Service Manual

GSM-205-323
CTU
31st Oct 01
Tech. 5–8
Technical Description: Horizon macro indoor
CONTROLLED INTRODUCTION
68P02902W07-B
CTU
Overview of
CTU
This section provides the technical description of the compact transceiver unit
(CTU).
NOTE
The CTU may be an 850 MHz, 900 MHz, 1800 MHz or a
1900 MHz transceiver, depending on requirements. The
functionality of the CTU is the same for all variants.
The CTU:
 Generates the RF frequencies required to perform the transmit and
receive functions.
 Contains the digital circuits required for eight timeslots of channel
equalization, encoding and decoding, and transceiver control logic.
The CTU provides the air interface between a BSS and MSs, with the following
features:
 Capability of diversity reception (input from two antennas) which improves
the quality reception in the presence of multipath fading and interference.
 Frequency change on a timeslot basis for frequency hopping and
equipment sharing.
 Transmit power control.
CTU Tx RF output specification
For Tx RF output, see Technical Description: GSM-205-323 Overview and
specifications .
Location and requirements
The CTU shelf is adjacent to the digital module shelf in the base of the cabinet.
The cabinet can contain six CTUs. A minimum of one CTU must be fitted in
each cabinet.
CTU internal
boards
The CTU is a single field replaceable unit (FRU), which contains:
 CTU transceiver (XCVR) board.
 Power amplifier (PA) board.
 Power supply unit.