A method for monitoring a line for a change in ambient conditions. The line includes a measurement line of a predetermined length which has a measuring conductor enclosed in an insulation with a known dielectric coefficient. An analog signal of defined frequency is generated and injected at a feed site. The signal is reflected at a predetermined reflection site and a resulting signal amplitude is measured at a defined measuring point. A measure for the ambient condition, particularly a temperature, is determined from the signal amplitude.

A method uses at least: one line made up of at least two conductors insulated by a material whose insulation impedance depends locally on the temperature, the line running through the installation; a reflectometer periodically transmitting a reflectometry signal at one end of the line, the signal being propagated along the line, the reflectometer measuring the echoes received and comparing the amplitudes of the echoes with a given reference; a hot spot being detected when the amplitudes of a given number of successive echoes are greater than the given reference, the echoes being provoked by a local reduction of the value of the insulation impedance.

A system and method for determining an object characteristic from a timed sequence of measured characteristics wherein the object characteristic is determined based on a comparison of a current measured characteristic against a variable reference characteristic. The variable reference characteristic is selected by iterating through the timed sequenced and determining a separate quality metric for the current measured characteristic against each earlier measured characteristic and selecting the variable reference as a function of the determined quality metrics. In one embodiment, iteration continues only until an earlier measured characteristics is found with a quality metric that meets or exceeds a threshold value. In another embodiment, iteration continues through a plurality of earlier measured characteristic (perhaps all) and the variable reference is selected as the earlier measured characteristic with the highest quality metric. The measured characteristics may include OFDR measurements.

A method for monitoring a line is done in a simple manner by feeding test pulses and determining any interference on the test pulses by reflected portions of the same test pulses. In a normal state of the line, the measuring pulses have a transit time which is known in advance due to the predetermined length of the line, and the respective reflected portions of the measuring pulses are generated which propagate in an opposite direction to the measuring pulses. A deviation of the transit time from a previously known transit time, and a deviation from the normal state are recognized in dependence on the overlay.

A method for monitoring a line for a change in ambient conditions. The line includes a measurement line of a predetermined length which has a measuring conductor enclosed in an insulation with a known dielectric coefficient. An analog signal of defined frequency is generated and injected at a feed site. The signal is reflected at a predetermined reflection site and a resulting signal amplitude is measured at a defined measuring point. A measure for the ambient condition, particularly a temperature, is determined from the signal amplitude.

A method monitors a line for changed ambient conditions. The line has a measuring line with a predetermined length and a measuring conductor surrounded by insulation having a known dielectric constant. In the method, an analog signal having a predetermined frequency is generated, the signal is divided into a reference signal and an operating signal, the operating signal is fed into the measuring conductor, a return signal obtained from the operating signal is combined with the reference signal and by a phase shift between the reference signal and the return signal, a measure is determined for the changed condition, particularly for a temperature change.

A system and method for determining an object characteristic from a timed sequence of measured characteristics wherein the object characteristic is determined based on a comparison of a current measured characteristic against a variable reference characteristic. The variable reference characteristic is selected by iterating through the timed sequenced and determining a separate quality metric for the current measured characteristic against each earlier measured characteristic and selecting the variable reference as a function of the determined quality metrics. In one embodiment, iteration continues only until an earlier measured characteristics is found with a quality metric that meets or exceeds a threshold value. In another embodiment, iteration continues through a plurality of earlier measured characteristic (perhaps all) and the variable reference is selected as the earlier measured characteristic with the highest quality metric. The measured characteristics may include OFDR measurements.

A method for detecting a hot spot at a connector (2) arranged on an electrical line, a heat-sensitive impedance module (4, 4a, 4b, 4c) being arranged at the connector (2), the electrical line and the heat-sensitive impedance module having an overall heat-sensitive impedance, the method comprising the following steps: determining a physical characteristic that is a function of said overall heat-sensitive impedance, and if said physical characteristic deviates from a predetermined reference value, emitting an alarm for detecting and locating a hot spot at said connector.

A method uses at least: one line made up of at least two conductors insulated by a material whose insulation impedance depends locally on the temperature, the line running through the installation; a reflectometer periodically transmitting a reflectometry signal at one end of the line, the signal being propagated along the line, the reflectometer measuring the echoes received and comparing the amplitudes of the echoes with a given reference; a hot spot being detected when the amplitudes of a given number of successive echoes are greater than the given reference, the echoes being provoked by a local reduction of the value of the insulation impedance.

A method for monitoring a line is done in a simple manner by feeding test pulses and determining any interference on the test pulses by reflected portions of the same test pulses. In a normal state of the line, the measuring pulses have a transit time which is known in advance due to the predetermined length of the line, and the respective reflected portions of the measuring pulses are generated which propagate in an opposite direction to the measuring pulses. A deviation of the transit time from a previously known transit time, and a deviation from the normal state are recognized in dependence on the overlay.