Product Info
XMI (T r ansceiv er Module Internal) Module Chapter 7: XMI R eplacement Procedures
TX RF Small Signal Handling
F or 800 MHz XMIs, the TX RF small signal from each sector RF transmitter in the XMI is
routed to the TXD connector on the front panel of the XMI. When the TXD connector is properly
terminated, each sector TX RF path is completed and the TX RF small signal from each sector
RF transmitter in the XMI is applied to the 3 -sector TX RF input FTM. The FTM provides
3 -sector TX RF output signals which drive the LP As.
F or proper operation of the XMI TX RF outputs, the XMI TXD connector must be
terminated with either a TXD attenuator or a TXD cable connected to a TX combiner .
Currently the 800 MHz UBS Macro BTS frame do not support the use of a TX
combiner , but it will in the future. Therefore a TXD attenuator must be installed in
the TXD connector on all 800 MHz XMIs.
F or 1.9 GHz XMIs, the TX RF small signal from each sector RF transmitter in the XMI is routed
directly to the 3 -sector TX RF input FTM. The FTM provides 3 -sector TX RF output signals
which drive the LP As.
The 1.9 GHz XMIs do not have a TXD connector .
In the future, the 1.9 GHz UBS Macro BTS frames will be equipped with 2:1 cavity
combiners that will connect to the TX output of the XMI LP As.
TX RF Power Amplication
The 3 -sector TX RF input FTM transforms the phase of each sector TX RF small signal. Each of
these phase transformed input signals drives the corresponding sector TX RF LP A section.
The sector TX RF LP A section amplifies the low power multi -carrier TX RF signal (i.e., TX RF
small signal) to the final XMI TX RF power output for the sector . (Note that each XMI sector TX
RF LP A section is capable of providing 30 W maximum TX RF power output). The final TX RF
power output signal of each sector TX RF LP A is applied to the 3 -sector TX RF output FTM.
The output FTM transforms the phase of each sector final TX RF power output signal. Each of
these phase transformed sector output signals is applied to a corresponding RF coaxial switch
that is relay actuated. Each RF coaxial switch routes the sector final TX RF power output signal
to the corresponding sector TX RF output port (i.e., TX1, TX2 or TX3) on the XMI front panel.
The open/closed state of each RF coaxial switch is controlled by its associated relay . When the
relay is unenergized, its RF coaxial switch is open (N .O . = Normally Open). This condition
occurs when the XMI looses DC power and may also occur under XP AC control.
In the UBS Macro frame, the final TX RF power output signal from each sector of XMI 1 is
routed to the corresponding sector TX antenna via the corresponding sector IDRF .
7 -6 68P09283A64 -3
FOA SEP 2007