User Manual

MOTOROLA IN CONFIDENCE
phn_1151 000V001 10/03/2008 Page 3 of 5
OPERATIONAL PARAMETERS OF THE PTP54500/PTP54300 PRODUCT
1 Scope
The purpose of this brief working paper is to identify the RF power produced by the
PTP54500/PTP54300 equipment under various operating conditions. This mean RF
power plus the antenna gain used in specific installations identifies the effective power
density (dBm/cm
2
) that is to be compared against allowed limits for human exposure.
The two part numbers in the heading above reflect changes in product branding only;
the product performance is not affected.
2 References
Evaluating Compliance with FCC Guidelines for Human Exposure to Radio frequency
Electromagnetic Fields:
OET Bulletin 65, Edition 97-01, August 1997 [1]
3 Background
Reference [1] identifies how the radiated power density should be calculated for
different distances from the antenna. The variables used are Radiated Power Density
(S), conducted power (P), Antenna Gain (G) and distance (R) . The formula given is
S= (P * G)/(4 * Pi * R
2
)
The limit allowed for S depends on whether the exposure risk is to a member of the
public or not. The PTP54500/PTP54300 products are approved by the FCC under the
UNII Rules (Part 15.407). This requires (Part 15.407(f) that all products meet the radio
frequency radiation requirements for the “general population/uncontrolled
environment” case. At the frequency of operation of these products, this requires that
the value of S to be used is 1mW/cm
2
.
It is clear from [1] that the power to be used should be the maximum transmitted
power, subject to any allowance for source-based time-averaging.
Notes
a) the FCC require that the power density be calculated at a minimum distance of 20cm
b) the value of P * G is the same as the transmitted EIRP.
4 PTP54500/PTP54300 Specific Issues
4.1 FCC Regulations
The PTP54500/PTP54300 is approved under FCC Part 15.407 and this regulation
limits the maximum EIRP to 28.76dBm in a channel bandwidth of 15MHz. The
PTP54500/PTP54300 products ensure that this power cannot be exceeded.
4.2 Dual Polarisation
The PTP54500 and PTP54300 products use an integrated dual polarised antenna, with
each polarisation connected to an identical transceiver circuit inside the unit. In order
to comply with the FCC EIRP limits, the design of the products reduces by 3dB the
conducted power and EIRP of each of the two individual polarisations.
4.3 Power Control
The power levelling loops in the product measure the transmitted power on each
polarisation at all times and limit each to the Maximum Transmit Power –3dB. The