Research

Project Title:
Traceability for Mobile Telecommunications and Health Research (TMTHR)

Start Date:
December 2001

Expected Date of Completion:
End of Programme

Cost:
Up to £118,000 (dependent upon requirements for consultancy over the period of the programme)

Principal Investigator:
Mr R N Clarke

Contact Details:
CETM
National Physical Laboratory
Queens Road
Teddington
Middx
TW11 0LW

Expertise:

NPL maintains one the world’s most comprehensive RF and Microwave national standards laboratories with well-established field-strength, antenna and dielectric measuring facilities. Standards development is a major part of NPL’s activities and cells for calibrating Specific Energy Absorption Rate (SAR) measurement probes are one of the most recent additions to these facilities. The Magnetics Group at NPL maintains the national magnetic measurements standards and it will be engaged in quantifying Very Low Frequency (VLF) emissions from cell phones in this project. Both teams of metrologists at NPL include internationally recognised experts in their fields, with many years of measurement experience between them. Promotion of good standards of measurement practice and the accreditation of laboratory facilities both form part of NPL’s normal remit. Experience in these fields places the laboratory in a good position to advise MTHR participants on their measurements and dosimetry.

Approach:

The VLF magnetic studies will employ both national standard facilities and calibrated fluxgate magnetometer measurements of pulsed and continuous magnetic emissions from commercial cell phones, including Global System for Mobiles (GSM) and Terrestrial Enhanced Trunked Radio System (TETRA) devices. Consultancy on measurement and dosimetry will cover advice given to the Programme Management Committee on measurement and standards, advice on good practice to individual laboratories and contributions to workshops on measurement and uncertainty estimation. Where appropriate, NPL will be providing traceable calibrations of microwave parameters to the MTHR programme in support of dosimetry studies. These will typically include calibrations of fieldstrength and SAR sensors and of antenna and dielectric parameters. Calibrations will be undertaken in accordance with NPL’s established measurement practices.

Potential Difficulties:

In the provision of advice and consultancy on experimental design these are likely to include judgements over evaluation of electromagnetic field strength in complex cell/applicator geometries and the evaluation of systematic uncertainties. The magnetic measurements will require decisions to be made over the separation distance of the cell-phones from the measurement devices and over the derivation of emitted pulse-shapes from received waveforms – the measurement device’s own response must be taken into account.

Importance:

Researchers and the general public can only have confidence in measurements and the research they underpin if they are traceable to measurement standards and comply with good measurement practices. Telecommunications is a global industry, so the measurement standards must be internationally recognised. All measurements undertaken in the research investigations of the MTHR Programme should therefore be traceable to international standards in order to ensure confidence in its findings by peer groups and the public alike. Measurements should be accompanied by best estimates of uncertainty in accordance with international guidelines. Measurement environments (e.g. cells, exposure chambers) and protocols should be designed with the need for calibration, traceability and uncertainty estimation in mind. Without these features, past experience has shown that confidence in research can be undermined. It is part of NPL’s remit to provide the required traceability in this project and to advise MTHR participants on good standards of measurement practice, particularly in the dosimetry studies. Practical studies at NPL will also provide quantitative information on VLF magnetic emissions from a number of cell-phone models and this will support researchers who are studying possible physiological effects of magnetic fields.