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GC868-DUAL EVK2 User Guide
1vv0300803 Rev.1- May 2009
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 20
of 55
8
Audio Section
8.1 Overview
The BaseBand chip of our modules provides two audio paths both in receive and in transmit
sections, which could be active only one at time.
To turn on your well-suited section on EVK2, please refer to “
AF Amplifiers Setting
“paragraph
and followings.
To know which are the suggested performances of the EVK2 audio transducers, refer to
“
Audio Accessories
“paragraph.
8.1.1 History
The Baseband chip of our modules was developed for the cellular phones, which needed two
separated amplifiers both in RX and in TX section. A couple of amplifiers had to be used with
internal audio transducers (
Handset mode,
HS
) while the other couple of amplifiers must be used
with external audio transducers (
Handsfree mode,
HF
).
8.1.1.1 Transducers definitions
Headsets
are transducers that receive an electrical signal from a receiver and use speakers
placed in close proximity to the ears to convert the signal into audible sound waves.
In the context of telecommunication, the word
Headset
is also commonly understood to refer
to a combination of
Headphone
and Microphone used for two-way communication, like with a
mobile phone.
Earphones
are small Headphones that are placed directly outside of the ear canal, but without
fully enveloping it. They are generally inexpensive and are favored for their portability and
convenience.
Earpiece
A part whether of a telephone receiver or hearing aid, that fits in or is held next to the ear.
8.1.2 Actual
The
HS
and
HF
definitions have been kept in the Software and on the schematics of theTelit
modules. But with EVK2 we will refer to
Audio1
or
Audio2
section instead of
Handset
and
Handsfree
respectively, remembering that:
•
they can have fully equivalent electrical performances (
like the two microphone amplifiers
)
•
they can activate the same functionalities (
like the Echo Canceller module
)
•
they can offer slightly different performances (
like the two speaker buffering stages)