User's Manual

Bay Level Offset Calibration – continued
08/01/2001
3-69
1X SCt4812ET Lite BTS Optimization/ATP
PRELIMINARY
Table 3-33: Set Up Test Equipment (RF Path Calibration)
Step Action
! CAUTION
To prevent damage to the test equipment, all transmit (TX) test connections must be via the 30 dB
directional coupler for 800 MHz or via a 30 dB coupler with a 20 dB in–line attenuator for 1900
MHz.
4 For TX path calibration, verify that the coaxial cable from the appropriate ANTENNA connector
(Figure 1-6 or Figure 1-7) is connected to the test equipment RF input port via the directional
coupler.
Transmit (TX) Path Calibration
The assigned channel frequency and desired power level at the frame TX
ports for transmit calibration are derived from the BTS CDF file. Each
BBX2 at the site is assigned to a sector and carrier. These are specified
respectively in the sector and carrier fields of the
ParentCARRIER
parameter in each BBX2’s CDF file block. The channel frequency and
desired power for the assigned sector are specified respectively in the
ChannelList and SIFPilotPwr parameters of the CDF block for the
CARRIER to which the BBX2 is assigned.
The calibration procedure attempts to adjust the measured power to
within +
0.5 dB of the desired power. The calibration will pass if the
error is less than +
1.5 dB.
The TX BLO for the SC4812ET Lite is approximately 42.0 dB ±5.0 dB.
BLO is the gain in dB between the known power output of the BBX2
and the measured power at the TX port. BLO is derived by deducting the
known BBX2 power output from the power measured at the TX port or
(Measured Power) – (BBX2 TX Power Output).
Example:
Measured Power (at TX port) = 36.0 dBm
Known BBX TX Power Output = –6.0 dBm
BLO = (36.0) – (–6.0) = 42.0 dB gain
The CDMA LMF Tests menu list items TX Calibration and All
Cal/Audit perform TX BLO Calibration testing for installed BBX(s).
The All Cal/Audit menu item initiates a series of actions to perform TX
calibration, download BLO, and perform TX audit if the TX calibration
passes. The TX Calibration selection performs only the TX calibration.
When the TX Calibration selection is used, BLO download and TX
audit must be performed as separate activities. All measurements are
made through the appropriate antenna connector using the calibrated TX
cable setup.
In both the TX Calibration and All Cal/Audit dialog boxes, a Verify
BLO checkbox is provided and checked by default. After the actual TX
calibration is completed during either the TX Calibration or All
Cal/Audit process, the BLO derived from the calibration is compared to
a standard, acceptable BLO tolerance for the BTS. In some installations,
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