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This function is realised in the YUV domain by detecting the colours near to the skin tone. n Scan-Velocity modulation output. Also the SVM function can be activated for all incoming CVBS, Y/C and RGB/YPrPb signals. The delay between the RGB output signals and the SVM output signal can be adjusted (by means of the SVM2-SVM0 bits in subaddress 48H) so that an optimum picture performance can be obtained. Furthermore a coring function can be activated. It is possible to generate Scan Velocity Modulation drive signals during the display of ‘full screen’ teletext (not in mixed mode). Another feature is that the SVM output signal can be made dependent on the horizontal position on the screen (parabola on the SVM output). 5.2.9 Colour decoder The ICs decode PAL, NTSC and SECAM signals. The PAL/NTSC decoder does not need external reference crystals but has an internal clock generator which is stabilised to the required frequency by using the clock signal from the reference oscillator of the TCG u -Controller. Under bad-signal conditions (e.g. VCR-playback n feature mode), it may occur that the colour killer is activated although the colour PLL is still in lock. When this killing action is not wanted it is possible to overrule the colour killer by forcing the colour decoder to the required standard and to activate the FCO-bit (Forced Colour On) in subaddress3CH. The sensitivity of the colour decoder for PAL and NTSC can be increased by means of the setting of the CHSE1/CHSE0 bits in subaddress 3CH. The Automatic Colour Limiting (ACL) circuit (switchable via the ACL bit in subaddress 3BH) prevents that oversaturation occurs when signals with a high chroma-to-burst ratio are received. The ACL circuit is designed such that it only reduces the chroma signal and not the burst signal. This has the advantage that the colour sensitivity is not affected by this function. DTV R&D Europe CP-520/520A/520F Service Manual The SECAM decoder contains an auto-calibrating PLL demodulator which has two references, viz: the divided reference frequency (obtained from the-Controller) which is used to tune the PLL to the desired free-running frequency and the bandgap reference to obtain the correct absolute value of the output signal. The VCO of the PLL is calibrated during each vertical blanking period, when the IC is in search or SECAM mode. The frequency offset of the B-Y demodulator can be reduced by means of the SBO1/SBO0 bits in subaddress 3CH. The base-band delay line is integrated. In devices without CVBS comb filter this delay line is also active during NTSC to obtain a good suppression of cross colour effects. The demodulated colour difference signals are internally supplied to the delay line. The baseband comb filter can be switched off by means of the BPS bit (subaddress 3CH). The subcarrier output is combined with a 3-level output switch (0 V, 2.1 V and 4.5 V). The output level and the availability of the subcarrier signal is c...

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