About PAL Receiver:* - The block diagram of Pal Decoder is shown in figure. The modulated signal is applied at its input and the primary colour signals R, G and B are obtained at its output. These signals are applied to the colour picture tube to reproduce the coloured picture. - The Pal Decoder is similar to the NTSC decoder with an additional 64 µsec delay line and an electronic switch operated by a color burst which is separated from the received signal. - Electronic switch will reverse the phase of subcarriers applied to the V detector on every alternating line. The modulated signal received at the input is passed through a video detector which modulates it to obtain the composite colour video signal. - The luminance signal ‘Y’ is applied to the Y amplifier which is a wideband video amplifier with a bandwidth of 5 MHz. It is further passed through a delay Network and applied to the RGB matrix. - The colours sub-carrier and its sidebands are separated by using 3-5 MHz amplifier. This amplifier will allow only colour burst signal and the chroma signal to pass through it. The signal is applied to the subcarrier generator to generate the phase synchronous color sub-carrier.

• The colour burst is also applied to the line sync. identification circuit the output of which controls the phase reverse switch the identification signal derived from the colour burst is needed to synchronize the phase reversal switch.
• The Chroma signal is applied to 64 µsec delay line the output of which produces a delayed Chroma signal by one H-line period.
• The direct and delayed chroma signals are combined in an add and subtract network is also called as delay line matrix, and the output of adder and subtractor are applied to the U and V detectors respectively.
• The regenerated CSC is applied directly to the U detector produce U signal. The subtractor output and phase alternating CSC is applied to the V detector obtained V signal.
• The detected U and V signals are applied to a resistive matrix to produce the (R-Y), (B-Y) and (G-Y) signal which are applied to RGB matrix alongwith luminance signal ‘Y’ to produce R, G and B signals.

Advantages :

-The phase error causing error in reproduction of colour is eliminated

-Bandwidth of U & V is same .This simplifies filtering action

-Studio mixing is easy as compared to SECAM

-Use of delay lines before demodulators isolates U and V signal s from each other reduces crosstalk type of interference in colours better than NTSC-results in better picture quality

Disadvantages:

-Electronic circuit and Ident signals are necessary in PAL which makes the design complex

-Delay line technique reduces vertical resolution of chroma signal