Service Manual
GSM-204-323
Compact transceiver unit (CTU)
31st Oct 01
Technical Description: Horizon
macro
outdoor
68P02902W02-A
CONTROLLED INTRODUCTION
Tech. 5–17
2 Mbit/s TDM Links
The CTU interfaces to the redundant MCUF are by 2.048 Mbit/s links on the
backplane (or FMUX modules in extension cabinets). These links are
Manchester encoded, thus providing both clock and data in a single connection.
The recovered clock provides a frequency reference for the CTU. The Rx and
Tx circuitry supports FMUX fibre optic lengths of up to 1 km.
The TDM links are formatted into 32 x 64 kbit/s timeslots to provide:
Downlink and uplink TRAU speech data.
Downlink baseband hopping data to be routed to/from other CTUs.
Cell site air interface synchronization.
HDLC channel for control information between RSS and MCUF.
Baseband routeing information to indicate source of downlink baseband
hopping data.
RSS processor
The RSS processor function communicates with:
The MCUF via dedicated 64 kbit/s timeslots in the TDM link.
The rest of the digital control functions by the peripheral communications
interface (PCI) bus.
A dual port interface for communication with the CCCP.
A TTY interface is also provided for user support.
The RSS processor memory includes flash EPROM and 8 Mbytes of DRAM.
Flash EPROM is used for code storage.
EQCP processor
The EQCP processor handles all radio control functions and the channel
equalizer function. The EQCP controls the Rx and Tx function via the CTU
control function on a per timeslot basis. These EQCP functions include:
Alarm management.
Downlink burst building and modulator control.
Transmitter power control.
Synthesizer channel control.
RF frequency hopping.
Receiver front end and remote tune combiner control.
Uplink synchronization and equalization.
Diversity receiver control.
Receiver Automatic Gain Control (AGC).
Receive signal strength (RXLEV) calculation.
Timing advance calculation.
Support of front panel indicators.
The EQCP communicates with the rest of the digital control functions via the
common PCI bus interface. A TTY interface is provided for radio level
calibration, system monitoring, and CTU level test.