Reference Manual

Table Of Contents
Product Data
5.7.1 Tower Mounted Amplier (TMA)
P006375B
Bias-T Injector
TMA-CM
RBS
ddTMA
Ant
RX/TX
CDU-F
CDU-G
900/1800/1900 MHz
TX/RX
Figure 39 TMA connections for 12 TRX RBSs
Function
The TMA compensates for signal loss in the receiver antenna cables,
reduces system noise and improves uplink sensitivity. The TMA can
consist of a duplex lter. Duplex is the function that allows
communication in two directions (sending and receiving) on the same
communication channel.
The TMA used for 12 TRX products is Dual Duplex TMA (ddTMA).
Requirements
The TMA is mounted as close to the antennas as possible in the
GSM 900, 1800 and 1900 systems, preferably on the same support.
Cable length is approximately 1 m.
Feeder Loss
The GSM 1800 and 1900 receivers are optimized to have a maximum
sensitivity with a feeder loss of 4 dB. Feeder loss of less than 4 dB will
cause a deterioration of receiver sensitivity if strong interfering signals
are present. Feeders with 4 dB loss or more must be selected at sites
where strong interfering signals are expected.
It may be necessary to select a feeder with higher loss and calculate the
length to obtain a total loss of 4 dB.
EN/LZT 720 0008 R1A
2001-06-26
99 (421)
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