ad6422 Analog Devices, Inc., ad6422 Datasheet - Page 4

• Manufacturer Part Number: ad6422
• Description: Gsm/dcs1800/pcs1900 Baseband Processing Chipset
• Manufacturer: Analog Devices, Inc.

AD20msp415
Generation of Auxiliary Audio Signals
Under control of Layer 1, the GSMP can generate a variety of
fixed and user-programmable tones. This includes all standard
DTMF and Call Progress tones as well as user defined tones.
The tone structure can consist of up to four frequency compo-
nents with individual durations. The GSMP also generates
Talker Sidetone as specified in the GSM recommendations. In
comparison to traditional hardware implementations, this soft-
ware implementation provides manufacturing flexibility over a
wide range of speaker/microphone sensitivities.
Figure 3 shows the audio section and the auxiliary ADC of the
VBC. Input signals can come from either a directly connected
microphone or from a remote microphone in a car kit. Input
gain can be set to 0 dB or +26 dB. The output signal can be
directly connected to a small earpiece and, for further amplifica-
tion, to an external car kit. The output PGA can be programmed
for –15 dB or +6 dB.
DATA SERVICES
Data Services is considered to be an essential feature for GSM
terminals and the AD20msp415 chipset is designed to provide
flexible and low cost implementation of Data Services supported
via the GSM air interface.
The selected system architecture shown in Figure 4 provides for
minimum terminal Bill of Materials, the lowest possible number
of interconnection points and the lowest power consumption
when running speech traffic only. The GSMP performs full
channel coding and decoding for TCH/F9.6, TCH/F4.8 and
TCH/F2.4 data rates. The interface to the chipset is a user-
configurable, 3-wire synchronous or asynchronous serial inter-
face supplying V110´ data packets as defined in GSM 05.03,
combined with protocol information and control to the Applica-
tion Layer.
External to the terminal is the Data Terminal Adapter (DTA)
that runs the Data Services Software. Included in the DTA are
the rate adaptation functions and the Data Services application.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD20msp415 features proprietary ESD protection circuitry, permanent damage
may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
Figure 3. Audio/Auxiliary Section of the AD6421
AUXILIARY
SERIAL
SERIAL
AD6421
VOICE
PORT
PORT
FILTER
ADC
FILTER
ADC
AUXILIARY ADC
PGA
PGA
MUX
MUX
MUX
CAR
KIT
TEMP
U
OTHER
BAT
–4–
The Command Interpreter resident on the mobile supports a
serial interface protocol with the DTA by which both traffic data
and control information are communicated.
SOFTWARE IMPLEMENTATIONS
A full implementation of the GSM Layer 1 functionality is sup-
plied as an object code module, for execution on the controller,
embedded in the GSMP. Functions performed by this software
include:
• Initial scan of GSM/E-GSM/PCN band and selection of
• Mobile oscillator adjustment, timing synchronization and
• Base station frequency and timing measurements and BSIC
• Frequency hopping according to 05.02.
• Full implementation of discontinuous reception (DRX) and
• Reporting of received level and signal quality.
• Full engineering and test mode support.
• Support for all phase 1 and phase 2 handover modes.
• SIM Interface driver.
• Message interfacing to Layer 3 (Radio Resources Manager)
• External functions for AGC, AFC and synthesizer setting are
The higher layers of the protocol stack also reside on this em-
bedded processor.
APPLICATION LAYER
APPLICATION LAYER
PROTOCOL STACK
PROTOCOL STACK
strongest thirty channels as required by 03.22 and 05.08.
BCCH decoding from serving cell (camping-on).
extraction from neighbor cells under control of Layer 3.
transmission (DTX).
and Layer 2 (data link layer, both signaling and data).
called by Layer 1. These allow the user to configure the sys-
tem for a wide range of radio architectures.
FOREGROUND
BACKGROUND
AD20msp415
LAYERS 2/3
CHIPSET
LAYER 1
Figure 4. Implementation of Data Services
HANDSET
INTERPRETER
COMMAND
ROUTER
FRAME
FRAMES
WARNING!
V110'
DATA TERMINAL
DATA TERMINAL
RADIO LINK PROTOCOL (RLP)
ADAPTER
MAN MACHINE INTERFACE
ESD SENSITIVE DEVICE
EXTERNAL
ADAPTER
LAYER 2 RELAY (L2R)
DATA APPLICATION
RATE ADAPTION
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