6871620L01-C
May 28, 2008
VOCON Section
3-27
3.2.5.2 Receive Audio Path
. The receive audio data comes from the Abacus III IC (DOUTA) to the dual-core
processor SRDB pin. The DSP decodes the data and sends it out through the CODEC_RX line to
the MAKO IC VC_RX pin. The CODEC filters, adds digital programmable gain G1, then converts the
digital data into an analog audio signal, which in turn is sent to programmable attenuator G3. The
signal is then sent through an internal programmable differential preamplifier (G4). The preamplifier
outputs are on pins VC_OUT_P and VC_OUT_M of the MAKO IC.
This output from the preamp is first filtered through the circuitries R1326, R1327, C1355, C1356 and
C1357, and then sent back to two independent internal BTL differential power amplifiers, G5 & G6, of
the MAKO IC. The power amplifiers are programmed to a fixed gain through the dual-core processor
SPI lines and PA control registers.
The dual-core processor selects whether the amplified audio is routed to the internal speaker or the
external speaker through the SPI lines based upon which amplifier is turned on as shown in the PA
control block. The output audio is routed on MAKO IC pins INT_SPKR_P and INT_SPKR_M for
internal and EXT_SPKR_P and EXT_SPKR_M for external speaker lines. The external audio is then
routed to an audio switch (U20) where it switches the audio between the flip earpiece and the audio
jack earpiece. The logic behind the audio routing is set by the Patriot IC (depending on the user's
operating mode).
Figure 3-11. VOCON Receive Audio Path
ABACUS III
Patriot SAP / BBP
Patriot SPIB
Digital
LPF = 3.4 kHz
CODEC
16-Bit
D/A
G1 Digital Gain
= 0 or 1 dB
G3
Attenuator
= -52 to 0 dB
G4
Preamp =
0 to 10 dB
HP & LP
Filter = 22kHz,
200 Hz
Internal Speaker
PA Control
G5
EXT PA
G6
INT PA
Audio Switch
Earpiece
Audio Jack
RX_SSI_FSYNC
RX_SSI_CLK
RX_DATA
CODEC_RX
CODEC_FSYNC
CODEC_DCLK
MAKO_CS
SPI_MISOB
SPI_MOSIB
SCKB
VC_OUT_P
VC_OUT_M
MAKO IC
PA_IN_M
PA_IN_P
3
3
4
Summary of Contents for ASTRO XTSTM 4000
Page 1: ...COLOR CHORDS 7 ASTRO XTSTM 4000 Portable Radio Detailed Service Manual ...
Page 2: ......
Page 16: ...May 28 2008 6871620L01 C xiv Commercial Warranty Notes ...
Page 22: ...May 28 2008 6871620L01 C 1 6 Introduction Notes ...
Page 26: ...May 28 2008 6871620L01 C 2 4 Radio Power Notes ...
Page 56: ...May 28 2008 6871620L01 C 3 30 Theory of Operation Notes ...
Page 100: ...May 28 2008 6871620L01 C 6 8 Troubleshooting Waveforms Notes ...
Page 194: ...May 28 2008 6871620L01 C B 2 Motorola Service Centers Notes ...
Page 204: ...May 28 2008 6871620L01 C Glossary 10 Glossary Notes ...
Page 209: ......