To determine a burst frequency in a short time by decreasing a time necessary for deciding whether an APC circuit is locked or unlocked, when determining the burst frequency in a burst frequency determination circuit.
In a video signal processing circuit for entirely processing video signals of the broadcast systems including SECAM, PAL and NTSC, an FM demodulation circuit 200 for demodulating a SECAM signal is commonly used to the portion of the burst frequency determination circuit. After the frequency components of an input video signal are demodulated in the above FM demodulation circuit 200, only a burst signal component is extracted in a burst extraction circuit 14. The extracted demodulation signal is then integrated in an integration circuit 16, and thereafter, compared with a predetermined value 15 in a comparator 19, and depending on the magnitude, the burst frequency is determined. Accordingly, the burst frequency can be determined instantly, and the circuit scale can be reduced through the above common use to the FM demodulation circuit.
MIYOSHI TOSHIHIRO
Hiroshi Koyama
Hiroshi Takeuchi
Takahisa Shimada
Yuji Takeuchi
Katsumi Imae
Atsushi Fujita
Kazunari Ninomiya
Tomoo Harada
Iseki Katsumori