11.2 Antenna Unit: FB-1500/1250
11-19
2. Cable calibration function
In order to correct the Antenna coaxial cable loss, the Antenna coaxial cable will be
calibrated for 11 points per 3.5 MHz every time the power is turned on.
The required TX ATT value is the TX ATT value for when the output value for each
point is set at its maximum.
The transmitting output power will be set up based on the TX ATT value for the IF
board, which means it will be set based on the value measured for controlling the
transmitting output power.
Note that the TX ATT displayed value displayed after calibration is not fixed.
The transmitting ATT value can be confirmed via “TX ATT” in BDE for the Web MMI
Service menu.
The measured value will be reflected upon the input ATT value for the IF board
receiving circuit, and will be set so that the IF board receiving circuit would not be
saturated.
The value can also be confirmed via “RX ATT” in BDE for the Service menu.
The outline of the cable calibration process is as follows;
1) The Communication unit sends a cable calibration request to the Antenna unit.
2) When the Antenna unit is ready to execute the calibration, the Communication unit
sends the transmitting signal level for the default value.
3) Based on that output, the Antenna unit sends the transmitting output power
adjustment data: TX ATT, which will be the maximum EIRP to the Communication
unit.
4) Based on that data, the Communication unit will reset the transmitting level, and
execute transmission.
5) The procedures 3 to 4 will be repeated to identify the transmitting level from the
Communication unit where the maximum EIRP can be acquired.
6) The frequency is changed to the next measured frequency (3.5 MHz/11 points), and
the procedures described above are repeated.
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