Select Committee on Trade and Industry Appendices to the Minutes of Evidence


Supplementary memorandum submitted by British Telecommunications PLC


  I am very pleased to respond to Trade and Industry committee members' interest in issues raised in connection with the TETRA-based Airwave service, as a result of your Inquiry into mobile mast infrastructure.

  The Airwave Service is an integrated digital radio communications network for the exclusive use of "Public Safety Organisations". It enables the emergency services to communicate with each other far more effectively than their current very dated technology permits or by using the standard communications facilities offered by existing mobile phone systems.

  Airwave uses the Terrestrial Trunk Radio System (TETRA). Airwave base stations emit a continuous tone, which is not amplitude modulated. TETRA terminals however use a burst of energy from the terminal at a rate of 17.6HZ per second. They comply fully with the guidelines on exposure to electro-magnetic fields produced by the National Radiological Protection Board (NRPB) as well as those of the International Commission on Non-Ionising Radiation Protection (ICNIRP).

  The Stewart Report included references to the possible effects of radio frequency emissions at or near a modulation of 16Hz on the release of calcium from brain tissue. However, no health risks were suggested in the report and none have been identified.

  In recognition of this, and the many benefits that Airwave will undoubtedly bring the police service, the Home Secretary has concluded that the roll-out should continue as planned, but that in parallel, the Defence Evaluation and Research Agency and the NRPB should undertake a review of existing scientific data. BT fully supports the Home Office approach on its approach to this issue. Interestingly and quite coincidentally, the Western Daily Press newspaper of 16 March carried a report that Professor Colin Blakemore of Oxford University, who wrote the cautionary note about TETRA in the Stewart Report, is now saying that "on reflection (there is) absolutely no cause for alarm at all".

  The attached document contains further details on the characteristics of this service in the form of questions and answers. I apologise that some of the material repeats the points made in BT's earlier submission to the committee on this issue, but we felt it important that the TETRA material was grounded in the same context as the rest of the Inquiry.

20 March 2001


  This document describes the Airwave Service and in addition provides answers to some of the most commonly asked questions about the service. It explains why the system is needed and sets out BT's position on such issues as health, mast location and environment impact.


1.1  What is the Airwave Service?

  The Airwave Service is an integrated digital radio communications network exclusively for Public Safety Organisations.

1.2  What is BT's Interest in the Service?

  BT's role is that of a service provider. We will build the network and then manage the service on behalf of the Police Information Technology Organisation (PITO) and the Home Office.

1.3  Why is it being introduced?

  At present each of the 51 police forces in England, Wales and Scotland run their own analogue radio systems, many of which now need to be replaced urgently. Many also have difficulty inter-operating with neighbouring forces, a situation that can hamper operations during major incidents. Users that have a national remit such as British Transport Police, the National Crime Squad and the Scottish Crime Squad, all need access to a modern nationwide service to operate effectively.

  The situation is the same for the Fire and Rescue and Ambulance Trusts as well as other Public Safety Organisations, each of whom are responsible for their own radio systems. At major incidents it can be very difficult for the emergency services to inter-operate with each other and the wider pool of public safety organisations. Lack of adequate communications at major incidents such as the Clapham Junction train crash, Lockerbie, Hillsborough, Kings Cross and Hungerford has been highlighted as a major factor hampering effective rescue co-ordination.

  The situation is further complicated by the fact that by 2005 the Government will have withdrawn the existing frequencies used by the emergency services for their radio systems. Therefore the emergency services will have to migrate to alternative systems before the frequencies are withdrawn.

  During the 1980s, a Home Office study into the future of police radio communications concluded that there was a need for a project to plan the procurement of a modern, cohesive nationwide radio service for the Police which should also be available to other Public Safety Organisations. This became the Public Safety Radio Communications Project (PSRCP).

1.4  When will it be introduced?

  Implementation of a pilot service with Lancashire Police is already under way. Other Police forces in England, Wales and Scotland will migrate to the service over the next four years. It is expected all forces in England and Wales will be fully operational by the end of 2004 with Scottish forces being fully operational by 2005.


2.1  What are the benefits of Airwave Service?

  The Airwave Service offers its customers the following benefits:

    —  Digital voice quality, leading to improved voice clarity and reduced chance of misunderstanding.

    —  Direct access to local and national databases, leading to better and timely provision of information to officers/personnel in the field.

    —  Terminals will act as an integrated communications platform offering radio, mobile telephone and data services.

    —  Secure communications, which cannot be easily scanned or monitored, will contribute to combating crime and safeguarding sensitive information from unauthorised access.

    —  More effective use of control room resources to deal with complex incidents.

    —  Automatic vehicle and person location will give accurate information to the location of vehicles and officers/personnel, leading to quicker response to incidents, more efficient use of resources, and improving officer safety.

    —  Access to comprehensive management information will enable better control of resources.

    —  Interoperability between the Public Safety Organisations will lead to a more effective co-ordination of major incidents.

  From the public's perspective, the Airwave Service will facilitate much needed improvements in public safety by allowing the emergency services to work more efficiently and effectively and in a co-ordinated manner.

2.2  Is it future proof?

  The Airwave Service is designed to last for a minimum of 15 years plus. During this time we expect there to be many advances in technology. As and when appropriate these will be incorporated into the services. The system was independently evaluated by an expert in the field from Imperial College London. His report clearly indicates that Airwave Service offers the best option for the short and medium term and is adaptable to change in the longer term.

2.3  Will other emergency services use this new system?

  The Fire/Ambulance and a whole range of other Public Safety Organisations are all potential users of this service. The Airwave Service will not be available for use by commercial organisations.


3.1  What is BT's overall position on the health issue?

  Our position is summarised as:

    —  There is some speculation about health and safety issues surrounding base stations and the TETRA technology upon which the Airwave Service is based. BT is very conscious of its responsibility to the public, employees, customers and other stakeholders in this, as in all of our other mobile communications activities.

    —  BT bases its installation and development specifications on recommendations from The National Radiological Protection Board (NRPB), the independent, expert body in the UK that advises on this subject and publishes guidelines for operators to follow. The NRPB and other reputable agencies have advised that there is currently no convincing scientific evidence of a risk to health through exposure to radio frequency (RF) waves below the national guidelines. The views of the NRPB are supported by other international expert groups, such as the World Health Organisation (WHO) and the International Commission on Non-Ionising Radiation Protection (ICNIRP).

    —  BT welcomes the findings of the Independent Expert Group on Mobile Phones (IEGMP), which was commissioned by the Department of Health, under the chairmanship of Professor Sir William Stewart. Whilst recognising that the remit of the Stewart report was primarily concerning itself with the cellular industry, we support the spirit and sentiment of the report as applied to our broader wireless portfolio and will continue to implement the Airwave Service to the highest health and safety standards.

    —  Despite current scientific opinion that there is no convincing evidence of a risk, we will undertake a series of measures in keeping with the recommendations of the Stewart report. In particular we will work to ICNIRP (public) guidelines and will support the need for continuing, relevant and high quality research to ensure this issue is subject to the most up-to-date and rigorous scientific scrutiny.

3.2  What is being done to look into alleged associated health risks?

  We recognise the need for continuing, relevant and high quality research, to ensure this issue is subject to the most up-to-date and rigorous scientific scrutiny. We support and contribute to continuing research and are pleased to be involved in this important and developing area.

3.3  What is BT's contribution to this?

  BT has committed to contributing our share toward funding the Government's £7.68 million radio frequency research programme as recommended by the Stewart Report. The programme will be conducted independently of industry and will be managed by an expert scientific advisory committee chaired by Sir William Stewart. The World Health Organisation (WHO) co-ordinates and interprets research, shares the results and, most importantly, recommends what further research needs to be done at a global level. Moreover, the European Union has announced a major research and risk evaluation programme related to the safety of mobile communications. BT continues to track these and other relevant developments as part of our ongoing commitment to addressing any concerns. BT and the UK government have people monitoring the issues around "Wireless Health" and attending international conferences to keep abreast of the very latest research results.

3.4  What are base stations and are they safe?

  A base station is a low power radio transmitter with an antenna to transmit radio waves to mobile phones or handsets. According to The World Health Organisation (WHO) one of the international expert bodies that monitor research in this area and advise on safety, "RF field levels around base stations are not considered a health risk".

3.5  What if I live near a base station, am I in danger?

  Base stations operate at power levels many times below the National Radiological Protection Broad (NRPB) guidelines. The Independent Expert Group established by the Minister of Health concludes "the balance of evidence indicates that there is no general risk to the health of people living near to base stations on the basis that exposures are expected to be small fractions of the guideline".

3.6  The Stewart Report stating that as a precautionary measure, amplitude modulation around 16Hz should be avoided, if possible, in future development of signal coding. Does this not pose question mark over the safety of base stations and terminals?

  Airwave base stations emit a continuous tone, which is not amplitude modulated.

  TETRA terminals use Time Division Multiple Access (TDMA) to enable up to four users to access a single TETRA radio channel simultaneously. It is this TDMA which produces a "burst" of energy from the terminal at the rate of 17.65 times per second. Whilst there is no convincing scientific evidence of a health risk to humans resulting from mobile phone use, it is a precautionary measure to minimise the power level within these bursts. TETRA terminals use a process known as "Power Control" which dynamically controls the power transmitted by a terminal to keep it to the minimum necessary to maintain communication with the base stations.

  BT has agreed to follow the "precautionary" approach as recommended by the Stewart Report. Emissions from the system are within the levels specified by NRPB and ICNIRP. These levels are based on independent research by a large number of expert bodies, subject to extensive peer review and are set many times below the levels where adverse health effects can be observed.


4.1  How many masts or base stations will be needed to provide the Airwave Service?

  To provide the geographical coverage and capacity that Public Safety Organisations demand, it is currently estimated that around 3,000 masts will be needed.

4.2  What criteria does BT use to decide where to site base stations?

  The positioning of any new installations is always considered very carefully. Mindful of the need to minimise inconvenience and visual impact, we work in close consultation with local authorities, the Police as the primary users and many other relevant organisations to select sites that provide the coverage needed. Unlike mobile networks, the Airwave Service needs to provide a very high level of national geographical coverage, regardless of population density. In keeping with the spirit of a precautionary approach and mindful of public concern, we will commit to locate, as far as possible, new base stations on sites that minimise their social impact on the local community. We also support the development of new technology to help improve base station design.

4.3  Do you consult local planning authorities?

  We recognise that local planning authorities are a key participant in the network development process and that improved communication with them is a vital element in addressing the issue. To this end, we, together with other operators, will increase the provision of information to planners on network design strategies and give them access to the Radio Sites Databank.[4]

4.4  Do you share with other operators?

  We aim to use existing sites and masts and only build new ones where this option is not available to us. We redevelop sites and share with others wherever possible.

4.5  How does BT engage in community consultation?

  BT takes its responsibility for any effects on the community very seriously. We have a dedicated team of people who work in close partnership with the police and local planning authorities to deliver a bespoke programme of community consultation activities. We undertake surveys to ensure areas of outstanding natural beauty and special scientific interest are respected.

4.6  What steps are BT willing to take to minimise the visual impact of masts and aerials?

  In sensitive areas we aim to erect the minimum installation which will provide optimum coverage. Where possible, we will try to meet any requests to disguise masts by altering the colour and/or providing screening such as foliage.

4.7  What is BT's response to groups that are taking action to prevent masts being built?

  We work with the relevant bodies and organisations to ensure we are aware of all opinions and concerns. These help inform the process for deciding the most appropriate site, which will also take account of other factors, such as planning and technical considerations.


5.1  What technology is the Airwave Service based upon?

  TETRA (Terrestrial Trunked Radio) is an open standard for digital private mobile radio approved by the European Telecommunications Standards Institute (ETSI) and used by Public Safety Organisations throughout Europe and beyond for a number of years.

5.2  In basic technical terms how does the Airwave Service enable forces to speak directly to each other?

  Since the Airwave Service uses a single national infrastructure, there is no technical restriction on where an individual user can be located (provided they are within radio coverage) or on the Public Safety Organisation to which they may belong. The functionality within the service enables users to make calls, send and receive data messages including status messages and access the telephone network. The Airwave network comprises of a series of base stations connected to switches. Users access the network over the air interface (radio link to a base station) using either a vehicle mounted or handportable terminal.

5.3  In basic terms what is amplitude modulation?

  In order to transmit information some form of modulation is necessary. Amplitude Modulation (AM) is the variation of the power level radiated from a radio transmitter. TETRA uses a modulation type that modulates the phase of the carrier signal. There is an important distinction between AM and Time Division Multiple Access (TDMA). It is the TDMA that causes the "burst" of energy from the handset at the rate of 17.65 times per second. TETRA does not use Amplitude Modulation.

5.4  Do transmissions from Tetra handsets have an element of amplitude modulation in the signal coding?

  TETRA terminals use a type of modulation that modulates the phase of the transmitted power level rather than amplitude. However, in order to allow up to four TETRA handsets to use the same radio channel simultaneously, their transmissions are confined to "bursts" of approximately 14 milliseconds every 56 milliseconds—a technique known as Time Division Multiple Access (TDMA).

5.5  Does transmission from a TETRA base station have an element of amplitude modulation?

  Motorola TETRA base stations, as used for the Airwave Service have a constant RF transmission and do not transmit pulsed signals.

5.6  Does TETRA radiate energy at 17.6Hz?

  TETRA systems radiate energy in accordance with the conditions of their licence. For example, in the UK, public safety operators radiate energy from 380 MHz to 400 MHz. However, in order to allow up to four TETRA terminals to use the same radio channel simultaneously, their transmissions are confined to "bursts" at a rate of 17.65 times per second.

5.7  In basic terms what is signal coding?

  Signal (or Channel) Coding is a process whereby additional data is added to the user signal (digitized voice or data) being transmitted over the radio channels in order to make it less sensitive to errors introduced by the radio environment. This process enhances the transmission quality of the user signal in the presence of disturbances such as electrical noise, interference from other radio sources and so on. Coding of the signals in a particular arrangement conveys a certain character or message (eg Morse Code). Present systems are designed to efficiently utilise the available medium whilst also combating the effects of transmission errors. An effective coding system will remove all unnecessary symbols but add others to allow the checking to detect errors. The Airwave Service uses an efficient Adaptive Code Excited Linear Predictive (ACELP) voice coding.

5.8  Is the TETRA Technology more powerful than GSM?

  The TETRA and GSM standards define several classes of power for mobile stations. These are maximum powers that are considerably reduced by the power control mechanisms in both systems. Whilst the TETRA standard actually allows for a higher power level than a GSM mobile station, a typical TETRA mobile station would be expected to transmit no more than half the power that a GSM mobile station transmits.

4   The Radio Sites Databank outlines the location of many UK radio communications structures, and can be used to locate existing structures appropriate for base station sites. Back

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