Technicolor - Thomson ICC19, Принципы и обслуживание

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IV601, TDA9143
This is a specialised processor that handles video processing from a CVBS or
Y/C signal. It is fully controlled via a IIC bus, and has its own internal filters.
It requires no adjustment.
RECOGNITION OF STANDARD
The circuit performs automatic digital recognition of standards from bursts.
Two oscillator crystals (4.43 MHz and 3.58 MHz) are used for this purpose.
Y CHANNEL PROCESSING
According to the standard recognised, the circuit switches the appropriate
traps, or allows the signal to pass through in the event of SVHS recognition.
A 60-ns delay line internal to the circuit performs delay compensation.
CHROMINANCE CHANNEL PROCESSING
The internal band pass (for PAL/NTSC) or bell (for SECAM) filters operate
according to the standard recognised. The resonance frequency of the bell,
4.28 MHz, is controlled via a circuit using the 4.43-MHz oscillator during the
frame flyback.
PAL/NTSC demodulation requires an oscillator that works with one of the
external oscillator crystals. The SECAM decoder is a self-calibrated PLL
demodulator (Pin 29) whose VCO is adjusted during frame flyback.
Demodulation is completed via a 64-µs CCD delay line, IV602 (TDA4665).
This circuit is controlled by the SC signal from Output 10 of IV601.
MATRIXING AND SWITCHING OF EXTERNAL RGB SIGNALS
RGBs from a SCART source are matrixed so that they can be digitally
processed in the same way as CVBS or Y/C signals. External command
FBAV1 enables the acceptance of these SCART RGBs.
SYNCHRONISATION PROCESSING
A second PLL control loop (Pin 24) delivers the line synchronisation (HA) and
frame synchronisation (VA) signals via a time base and based on
synchronisation separation and frame sorting.
The VCO operates at 6.875 MHz = 440 x 15625 Hz.
This loop is connected via Bus IIC. Its time constant can therefore be software-
modified according to the noise level in the incident signal. When the signal is
too noisy or non-existent, the system operates in an open loop and produces a
stable frequency.
CENTRE DE
FORMATION TECHNIQUE
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