| 摘要 |
<p>PURPOSE: To monitor the signals received from a cable converter unit by a VCR and to confirm the fact that the instructions transmitted to the unit from the VCR are executed. CONSTITUTION: A control device 110 detects the signal level fluctuation, which shows the fact that a cable box changed the channel, by monitoring IFAGC signals on a conductor 131. In order words, for example, the output signals of the cable box, which are remodulated against the RF carrier frequency of a channel 3, are temporarily lost during the period in which the cable box changes the channel and the judgment is made whether the channel is changed or not. Moreover, the effective synchronization detection signals on a conductor 151 or other signals such as video AGC signals are also monitored and the information, which tells whether the commands transmitted to the cable box are actually received and executed or not, is also supplied.</p> |
