Method and a system for determining a physical property as a function of position

1. A frequency modulated continuous wave (FMCW) backscattering measurement system, comprising a non-transitory computer readable medium having stored thereon a computer readable program code for performing a method for processing a data series obtained by frequency modulated continuous wave (FMCW), the data series comprising data points from one or more channels, the method comprising:

a. measuring a number of data points, corresponding to N da different values of frequency of modulation {f m,0 , f m,1 , f m,n , . . . , f m,Nda }, thereby obtaining at least one primary data series from each channel,

b. performing one or more processing steps comprising at least part of said primary data series to obtain at least one secondary data series comprising N data points for the values of frequency of modulation {f 0 , f 1 , f n , . . . , f N }, said processing steps comprises filling in data points with a filling series {f f,0 , f f,1 , f f,n , . . . , f f,N-Nda } comprising values of frequency of modulation not included in {f m,0 , f m,1 , f m,n , . . . , f m,Nda },

c. performing a transformation of said secondary data series from frequency domain to obtain at least one back scattering curve in space domain,

d. optionally relating said back scattering curve(s) to one or more physical properties as a function of position,

wherein N>N da .

2. The FMCW backscattering measurement system of claim 1 , wherein said filling series comprises previously selected values for one or more data points.

3. The FMCW backscattering measurement system of claim 1 , wherein said filling series comprises data points based on the primary data series and/or one or more previously measured data points.

4. The FMCW backscattering measurement system of claim 1 , wherein the filling series and the primary data series comprises an overlapping frequency interval where the data points of the filling series has an average spacing Δf f , and the data points of the primary data series has an average spacing Δf m , where Δf f is substantially equal to Δf m .

5. The FMCW backscattering measurement system of claim 1 , wherein the filling series and the primary data series comprises an overlapping frequency interval where the data points of the filling series has an average spacing Δf f and the data points of the primary data series has an average spacing Δf m , where Δf f is equal to or less than Δf m .

6. The FMCW backscattering measurement system of claim 1 , wherein the filling series and the primary data series comprises an overlapping frequency interval where the data points of the filling series has an average spacing Δf f and the data points of the primary data series has an average spacing Δf m , where Δf f is equal to or more than Δf m .

7. The FMCW backscattering measurement system of claim 1 , wherein the filling series and the primary data series comprises an overlapping frequency interval where the number of data points in the filling series is equal to or more than the number of data points in the primary data series.

8. The FMCW backscattering measurement system of claim 1 , wherein the filling series and the primary data series comprises an overlapping frequency interval where the number of data points in the primary series is equal to or more than the number of data points in the filling series.

9. The FMCW backscattering measurement system of claim 4 , wherein said overlapping frequency interval has a beginning frequency f min and an end frequencies f max , where f max is a fraction of f N .

10. The FMCW backscattering measurement system of claim 4 , wherein said overlapping frequency interval has a beginning frequency f min and an end frequencies f max , where f min is zero or a fraction of f N .

11. The FMCW backscattering measurement system of claim 1 , wherein at least one backscattering profile is determined to update a previously determined physical property as a function of position.

12. The FMCW backscattering measurement system of claim 11 , wherein the set of measured frequencies of modulation {f m,0 , f m,1 , f m,n , . . . , f m,Nda } is substantially identical to the set of measured frequencies of modulation applied to determine the previously determined physical property as a function of position.

13. The FMCW backscattering measurement system of claim 12 , wherein the set of measured frequencies of modulation {f m,0 , f m,1 , f m,n , . . . , f m,Nda } differ from the set of measured frequencies of modulation applied to determine the previously determined physical property as a function of position in at least one of the following ways: the number of measured frequencies of modulation, one or more values of the measured frequencies of modulation is omitted and one or more values of the measured frequencies of modulation is added.

14. A frequency modulated continuous wave (FMCW) system comprising

at least one excitation source and

an evaluation unit,

wherein the evaluation unit comprising one or more signal processing units, and wherein the one or more signal processing units comprises a non-transitory computer readable medium having a code therein when executed by said processing units for: (i) measuring a number of data points, corresponding to N da different values of frequency of modulation {f m,0 , f m,1 , f m,n , . . . , f m, Nda }, thereby obtaining at least one primary data series from each channel; (ii) performing one or more processing steps comprising at least part of said primary data series to obtain at least one secondary data series comprising N data points for the values of frequency of modulation {f 0 , f 1 , . . . , f N }; said processing steps comprises filling in data points with a filling series {f f,0 , f f,1 , f f,n , . . . , f f,N-Nda } comprising values of frequency of modulation not included in {f m,0 , f m,1 , f m,n , . . . , f m,Nda }; (iii) performing a transformation of said secondary data series from frequency domain to obtain at least one back scattering curve in space domain; (iv) optionally relating said back scattering curve(s) to one or more physical properties as a function of position, wherein N>N da .

15. The FMCW backscattering measurement system of claim 1 , wherein said filling series comprises previously measured data points.

16. A non-transitory computer readable medium comprising computer program code stored therein for causing a computer processor to perform a method for processing a data series obtained by frequency modulated continuous wave (FMCW), the data series comprising data points from one or more channels, the method comprising:

a. measuring a number of data points, corresponding to N da different values of frequency of modulation {f m, 0 , f m, 1 , f m, n , . . . , f m Nda }, thereby obtaining at least one primary data series from each channel,

b. performing one or more processing steps comprising at least part of said primary data series to obtain at least one secondary data series comprising N data points for the values of frequency of modulation {f 0 , f 1 , f n . . . f N }, said processing steps comprises filling in data points with a filling series {f f,0 , f f,1 , f f,n , . . . f f,N-Nda } comprising values of frequency of modulation not included in {f m,0 , f m,1 , f m,n , . . . , f m, Nda },

c. performing a transformation of said secondary data series from frequency domain to obtain at least one back scattering curve in space domain,

d. optionally relating said back scattering curve(s) to one or more physical properties as a function of position, wherein N>N da .

17. The FMCW backscattering measurement system of claim 1 , wherein the FMCW backscattering measurement system is an optical FMCW backscattering measurement system.

18. The FMCW backscattering measurement system of claim 2 , wherein the previously selected values are 1, 0 and/or 1+j.

19. The FMCW backscattering measurement system of claim 3 , wherein the data points are interpolated values, averages and/or the value of the closest measured data point.

20. The FMCW backscattering measurement system of claim 5 , wherein Δf f is equal to or less than ½Δf m , ⅓Δf m , ¼Δf m , ⅕Δf m , ⅙Δf m , 1/7Δf m , ⅛Δf m , 1/9Δf m , or 1/10Δf m .

21. The FMCW backscattering measurement system of claim 6 , wherein Δf f is equal to or more than 2Δf m , 3Δf m , 4Δf m , 5Δf m , 6Δf m , 7Δf m , 8Δf m , 9Δf m , or 10Δf m .

22. The FMCW backscattering measurement system of claim 9 , wherein the number of data points in the filling series is equal to or more than 2 times the number of data point in the primary data series, 3 times the number of data point in the primary data series, 4 times the number of data point in the primary data series, 5 times the number of data point in the primary data series, or 10 times the number of data point in the primary data series.

23. The FMCW backscattering measurement system of claim 8 , wherein the number of data points in the primary series is equal to or more than 2 times the number of data point in the filling data series, 3 times the number of data point in the filling data series, 4 times the number of data point in the filling series, 5 times the number of data points in the filling series, or 10 times the number of data point in the filling series.

24. The FMCW backscattering measurement system of claim 9 , wherein the end frequencies f max is a fraction of 1f N , ¾f N , ½f N , or ¼f N .

25. The FMCW backscattering measurement system of claim 10 , wherein the beginning frequency f min is ¾f N , ½f N , ¼f N .