Single Side Band QPSK

[curious9]

A quick question regarding single sideband and double sideband modulation.

I have always thought that a single side band contained all the information that is transmitted and the second sideband is not necessary to receive the transmitted information, ergo SSB. However, when I recently performed a QPSK simulation modulating to RF, when I filtered anywhere close to the lower sideband, my quadrature get completely clobbered. It seemed I needed both sidebands to do quadrature. My question is, do you need to have both sidebands to do QPSK or any type of quadrature. It is possible to do SSB with quadratures.

Thanks for the help

 

[2dye4]

Yes it is theoretically possible to use only half the spectrum and still recover a precise waveform.

But it is somewhat complicated.

This may help.

http://www.mathworks.com/products/s...mos/shipping/signal/hilberttransformdemo.html