User's Manual
Bay Level Offset Calibration
68P09255A69-3
Aug 2002
1X SC4812ET Lite BTS Optimization/ATP Software Release 2.16.1.x
PRELIMINARY
3-76
Bay Level Offset Calibration
Purpose of Bay Level Offset Calibration
Bay Level Offset (BLO) calibration is the central activity of the
optimization process. BLO calibration compensates for normal
equipment variations within the BTS RF paths and assures the correct
transmit power is available at the BTS antenna connectors to meet site
performance requirements.
What is BLO Calibration?
Description
BLO calibration is the complete title of what is normally referred to as
“calibration.” Calibration identifies the accumulated gain in every
transmit path at the BTS site. The transmit path BLO values determined
during calibration are stored in the LMF calibration data file, and are
subsequently downloaded to each BBX. When transmit path calibration
is performed, receive path BLO values will automatically be set to the
default value in the LMF calibration file and downloaded.
BTS RF Path Descriptions
Transmit (TX) path - A TX path starts at an SCCP shelf BBX
backplane slot, travels through the CIO card, is routed to the Linear
Power Amplifier (LPA) trunking module for sector phase shifting,
through the LPAs, back through the LPA trunking module for sector
phase selection, through the TX bandpass filter (starter frames) or 2:1
TX combiner (companion frames), through the Transmit & Receive Dual
Directional Coupler (TRDC) or Duplexer Directional Coupler (DRDC),
and ends at the TRDC TX or DRDC antenna connector.
Receive (RX) main path - A main RX path starts at ANTENNAS
connectors 1A, 2A, or 3A and travels through the associated TRDC or
DRDC, the MPC in SCCP cage slot MPC-1, the CIO card, and
terminates at a backplane BBX slot in the SCCP shelf.
Diversity RX path - Diversity RX paths differ for SC4812ET Lite
starter (stand-alone) and companion frames. The following describe each
type of path:
Starter frame diversity RX path - A starter frame diversity RX path
is the same as a main RX path except that it starts at ANTENNAS
connectors 1B, 2B, or 3B, travels through the associated TRDC or
DRDC, and the MPC card in SCCP cage slot MPC-2 (refer to
Table 1-5).
Companion frame diversity RX path - The companion frame main
RX signal is used for the collocated companion frame diversity RX
signal. A companion frame’s diversity RX path starts at ANTENNAS
connectors 1A, 2A, or 3A in the collocated companion frame. It
travels through the associated TRDC or DRDC, the MPC in SCCP
cage slot MPC-1, and the CIO card where it is then routed out of the
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