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Altera_Forum's avatar
Altera_Forum
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10 years ago

Best demodulation method

Hi, I have to transmit data modulated with 250Hz carrier and bit time of 12ms (3 period of carrier). Obviously i need to demodulate that message on receiver side. The problem is that on the...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

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Yes it is an interferer, "noise" is a wrong term.

Actually on channel where i have to transmit my 250Hz messagge 60 an 180Hz signals are just present.

The amplitude of 250Hz signal should be half or less of the 60 and 180Hz signals.

What about cdma or similiar?

Let me know.

Thanks.

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I suggest you go for the simplest modulation of ASK(or OOK). you can multiply the symbol stream with 250Hz carrier before sending it to DAC.

Your bandwidth will be your symbol rate spread on either side of carrier and so you have very narrow space indeed. For example if symbol rate is 200Hz your bandwidth becomes 200Hz i.e. 100Hz on either side of 250Hz carrierand gets mixed with interferer. What is your data bandwidth (or symbol rate) and what do you actually want to achieve at system level.

cdma ? no way, you don't need that complexity unless you want practice.