User's Manual

Bay Level Offset Calibration
68P09255A61-4
Aug 2002
1X SC 4812T BTS Optimization/ATP Software Release 2.16.1.x
FIELD TRIAL
3-72
Test Equipment Setup: RF Path Calibration
Follow the procedure in Table 3-35 to set up test equipment.
Table 3-35: Test Equipment Setup (RF Path Calibration)
Step Action
NOTE
Verify the GPIB controller is properly connected and turned on.
! CAUTION
To prevent damage to the test equipment, all transmit (TX) test connections must be via the 30 dB
directional coupler for 800 MHz with an additional 20 dB in-line attenuator for 1.7/1.9 GHz.
1 Connect the LMF computer terminal to the BTS LAN A connector on the BTS (if you have not
already done so). Refer to the procedure in Table 3-2 on page 3-6.
 If required, calibrate the test equipment per the procedure in Table 3-26 on page 3-60.
 Connect the test equipment as shown in Figure 3-12 on page 3-50.
TX Path Calibration
The assigned channel frequency and power level (as measured at the top
of the frame) for transmit calibration are derived from the site CDF files.
For each BBX, the channel frequency is specified in the
ChannelList
CDF file parameter and the power is specified in the SIFPilotPwr
CDF file parameter for the sector associated with the BBX (located
under the
ParentSECTOR field of the ParentCARRIER CDF file
parameter).
NOTE
If both the BTS-x.cdf and CBSC-x.cdf files are current, all
information will be correct on the LMF. If not, the carrier and
channel will have to be set for each test.
The calibration procedure attempts to adjust the 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 Bay Level Offset at sites WITHOUT the directional coupler
option, is approximately 42.0 dB ±3.0 dB.
 At sites WITHOUT RFDS option, BLO is approximately
42.0 dB ±4.0 dB. A typical example would be TX output power
measured at BTS (36.0 dBm) minus the BBX TX output level
(approximately -6.0 dBm) would equate to 42 dB BLO.
The TX Bay Level Offset at sites WITH the directional coupler option,
is approximately 41.4 dB ±3.0 dB. TX BLO = Frame Power Output
minus BBX output level.
 Example: TX output power measured at RFDS TX coupler
(39.4 dBm) minus the BBX TX output level (approximately
-2.0 dBm) and RFDS directional coupler/cable (approximately
-0.6 dBm) would equate to 41.4 dB BLO.
The LMF Tests menu list items, TX Calibration and All Cal/Audit,
perform the TX BLO Calibration test for a XCVR(s). The All Cal/Audit
menu item performs TX calibration, downloads BLO, and performs TX
audit if the TX calibration passes. All measurements are made through
the appropriate TX output connector using the calibrated TX cable setup.
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