Samsung DVD-V940K Training Manual page 91

7-7 TM
(1) Outline
RF and frequency synthesized tuning system
General description : The receiving circuit consists of both ANT input and output circuits, channel selection cir-
cuit, PIF circuit and SIF circuit. The receiving circuit selects a desired broadcast signal from TV signals induced on
an antenna and sends stable video and audio signals to their respective processing circuits. The output signals
from the video and audio circuits are converted into a conventional TV signal modulated for channel 3 or channel
4 by an RF modulator so that the signal can be received by conventional TV receivers.
(2) Tuner modulator block
As explained, this model is designed in one package to contain a RF MODULATOR BLOCK, TUNER BLOCK
AND IF DEMODULATOR BLOCK. Its size is greatly reduced and other noise interference can be minimized to
make performance high.
ANT INPUT
Off
through
SW
ANT OUT
TV SET
(MODULATOR SECTION)
RF Carrier
OSC
Video
Modulator
FM Modulator
2
AUDIO IN VIDEO IN
Fig. 7-30 Tuner/demodulator Block Diagram
(TUNER SECTION)
VHF Mixer
RF AMP IC
UHF UHF
RF AMP Mixer
UHF
OSC
6
5 11 3
SCL SDA
Circuit Operating Descriptions
(IF SECTION)
SAW IF
Filter AMP
VHF FM
OSC Detector
AFT
PLL
IC
AGC
12 21 23
AUDIO OUT
AFT OUT
Video
Detector
SIF
Filter
24
VIDEO OUT
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