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Thanks.

Do you mean that I don't need to change anything and the current design (7.40) already supports 40MHz bandwidth transmission  and reception?

murphpo wrote:

The WARPLab Reference Design runs the ADCs and DACs at 40MSps. There are separate analog converters for the I and Q paths of the complex baseband Tx/Rx signals. This design gives 40MHz bandwidth centered at 0Hz (-20MHz to +20MHz), the full analog bandwidth of the MAX2829.

I still have two questions here. I can found several other threads talking about using 40MHz bandwidth but there is no detail how to do this.

1. wl_interfaceCmd(nodes,'RF_ALL','channel',2.4,11); 

In warplab 7.4 matlab code, there is the above line to set channel. Once I select the channel, only 20Mhz is used (Am I correct?). What should I change here to enable the receiver to listen on 40MHz??
Can I listen on two channels like 10, 11 at the same time?


2. At the transmitter side, I also need to built the packet which occupys all the 40Mhz bandwidth, right?
In wl_example_siso_txrx_nodeSync.m, there is a packet built with short training symbol +  sine-wave payload.

Does this short preamble occupy 20MHz or 40MHz? If it only occupy 20MHz, is it because the two 'zeros(32,1)' before and after 'shortSymbol_freq'? 
If I make 'zeros(32,1)' no-zero , then the short preamble occupys  the whole 40Mhz now?

Thanks and please help!

matlab code from WARPLAB example:

shortSymbol_freq = [0 0 0 0 0 0 0 0 1+1i 0 0 0 -1+1i 0  0 0 -1-1i 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 1-1i 0 0 0 0 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 -1+1i 0 0 0 1+1i 0 0 0 0 0 0 0].';
shortSymbol_freq = [zeros(32,1);shortSymbol_freq;zeros(32,1)];
shortSymbol_time = ifft(fftshift(shortSymbol_freq));

welsh wrote:

Correct.  See complex sampling for more information on the theory behind this.

Thanks a lot. I have another question:

In the matlab example, short training symbol is made as below:

Does this short training symbol occupy the whole 20Mhz? How can I know this?
If I want to make a new one occupies 40Mhz, I should change the zeros(32,1) to no-zero values?

shortSymbol_freq = [0 0 0 0 0 0 0 0 1+1i 0 0 0 -1+1i 0  0 0 -1-1i 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 1-1i 0 0 0 0 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 1-1i 0 0 0 -1-1i 0 0 0 -1+1i 0 0 0 1+1i 0 0 0 0 0 0 0].';
shortSymbol_freq = [zeros(32,1);shortSymbol_freq;zeros(32,1)];
shortSymbol_time = ifft(fftshift(shortSymbol_freq));

murphpo wrote:

In warplab 7.4 matlab code, there is the above line to set channel. Once I select the channel, only 20Mhz is used (Am I correct?). What should I change here to enable the receiver to listen on 40MHz??

Setting the channel only sets the center frequency of the Tx/Rx mixers. The bandwidth used at that center frequency is defined by:
  -Tx: your baseband waveform -> Tx LPF (configured via the tx_lpf_corn_freq command)
  -Rx: Rx LPF (configured via the rx_lpf_corn_freq command)

Last edited by nudu (2014-Sep-02 19:04:42)