Mumbai University > Computer Engineering > Sem 3 > Electronic Circuits and Communication Fundamentals

Marks: 10 Marks

Year: May 2016

The phase shift method of SSB generation uses two balanced modulators and 90° phase shiftier but avoids the requirement for filters. The audio is shifted a total of 90° either by a pair of ± 45° phase shiftier or a single 90° phase shifter. A simplified block diagram of phase-shift method of SSB generation is as shown in Figure.

The RF carrier f1 is shifted 90° before it is applied to the modulators. Each modulator output is the expected upper and lower sideband. The upper sideband lead the carrier by 90°, but the lower sidebands are leading and lagging the carrier by 90°. The net result is two lower sidebands out of phase and cancelling each other. The upper sidebands are in phase and add, resulting in upper sideband output from the adder.