A METHOD FOR DETERMINING A DISTANCE TO A PASSIVE INTERMODULATION SOURCE, AN APPARATUS AND A COMPUTER PROGRAM PRODUCT

• US 20190312655A1
• Filed: 11/03/2017
• Published: 10/10/2019
• Est. Priority Date: 11/03/2016
• Status: Active Grant

• Current Assignee: Nokia Shanghai Bell Company Limited (Nokia Corporation), Universite De Rennes I
• Original Assignee: Nokia Shanghai Bell Company Limited (Nokia Corporation), Universite De Rennes I
• Inventors: HAREL, Jean-Pierre, DUTEIL, Gilles, LECAM, Patrick, COLOMBEL, Franck, AVRILLON, Stephane
• Granted Patent: US 10,735,111 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 23/20 Measurement of non-linear distortion
• CPC Class Codes: G01R 31/11 using pulse reflection methods
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/23 Indication means, e.g. displays, alarms, audible means
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/30 of propagation channels
• CPC Class Codes: H04M 3/085 Fault locating arrangements
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/04 Arrangements for maintaining operational condition
• CPC Class Codes: H04W 24/06 Testing, supervising or monitoring using simulated traffic

Abstract

A method for determining a distance to a passive intermodulation source in a device under test, the method comprising transmitting at least two signals with respective different frequencies to the device under test, receiving a complex response signal from the device under test, the complex response signal comprising a passive intermodulation of the at least two signals, generating an autocorrelation matrix using the complex response signal, the autocorrelation matrix representing power information of the complex response signal, decomposing the complex response signal, using the autocorrelation matrix, into a signal component part and a noise component part and determining a distance to the passive intermodulation source in the device under test using the noise and/or signal component part.

Claims

1. A method for determining a distance to a passive intermodulation source in a device under test, the method comprising:

(i) transmitting at least two signals with respective different frequencies to the device under test;

(ii) receiving a complex response signal from the device under test, the complex response signal comprising a passive intermodulation of the at least two signals;

(iii) generating an autocorrelation matrix using the complex response signal, the autocorrelation matrix representing power information of the complex response signal;

(iv) decomposing the complex response signal, using the autocorrelation matrix, into a signal component part and a noise component part; and

(v) determining a distance to the passive intermodulation source in the device under test using the noise or signal component part.

2. The method according to claim 1, wherein the passive intermodulation source corresponds to a fault in the device under test.

3. The method according to claim 1, wherein the complex response signal is filtered to remove components with amplitudes below a predetermined threshold.

4. The method according to claim 3, further comprising interpolating the filtered complex response signal to reconstruct phase information.

5. The method according to claim 1, wherein the complex response signal from the device under test is de-correlated from passive intermodulation signals generated from test equipment used to create the at least two signals.

6. The method according to claim 5, wherein a phase calibration signal is derived from the test equipment and is used to de-correlate the complex response signal from the passive intermodulation signals generated from the test equipment.

7. The method according to claim 1, further comprising:

transforming the complex response signal into a time domain signal using an inverse Fast Fourier Transform; and

applying a temporal window to the transformed complex response signal whereby to remove the passive intermodulation signals generated from the test equipment.

8. The method according to claim 1, further comprising applying a mechanical stress to the device under test so as to introduce additional passive intermodulation sources within the device under test.

9. The method according to claim 8, further comprising:

determining a relationship between a periodicity of the applied mechanical stress and the periodicity of the response signal; and

expurgating the response signal of all signals unrelated to the periodicity.

10. The method according to claim 1, wherein different states of a phase shifted network are measured whereby to determine the distance to the passive intermodulation source, the different states relating to respective different directions of an antenna main lobe pattern.

11. A computer program product embodied on a non-transitory computer-readable medium having computer readable program code embodied therein, said computer readable program code configured to be executed on a processor to implement a method for determining a distance to a passive intermodulation source in a device under test as claimed in claim 1.

12. An apparatus for determining a distance to a passive intermodulation source in a device under test, said apparatus comprising:

a vector network analyser arranged to transmit a test signal comprising at least two signals with respective different frequencies into the device under test;

one or more couplers arranged to transmit the test signal or to receive a passive intermodulation response signal from the device under test; and

a signal or data processor arranged to decompose the response signal, using an autocorrelation matrix of the response signal, into a signal component part and a noise component part, and to determine the distance to the passive intermodulation source in the device under test using the noise or signal component part.

13. The apparatus according to claim 12, further comprising one or more of:

a filter unit;

a stress unit arranged to apply a mechanical stress to the device under test;

a low noise amplifier; and

a phase shifter network.

14. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to

transmit a test signal comprising at least two signals with respective different frequencies into the device under test;

transmit the test signal or to receive a passive intermodulation response signal from the device under test; and

decompose the response signal, using an autocorrelation matrix of the response signal, into a signal component part and a noise component part, and to determine the distance to the passive intermodulation source in the device under test using the noise or signal component part.

15. The apparatus according to claim 14, further comprising a filter for filtering amplitudes that are not within predetermined thresholds.

16. The apparatus according to claim 14, further comprising a stressor configured to apply a mechanical stress to the device under test.

17. The apparatus according to claim 14, further comprising a low noise amplifier configured to improve a system noise floor.

18. The apparatus according to claim 14, further comprising a phase shifter network configured to enable pattern variations.