Method and apparatus for performing optical time domain reflectometry

Claim 3

Method according to claim 1, wherein the common basic sequence comprises a set of complementary sequences.

Claim 4

Method according to claim 2, further comprising: successively injecting a plurality of complementary sequences into the light transmitting medium with the number (X-1) of inserted light signals being different from each other for different injections, and superposing the correlation results of the individual injections for generating a composite measurement result, thereby reducing the magnitudes of sidelobes relative to the magnitudes of peaks originating from reflections in the light transmitting medium.

Claim 5

Method according to claim 2 or 3, further comprising: determining the positions of peaks originating from reflections in the light transmitting medium, and calculating all possible sidelobe positions according to the equation SP=PP±iX; wherein SP denotes the sidelobe positions, PP denotes the peak positions, and i may be any integer from 1 to L-1, L being the length of the basic sequence, and replacing measured data values at sidelobe positions by calculated data values such that the calculated data values approximate adjacent sample values.

Claim 6

Method according to claim 2 or 3, further comprising: selecting the number (X-1) of inserted light signals such that the sidelobe positions for different injections do not overlap, and replacing data values representing distortions by sidelobes by sample values from another injection wherein the sample values at the sidelobe positions are not disturbed, thereby obtaining sample values which are substantially free of distortions by sidelobes.

Claim 7

Method according to claim 2, further comprising: successively injecting a plurality of complementary sequences into the light transmitting medium with the number (X-1) of inserted light signals being different from each other for different injections, and superposing the correlation results of the individual injections, thereby generating a composite measurement result and reducing the magnitudes of sidelobes relative to the magnitudes of peaks originating from reflections in the light transmitting medium, wherein the numbers X for different injections are prime relative to each other.

Claim 8

Method according to claim 2 or 3, further comprising: selecting the number (X-1) of inserted light signals such that the sidelobe positions for different injections do not overlap, and replacing data values representing distortions by sidelobes by sample values from another injection wherein the sample values at the sidelobe positions are not disturbed, thereby obtaining sample values which are substantially free of distortions by sidelobes, wherein the numbers X are prime relative to each other.

Claim 9

Method according to claim 1, wherein the common basic sequence comprise complementary sequences, and further comprising: successively injecting a plurality of complementary sequences into the light transmitting medium with the number (X-1) of inserted light signals being different from each other for different injections; superposing the correlation results of the individual injections thereby generating a composite measurement result and reducing the magnitudes of sidelobes relative to the magnitudes of peaks originating from reflections in the light transmitting medium; determining the positions of peaks originating from reflections in the light transmitting medium; calculating all possible sidelobe positions according to the equation SP=PP±iX; wherein SP denotes the sidelobe positions, PP denotes the peak positions, and i may be any integer from 1 to L-1, L being the length of the basic sequences, and replacing measured data values at sidelobe positions by calculated data values such that the calculated data values approximate adjacent sample values; selecting the number (X-1) of inserted light signals such that the sidelobe positions for different injections do not overlap; and replacing data values representing distortions by sidelobes by sample values from another injection wherein the sample values at the sidelobe positions are not disturbed, thereby obtaining sample values which are substantially free of distortions by sidelobes.

Claim 10

Method according to claim 1, wherein the common basic sequences comprise complementary sequences, and further comprising: determining the positions of peaks originating from reflections in the light transmitting medium; calculating all possible sidelobe positions according to the equation SP=PP±iX; wherein SP denotes the sidelobe positions, PP denotes the peak positions, and i may be any integer from 1 to L-1, L being the length of the basic sequences; replacing measured data values at sidelobe positions by calculated data values such that the calculated data values approximate adjacent sample values; selecting the number (X-1) of inserted light signals such that the sidelobe positions for different injections do not overlap; and replacing data values representing distortions by sidelobes by sample values from another injection wherein the sample values at the sidelobe positions are not disturbed, thereby obtaining sample values which are substantially free of distortions by sidelobes.

Claim 11

Apparatus for performing optical time domain reflectometry on a light transmitting medium, comprising: light injection means for injecting a predetermined time sequence of light signals into the medium, a word generator connected to the light injection means for generating sequences of electrical pulses for activating the light injection means such that at least two different time sequences of light signals are injected into the light transmitting medium, with the different sequences being derived from a common basic sequence by insertion of a predetermined number of light signals of the same power level after each light signal of the basic sequence, and with the different time sequences differing from each other by the number (X-1) of the inserted light signals, detection means for detecting the light signals reflected from the light transmitting medium, signal processing means for correlating the detected signals from the light transmitting medium with the injected signals, and display means for displaying the correlated results.

Claim 12

Apparatus for performing optical time domain reflectometry on a light transmitting medium, comprising: light injection means for injecting a predetermined time sequence of light signals into the medium, a word generator connected to the light injection means for generating sequences of electrical pulses for activating the light injection means such that at least two different time sequences of light signals are injected into the light transmitting medium, with the different sequences being derived from a common basic sequence by insertion of a predetermined number of light signals of the same power level after each light signal of the basic sequence, and with the different time sequences differing from each other by the number (X-1) of the inserted light signals, detection means for detecting the light signals reflected from the light transmitting medium, signal processing means for correlating the detected signals from the light transmitting medium with the injected signals, and display means for displaying the correlated results.