Digital Modulation Techniques in Mobile Communications

MSK better than QPSKEven though the derivation of MSK was produced by analyzing the changes inphase, MSK is actually a form of frequency-shift-keying (FSK) with(where f1 and f2 are the frequencies used for the pulses). MSK produces anFSK with the minimum difference between the frequencies of the two FSKsignals such that the signals do not interfere with each other. MSKproduces a power spectrum density that falls off much faster compared to thespectrum of QPSK. While QPSK falls off at the inverse square of the frequency,MSK falls off at the inverse fourth power of the frequency. Thus MSK canoperate in a smaller bandwidth compared to QPSK.Fahredd'n Sadikoglu 33