March 1, 2002 Page E14
System Level Setting Notes
General
The head end and subscriber transmitters are designed for linear operation at the maximum output
power allowed for compliant operation under the FCC part 15 regulations. In both the head end
and the subscriber units the input power level to the ARCi radios determines that of the output.
There is no gain adjustment available to the user.
Downstream Power
The head end transmitter power is set by adding fixed attenuators to the downstream IF path,
adjusting the output level of the upconverter, or some combination thereof. The ARCi headend
ODU is factory calibrated to produce a +30 dBm maximum EIRP when this level is applied to the
headend ODU IF input.
This is the level required for FCC compliance
.
Downstream Power Adjustment Procedure
1. Disconnect the IF cable at the input to the head end ODU transmitter and connect the
cable to the input of a suitably calibrated spectrum analyzer.
2. Set up the spectrum analyzer as follows:
Center Frequency
IF frequency in use (481 – 571 MHz)
Span
100 MHz
RBW
1 MHz
VBW
30 KHz
Vertical Scale
linear, 10 dB / division
Reference
Level +40
dBmV
Attenuation
20
dB
Detection
Mode Averaging
3. Adjust the IF level at the upconverter or by inserting fixed attenuators as needed to
ensure that the observed modulation peaks do not 23 dBmV.
4. As an alternative to performing this adjustment at the rear of the headend ODU, it can
be made at the indoor equipment end of the IF cable, as above, if the loss of the cable at
the IF frequency is calculated. The observed modulation peaks can then be adjusted so as
not to exceed (+30 dBmV + loss dB). For example, the loss of typical good quality RG6
cable is 4.57 dB/100 ft. at 550 MHz.
Summary of Contents for AR1255
Page 4: ...March 1 2002 Page A1 A Table of Contents ...
Page 6: ...March 1 2002 Page B1 B Introduction C t t ...
Page 9: ...March 1 2002 Page C1 C System Description ...
Page 18: ...March 1 2002 Page D1 D Antenna and Frequency Planning ...
Page 24: ...March 1 2002 Page E1 E Hub Installation Detail ...
Page 29: ...March 1 2002 Page E6 Figure E4 Hub Antenna and Cable Installation Cable Access ...
Page 40: ...March 1 2002 Page F1 F Subscriber Inst l Details ...
Page 46: ...March 1 2002 Page G1 G Link Budget Parameters ...
