On Tue, Sep 23, 2008 at 9:35 AM, kaleem ahmad <[EMAIL PROTECTED]> wrote:
>
> Thanks Brian,
>
> But I am still confused what this code is doing:
>
> power = 0
> for tap in mywindow:
> power += tap*tap
>
> # FIXME the log10 primitive is dog slow
> log = gr.nlog10_ff(10, self.fft_size,
>
> -20*math.log10(self.fft_size)-10*math.log10(power/self.fft_size))
>
>
> Especially why this factor
> "20*math.log10(self.fft_size)-10*math.log10(power/self.fft_size)" is used???
The loop is calculating the gain of the window and subtracting to
maintain unity.
> moreover nlog10_ff block actually computes -> n*log10(input) + k, can
> someone explain what this k is doing and how can we compare this formulae to
> traditional dB formulae i.e. 10log(input), or 20log(input).
I haven't read the code, but I suspect it's for situations as stated above.
Brian
PS - Top posting is a little bit of a waste of bandwidth. Please try
some inline posting as it maintains a bit more clarity:
http://en.wikipedia.org/wiki/Posting_style
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