| 摘要 |
PURPOSE:To obtain a synchronizing signal having optional pulse width, by phase modulation without changing the frequency in a 1/2 horizontal synchronizing period, counting the signal at a counter means and obtaining a synchronizing signal. CONSTITUTION:An oscillating circuit 1 is oscillated in a frequency 4 times the frequency of a subcarrier. An output of the oscillating circuit 1 is inputted to an address counter 2, and 455 pulses corresponding to the period of the 1/2 horizontal synchronizing period are counted. A decoder circuit 3 decodes an output of the address counter 2 and generates a modulating clock. A sync counter circuit 4 counts the modulating clock from the decoder circuit 3 and outputs each synchronizing signal required for a television signal. In using a PROM in the decoder circuit 3, the pulse width of each synchronizing signal is decided optionally according to the contents of program. |
