| 摘要 |
<p>PROBLEM TO BE SOLVED: To extract WST(word system teletext) data inserted into a vertical synchronization period of PAL. SOLUTION: A WST detecting circuit 16 is provided with a timing oscillator 31 and a sampling rate converter 32, and extracts the WST data using a WST data clock and an asynchronous system clock. Also, in the circuit 16, a sampling timing is set at a frequency two times the WST data clock (horizontal synchronization frequency fH×888) to sample a piece of WST data twice at positions with different phases. The data is alternately apportioned for each sampling at time division to generate two pieces of WST data, and one WST data with higher reliability is outputted.</p> |
