| 摘要 |
PURPOSE:To shorten the time required for complete distribution to all subscriber terminals at the opportunity of one time distribution by designating different subscriber terminals by respective channels at the same time to distribute key data to subscriber terminals. CONSTITUTION:Each of scramble encoders 21, 22...2n inserts an ID specifying an indicated subscriber terminal to the ID part of transmission data and inserts data indicating the distribution mode to the control command part and inserts key data to the data part to form transmission data and inserts it to the vertical blanking period of a video signal. Key data is transmitted to each subscriber terminal in this manner. In this case, n-number of subscriber terminals related to key data transmitted with respective channels at the same time are different from one another. Thus, key data to each subscriber terminal required for descrambling is surely transmitted as quickly as possible. |
