ADC Sampling frequency to be used

[kalyansrinivasm]

Dear all

I have the Spectrum of a base band signal as attached figure

Now i want to know what is the sampling frequency of the ADC to be used

As I understand that to follow Nyquist Therom i need to sample at-least at double the highest frequency

But in the Digital board we have the ADC which samples at 2.568 GSPS and the modem works fine

Thanks in advance

M Kalyansrinivas

 

[FvM]

Nyquist theorem is about the requirements to reproduce an unknown signal from samples. In case of a modulation spectrum mask, you have to ask if the outlying sidebands contain essential information. Sampling with double the modulation symbol rate is probably sufficient to capture the data. The other question is if cutting part of the sidebands causes signal distortions that have to be compensated in the demodulator or reduces signal-to-noise ratio.

 

[kalyansrinivasm]

Nyquist theorem is about the requirements to reproduce an unknown signal from samples. In case of a modulation spectrum mask, you have to ask if the outlying sidebands contain essential information. Sampling with double the modulation symbol rate is probably sufficient to capture the data. The other question is if cutting part of the sidebands causes signal distortions that have to be compensated in the demodulator or reduces signal-to-noise ratio.

Thanks FVM

I need a bit of clarification

Can i assume that OFDM technology is having this advantage that the ADC sampling can be less than Nyquist as it doesnt have much essential information after 3dB point ,So that i can neglect without effecting the de-modulation