| 摘要 |
<p>PROBLEM TO BE SOLVED: To record pilot signals with specific regularity on a video tape based on an encipher signal and to keep the recorded information secret through a simple constitution. SOLUTION: An enciphering signal is synchronized with an RFSW through a flip-flop circuit 32 and delivered, as a control signal, to a switch SW4. According to the control signal, the switch SW4 selects a pulse having polarity inverted through the RFSW or an inverter 34. Output from the switch SW4 is delivered, as a control signal CS3, to a switch SW3. On the other hand, a switch SW2 is provided with a control signal CS2 obtained by subjecting the RFSW to÷2 frequency division. When the switches SW2 and SW3 are controlled, subtractors 24a, 24b are fed with frequency signals fa, fb at a predetermined timing and a track, including pilot signals Pa, Pb, is formed on a video tape based on the frequency signals fa, fb.</p> |
