US 5,479,610 AGranted

System interface fault isolator test set

AssigneeNorthrop Grumman Corporation

InventorsDoru T. Roll-Mecak, Stanley Teich

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Abstract

A system interface fault isolator uses time domain reflectometry test techniques to isolate faults from only one end of a cable, a cable string or component without requiring removal of the cable or component from the system interface. A separate maintenance control unit includes a mass storage means for storing TDR or VSWR signatures of a variety of systems and comparing the signatures with data obtained by the TDR measurement board connected to the cable or component to be tested. VSWR data is obtained by processing the TDR data using software built-in the maintenance control unit. The control unit is programmable to accommodate a variety of different system interfaces, and bit status data can be downloaded directly to the control unit. Two adaptors are also provided, one of which is connected to the control unit to analyze a multi-line digital bus, and the other of which allows differential TDR measurements to be taken by the SI-FI on a MIL-STD-1553 bus.

Claims21

Dependent claims

A system interface fault isolator apparatus, comprising:

TDR/oscilloscope measurement circuitry housed in a measurement unit, said TDR/oscilloscope measurement circuitry including
means including a time domain reflectometer for performing time domain reflectometry tests on a signal cable, signal cable string, component in a system, or system interface in order to detect faults and determine their location;
and
means for measuring at least one parameter of a signal in said signal cable, signal cable string, component in a system, or system interface;
means for connecting the TDR/oscilloscope measurement circuitry to an input switch means which selects an appropriate input channel of the measurement unit;
means for connecting the measurement unit to said signal cable, signal cable string, component in a system, or system interface under test;
means for protecting the measurement unit from accidental ESD by discharging any capacitively stored energy present in said connection means before measurements are made;
means for detecting a live circuit condition at the input of the measurement unit;
a separate maintenance control unit which includes mass storage means for storing reference data, test limits data and test results data for a plurality of different components, systems or system interfaces under test;
means for connecting the maintenance control unit to the TDR/oscilloscope measurement circuitry to cause the reflectometer to perform a measurement and upload test results data to the control unit, and processor means for comparing the test results data with reference and test limits data stored in the mass storage means of said control unit.

7 more elements

A system interface fault isolator apparatus, comprising:

a portable measurement unit containing a plurality of test instruments connected by means including a bus to which additional instrument modules can be connected for performing different types of measurements on different types of interfaces;
and a separate maintenance control unit which includes mass storage means for storing system interface data for a plurality of different system interfaces and processor means for comparing the system interface data with data obtained from said test instruments under control of a program in said maintenance control unit.
wherein said plurality of test instruments includes means for measuring at least one parameter of a signal in a signal cable, signal cable string, component in a system, or system interface, said at least one parameter including at least one parameter selected from the group consisting of:
frequency, voltage, rise time, and pulse width;
means for protecting the measurement unit from accidental ESD by discharging any capacitively stored energy present in a connection means before measurements are made;
means for detecting a live circuit condition at the input of the measurement unit;
and means for connecting the measurement unit to said signal cable, signal cable string, component in a system, or system interface under test and for connecting the maintenance control unit to the measurement unit to cause the measurement performing means to perform a measurement of said at least one parameter and upload test results data to the control unit.

4 more elements

Dependencies are inferred from the claim text.