QASK
QASK
QASK
improve if the signal vectors not only differ in phase but also in
amplitude. Thus QASK was introduced where direct modulation
of carrier in quadrature is involved.
• The QASK generator is as shown in the figure. The bit stream b(t) is
applied to a serial to parallel converter operating on a clock which has
a period of Ts sec. which is the symbol duration. The bits b(t) are
stored by the converter and then presented in the parallel form.
• Out of these four bits, the first two bits are applied to a D to A
converter and the other two bits are applied to the second D to A
converter.
BW=fs-(-fs)
=2fs …. As fs=1/Ts
=2/Ts …. Ts=N Tb
=2/NTb …. fb=1/Tb
BW =2fb/N