Re: [Discuss-gnuradio] Peak detector block does not really work. It need to be fixed

[Phong Do]

Hello Tom,

Can you explain me why should gr_peak_detector need negative inputs ?
What about the variable "look ahead" ? I wrote in the last message that
"look ahead" has no function in gr_peak_detector. Do you know how can I add
this feature in peak detector ?

Thanks in advance 
Phong Do


On Thu, Aug 12, 2010 at 8:26 AM, Phong Do <address@hidden> wrote:
>
> Hello,
>
> I'm working now with peak_detector block and find out that some functions
> don't really work.
> I've used the following 2 blocks:
>
> - Peak Detector (gr_peak_detector): the parameter "look ahead" seems have
> no
> function. I gave "look ahead" many values but the peak value did not
> change.
> I've seen in the gr_peak_detector_xx.cc that the variable d_look_ahead is
> called but it is not used in the main program. So I think the developer
> has
> forgotten this function.
>
> - Peak Detector 2 (gr_peak_detector2): in this block "look ahead" is used,
> but sometimes the peak detector freezes (output signal stops running in
> scope sink).
> I've changed the cpp code a little bit and it does not freeze anymore. But
> I'm not sure if the detector will work correctly after that.
> Here is what I've changed:
> original code: return tmp - 1;
> changed code: return tmp;
>
> Can anyone of the development team have a look at the 2 cpp ?
>
> best regards
> Phong Do

Keep in mind that the gr_peak_detector actually expects negative
inputs. So if your signal goes from 0 to 100, adjust it so that it
goes from -100 to 0.

Of course, I say "keep in mind" even though we probably haven't
provided any documentation in the code to that affect...

Tom

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