Passband gfsk modulation in simulink

I have implemented a simple model which simulates a baseband GFSK modulation, using as data source a bernoulli random generator with sample time of 1/2000s and the block "CPM" with a Gaussian filter for the signal modulation. I've analyzed it with a spectrum scope and it works pretty well at baseband.

Now I want to bring the signal at an higher frequency (~100Mhz), how to do it? I tried to multiply it by a carrier (sample time equal to the one used for the baseband signal), but the modulated signal seems that cannot go further than 900Khz. Why? Where I'm wrong?

Thank you. Giuseppe B.

[Giuseppe B]

Up!

[Giuseppe B]

Any suggestion?

[Jason Chang]

Excuse me, I have trouble in making a GFSK signal.

Would you like to tell me how you build the GFSK block in Simulink?

Thanks

[Emmanuel]

Hello @Jason Chang, could you create GFSK clock in simulink? i need de answer

[Emmanuel]

block*

Answer 1

[charan]

Hello,

Passband GFSK modulation can be performed in Simulink using the "CPM Modulator Baseband" block in Simulink. This can be done by setting the "M-ary number" parameter of the block to "2", "Input type" to "bit" and "Frequency pulse shape" to "Gaussian".

The following example provides more information about the same:

https://www.mathworks.com/help/bluetooth/ug/bluetooth-bredr-full-duplex-data-and-voice-communication-with-wlan-and-awgn-interference.html

In this example, the Bluetooth radio module uses GFSK, which represents a binary 1 as a positive frequency deviation and a binary 0 as a negative frequency deviation. This is implemented using the "CPM Modulator Baseband" block.

You can refer to the below links on CPM Modulator and Demodulator blocks:

• https://www.mathworks.com/help/comm/ref/cpmmodulatorbaseband.html
• https://www.mathworks.com/help/comm/ref/cpmdemodulatorbaseband.html