| 摘要 |
PURPOSE:To improve the reliability of a line without deterioration of S/N by adopting the constitution that a local oscillator is used in common as active/ spare oscillator, selecting automatically a spare local oscillator even a fault takes place in an active oscillator and continuing running without interrupting a receiver. CONSTITUTION:The local oscillation section 4 consists of a local oscillator 4-1, a spare local oscillator 4-2, a local oscillator supervising and switching device 4-3 and a power distributor 4-4. The device 4-3 selects normally the oscillator 4-1, its output power is distributed from the distributor 4-4 and transmitted to reception frequency converters 1-2, 2-2 of receivers 1, 2. If a fault takes place in the oscillator 4-1, the switch 4-3 is activated so as to select the oscillator 4-2, the signal is distributed by the distributor 4-4 and a local frequency output of the oscillator 4-2 is inputted to converters 1-2, 2-2 of the receivers 1, 2. Thus, even if a fault takes place in the oscillator 4-1, since the oscillator 4-2 is selected immediately, the receivers 1, 2 are operated normally and each base band signal is synthesized (3) and then the S/N is improved. |
