Abstract
Filtering of pulse-like FM signals with varying amplitude corrupted by impulse noise is considered. The robust DFT calculated for overlapped intervals is used for this aim. This technique is proposed in order to decrease amplitude distortion of output signals that can be introduced by the robust DFT calculated within a wide interval including possible zero-output. The proposed algorithm is realized through the following steps. In the first stage, the robust DFT is calculated for the intervals. Filtered signals from the intervals are obtained by applying the standard inverse DFT for the robust DFTs applied to input data. In the second stage, results for different overlapped intervals are combined using the appropriate order statistics. In addition, an algorithm inspired by the intersection of the confidence intervals rule is used for adaptive selection of the interval width in the robust DFT. Algorithm accuracy is tested on numerical examples. Computational complexity analysis is also provided.
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Abbreviations
- x(n):
-
signal
- A(n):
-
signal amplitude
- \({\phi (n)}\) :
-
signal phase
- X(k):
-
standard DFT
- X α(k):
-
robust L-DFT
- r k (i),i k (i):
-
sorted real and imaginary parts of modulated signal sequence
- a :
-
parameter of the L-filter
- a i :
-
coefficients of the L-filter
- \({\hat{f}(n)}\) :
-
filtered signal
- N :
-
signal duration
- W N :
-
exp (−j2π /N)
- Δt :
-
sampling rate
- Q :
-
number of subintervals
- x i (n):
-
signal within interval i
- δ:
-
overlapping coefficient
- IDFT{}:
-
standard inverse DFT
- F(ξ):
-
loss function
- p ν(ξ):
-
pdf of noise
- MAE, MAE l :
-
mean absolute value and its
- :
-
locally calculated version
- RMSE, RMSE l :
-
root mean squared error and its locally calculated version
- R :
-
number of trial in the Monte Carlo simulation
- N l :
-
number of instants within “high” amplitude interval
- κ:
-
parameter of the ICI procedure
- Γ:
-
parameter of the CV procedure
- ξ i :
-
ξ i = N/Q i interval width
- p(n;ξ i ), \({\hat{f}_{\xi _{i}}(n)}\) :
-
estimates produced by interval width ξ i
- σ (n;ξ i ):
-
standard deviation of estimate \({\hat{f}_{\xi_{i}}(n) }\)
- ρ:
-
parameter of noise
- \({\Gamma _{{\rm opt}},\hat{f}_{\Gamma _{{\rm opt}}}(n)}\) :
-
optimal value of Γ and corresponding estimate
- \({\hat{f}_{\Gamma _{l}}(n),\xi _{\Gamma _{l}}(n)}\) :
-
estimate and optimal interval width for Γ l
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Djurović, I., Lukin, V.V. Robust DFT-based filtering of pulse-like FM signals corrupted by impulsive noise. SIViP 1, 39–51 (2007). https://doi.org/10.1007/s11760-007-0005-8
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DOI: https://doi.org/10.1007/s11760-007-0005-8