Circuit Description; Small Signal Part; Tuner And If Output Tuner; Vision If - Panasonic Z-421V Technical Manual

1 Circuit Description

1.1 Small signal part

1.1.1 Tuner and IF output Tuner:

Type TV standard
DT5-BF15P
(DAEWOO)
The RF tuner selects the picture and sound signals of the desired station by converting the RF signal
into the Intermediate Frequency (IF) of the receiver.
The common UHF/VHF input is realized by an aerial connector (75Ω) (DIN IEC jack). The IF output is
balanced (75Ω). The tuning mode is voltage synthesis.
IF output and SAW filter
The high gain tuner, balanced output can be connected directly to tile SAW filter input.
The surface Acoustic Wave filters are based on the interference of mechanical surface waves.
TV standard
Picture carrier 38.9 MHz
Color carrier 34.47 MHz
Sound carrier 33.4 MHz

1.1.2 Vision IF

See also the related block diagram as well as the diagrams at the end of the report.
The main functions are:
* IF amplifier
* PLL-demodulator and alignment free VCO
* Video buffer
* AFC
* AGC
* Tuner AGC
* Video identification
These functions will be described next in this section.
The TDA884X includes an integrated vision-IF. This gives advantages compared to a stand alone IC
for vision-IF only. Some advantages are:
Π2
I C bus commands are available for many control functions and alignment. This saves a pins and
external components.
Œ
Optimal performance is achieved by means of timing/gating signals derived from the
synchronization part.
Œ
Build-in accuracy of circuits is derived by use of the available chroma crystal oscillator.
PIF
B/G 38.9 MHz
L/L' 38.9 MHz
I 38.9 MHz
B/G
38.9 MHz
34.47 MHz
33.4 MHz
Channel coverage
VHF_L : CH E2 -- CH S7
VHF_H : CH S8 -- CH S36
UHF : CH S37 -- CH E69
L/L'
38.9 MHz
34.47 MHz
33.4 MHz
3
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