CXA1734S
Description of Operation
The US audio multiplexing system possesses the base band spectrum shown in Fig. 1.
PEAK DEV
kHz
50
AM-DSB-SC
50
L-R
dbx-TV
NR
25
5
25
15
L+R
50-15kHz
SAP
dbx-TV NR
FM 10kHz
50-10kHz
TELEMETRY
FM 3kHz
3
f
fH
2fH
3fH
4fH
5fH
6fH
6.5fH
fH=15.734kHz
Fig. 1. Base band spectrum
I2C BUS
DECODER
MODE
2fHL0°
PLL
PILOT
DET
fHL90°
fHL0°
(VCO 8fH)
CONTROL
STEREO LPF
MAIN LPF DE.EM
(MAIN OUT)
(MAIN IN)
(COMPIN)
11
PILOT
7
8
MVCA
CANCEL
4.7µ
L+R
WIDEBAND
SUB LPF
(ST IN)
(SUBOUT)
MATRIX
L-R (DSB)
DET
(L-OUT)
29
SUBVCA
13
4.7µ
L-R
14
NR SW
(R-OUT)
28
A
B
SAP(FM)
dbx-TV
BLOCK
DET
INJ.
SAP BPF
SAP LPF
(SAP OUT)
18
LOCK
(SAP IN)
19
NOISE
DET
I2C BUS
DECODER
4.7µ
MODE
CONTROL
I2C BUS
DECODER
MODE
SAP
DET
CONTROL
Fig. 2. Overall block diagram (See Fig. 3 for the dbx-TV block)
FIXED
VARIABLE
NR SW
DEEMPHASIS
DEEMPHASIS
14
(VE OUT) (VCA IN)
A
B
23
24
TO
VCA
MATRIX
4.7µ
19
HPF
LPF
RMS
DET
LPF
RMS
DET
Fig. 3. dbx-TV block
—17—
SONY [ SONY CORPORATION ]
