| 摘要 |
<p>853,361. Unattended repeaters. WESTERN ELECTRIC CO. Inc. May 1, 1959 [May 15, 1958], No. 14897/59. Drawings to Specification. Class 40 (4). In an electric signal transmission system, a repeater comprises an amplifier, a temperaturesensitive resonant device for producing an irregularity in the gain-frequency characteristic of the amplifier, and means for controlling the temperature of the resonant device (and hence the frequency at which the irregularity occurs) in accordance with the signal level at the amplifier. The resonant device preferably comprises a piezo-electric crystal, as described in Specification 702,397 and may be connected in shunt across the feed-back circuit or in series or shunt in the input or output circuit. The crystal is enclosed in an insulated envelope with a heating coil controlled by either the input signal or the output signal of the amplifier. In a modification, two such devices are provided in order to measure both the input and the output of the amplifier. The Specification describes a method of using such devices to supervise the performance of a plurality of unattended repeaters spaced along a transmission channel.</p> |
