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Altera_Forum's avatar
Altera_Forum
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14 years ago

Beamforming

hi,

I have a stream of 50 transducers and want to apply beamforming to the data coming from it. I have ADCs connected to each transducer.

Q#1: DO i need to see for the ADC giving real and imaginary I and Q aprts or this is not important for the Beamforming?

After the ADC, there are deserializers which give 8 bit output . Now i need to implement the beamforming. I want to design it for an aperture size of 8 and sampling frequency of 25Mhz. I want to apply simplest delay and sum beamforming. As far as i could study, the weights are same for the simplest kind. But i need to add delay which again i could understand is the phase delay or its the time delay??

Please if some one could help in implementing this basic beamformer using verilog.

Also, I think i would need some kind of FIFO or registers at start of the beamformer to buffer all the data required, am i right?

I shall be thankful for any basic implementation code or help.

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  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    could you please also explain apodization? We are doing beamforming to exagerate the main lobe and aren't the side lobes being supressed by it? or still we need apodization to reduce the side lobe? If yes, please explain in general terms what is it exactly?

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    --- Quote Start ---

    could you please also explain apodization? We are doing beamforming to exagerate the main lobe and aren't the side lobes being supressed by it? or still we need apodization to reduce the side lobe? If yes, please explain in general terms what is it exactly?

    --- Quote End ---

    You aren't performing the apodization (windowing) of the receiver responses to exagerate the main lobe, you are applying the apodization to reduce the sidelobes, and that has the side-effect of increasing the main-lobe width. To compensate for this, you can obtain a narrower main-lobe, by adding more receiver elements.

    The relationship between the increase in mainlobe width relative to the window function can be calculated using tools like MATLAB. The paper by Harris 1978 has a number of standard windows. It looks like Wikipedia has an explanation as well as a link to the Harris paper:

    http://en.wikipedia.org/wiki/window_function

    http://web.mit.edu/xiphmont/public/windows.pdf

    Cheers,

    Dave