Internal Microphone And Earpiece; Figure 12: Audio Control - Nokia NSB-5 Series Technical Documentation Manual

PAMS Technical Documentation
Slide
EMI
Preamp
Bias +
EMI
Premult.
MIC2
MIC1
MIC3
EMI+ACC
Interf.
XMIC
SGND
XEAR
AuxOut
HF
EAR
Display
EMI
The baseband supports three microphone inputs and two earphone outputs. The inputs
can be taken from an internal microphone, a headset microphone or from an external
microphone signal source. The microphone signals from different sources are connected
to separate inputs at the COBBA–GJP asic. Inputs for the microphone signals are differ-
ential type.
The MIC1 inputs are used for a headset microphone that can be connected directly to the
system connector. The internal microphone is connected to MIC2 inputs and an external
pre–amplified microphone (handset/handfree) signal is connected to the MIC3 inputs. In
COBBA there are also three audio signal outputs of which dual ended EAR lines are used
for internal earpiece and HF line for accessory audio output. The third audio output AUX-
OUT is used only for bias supply to the headset microphone. As a difference to DCT2 gen-
eration the SGND does not supply audio signal (only common mode). Therefore there are
no electrical loopback echo from downlink to uplink.
The output for the internal earphone is a dual ended type output capable of driving a
dynamic type speaker. The output for the external accessory and the headset is single
ended with a dedicated signal ground SGND. Input and output signal source selection
and gain control is performed inside the COBBA–GJP asic according to control messages
from the MAD2. Keypad tones, DTMF, and other audio tones are generated and encoded
by the MAD2 and transmitted to the COBBA–GJP for decoding.

Internal Microphone and Earpiece

The baseband supports three microphone inputs and two earphone outputs. The inputs
can be taken from an internal microphone, a headset microphone, or from an external
microphone signal source. The microphone signals from different sources are connected
to separate inputs to the COBBA_GJP asic. Inputs for the microphone signals are of a dif-
ferential type.
Issue 1 03/01
COBBA
Multipl.
Pre
& LP
Amp
Multipl.
LP

Figure 12: Audio Control

Nokia Mobile Phones Ltd.
MAD
DSP MCU
A
D
D
A
NSB-5
System Module
Buzzer
Driver
Circuit
Buzzer
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