| 摘要 |
1469499 Amplitude modulators INTERNATIONAL STANDARD ELECTRIC CORP 6 May 1975 [7 May 1974] 18925/75 Heading H3R An R.F. double side band suppressed carrier signal generator comprises an amplitude modulator 2, a switchable 0/180 degree phase shifter (1) for phase shifting the carrier before or after modulation and an arrangement 5 for applying to the phase shifter 1 a periodic switching signal in phase with the modulating signal. The phase shifter 1 with PIN diodes 9 alternately switched on and off correspond to a line alternately short circuited or open circuited. The modulator 2 may be an absorption modulator including hybrid couplers 6,7 and PIN diodes 8 causing attenuation of the carrier by damping and by reflection in response to the applied modulating signal. Carrier suppression is obtained by phase reversal of the modulated carrier at zero crossings of the modulation envelope. In the arrangement of Fig. 2 (not shown), the modulation characteristic is linearized by feed-back of the modulated carrier. |
