Motorola D10 Service Manual page 58

BenQ
voltage regulation, battery charging control and switch ON/OFF
system analysis.
NAUSICA interfaces with the digital base-band device through a
set of digital interfaces dedicated to the main functions of Ulysse,
a base-band serial port (BSP) and a voice-band serial port (VSP) to
communicate with the DSP core (LEAD), a micro-controller serial
port to communicate with the micro-controller core and a time
serial port (TSP) to communicate with the time processing unit
(TPU) for real time control.
NAUSICA includes also on chip voltage reference, under voltage
detection and power-on reset circuits.
Major functions of this chip are as follows:
3.2.1 Baseband Codec (BBC)
The baseband codec includes a two-channel uplink path and a
two-channel downlink path.
The baseband uplink path (BUL) modulates the bursts of data
coming from the DSP via the baseband serial port (BSP) and to be
transmitted at the antenna. Modulation is performed by a GMSK
modulator. The GMSK modulator implemented in digital technique
generates In-phase (I) and Quadrature (Q) components, which are
converted into analog base-band by two 10 bits DACs filters. It
also includes secondary functions such as DC offset calibration and
I/Q gain unbalance.
The baseband downlink path (BDL) converts the baseband analog I
& Q components coming from the RF receiver into digital samples
and filters these resulting signals through a digital FIR to isolate the
desired data from the adjacent channels. During reception of burst
I & Q digital data are sent to the DSP via the baseband serial port
(BSP) at a rate of 270 KHz.
3.2.2 Automatic Frequency control (AFC)
The automatic frequency control function consists of a digital
to analog converter optimized for high resolution DC
conversion. Its purpose is to control the frequency of the GSM
13Mhz oscillator to maintain mobile synchronization on the
base station and allow proper transmission and demodulation.
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