| 摘要 |
687,174. Radio signalling. PATELHOLD PATENTVERWERTUNGS- & ELEKTROHOLDING AKT.-GES. Aug. 23, 1950 [Sept. 17, 1949], No. 20843/50. Class 40 (v). In a multi-channel pulse modulation radio system, with relay stations, the non-reception of a pulse train at a relay station automatically introduces a local pulse generator. The normal detected input pulse train from conductor e1, Fig. 2, is fed to a three-stage amplifier and thence to the transmitter over conductor e3. It is also fed to a circuit K which de-energizes relay Re, when the pulses fail, to close contacts r2 to energize the local pulse generator JG feeding the output valve, and to operate contacts r1 to block the input valve by applying a negative voltage to its screen grid. The circuit K is made responsive to the long synchronizing pulses of the normal pulse train by feeding the pulses to condenser C, Fig. 2a, to produce sawtooth pulses of amplitude proportional to the pulse duration. The synchronizing pulses are of sufficient amplitude to overcome the bias on a second amplifier, which is provided by grid current, and the negative pulses at the anode give rise to positive pulses by the action of the grid condenser and rectifier G of the output valve which operates the relay Re. The substituted pulses are made to have the same duration as the normal synchronizing pulses and may be duration modulated to indicate a disturbance, or by speech, or further modulated pulses may also be generated. |
