Motorola SSETM 5000 - Manual (Page 55)

6881094C12-A November 11, 2004
Theory of Operation: VOCON Board 2-33
Figure 2-11. VOCON Transmit Audio Path
2.5.5.2 Receive Audio Path
Refer to Figure 2-12 . The receive audio data comes from the Abacus III IC U500 through the RF
interface connector P201 pin 12 (RX_DATA) to the dual-core processor SRDB pin. The DSP
decodes the data and sends it out through the CODEC_RX line to the GCAP II IC RX pin. The
CODEC filters and converts the digital data into an analog audio signal, which, in turn, is sent to a
programmable gain amplifier. The dual-core processor programs a multiplexer to route the audio
signal to the A4 amplifier, which has a fixed gain of 3.5 dB. The output of the A4 amplifier is pin
EXTOUT.
From the EXTOUT pin, the audio signal goes through the pre-amplifier U502 and then to the audio
power amplifier U503, which together provide approximately 30 dB of gain. The dual-core processor
selects whether the amplified audio is routed to the internal speaker or the external speaker.
TP214
INTERNAL MIC
Bias (R531,
R533, C519, C521)
and Input
(R540, C522)
EXTERNAL MIC
Bias (R563,
R565, C547, C548)
and Input
(R566, C549)
GCAP II IC U501
EEPOT U509
0 - 50K, 256 taps
MIC PREAMP
A3
Gain =
-14dB to 16dB
MIC PREAMP
A5
Gain =
-14dB to 16dB
EEPOT U509
0 - 50K, 256 taps
MUX
PGA
-7 to +8dB
in 1dB steps
Set at 6dB
CODEC A/D
13-bit
HP FILTER
cutoff = 200HZ
LP FILTER
cutoff = 3.5KHZ
Patriot GPIO
PB4, PB5,
PB6, PB7
Patriot SPIB Patriot SAP/BBP
Flipper
U301
RF D/A
U203
(On RF Board)
TX_SSI_FSYNC
TX_SSI_CLK
TX_DATA
CODEC_FSYNC
CODEC_DCLK
CODEC_TX GCAP_CE, SCKB
SPI_MISOB
SPI_MOSIB
AUX_OUT
R561
MIC_OUT
R555
4
EEPOT_CS_EXT*
EEPOT_CS*
EEPOT_U_D*
EEPOT_INC*
4
3
MICIN
_NEG
AUX_MIC
_NEG
MAEPF-27418-A