vii
Controlled Environment
Power density = 0.6455*frequency (in MHz)
0.5
W/m
2
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 18 in (45 cm) for the Controlled
environment and 47 in (120 cm) 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.
With the equipment installed and running at the maximum transmit power of 2.0W (33dBm), 0
dB transmit attenuation, using the highest gain antenna that the equipment is certified for, the
recommendation for each of the operation environments is as follows:
1 ) The antenna should be installed at least 47 in (120 cm) from the General Population/Public i.e.
Uncontrolled Environment.
2 ) Maintenance personnel (i.e. Occupational/Controlled Environment) must remain at least 18 in
(45 cm) from the antenna and limit their time in the environment to 6 minutes when the system
is operating.
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
