TransCore encompass 4 - Page 7

Encompass 4 Reader System Guide
vii
maximum permissible exposure for general population/ uncontrolled exposure at 915MHz is 2.77 W/m2. The
average time is 6 minutes. The maximum permissible exposure (MPE) is the following:
Controlled Environment
Power density = 0.6455*frequency(in MHz)
0.5
W/m2 with a Reference Period time of 6 Min
General Public/Uncontrolled Environment
Power density = 0.02619*frequency(in MHz)
0.6834
W/m
2
with a Reference Period time of 6 Min
Using the frequency (in the middle of the band of operation of this equipment) of 915MHz and
the highest antenna gain that this equipment is certified for use in a final installation, the
minimum safe distance was calculated. The MPE minimum distances are 18in (45cm) for the
Controlled environment and 47in (120cm) for the General Public/Uncontrolled environment.
TransCore Recommendation on MPE (Maximum Permissible Exposure)
The calculated power densities and MPE distance for each of the agencies respective to the
environment is shown below.
Occupational/Controlled Environment
Agency
Power Density (mW/cm
2
)
MPE minimum distance
Time (min)
in cm
OSHA 10 8 20 6
FCC 3.05 14 36 6
IC 1.95 18 45 6
General Population/Public/Uncontrolled Environment
Agency
Power Density (mW/cm
2
)
MPE minimum distance
Time (min)
In cm
OSHA 10 8 20 6
FCC 0.61 31.5 80 30
IC 0.28 47 120 6