User Manual

MOTOROLA IN CONFIDENCE
phn_1151 000V001 10/03/2008 Page 4 of 5
Maximum Transmit Power during the transmit period (total for both polarisations) for
PTP54500/PTP54300 equipments in production is set to not exceed 5dBm to ensure
that the Maximum EIRP requirement during the burst (27.76 dBm) is not exceeded
when the product is used with the supplied integrated antenna (G = 23dBi).
The PTP54500/PTP54300 equipments operate on a TDD basis using the same
frequency for up/down link. The transmit duty cycle resulting from the TDD operation
is fixed at <50%. .
The FCC regulations allow source-based time averaging to be used in working out the
EIRP value for the exposure calculation. This reduces the effective mean conducted
power and EIRP by at least 3dB from the levels of conducted power and EIRP that
would be applicable if the products were to transmit with a duty cycle of 100%.
It should be noted that this is very much a worst case as the product operates Receiver
driven Transmit power control.
4.4 FCC Testing
The testing has confirmed that the maximum conducted power and EIRP limits were
not exceeded by the product. The effect of the dual polarised antenna on the EIRP was
calculated by taking the linear sum of the results for each polarisation.
5 Analysis
5.1 Transmitted Levels
The Radiated Power Density can be assessed on the basis of the antenna gain for each
polarisation and the linear sum of the transmitter powers on the two polarisations.
More simply it could be based on the total EIRP allowed by the FCC regulations (as
the test reports show that the linear sum of the EIRPs from each of the two
polarisations on the product is less than this limit). This would present a conservative
assessment as the calculated power density levels would be less using the actual test
results. This is the approach that is used for the analysis below.
Example
Channel BW = BW
Allowed Conducted Power = 11dBm + 10*Log(BW) - (Actual Antenna Gain -
6dBi)
Antenna Gain = Antenna Gain of each polarisation
Allowed EIRP = Allowed Conducted Power + Actual Antenna Gain
EIRP used for Radiated Power Density Calculation = Allowed Conducted
Power - Allowance for source-based time-averaging in the product TDD
structure