Reflectometry system for analysing defects in at least one transmission line, the system comprising a complex correlator

Patent metadata

Field	Value
Publication number	US-10969418-B2
Application number	US-201816634511-A
Country	US
Kind code	B2
Filing date	Jul 18, 2018
Priority date	Jul 28, 2017
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A reflectometry system includes at least one measurement means for measuring a reference signal retro-propagated in at least one transmission line, at least one analog-digital converter for converting at least one measured signal into a set of at least one first digital signal and one second digital signal, at least one complex correlator configured to correlate the real reference signal with a complex signal whose real part is formed by a first digital signal of the set and whose imaginary part is formed by a second digital signal of the set, so as to produce a first reflectogram corresponding to the real part of the complex signal and a second reflectogram corresponding to the imaginary part of the complex signal, an analysis module for analyzing at least the first reflectogram and the second reflectogram so as to identify the presence of defects in at least one transmission line.

First claim

The invention claimed is:

1. A reflectometry system for the analysis of defects in a group of transmission lines comprising at least one line (L,L 1 ,L 2 ), a generated real reference signal being injected into each transmission line (L,L 1 ,L 2 ) of said group, said system comprising:
at least one measurement means (CPL,CPL 1 ,CPL 2 ) for measuring the reference signal retro-propagated in each transmission line (L,L 1 ,L 2 ) of said group,
at least one analog-digital converter (ADC,ADC 1 ,ADC 2 ) for converting at least one measured signal into a set of at least one first digital signal and one second digital signal,
at least one complex correlator (COR,COR 1 ,COR 2 ) configured to correlate the real reference signal with a complex signal whose real part is formed by a first digital signal of said set and whose imaginary part is formed by a second digital signal of said set, so as to produce a first reflectogram corresponding to the real part of the complex signal and a second reflectogram corresponding to the imaginary part of the complex signal,
an analysis module for analyzing at least the first reflectogram and the second reflectogram so as to identify the presence of defects in at least one transmission line of said group.

2. The reflectometry system as claimed in claim 1 , wherein a complex correlator (COR,COR 1 ,COR 2 ) comprises a first Fourier transform module (TFD 2 ) able to receive on an input the reference signal and whose second input is set to zero, a second Fourier transform module (TFD 1 ) able to receive the first digital signal on a first input and the second digital signal on a second input, a multiplier (MUL) designed to multiply a complex signal delivered as output of the first Fourier transform module (TFD 2 ) with a complex signal delivered as output of the second Fourier transform module (TFD 1 ), and an inverse Fourier transform module (TFDI) designed to receive the complex signal delivered as output of the multiplier (MUL) and provide as output the first reflectogram on a real pathway and the second reflectogram on an imaginary pathway.

3. The reflectometry system as claimed in claim 1 , wherein said group of transmission lines comprises two transmission lines (L 1 ,L 2 ), said system comprising two analog-digital converters (ADC 1 ,ADC 2 ), the first digital signal and the second digital signal corresponding to the two respective transmission lines (L 1 ,L 2 ).

4. The reflectometry system as claimed in claim 1 , wherein said group of transmission lines comprises a single line (L), said system comprising a single analog-digital converter (ADC), a device (DEC) for decomposing a signal into several signals, with one input and an even number N of outputs, which is configured to receive the converted digital signal and to deliver, on each output, an undersampled, by a factor N, version of the input signal, and a multiplexer (MUX), with N inputs and one output, each input of which is linked to a respective output of a complex correlator, the multiplexer (MUX) being configured to produce as output a single reflectogram on the basis of at least the first reflectogram and the second reflectogram, said system comprising a number N/2 of complex correlators.

5. The reflectometry system as claimed in claim 4 , wherein the device (DEC) for decomposing a signal into several signals is configured to transmit each new sample received as input to a new output of index incremented by one modulo N, and the multiplexer (MUX) is configured to deliver as output, at each new instant, a new sample received on a new input of index incremented by one modulo N at each new instant.

6. The reflectometry system as claimed in claim 4 , wherein the sampling frequency (Fe ADC ) of the analog-digital converter is substantially equal to N times the sampling frequency (Fe DAC ) of the signal injected into the line and the processing frequency (F cor ) of the complex correlator(s) (COR,COR 1 ,COR 2 ) is greater than or equal to the sampling frequency (Fe DAC ) of the signal injected into the line and strictly lower than the sampling frequency of the analog-digital converter (Fe ADC ).

7. The reflectometry system as claimed in claim 4 , wherein the device (DEC) for decomposing a signal into several signals is configured to, transmit each new block of samples received as input to a new output of index incremented by one modulo N and the multiplexer (MUX) is configured to deliver as output, at each new instant, a new block of samples received on a new input of index incremented by one modulo N at each new instant, the system furthermore comprising a number N of input FIFO memories (FIFO e1 ,FIFO e2 ) each being connected between a distinct output of the device (DEC) for decomposing a signal into several signals and a distinct input of a distinct complex correlator (COR), the system also comprising a number N of output FIFO memories (FIFO s1 ,FIFO s2 ) each being connected between a distinct output of a distinct complex correlator (COR) and a distinct input of the multiplexer (MUX).

8. The reflectometry system as claimed in claim 6 , wherein the reference signal is periodic and the number of samples per block is equal to the number of samples per period of the reference signal.

9. The reflectometry system as claimed in claim 4 , wherein the sampling frequency of the analog-digital converter (Fe ADC ) is substantially equal to the sampling frequency (Fe DAC ) of the signal injected into the line and the processing frequency (F cor ) of the complex correlator(s) (COR,COR 1 ,COR 2 ) is at least equal to the sampling frequency of the analog-digital converter (Fe ADC ) divided by N and strictly lower than the sampling frequency of the analog-digital converter (Fe ADC ), divided by (N−2) if N is different from two.

10. The reflectometry system as claimed in claim 1 , comprising a generator of the reference signal (GEN), at least one digital-analog converter (DAC) and at least one injection device (CPL,CPL 1 ,CPL 2 ) for injecting the analog reference signal into each transmission line (L,L 1 ,L 2 ) of said group.

Assignees

• Commissariat Energie Atomique

Inventors

• Layer Christophe
• Cabanillas Esteban
• Cartron Mickael

Classifications

• G01R31/088

  Aspects of digital computing · CPC title

• G01R31/083

  in cables, e.g. underground · CPC title

• G01R31/11 Primary

  using pulse reflection methods · CPC title

• G01R31/085

  in power transmission or distribution lines, e.g. overhead · CPC title

• G01R31/08

  Locating faults in cables, transmission lines, or networks · CPC title