Samsung SV-DVD40, Training Manual

Page: 108 / 189

Circuit Operating Descriptions
7-33
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.
Fig. 7-30 Tuner/demodulator Block Diagram
11 3 5 12
21 23 24
ANT INPUT
(MODULATOR SECTION) (TUNER SECTION) (IF SECTION)
ANT OUT
Off
through
SW
RF Carrier
OSC
VHF
RF AMP
UHF
RF AMP UHF
Mixer VHF
OSC FM
Detector SIF
Filter
UHF
OSC PLL
IC
AGC
AFT
Mixer
IC SAW
Filter IF
AMP Video
Detector
Video
Modulator
FM Modulator
TV SET
AUDIO IN VIDEO IN SCL SDA AUDIO OUT
AFT OUT
VIDEO OUT
2
6
7-7 TM
(1) Outline