u

src/yapsut/colored_noise.py

@@ -10,6 +10,7 @@ Also look at:
 https://pypi.org/project/colorednoise/
 pip3 colorednoise --user
 
+Note that the kneew frequency fknee can have any value, it is not restricted to fsamp/2
 
 """
 
@@ -30,7 +31,7 @@ class gaussian_colored_noise :
       return self._wn_sigma
    @property
    def fknee(self) :
-      """fknee in units of the fsamp, fknee in [0,0.5]"""
+      """fknee>=0 in units of the fsamp"""
       return self._fknee
    @property
    def alpha(self) :
@@ -38,7 +39,7 @@ class gaussian_colored_noise :
       return self._alpha
    @property
    def freq(self) :
-      """the frequencies in units of fsamp in the range [0,0.5]."""
+      """the sampled frequencies in units of fsamp in the range [0,0.5]."""
       return self._freq
    @property
    def ps_shape(self) :
@@ -73,6 +74,7 @@ Keywords:
                     'I' : P(0)**0.5 is left as it is
                     'M' : P(0)**0.5 = wn_mean
                     '100x1' : P(0)**0.5=(1+100*fknee/freq[1])**alpha/2
+                    'midf1' : P(0)=P(f[1]/2) = exp((log P[2]-log P[1])/(log f2 - log f1)*(log f1/2 - log f1)+log P(1))
                     note that zero_policy affects the mean value of the chunck but not its variance
                     default value is 'I' that for alpha > 0 gives P(0)=1
       
@@ -105,6 +107,14 @@ Keywords:
          self._S[0]=self.wn_mean
       elif self._zero_policy=='100x1' :
          self._S[0]=1 if fknee>ff[1] else (1+100*(self.fknee/self._freq[1])**pl)**0.5
+      elif self._zero_policy=='midf1' :
+         y1=np.log(self._S[1])
+         y2=np.log(self._S[2])
+         x1=np.log(self._freq[1])
+         x2=np.log(self._freq[2])
+         r=(y2-y1)/(x2-x1)
+         z=r*(np.log(self._freq[1]/2)-x1)+y1
+         self._S[0]=np.exp(z)
       else : # self._zero_policy=='I' :
          # left things as they are
          pass