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Accessories
Microphone Amplifier
The Microphone Amplifier has got two individual inputs for the two types of micro-
phones being available:
• Stick-On microphone (standard)
• Goose-Neck microphone (optional)
The microphone signal passes through two amplifier stages which results in a total
gain of 31dB and 21dB for the Stick-On and Goose-Neck microphone resp.
Speaker Amplifier
The AFMS (audio-from-mobile-station) signal received from the phone is amplified
by a programmable gain amplifier and fed to a differential amplifier consisting of
four power transistors resulting in a total gain of 21dB. To protect the power transis-
tors and the speaker against high current, a feed back signal from the power transis-
tors to the programmable amp will allow only short peaks of high current to get
through but reduce continuous high current to approximately 1.2A corresponding to
just about 5W output power.
Modem/Handset Option
The Data Communication connector can be utilised for connection of two different
options:
• analog PCMCIA modem
• external handset
When any of these devices is connected the audio signal ATMS (Audio-To-Mobile-
Station) is switched to this connector, while AFMS (audio-from-mobile-station)
always is available.
Note: A Data Extension Unit is required for the connection between the optional
unit and the Data Communication connector.
Audio Switch Control
The Audio Multiplexer Control is used to switch the audio paths between the exter-
nal microphone and the modem/handset connector.
Control signals such as EXTAUD (external audio control) and MUTEINV (inverted
mute) are derived from logical gates controlled by the signals PORTHF (portable
handsfree), DV (data/voice), and HOOKSNS (hook sense).
External Audio Control
The EXTAUD (external audio control) signal informs the phone when an accessory
which is using the two external audio signals AFMS and ATMS has been connected
to the HandsFree Unit
Music Mute Control
An optional Music Mute unit can be supplied with +12V from the vehicle battery.
The Music Mute function is controlled from the phone by the MUTE signal which is
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