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sfit4: if interpolated DFT fails, use peak

tags/nilmtools-1.4.10^0
Jim Paris 8 years ago
parent
commit
f530edd8a0
1 changed files with 15 additions and 11 deletions
  1. +15
    -11
      nilmtools/math.py

+ 15
- 11
nilmtools/math.py View File

@@ -37,17 +37,21 @@ def sfit4(data, fs):
i = argmax(F[0:int(N/2)] + F[1:int(N/2+1)])

# Interpolate FFT to get a better result (from Markus [B37])
U1 = real(Fc[i])
U2 = real(Fc[i+1])
V1 = imag(Fc[i])
V2 = imag(Fc[i+1])
n = 2 * pi / N
ni1 = n * i
ni2 = n * (i+1)
K = ((V2-V1)*sin(ni1) + (U2-U1)*cos(ni1)) / (U2-U1)
Z1 = V1 * (K - cos(ni1)) / sin(ni1) + U1
Z2 = V2 * (K - cos(ni2)) / sin(ni2) + U2
i = arccos((Z2*cos(ni2) - Z1*cos(ni1)) / (Z2-Z1)) / n
try:
U1 = real(Fc[i])
U2 = real(Fc[i+1])
V1 = imag(Fc[i])
V2 = imag(Fc[i+1])
n = 2 * pi / N
ni1 = n * i
ni2 = n * (i+1)
K = ((V2-V1)*sin(ni1) + (U2-U1)*cos(ni1)) / (U2-U1)
Z1 = V1 * (K - cos(ni1)) / sin(ni1) + U1
Z2 = V2 * (K - cos(ni2)) / sin(ni2) + U2
i = arccos((Z2*cos(ni2) - Z1*cos(ni1)) / (Z2-Z1)) / n
except Exception:
# Just go with the biggest FFT peak
i = argmax(F[0:int(N/2)])

# Convert to Hz
f0 = i * float(fs) / N


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