METHOD AND DEVICE FOR MULTICHANNEL MULTIFREQUENCY ANALYSIS OF AN OBJECT

• US 20100225303A1
• Filed: 04/24/2007
• Published: 09/09/2010
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Ou Eliko Tehnoloogia Arenduskeskus
• Original Assignee: Ou Eliko Tehnoloogia Arenduskeskus
• Inventors: Land, Raul, Haapalainen, Antti, Ronk, Ants, Kuusik, Alar, Parve, Toomas, Min, Mart, Annus, Paul
• Granted Patent: US 8,773,151 B2
• Time in Patent Office: Days
• US Class Current: 324/76.240
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: G01R 23/00 Arrangements for measuring frequencies; Arrangements for analysing frequency spectra

Abstract

A method for multichannel multifrequency analysis of an object, applying a set of excitation signals to the object and sampling the response signal from the object, using uniform and non-uniform undersampling. Non-uniform sampling of the response signal is performed, i.e., the sampling is performed for two or more different frequencies in one observation time slot. Also, uniform sampling of the response signal is performed, i.e., the sampling of a signal, corresponding to one frequency, is performed for two or more channels within one observation time slot and then sampling the same signal for another frequency for two or more channels within the next observation time slot.

Claims

1-30. -30. (canceled)

31. Method for multichannel multifrequency analysis of an object, comprising:

generating a set of excitation signals, said set comprising at least one component with a predetermined first frequency and applying said set of excitation signals to the object through an excitation electrode;

generating a set of phase related sampling instances, corresponding to said set of excitation signals;

receiving a response signal from the object through at least one response electrode; and

sampling said response signal with said set of phase related sampling instances, during a predetermined observation slot, wherein length of said observation slot is determined by said first frequency, so that the observation slot comprises an integer number of periods of the signal with first frequency.

32. A method for providing increased analog-to-digital conversion rate at required speed, the method comprising:

converting a first analog signal in first analog to digital converter to a first digital signal;

converting said first digital signal into a second analog signal in a digital to analog converter;

summing the first analog signal and the second analog signal;

amplifying the resulting signal by a factor, representing a required number of bits; and

converting the amplified signal into a second digital signal in a second analog to digital converter.

33. Method for multichannel multifrequency analysis of an object, comprising:

generating a set of excitation signals wherein all excitation signals are periodic signals with preselected frequencies;

applying said set of excitation signals simultaneously to the object;

receiving from the object, in response to said set of excitation signals, a response signal corresponding to said set of excitation signals, modulated by the object'"'"'s properties, said response signal comprising a set of components with different frequencies;

calculating a set of phase-related sampling instances based on said set of excitation signals, for each frequency of interest and for at least one predetermined observation time slot;

demodulating said response signal to separate the response to each excitation signal by quantizing and processing of said response signal at each sampling instances of said set of sampling instances, wherein said quantizing is performed for each frequency of interest of said response signal in predetermined mode; and

obtaining a set of main frequency and time tagged estimates, each of said estimates comprising a plurality of sub-estimates, said sub-estimates representing a signal value, for said observation time slot.

34. A method as in claim 33, wherein said response signal is sampled with predetermined sampling pattern within said observation time slot.

35. A method as in claim 34, wherein said response signal is sampled uniformly within said observation time slot.

36. A method as in claim 34, wherein undersampling is applied to demodulate at least one of said components of said response signal.

37. A method as in claim 33, wherein the length of said observation time slot is selected so that it contains integer numbers of periods of each excitation signal of said set of excitation signals, wherein each of said frequency tagged estimates are sorted separately so the estimates at each frequency of interest can be obtained while impacts of other estimates are cancelled out.

38. A method as in claim 34, wherein separating measurement channels in time domain is performed by uniformly sampling said response signal for one frequency of interest for every measurement channel in one observation time slot and for each additional frequency of interest for every measurement channel in corresponding additional observation time slot.

39. A method as in claim 34, wherein separating measurement channels is performed by non-uniformly sampling said response signal for each frequency of interest for one measurement channel in first observation time slot and for each frequency of interest for each additional measurement channel in corresponding additional observation time slot.

40. A method as in claim 39, wherein said response signal is quantized more than once at predetermined sampling rate for at least one sampling instance of said set of sampling instances.

41. A method as in claim 40, wherein said sampling instances are calculated, using said preselected frequencies of each excitation signal of said set of excitation signals and for each frequency of interest.

42. A method as in claim 41, wherein said sampling instances are estimated for said set of excitation signals and for each frequency of interest.

43. A method as in claim 33 wherein at least one frequency of interest of said response signal is compensated by a predetermined signal.

44. A method as in claim 33 wherein at least one frequency of interest of said response signal is compensated by an estimated signal.

45. A method as in claim 33 wherein at least one frequency of interest of said response signal is compensated using analogue compensation.

46. A method as in claim 33 wherein at least one frequency of interest of said response signal is compensated using digital compensation.

47. A method as in claim 33, wherein an inphase sampling is applied for said frequency of interest, wherein obtained inphase samples are used to separate inphase estimates.

48. A method as in claim 33, wherein a quadrature sampling is applied for said frequency of interest, wherein obtained quadrature samples are used to separate quadrature estimates.

49. A method as in claim 33, wherein a paraphase sampling is applied for each frequency of interest, whereas obtained paraphase samples are used for extracting an additive signal component or removal of an offset, or a common-mode noise by summing cancellation technique.

50. A method as in claim 49, wherein said preselected frequencies f_p of said excitation signals of said set of excitation signals are chosen according to formula

f_p=J_p*2^p−

1*f_R,

where J_p is an integer, p is an integer from 1 to P, where P is the number of excitation signals in said set of excitation signal, and f_R is a repetition rate of an excitation and measurement cycle.