Just  just overall
It 's a  it 's a  o i w the band  the band is , eh , from zero to  to four kilohertz. And I  I ot I
And you just take the instantaneous frequency ?
Yeah. I u m t I  I used two m two method  two methods. Eh , one , eh , based on the F  eh , FTT. to FFT to  to obtain the  or to study the harmonics from  from the spectrum directly ,