| 摘要 |
PURPOSE:To attain an error-free switching system of circuits by knowing the fading direction to switch a relevant circuit to a spare circuit before receiving the effects of fading. CONSTITUTION:The 1st spare circuit SP-1 having a frequency higher than the highest frequency of a using circuit containing (n) circuits is provided together with the 2nd spare circuit SP-2 having a frequency lower than the lowest frequency of said using circuit, a distributor 13 which is branched in three ways at the transmission side of a digital radio device, two sending-end switches 7-1 and 7-2, transmitters TX-1 and TX-8 of the using circuit and spare transmitters TX-009-0 and TX-019-1 respectively. While (n) pieces of using receivers RX-110 corresponding to the using circuit is provided at the reception side together with spare receivers RX-0011-1 and RX-0111-2 and receiving-end switches 12-1 and 12-2 which replace the two spare circuits with the using circuit with no hit. The signal deterioration information is received by the receiver; while the direction information showing whether the fading is shifted to a high frequency from a low one or vice versa is received by a circuit switching device. Then the using circuit with which the deterioration of signals is expected is switched previously to a spare circuit. The spare circuit is changed again to the using circuit when the signal of the using circuit is reset to its original state. |
