| 摘要 |
The PAL switch phase correction circuit for a colour television receiver, has a phase comparator comparing the input and output of the delay line leading to the PAL demodulator for obtaining the U and V signals. The input passes over a switch operated by line flyback pulses to the comparator. The output of the delay line passes over a second switch (15) and a 90 phase shifter (9) to the comparator. The second switch is controlled by pulses at the control input of the PAL switch, i.e. it is closed during every second line. The output of the comparator passes through a filter to the control input of a generator (11), synchronised with the line flyback pulses and controlling the PAL switch. |
