RF Exposure Audits

1
RF Exposure Audits
EDDIE BULL Baldock Operations Manager Fixed and
Mobile Monitoring and Measurements
Section Radiocommunications Agency
2

• The Stewart Report
• We recommend that an independent, random, ongoing
  audit of all base stations be carried out to
  ensure that exposure guidelines are not exceeded
  outside the marked exclusion zone and that base
  stations comply with their agreed specifications.
  If base station emissions are found to exceed
  the guideline levels, or there is significant
  departure from the stated characteristics, then
  the base station should be decommissioned until
  compliance is demonstrated. We recommend that
  particular attention should be paid initially to
  the auditing of base stations near schools and
  other sensitive sites.

3

• The following Table gives a summary of the
• RF Audit progress in 2002 on Cellular Radio base
  station activity on or near Schools and
  Hospitals.

4
(No Transcript)
5

• RF exposure comes from many sources, not just
  from cellular systems. In fairness to the
  cellular operators the Agency decided to carry
  out a number of RF Audits across the radio
  spectrum covering the band 30MHz to 2GHz and post
  the results on the RF Audit Web site.
• Residential locations close to major TV and Radio
  broadcast sites were chosen to compare RF levels
  from broadcast, paging, PBR and hobby radio
  sources etc with emission levels from cellular
  systems.
• The following slides show how the Exposure
  Quotient for a single emission and multiple
  emissions is calculated.

6
Calculations

• Exposure Quotient. (Single Signal)
• The measurement of a single signal can be given a
  dimensionless quantity known as the exposure
  quotient. This quantity is derived by dividing
  the measured power density (Smeas) by the
  guideline level (Sguid) for the measured
  frequency.
• An exposure less than unity indicates compliance
  with the guidelines.

7
Calculations

• Exposure Quotient. (Many Signals)
• RF exposure surveys are concerned with
  simultaneous exposure to many different radio
  signals spread throughout the radio spectrum.
  All signals impinging on the measurement site
  will contribute to the total exposure at the
  point of measurement. The total exposure
  quotient will be equal to the sum of the
  quotients for all signals in the measured bands.

8

• The following spectrum plot examples show RF
  activity in the two sub-bands 30 - 860MHz and
  860MHz - 2GHz.

9
(No Transcript)
10
SANDY HEATH Comparison of Cellular V Other
Broadcasts. Extracted from Report ML2-016-02
11
Summary of example plots The total Exposure
Quotient for the whole band RF emissions (30MHz
2GHz) is 3.51e-3.The Exposure Quotient for the
sub-band 30 - 860MHz is 3.46e - 3. (1/289th of
the ICNIP guidance level) The Exposure Quotient
for the sub-band 860MHz - 2GHz is 4.95e - 5.
(1/20202th of the ICNIP guidance level)
12
Although these measurements are site specific
and represent only a snapshot of the RF activity
at the time of the survey, the ratio of cellular
activity to other types of emissions appear to be
typical at most of the locations surveyed.At
the example location the dominant emissions were
Analogue TV and T-DAB signals At most of the
other survey locations Band 2 broadcast, T-DAB
and TV emissions yielded the highest levels.