GE864-AUTO Hardware User Guide
1vv0300779 Rev.0 - 20/06/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 37 of 62
9 Audio Section Overview
The Base Band Chip of the GE864-AUTO Telit Module provides two different audio blocks; both in
transmit (
Uplink
) and in receive (
Downlink
) direction:
“
MT lines
” should be used for handset function,
“
HF lines
” is suited for hands -free function (car kit).
These two blocks can be active only one at a time, selectable by
AXE
hardware line or by AT
command.The audio characteristics are equivalent in transmit blocks, but are different in the receive
ones and this should be kept in mind when designing.
G
E
86
3-
G
P
S
A
ud
io
P
at
hs
D
iff
er
en
tia
l
Li
ne
-O
ut
D
riv
er
s
Fu
lly
D
iff
er
en
tia
l
P
ow
er
B
uf
fe
rs
EXTERNAL
AMPLIFIER
-1
2d
B
FS
1
6
8
16
+1
0d
B
-4
5d
B
V
/P
a
M
ic
_H
F-
E
ar
_H
F-
B
al
an
ce
d
S
in
gl
e
en
de
d
M
ic
_H
F+
E
ar
_H
F+
50
cm
23
m
V
rm
s
0,33mV rms
au
di
o2
.s
kd
G
M
86
3-
G
P
S
+2
0d
B
7c
m
-4
5d
B
V
/P
a
3,3mVrms
36
5m
V
rm
s
M
ic
_M
T+
E
ar
_M
T+
M
ic
_M
T-
E
ar
_M
T-
