May 28, 2008
6871620L01-C
3-26
VOCON Section
3.2.5.1 Transmit Audio Path
The single-ended internal microphone audio enters the VOCON section through the 30 pin
connector (J2), and the internal microphone bias is set by circuitry that includes R1324, R1325,
C1349, C1350 and C1351. The internal microphone signal is connected to the INT_MIC_P pin,
which is the input terminal on the MAKO IC internal op-amp G1 after the signal is multiplexed. The
gain is programmed by the dual-core processor via SPI lines.
The external microphone audio enters the VOCON section through the 30 pin connector J2 as well
and the external microphone bias is set by circuitry that includes R1322, R1323, C1346, C1347 and
C1348. The external microphone signal is connected to the EXT_MIC_P pin, which is an input
terminal on the MAKO IC internal op-amp G1 after the signal is multiplexed. The gain is programmed
by dual-core processor via SPI lines.
The dual-core processor, through the SPI bus, programs a multiplexer internal to the MAKO IC to
select one of the microphone signals. Then, the selected microphone signal goes through the G1
pre-amplifier stage and on to a programmable gain amplifier (G2) before it goes to the CODEC for A/
D conversion. The resulting digital data is filtered and sent to the DSP on the CODEC_TX line from
the MAKO IC VC_TX3V pin. After additional filtering and processing, the DSP sends the data out
from the STDB pin, labeled TX_SSI_DATA to the RF transceiver section.
Figure 3-10. VOCON Transmit Audio Path
INTERNAL MIC BIAS
R1324, R1325, C1349,
C1360, C1351
EXTERNAL MIC BIAS
R1322, R1323, C1346,
C1347, C1348
MUX
Pre-amp
G1 Gain = 15 dB
Amp G2
Gain = -30 to 0 dB
CODEC
A/D 16-Bit
HPF = 200 Hz
& LPF = 3.4 kHz cutoff
RF D/A
U201
Patriot
SAP / BBP
Patriot
SPIB
INT_MIC_P
EXT_MIC_P
CODEC_TX
CODEC_FSYNC
CODEC_DCLK
3
TX_SSI_FSYNC
TX_SSI_CLK
TX_DATA
MAKO_CS
SPI_MISOB
SPI_MOSIB
SCKB
4
MAKO IC
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: ......