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3 - 3
-VIDEO AM-DEMODULATION- (except for USA version)
The 2nd IF signal divide at the splitter is amplifi ed and fi ltered, then converted into the 3rd IF (video IF) signal at 3rd mixer (IC2201).
The converted video IF signal is amplifi ed, then passed through the video IF fi lters. The fi ltered video IF signal is applied to the
video demodulation IC and AM-demodulated.
The demodulated video signals are passed through Band Eliminate Filter (BEF; as the trap) to remove unwanted beat
components. The fi ltered signal is buffer-amplifi ed and output from the video jack on the CONNECT-B UNIT.
3-2 FREQUENCY SYNTHESIZER
OSC UNIT
The OSC UNIT supplies very high stability 10.000000 MHz
standard frequency signal generated by the OCXO (Oven
Controlled X’tal Oscillator). The oscillated reference
frequency signal is buffer-amplifi ed and amplifi ed and fi ltered
to remove harmonic components at the LPF. The filtered
reference frequency signal is applied to the PLL UNIT via
the buffer.
The reference frequency signal is also available from the
external reference frequency source (10.000000 MHz)
via [REF I/O] (CONNECT-B UNIT; J201). The reference
frequency signal from the CONNECT-B UNIT is passed
through the attenuators, BPF and switches, then buffer-
amplifi ed before being applied to the PLL UNIT.
BPF
ATT
IF
AMP
Q1
IC101
IC2201
SPM5001
IC201/IC203
IC202/IC204
BUFF
Q2
ATT
ATT
IF
AMP
Q2101
BPF
BPF
BUFF
Q301
IF
AMP
Q2181
BPF
BPF
VIDEO
48MHz
AGC
TPSCC4.5MB
TPSCC5.5MB
TPSCC6.0MB
TR4_5M
TR5_5M
TR6_0M
-10dBm
TR4_5M
TR5_5M
TR6_0M
TR6_5M
TR6_5M
TPSCC6.5MB
SW
FILTER
FILTER
SW
TRAP
TRAP
TRAP
TRAP
DETECT
2nd IF signal
from the RF-A UNIT
2nd LO signal
from the PLL UNIT
Composit video signal
to the J601 (CONNECT-B UNIT)
• VIDEO AM-DEMODULATION CIRCUIT
BPF
ATT
BUFF
Q70
LPF
BUFF
2SC4081
Q21
AMP
Q61/Q62
AMP
Q22
X1
AMP
Q42
LPF
EXT-REF OUT
(10.000000MHz OCXO)
EXT-REF IN
10MHz
10MHz
10MHz
• OSC CIRCUITS
From [REF I/O] (CONNECT-B; J201)
10.000.000 MHz
Standard signal
FIL
LOOP
IC1001
Q1201
BUFF
Q1102
ATT
ATT
AMP
IC1351
BUFF
Q1202
Q1101
ATT
BUFF
Q1302
ATT
Q1301
AMP
IC1300
PLL
IC
IC1000
Ref 500kHz
514.35~639.35MHz
317.8~391.3MHz
389.35~521.3MHz
10.5MHz
LH1V
LH2V
LH3V
DATA
CK
PST1P
6dB
HYB
317.8~639.35MHz
317.8~639.35MHz
VCO-C
VCO-B
VCO-A
To FIL1 BOARD
1st LO signals
to RF-A UNIT
VCO1 BOARD
• VCO-A, VCO-B, VCO-C LOOP
PLL UNIT
PLL UNIT supplies the LO (Local Oscillator) signals
(1st, 2nd, 3rd and 4th), still more the clock signals for
DSP circuits. To obtain physical strength for the VCO1,
VCO2, DOUBLER, FIL1 and FIL2 BOARDs, these circuits
are shielded and isolated perfectly, by being patterned
separately on different P.C. boards.
VCO1 BOARD
VCO1 BOARD has tree VCOs ;VCO-A, VCO-B and VCO-C.
VCO-A (Q1301), as an example, is a colpitts-typed oscillator
circuit, and its output signal is buffered by Q1302 and output
via diode switch. Q1303 controls the power supply for the
VCO, and the voltage of LH3V line adjusts the oscillation
level for suitable LO signal level.
The buffer-amplifi ed VCO output signals are divided by the
divider, and applied to the LO amplifier via attenuator (as
a pad). The amplified LO signals are applied to the RF-A
UNIT or FIL1 BOARD as the 1st LO signals, via fi lters and
amplifi ers.
The VCO-A is mounted on the nearest to VCO1 board to
reduce the signal loss. The resonators are employed strip
lines which had been used with SMD electric parts. The
oscillating frequency ranges are divide into three for wide
oscillation frequency coverage.