CXA2094Q
Description of Operation
The US audio multiplexing system possesses the base band spectrum shown in Fig. 1.
PEAK DEV
AM-DSB-SC
kHz
50
50
L-R
dbx-TV
NR
25
5
25
15
SAP
dbx-TV NR
FM 10kHz
50 – 10kHz
TELEMETRY
FM 3kHz
L + R
50 – 15kHz
3
f
fH
2fH
3fH
4fH
5fH
6fH
6.5fH
fH = 15.734kHz
Fig. 1. Base band spectrum
2
I C BUS
2fHL0°
fHL90°
fHL0°
DECODER
PLL
(VCO 8fH)
PILOT
MODE
DET
CONTROL
STEREO LPF
MAIN LPF DE.EM
(MAIN OUT)
(COMPIN)
12
(MAIN IN)
PILOT
CANCEL
4
3
MVCA
4.7µ
L + R
WIDEBAND
SUB LPF
(SUBOUT)
22
(ST IN)
23
MATRIX
L-R (DSB)
DET
SUBVCA
(Lch)
4.7µ
L – R
to
TVSW
NR SW
(Rch)
A
B
SAP(FM)
DET
dbx-TV
BLOCK
SAP BPF
SAP LPF
(SAP OUT)
25
(SAP IN)
27
(TVOUT-S)
40
INJ.
LOCK
4.7µ
I2C BUS
DECODER
NOISE
DET
MODE
CONTROL
LPF
I2C BUS
DECODER
MODE
CONTROL
(SOUT) (ESAPIN)
38
SAP
DET
39
4.7µ
Fig. 2. Overall block diagram (See Fig. 3 for the dbx-TV block)
FIXED
DEEMPHASIS
(ST IN)
23
VARIABLE
DEEMPHASIS
NR SW
(VE OUT) (VCA IN)
A
B
to
MATRIX
VCA
35
34
(SAP IN)
27
4.7µ
HPF
LPF
RMS
DET
LPF
RMS
DET
Fig 3. dbx-TV block
– 16 –
SONY [ SONY CORPORATION ]
