| 摘要 |
946,249. Amplitude modulation systems; multiplex radio signalling. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 15, 1961 [Dec. 2, 1960], No. 41574/60. Heading H4L. [Also in Division G4] In an S.S.B. modulator carrier in quadrature phase is respectively added to quadrature phase modulation signals (each of whose corresponding frequency components are in phase quadrature) and the resulting summation signals multiplied together to produce an output with S.S.B. component and doubled carrier frequency components which are suppressed by a crystal or other filter. The multiplier may be a diode ring modulator or a single Hall plate, a four quadrant beam tube or, Fig. 4, two Hall multipliers with their magnetic coil and plate inputs cross-connected and in series to provide similar input impedances for both of inputs x and y. Inputs other than in phase quadrature may be used if amplitudes are suitably selected. As change-over between upper and lower sideband outputs is produced by reversing the phase sense or polarity of the carrier or modulation input, two modulations may be simultaneously applied to the S.S.B. modulator to produce different S.S.B. signals on both upper and lower sidebands. |
