Issue |
Astron. Astrophys. Suppl. Ser.
Volume 124, Number 3, September 1997
|
|
---|---|---|
Page(s) | 579 - 587 | |
DOI | https://doi.org/10.1051/aas:1997208 | |
Published online | 15 September 1997 |
Noise reduction in astronomical spectra using wavelet packets
Institut für Astronomie, ETH-Zentrum, CH-8092 Zürich, Switzerland
Received:
15
May
1996
Accepted:
6
December
1996
The wavelet representation of a signal offers greater flexibility in de-noising astronomical spectra than classical Fourier smoothing due to the additional wavelength resolution of the decomposed signal. We present here a new wavelet-based approach to noise reduction. It is similar to an application of the splitting algorithm of a wavelet packets analysis using non-orthogonal wavelets. It clearly separates the signal from the noise, in particular also at the noise-dominated highest frequencies. This allows a better suppression of the noise, so that the spectrum de-noised in this manner provides a closer approximation of the uncorrupted signal than in the case of a single wavelet transformation or a Fourier transform. We test this method on intensity and circularly polarized spectra of the sun and compare with Fourier and other wavelet-based de-noising algorithms. Our technique is found to give better results than any other tested de-noising algorithm. It is shown to be particularly successful in recovering weak signals that are practically drowned by the noise.
Key words: methods: data analysis / methods: numerical
© European Southern Observatory (ESO), 1997