SE338595B - - Google Patents

Abstract

1,227,440. Single sideband modulators. SIEMENS A.G. 19 June, 1968 [20 June, 1967], No. 29111/68. Heading H3R. In a quadrature modulator in which two modulator circuits are provided for converting two signals which are 90 degrees out of phase with one another and are supplied with respective carrier waveforms which are 90 degrees outof phase with one another, the carrier waveforms are produced from a rectangular waveform having a pulse repetition frequency four times the desired carrier frequency by means of a selector circuit which forms a rectangular pulse train of the desired repetition frequency by selectively gating said rectangular waveform. A sinewave U40, Fig. 3, of four times the carrier frequency is converted by a limiter 41, Fig. 2, into the corresponding rectangular waveform U46. This is applied to the input of a bi-stable trigger circuit producing on lines 47, 48 the oppositely phased rectangular waveforms U47, U48 respectively, of double the carrier frequency. The output on line 47 is applied to the input of a second bi-stable trigger circuit 43, producing on line 49 rectangular waveform U49 of the desired carrier frequency. Waveforms U46, U48 and U49 are applied to an AND gate 44, and waveforms U46, U47 and U49 to an AND gate 45 to produce on the output lines 37, 57 respectively the 90 degrees out of phase pulse trains U37, U57 respectively which are applied to the two carrier inputs of the modulator. The Specification also describes a modulator of the type disclosed in Specification 1,227,439.