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Hi,
1) With reference to the channel hopping mac code given in workshop lab exercise 6, i would like to write the modulated data i receive into a text file before any demodulation or decoding takes place so that i can get a collection of real time data which i would like to process offline on matlab. How can this be done? Does the receive buffer contain the data just after the A/D converter or does it contain the demodulated and decoded data?
2) Also i would like to know where exactly the FFT has been implemented in the OFDM reference design (which vhdl or verilog code exactly as i need to design a VHDL code of my own for a different fft length).
Last edited by Abhinandan (2009-Jun-02 07:08:34)
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1) In the OFDM design, raw I/Q samples are processed in the FPGA and cannot be saved directly to a file. To capture raw samples, you can use the WARPLab flow.
2) The FFT is implemented in the FPGA fabric, inside the OFDM transceiver core. This core is designed in System Generator. The source model is available in the repository.
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I understand that the current OFDM ref design can not output raw I/Q samples directly. While WARPLab can do this, its PHY is not OFDM and I am interested in some of OFDM properties. If I want to modify OFDM design to make it output raw I/Q, my understanding is that I need to extract samples from registers, write them into Ethernet packets, and transmit that back to host machine. Is this correct? Can you think of anything else I should pay attention to? Many thanks!
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The real-time OFDM PHY does not route I/Q samples to any memory-mapped buffer/registers. You would have to add this logic to the PHY. I think WARPLab is what you want. There is no WARPLab "PHY"- you can implement any processing you want in m-code. It will be much easier to implement a simple OFDM system in WARPLab / m-code than it will be to modify the real-time PHY.
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