User's Guide

HE863 Family Hardware User Guide
1vv0300891 Rev.5
- 2011-03-18
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights
Reserved. Page 66 of 89
11. Audio Section (HE863-EUR/EUG/NAR/NAG/AUG only)
The Baseband chip 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 while the other couple of amplifiers had to be
used with external audio transducers.
To distinguish the schematic signals and the Software
identifiers, two different definitions were introduced, with
the following meaning:
 internal audio transducers  HS/MT differential/Single
ended type (from HandSet or MicroTelephone )
 external audio transducers  HF only single-ended output
type (from HandsFree )
Actually the acronyms have not the original importance.
In other words this distinction is not necessary, being the
performances between the two blocks like the same.
Only if the customer needs higher output power to the speaker,
he has a constraint. Otherwise the choice could be done in
order to overcome the PCB design difficulties.
For these reasons we have not changed the HS and HF acronyms,
keeping them in the Software and on the schematics.
11.1. Selection mode
Only one block can be active at a time, and the activation of
the requested audio path is done via hardware by AXE line or
via software by AT#CAP command.
Moreover the Sidetone functionality could be implemented by
the amplifier fitted between the transmit path and the receive
path, enabled at request in both modes.