| 摘要 |
993,873. Pulse modulation systems. SIEMENS & HALSKE A.G. Oct. 10, 1962 [Oct. 23, 1961], No. 38300/62. Heading H4L. In a bandwidth compression system in which a broad-band input signal is applied to a plurality of parallel-connected band-pass filters B each of which is connected via an asymmetric resistor G1 to a storage device Sp, each of the stores is scanned periodically (Se, G) in order to transmit each range of frequencies of the original signal in a time-divided manner along one or a plurality of output channels A 0 . The storage device C (Fig. 2) is charged to a datum value - U 1 by a constant current source U 2 when the electronic switch S is closed in each scanning period, the frequency of which is at least double that of the highest frequency to be transmitted. The stored energy in capacitor C is applied as an amplitude modulated pulse to its individual channel A (Fig. 3) or as a constant amplitude pulse of variable phase or duration from modulator M to a multiplex highway connected to A<SP>11</SP> (Fig. 3). The instant at which one of the latter pulses commences, e.g. t<SP>1</SP> 1 (Fig. 3) is governed by the time tt<SP>1</SP> (t is the time at which S closes) during which the capacitor restores to its datum level. The amplitude modulated pulses at the individual outputs A may be gated into a multiplex highway. |
