FFT Web is an Out-Of-Tree block which sends a signal FFT by UDP to a websocket server. This websocket server packs and broadcast this FFT data to websockets, which can be opened by html/javascript code for real-time display of the fft in web-browsers (don't worry we are already providing that part ;) ).

FFT Web block come along with the CorteXlab OOT module, but it can also be found on github.

FFT web is a FFT sink block you have to feed with the signal you want to analyse. for example you can put it just ater an USRP Source block to act as a spectrum analyser.

FFT Web can be tune with several parameters :

• fft_size The size of the FFT ( 256 is a good start)
• power max The upper limit of the measured power in dB (-30 is a good start)
• power min The lower limit of the measured power in dB (-100 is a good start)
• port The port use to send the data. Usefull when you are using multiple fft web block. (default is 6663)
• frame rate The frequency of the acquisition (10 is a good start)
• samp rate This correspond to the bandwith of the signal
• ip address The address of the websocket server the data will be sent to. The address of our server is “srvwww.cortexlab.fr”.

The resolution of graphic will be samp rate/fft size.

To see the live results you can go to our web page http://xp.cortexlab.fr/fft/.

You will land on an empty page because you will have to configure graphics corresponding to each of your fft web block. There is several parameters to set up before adding a new graphic :

• host
• port
• UDP port
• width
• height
• rearrange halves
• mean window
• title
• x_min
• x_max
• y_min
• y_max