| 摘要 |
<p>A repeater monitoring and fault location system is disclosed for a submarine cable system which includes repeaters of the type having separate high band and low band amplifiers for two-way transmission over one cable. Each repeater includes an oscillator for generating a signal at a frequency in the cutapart region between the high frequency and low frequency transmission bands and which is uniquely identifiable to that repeater. A test tone at a frequency in the low frequency transmission band is transmitted from the low frequency transmitting end along the cable. The low band amplifiers intermodulate the local oscillator signals with the transmitted test tone to generate a series of seond order modulation products at frequencies in the high frequency band. A low pass filter, designed to have a controlled moderate level of loss in the portion of its high frequency stop band over which the frequencies of the second order modulation components lie, is connected to the output of each low band amplifier. A series of second order modulation components at frequencies uniquely identifiable to each repeater is coupled to the high frequency transmitting path for transmission to the low frequency transmitting end. By comparing the magnitudes of the returned modulation components with reference levels, the modulation performance of each low band amplifier is determined and a faulty amplifier can be located.</p> |
