| 摘要 |
PURPOSE:To form a satellie communication channel controlling system to enable even an unskilled operator to transmit desired information easily and correctly by using a dead satellite channel. CONSTITUTION:Earth station supervisory and controlling equipment 18 sets the frequency of a selected channel to a receiving frequency converting device 13. A TV DEM 14 demodulates the inputted received signal of the selected channel, and on the other hand, it measures its carrier power to noise power ratio (C/N). On the basis of a measured C/N value from the TV DEM 14, the earth station supervisory and controlling equipment 18 size-compares it with a reference value set beforehand. In the case that the measured C/N value is over the reference value, it judges that this selected channel has been occupied before, and interrupts transmission, and in the case that it is below the reference value, it judges that the selected channel is the dead channel, and executes transmission operation by using the selected channel. |
