website for the Independent Expert Group on Mobile Phones at www.iegmp.org.uk/. Alternatively a copy can be obtained directly from the Secretariat of the Expert Group. Their telephone number is 01235 822742, fax number 01235 822746, address IEGMP Secretariat, c/o Information Office, National Radiological Protection Board, Chilton, Didcot, Oxon, OX11 0RQ.

A booklet detailing the Summary and Recommendations contained in the report can also be obtained from the Secretariat at a cost of £2.

Cellular base stations transmit and receive signals from mobile phones or other types of mobile radio. Each base station provides coverage for a given area, termed a cell. Base stations can be a few hundred metres apart in major cities or several kilometres apart in rural areas. The transmissions from any particular base station are variable and dependent on several factors, including the number of calls and the distance between the base station and the mobile phones making the calls. The RA has produced information, 'How mobile phone networks operate', which gives more detail on this subject.

A base station is not necessarily a mast. A mast is a free-standing structure that supports the antennas. A base station might equally consist of an antenna and equipment cabin attached to a pre-existing building or other structure.

Operators are entering into more and more site-sharing agreements where that is a viable option. However, limitations on site sharing include:

technology. In some cases, transmission frequencies (900 and 1800 MHz) will interfere with each other if placed wrongly. Apart from this, the placing of sites within each operator's network is designed to give maximum coverage. A particular site may be appropriate to one operator, but not another;

amenity issues. Site-sharing entails more than one antenna, which may not be what the local community wants to see.

The made a broad ranging set of recommendations to Government. Government is implementing these recommendations by giving specific tasks and duties to a number of different Departments and Agencies (see Government's response).

The Stewart Report recommended that there be an audit of mobile phone base stations to ensure that exposure guidelines are not exceeded. As experts in the field of measuring radio frequency emissions RA will be undertaking the audit to ensure that emissions from base stations do not exceed public exposure guidelines.

The Stewart Report also identified a general need to ensure that the public had better access to information about mobile phone technology. As part of this process it was recommended that reliable and openly available information about the location and operating characteristics of all base stations is provided by Government. In response to this recommendation RA is developing a national database giving details of all mobile phone base stations and their emissions.

Details of these two activities are available on our web site, at the following locations:

Audit Programme
Sitefinder - Mast Database

The database provides information on all operational, externally sited, cellular radio transmitters in the United Kingdom. The information provided on each site is described in Table 1 below.

Table1. Information Provided on Site Database.

Parameter	Comments
Name of Operator	The name of the organisation that operates the transmitter
Height of Antenna	In terms of metres above ground level.
Frequency range	Cellular radio operate in one of three bands in the UK; 900 MHz, 1800 MHz and 2 GHz.
Transmitter power	Specified in terms of Effective Isotropic Radiated Power (EiRP dBW) per channel.
Maximum licensed power.	In EiRP dBW per channel. The maximum licensed power is the highest power that would ever be permitted from a particular transmitter. In practice, most transmitters would operate substantially below this limit.
Type of Transmission	This is specified in terms of the technology used. Two types of cellular technologies operate in the UK; GSM and UMTS.

The parameters identified above are important determinants on how far a radio signal will travel. However, the relationship between these parameters and the strength of a radio signal at a particular distance from a transmitter is complex. On the Sitefinder website RA will provide further background, and some useful links, so it will be possible to obtain more information on this complex subject.

The database will be updated every three months. It should be noted that only operational transmitters, i.e. those that are actually transmitting, are included on the database. Consequently, sites that are currently going through the planning process, are in the process of being built, or are yet to be switched on, will not be found on the database.

Only operational cellular transmitters will be included on the database. The database will be updated on a three monthly cycle. Thus, if a site has not started transmitting, or has only recently become operational, it may not be on the database.

It is also possible that the site that a user is interested in is not a cellular radio site, and is used instead by one of the many other types of radio user. These include radio and television broadcasters, electricity companies, the emergency services, taxi companies, government services, aeronautical radio, and the paging industry.

Mapping data of the quality available for England, Scotland and Wales is not available for Northern Ireland.

Currently the level of details is not as high as that for Britain. We will periodically review whether more suitable mapping data becomes available for Northern Ireland.

All efforts have been made to ensure that the information provided on Sitefinder is as accurate as possible. Detailed street level maps are provided for the entirety of mainland Britain, and transmitters locations are plotted to within 10 metres of their recorded location. In addition, site data is regularly updated to help ensure its accuracy.

However, despite these measures it is not possible to guarantee the absolute accuracy of the mapping information or the technical data provided on each transmitter. There are a number of reasons for this, which include the systematic errors in the satellite based positioning systems used to identify the map co-ordinates of base stations, and the dynamic nature of cellular radio planning, which may require modification of a transmitter subsequent to the last update of the database.

Should you have a query regarding the data please use the 'Contact Us' function at www.Sitefinder.radio.gov.uk to inform us.

It is possible that the site that you are interested in is not a cellular radio site, and is used instead by one of the many other types of radio user. These include radio and television broadcasters, electricity companies, the emergency services, taxi companies, government services, aeronautical radio, and the paging industry. Nonetheless, it is also possible that our data contains minor inaccuracies, for the reasons explained in the previous question (How accurate is the information on Sitefinder ?). This could, for example, lead to a site that is actually shared by several operators being displayed as several different sites in slightly different locations.

Should you notice an inaccuracy in our data please use the 'Contact Us' function at www.Sitefinder.radio.gov.uk to inform us. Your information will help us with our ongoing programme to ensure the data we present is as accurate as possible.

From time to time, RA reviews comments and feedback received from users of Sitefinder to examine if the facility can be improved in any way. Thus you might, on occasion, notice slight changes in the way Sitefinder works, such as improvements to the map zoom function introduced in January 2003 or the addition of TETRA sites in July 2003. When this happens, full information on the changes will be provided at www.sitefinder.radio.gov.uk. Alternatively you can contact the Sitefinder Enquiry Point on 020 7211 0816 or by email to sitefinder@ra.gsi.gov.uk.

This could be due to the way your internet browser is configured. In most cases your browser’s standard settings will enable Sitefinder to work successfully. However, certain browser settings may interfere with the successful operation of Sitefinder because of the way the facility uses internet ‘cookies’. The following section of this answer gives a description of how Sitefinder uses cookies and how you can set your browser to view Sitefinder successfully.

Portions of our site use per-session cookies. Per-session cookies store information within a session (or visit to our website). For instance, if you are zooming in, you will need per-session cookies to "remember" where you are on the large scale of map of an area until you zoom out again. Unlike persistent cookies, which are stored on your hard drive for a length of time set by the website, per-session cookies are cached (stored in memory) while you are visiting the website and are deleted from your cache when you leave the website. If we did not use per-session cookies, you would be unable to use the zoom facility on Sitefinder.

Per-session cookies are stored in memory and are only available during an active session, in other words, while you are on the website. They do not permanently record data and are not stored on your computer's hard drive. Per-session cookies do not give the website access to anything else on your system, including any private information about you. Also, only the website that placed the cookie can retrieve it.

Table 2: How to change your browser settings.

TETRA stands for Terrestrial Trunked Radio. It is a digital mobile radio standard especially designed for professional users who need high reliability and security. TETRA networks are cellular and very similar to mobile phone networks. TETRA systems are used by emergency services in a number of countries and also by commercial organisations with mobile workforces or large vehicle fleets.

In 2001, the published a report prepared by the AGNIR experts on the possible health effects of TETRA (http://www.nrpb.org/publications/documents_of_nrpb/abstracts/absd12-2.htm).

The report concluded that "Although areas of uncertainty remain about the biological effects of low level RF radiation in general, including modulated signals, current evidence suggests that it is unlikely that the special features of the signals from TETRA mobile terminals and repeaters pose a hazard to health." The report also confirmed that emissions from TETRA masts are not pulsed. This means that TETRA masts are very similar to mobile phone masts in terms of health issues.

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