Re: [Discuss-gnuradio] Determine index of max value in FFT

[Paul Boven]

Hi Tom,

On 9/30/19 3:27 PM, tom sutherland via Discuss-gnuradio wrote:
> How do you determine the index of the maximum value of the output of a 
> FFT? e.g. I have a FFT  and then a "ComplexToMag^2" block and I want to 
> know the max value and its corresponding index (i.e. for a 4096 point 
> FFT the index occured at 63).

The argmax block will give you the index to the vector element with the 
largest value. Set its number of inputs to 1, and the vector length as 
appropriate. The 'max_vec' output gives the number you are looking for.

As there is only one vector, the 'max_inp' should be connected to a null 
sink. (I would argue that the port in question should disappear when 
there's only one input).

For the value itself, there's the 'max' block, set number of inputs and 
length of output vector to 1.

Regards, Paul Boven.