PROCESS AND INSTRUMENT FOR RECONSTRUCTION OF AN IRREGULARLY SAMPLED NARROW-BAND SIGNAL

• US 20110199616A1
• Filed: 09/01/2009
• Published: 08/18/2011
• Est. Priority Date: 10/13/2008
• Status: Active Grant

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: Christophe, Emmanuel, Cansot, Elodie, Rosak, Alain
• Granted Patent: US 8,780,355 B2
• Time in Patent Office: Days
• US Class Current: 356/456
• CPC Class Codes: G01J 3/453 by correlation of the amplitudes
• CPC Class Codes: G01J 3/4531 Devices without moving parts
• CPC Class Codes: G01J 3/4535 Devices with moving mirror G01J3/4532 takes precedence
• CPC Class Codes: G01J 3/457 Correlation spectrometry, e.g. of the intensity G01J3/453 takes precedence

Abstract

According to a first aspect the invention relates to a reconstruction process of a narrow-band signal acquired by an instrument producing irregular sampling, in which two series of samples are acquired at the same sampling period, the two series being offset relative to one another such that the sampling errors are identical or quasi identical over both series. According to a second aspect, the invention relates to an instrument configured to carry out the process according to the first aspect of the invention.

Claims

1. A process for reconstruction of a narrow-band signal acquired by an instrument undertaking an irregular sampling, in which a first interferogram and a second interferogram are acquired at the same sampling period, the first interferogram corresponding to the acquisition of a first series of samples of the narrow-band signal by creation of a finite number of path-length differences, and the second interferogram corresponding to the acquisition of a second series of samples of the narrow-band signal by offsetting each path-length difference of the first interferogram, such that the sampling errors are identical or quasi identical over both series of samples.

2. The process as claimed in claim 1, in which the offset between the series is substantially equal to the quarter of the inverse of the average frequency of the narrow-band signal.

3. The process as claimed in claim 1, in which the sampling period is less than or equal to the inverse of the spectral width of the narrow-band signal.

4. The process as claimed in claim 1, further comprising a resolution step of a matricial equation by the technique of least squares to proceed directly from the samples of the two series to the spectrum of the narrow-band signal.

5. The process as claimed in claim 1, further comprising a step for determining regular theoretical samples from the samples of the two series.

6. The process as claimed in claim 5, in which the sampling period Te of the regular theoretical samples is restricted according to:

k/(2*F_min)<

Te<

(k+1)/(2*F_max) with k a whole number, and F_min and F_max respectively the minimal frequency and the maximal frequency of the narrow-band signal.

7. The process as claimed in claims 5, further comprising an inverse Fourier transform operation to reconstruct the narrow-band signal from the regular theoretical samples.

8. The process as claimed in claim 1, in which the two series of sample are acquired by an interferometer.

9. The process as claimed in claim 8, in which the interferometer is a static grating interferometer.

10. The process as claimed in claim 9 in which the offset between the two series of samples is made temporally, the process successively comprising the operations of acquisition of the first series, displacement of a mobile element of the interferometer adaptively to carry out the offset and acquisition of the second series.

11. The process as claimed in claim 9 in which the two series of samples are acquired simultaneously.

12. An instrument undertaking an irregular sampling of a narrow-band signal, characterised in that it comprises means for acquiring a first interferogram and a second interferogram at the same sampling period, the first interferogram corresponding to the acquisition of a first series of samples of the narrow-band signal by creation of a finite number of path-length differences, and the second interferogram corresponding to the acquisition of a second series of samples of the narrow-band signal by offsetting each path-length difference of the first interferogram such that the sampling errors are identical or quasi-identical over both series.

13. The instrument as claimed in claim 12, in which said means comprise a mobile element capable of being moved to cause said offset between two series of samples acquired respectively before and after displacement of said element.

14. The instrument as claimed in claim 12 comprising grating mirrors where each grating is divided into two zones, and in which said means are formed by an overthickness in one of the zones of each grating.

15. The instrument as claimed in claim 12 comprising grating mirrors, in which said means are formed by the inclination of one of the mirrors.