Re: [Discuss-gnuradio] missing functions in gnuradio?

[Eric Blossom]

On Sat, Apr 15, 2006 at 11:03:23AM +0200, Horst Eyermann wrote:
> Hello,
> 
> I am relatively new to gnuradio and plan to write a weatherfax decoder
> in gnuradio.
> 
> I want to try different schemes for decoding the signal (coherent /
> noncoherent / short-time DFT)
> 
> As there is phasing in the signal I am most interested in the
> non-coherent approach. But there I am really lacking a square-root block
> in gnuradio. It should not be difficult for me to implement it - but I
> wondered why such a block is not present in the library.
> 
> Should such a block (or a general "power of" block) included in the
> library?

Hi Horst,

We do have gr.rms_cf and gr.rms_ff which compute estimates of RMS
power for complex and float signals respectively.

There's also gr.complex_to_mag for complex signals.

We generally avoid continuously computing the square root (it's
expensive).  In our examples so far we've generally wanted to compare
power to a threshold, and in that case it was easier to factor the
(absence of) square root into the threshold setting than to burn the
cycles computing sqrt on every sample.

Eric