FHT to frequency

[jbolfiil]

Hello,

I am trying to get the FHT converted to frequency. I saw that the formula was k*(samples/FHT_N) but I can't seem to get what I want...

1. Does k need to be unsigned? I am getting negative values when ever I try to print it out to the serial monitor.

2. How do you find out what the sampling rate is? I have read that you need to look at the prescalar but I am not sure what that is.

I am just trying to write a high on a digital pin when a certain frequency is present. Any help will be appreciated!

Also, will I need to set a magnitude threshold somehow? I only want the high on the digital pin when there is an intentional sound.

(I just realized that I did not bias the signal so that maybe a cause for off numbers.)

[guest]

so to figure out which bin relates to what frequency, you need to know the sample rate. if you are using the default example from the library, that is 38kHz.

Frequency(k) = (k)*(sample_rate)/(FHT_N)

k is just the bin number.

if you want a pin to go high based on a certain frequency, just figure out which bin that is, and then check the value in that bin compared to a threshold, and set the pin high if its above the threshold

[jbolfiil]

[guest]

[jbolfiil]

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[jbolfiil]

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[jbolfiil]

[guest]