Service Manual

GSM-205-323
RF overview and RF test function
31st Oct 01
Tech. 5–4
Technical Description: Horizon macro indoor
CONTROLLED INTRODUCTION
68P02902W07-B
RF overview and RF test function
RF overview
This section explains the RF functional blocks and additional RF loopback test
capability.
The terminology, functionality and optional capabilities are set out, as a basis for
understanding more detailed descriptions in RF module sections of this chapter.
RF main
component
explanation
The following description should be read in conjunction with Figure 5-1.
The RF equipment consists of three main blocks:
 The CTU.
 The SURF module.
 The Tx block or alternatively CCBs.
CTU
The CTU can operate at 850 MHz, 900 MHz, 1800 MHz or 1900 MHz,
depending on the BTS variant ordered. It can receive two inputs, RxA and RxB,
from the SURF. These inputs are converted into digital voice/data. The two Rx
signals provide diversity of the Rx function from the MS (uplink).
The CTU also generates a Tx data signal, translated from received digital
voice/data, which is transmitted by cable to the Tx block for antenna
transmission to the MS (downlink).
The third (middle) port provides an RF loopback test signal capability, for
automatic transmission of RF test signals to the SURF.
SURF module
One of six variants of the SURF module can be installed in the Horizon macro
indoor:
 Single band 850 MHz SURF.
 Single band 900 MHz SURF.
 Dual band 900 MHz SURF.
 Single band 1800 MHz SURF
 Dual band 1800 MHz SURF.
 Single band 1900 MHz SURF.
The single band SURF modules accept up to three pairs of antenna inputs, and
the dual band SURF modules accept up to four pairs of antenna inputs. The
SURF switches the inputs to the appropriate CTUs under the control of the
database via the MCUF. There are two inputs to each CTU for Rx diversity.
The SURF also contains loopback test circuitry, connecting with a test signal
from each CTU.