FCC Filing Package for Motorola i285 Transciever FCC ID: AZ489FT5827 6.7 Effective Radiated Power (ERP) As described in Exhibit 7.1, the radiated power received at a spectrum analyzer was measured from the radio product specimen with integral antenna at 2 degrees increments as the specimen was rotated. These recorded power readings are uncalibrated ERP measurements. To convert these readings to ERP values a reference reading was obtained from a calibrated (to an ideal dipole) antenna to which was applied the same power level as the measured output power of the radio specimen. The reading at the spectrum analyzer from this calibrated reference antenna served to calibrate the spectrum analyzer readings for ERP measurements. By comparing the readings between the reference antenna and the radio product specimen, and with a measurement of the output power of the radio product specimen, this measurement also serves to determine the radio specimen antenna gain.
6.7.1 ERP in 806 MHz - 825 MHz band
The following calculation shows how ERP was determined, at a test frequency of 813.5625. Following example describes the procedure used to calculate the ERP shown in Figure 6 – 37.
a.) Analyzer reading for radio specimen, as tested at 28.4572dBm (701mW) output power: -18.2 dBm b.) Analyzer reading for a substitution antenna, at 28.4757dBm applied power: -16.2 dBm c.) Antenna gain (logarithmic) compared to an ideal dipole: (-18.2) - (-16.2) + (-0.8) = -2.8 dBd d.) Measured ERP: (28.4572) + (-2.8) = 25.6572dBm e.) Measured ERP: 367.8917 milliwatts
However, the measured ERP value above was not determined at the production controlled maximum output power of the radio product so it is necessary to scale this number. The antenna gain permits the ERP to be calculated for any output power value in a manner similar to steps c and d above. The following calculations were used to determine the maximum ERP based upon the maximum output power rating (700 milliwatts) stated in Exhibit 6.1.1.
f.) Maximum output power rated: 700 milliwatts g.) Output Power measured: 701 milliwatts h.) Maximum calculated ERP: 367.8917 x (700/701) = 367.3669 milliwatts
The method above was used to process all rotational measurement data and, for brevity, the following graph (Figure 6-37) summarizes in a visual fashion the radio ERP at the 90 degree location and other rotational positions.
IDEN, Motorola Inc., 8000 W. Sunrise Blvd., Plantation, FL 33322 WWW.MOT.COM/iDEN Page: 6-41
FCC Filing Package for Motorola i285 Transciever FCC ID: AZ489FT5827
6.7.2 896 MHz - 901 MHz band
The above calculations were repeated at a test frequency of 896.01875 MHz. Following example describes the procedure used to calculate the ERP shown in Figure 6 – 37.
a.) Analyzer reading for radio specimen, as tested at 28.3378 dBm (682 milliwatts) output power: -15.9 dBm b.) Analyzer reading for a substitution ideal dipole antenna, at 28.3505 dBm applied power: -16.1 dBm c.) Antenna gain (logarithmic) compared to an ideal dipole: (-15.9) - (-16.1) + (-0.3) = -0.1 dBd d.) Measured ERP: (28.3378) + (-0.1) = 28.2378 dBm e.) Measured ERP: 666.4691 milliwatts f.) Maximum output power rated: 700 milliwatts g.) Output Power measured: 682 milliwatts h.) Maximum calculated ERP: 666.4691x (700/682) = 684.0592 milliwatts
The following graph of item is provided to serve as a simplified summary of that measured data and to visualize the maximum calculated ERP at the azimuth positions.
Maximum calculated ERP vs Azimuth Angle 800MHz 900MHz
800.0
700.0
600.0
500.0
400.0
300.0 Maximum Calculated ERP (mW) 200.0
100.0
0.0 0.6 10.5 20.6 30.6 40.6 50.6 60.6 70.6 80.6 90.6 100.6 110.6 120.6 130.6 140.6 150.6 160.5 170.6 182.0 192.6 202.6 212.6 222.6 232.6 242.6 252.6 262.6 272.6 282.6 292.5 302.6 312.6 322.6 332.6 342.6 352.6 Azimuth Angle (Deg)
Figure 6-37: Figure 6-37: Scaled ERP vs. Azimuth Angle
IDEN, Motorola Inc., 8000 W. Sunrise Blvd., Plantation, FL 33322 WWW.MOT.COM/iDEN Page: 6-42
FCC Filing Package for Motorola i285 Transciever FCC ID: AZ489FT5827
IDEN, Motorola Inc., 8000 W. Sunrise Blvd., Plantation, FL 33322 WWW.MOT.COM/iDEN Page: 6-43