| 摘要 |
<p>792,529. Unattended repeaters. COMPAGNIE GENERALE D'ELECTRICITE. June 15, 1956, No. 18527/56. Class 40 (4). In a telephone transmission system including a series of unattended repeaters 9 to which power is fed over the transmission line 10, the repeaters which include a chain of series connected valve filaments 5 have a highly selective resonator 13, a rectifier 14 and a low-pass filter 15 connecting the output of the amplifier 1 to the input end of the filaments 5 so that a frequency modulated test signal from a generator 12 at a terminal station is returned as a current of low frequency of the order of tens of cycles for display on an element such as an oscilloscope 16 so that the returning levels may be observed for test purposes. The application of the invention to two-way repeaters is described with reference to Fig. 6 (not shown). The duration of the frequency modulated signal does not exceed a few hundred cycles per second and the rhythm of deviation is of the order of a few cycles per second. The resonators 13 are tuned to a different frequency in each repeater. In an alternative testing arrangement the frequency sweep is made to cover all the resonators and a sequence of peaks returned after different time intervals is observed. Specification 446,225 is referred to.</p> |
