| 摘要 |
<p>1,043,733. Amplitude modulation; phasesensitive Circuits. G. NEUMANN. May 29, 1963 [May 31, 1962 (3)], No. 21497/63. Headings H3A and H3R. A capacitive transducer 6 is connectd in one arm of a normally balanced L-C bridge which is resonant with and determines the frequency of an oscillator 1. An output is derived from the diagonal 5, 8 of the bridge through an inductance 19 series resonant with the impedance of the bridge seen from the inductance. A phasesensitive rectifier 12, 13 then demodulates the balanced amplitude modulated carrier output to reproduce the modulation. In a modification, Fig. 3 (not shown), the demodulating carrier is derived in push-pull from tappings on either side of centre tap 5 and each push-pull lead has an inductance series resonating with the bridge capacity seen from the centre tap. The oscillator may be a Class C transistor oscillator, Fig. 4 (not shown). The transducer 6 may be a capacitor microphone, sound pick-up, pressure or thickness gauge &c.</p> |
