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Altera_Forum's avatar
Altera_Forum
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14 years ago

GFSK modulation

Hello! I have to write a GFSK modulaton using verilog HDL but I just use it 1month. I find a lot infotmation and paper about GFSK, but it does not work. Anyone has done something similar before?...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Hi,

You need to breakup your task into:

1) input generator (usually for test until actual input connected).

generate a random sequence of zeros/ones using PRBS or a text file.

2) apply pulse shaping using Gaussian filter.

3) convert the filtered output into frequencies using NCO(modulation).

4) upsample if required to your DAC input speed.

If you mean by modulation just step 3 then you are lucky.

Note that ordinary FSK uses only two frequencies to modulate but GFSK needs proper modulation of all filtered levels.

Good luck