This model shows how to visually compare Gaussian minimum shift keying (GMSK) and minimum shift keying (MSK) modulation schemes.
The example model, doc_gmsk_vs_msk, includes these blocks:
Random Integer Generator block, which provides a source of uniformly distributed random integers in the range [0, M-1], where M is the constellation size of the GMSK or MSK signal
GMSK Modulator Baseband block
MSK Modulator Baseband block
AWGN Channel block
Eye Diagram block
The example illustrates the difference between the two modulation schemes. The Eye Diagram blocks show the eye diagrams of the noisy GMSK and MSK signals.
The eye diagrams show the similarity between the GMSK and MSK
signals when you set the Pulse length of the GMSK
Modulator Baseband block to 1. Setting the Pulse
length to 3 or 5 enables you to view the difference that
a partial response modulation can have on the eye diagram. The number
of paths increases, showing that the CPM waveform depends on values
of the previous symbols as well as the present symbol. You can change
the pulse length to 2 or 4, but you should change the Phase
pi/4 for a better view of
the modulated signal. In order to more clearly view the Gaussian pulse
shape, you must use scopes that enable you to view the phase of the
signal, as described in the CPM Phase Tree example.