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Radiocommunications in the community - L3

Additional Information on Radio Communications

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Radiocomunications in the community - L2

Introduction
What communication systems use radio frequency?
How do the transmitter powers compare?
How strong are the environmental or background EMF levels in the community?
Spectrum Plot showing typical radio signals?
What research has been done on radio communications and EMF safety?
Radio communications poster
Mobile Communications & Health Booklet

Introduction

Radio communications are a part of everyday life in today's society. All radio communications systems utilise EMF in the radiofrequency (RF) part of the electromagnetic spectrum.  Typical background EMF levels from radio communications systems are very low and well below safety guidelines.

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What communications systems use radio frequency technology?

Radio frequency technology is used by

  • TV and AM / FM broadcasts
  • Mobile phones and their base stations
  • Wireless broadband
  • Radio paging services
  • Cordless phones
  • Baby monitors
  • Emergency services communications (police, fire, ambulance)
  • Government communications
  • Air traffic control
  • Rural and country communications.

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How do the transmitter powers compare?

High powered systems are used for television and radio broadcast, usually from a single transmitting tower in an elevated location.

Medium powered systems are used for two-way communications typically from a repeater tower to vehicle radio systems like emergency services.

Low powered systems are used for mobile communications and rely on a network of transmitting sites like mobile phone base stations.

 

Radio Systems*

Typical Transmitter Power (Watts)

TV & Radio broadcast

5,000 – 100,000

 Air traffic control radars

 5000 – 20,000

 Radio paging services

 50 – 100

 Emergency communications

 50 – 100

 Government radio systems

 50 – 100

 Mobile phone base station

 2 – 50

 Wireless Broadband base station

 2 – 50

 

 

 Radio Devices

 

 Walkie Talkies

 0.1 – 5

 Mobile phones

0.002 – 0.2 

 Wi-Fi Modem

 0.1

 Cordless phones

  0.01 – 0.2 

 Baby monitors

 0.01 – 0.1

Car remote control

0.001 – 0.1

* typical power into antenna

Note - whilst transmitter power is important, the distance from the transmitter (or antenna) is a major factor in determining a persons RF exposure.  For example a baby monitor inside a house is often the highest source of RF exposure given the proximity.  (refer to comparison in WiFi Explained)

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How strong are the environmental or background EMF levels in the community?

In a typical community, broadcast television and radio signals are similar in strength to signals from mobile phone networks and other two-way communications systems.  These signals are overall very low and well below the established safety guidelines

The World Health Organisation has reviewed the background EMF levels from wireless systems and says,

"Recent surveys have shown that the RF exposures from base stations range from 0.002% to 2% of the levels of international exposure guidelines, depending on a variety of factors such as the proximity to the antenna and the surrounding environment. This is lower or comparable to RF exposures from radio or television broadcast transmitters"

Specifically on EMF levels in public areas the WHO says,

"Recent surveys have indicated that RF exposures from base stations and wireless technologies in publicly accessible areas (including schools and hospitals) are normally thousands of times below international standards."

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Spectrum plot showing typical radio communications signals in a community

This picture is a plot from a spectrum analyser (specialised radio measurement equipment) showing the various radio communications signals measured in a typical community.  The plot is taken at one location to illustrate typical radio communication signals present, and to make a comparison of signal level. 

The type of radio service is indicated on the plot along horizontal axis and signal level in dBm (level relative to 1 milli-watt) on the left hand axis.   The units are not really important here except to show relative levels.  The picture also shows how many radio services are used in a typical community.

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What research has been done on radio communications and EMF safety?

There has been a lot of research conducted worldwide to investigate possible health effects of radio communications and wireless technology.

In relation to radio frequency exposures and wireless technology and health, the general conclusion from the World Health Organization (WHO) is

"Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health"

Summary of health Effects – Key point 6  http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html

The WHO also says,

"radio and television broadcast stations have been in operation for the past 50 or more years without any adverse health consequence being established”

Electromagnetic Fields and public health – Fact sheet 304 http://www.who.int/mediacentre/factsheets/fs304/en/index.html

Download the Mobile Communications & Health Booklet from the GSMA

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Radiocommunications in the community - L3

Additional Information on Radio Communications

Health Authority & Educational Resources

 

Other Resources