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Dither Filtering of Real RLG Signal Using Wavelet Transforms

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Abstract—

Ring Laser Gyroscopes (RLGs) are widely used in many airborne and navigation systems for accurate measurement of the true rotation of the body movement. But the RLG’s suffer a serious problem at low frequencies known as Lock–in frequency. To avoid lock-in problem, the RLG is vibrated mechanically to a high frequency which is known as Dithering. In order to get the true rotation of the body the dither signal has to be removed. Single stage, multistage and multirate filters are suggested to remove the dither signal. These filters have the disadvantage that either the FIR filter length is too large or the phase characteristics are nonlinear. In this work, multiresolution Wavelet Transform (WT) techniques are used to remove the dither signal. Five level multiresolution analysis is carried out with various types of wavelets like Discrete Meyer and Daubechies 45 (db45) etc. With none of the standard wavelets, the original and reconstructed signals are matched. A new wavelet is designed to remove the dither signal. The required signal can be reconstructed back using the approximation coefficients at level 5. The dither signal is attenuated by 107.0 dB, and the phase characteristics are found to be linear in the pass band. The computational complexity is also less compared to the three stage combined filter reported earlier.

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ACKNOWLEDGMENTS

The authors are very much thankful to the Director, RCI (DRDO), Hyderabad for providing the financial support to carry out the research work under the grant RCI/DCMM/LPD/CARS/368.

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Authors and Affiliations

  1. Department of Electronics and Communication Engineering, Chaitanya Bharathi Institute of Technology, 500075, Hyderabad, India

    Bharath Regimanu, Kakarla Subba Rao & N. V. Koteswara Rao

  2. Research Centre Imarat, (Defence Research Development Organisation), 500 069, Hyderabad,, India

    Kishore Chandra Das

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  1. Bharath Regimanu
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  2. Kishore Chandra Das
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  3. Kakarla Subba Rao
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  4. N. V. Koteswara Rao
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Correspondence to Bharath Regimanu.

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Bharath Regimanu, Das, K.C., Rao, K.S. et al. Dither Filtering of Real RLG Signal Using Wavelet Transforms. Gyroscopy Navig. 10, 275–282 (2019). https://doi.org/10.1134/S2075108719040047

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  • DOI: https://doi.org/10.1134/S2075108719040047

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