Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2002-10-08
2004-10-12
Nolan, Jr., Charles H. (Department: 2854)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S514000
Reexamination Certificate
active
06803770
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to systems and methods for testing multi-conductor cables and, more particularly, to a wireless multiconductor cable tester and method.
(2) Description of the Prior Art
Multiconductor cable is required for many electronic devices such as digital equipment to provide a plurality of signal paths for digital signals. A typical multiconductor cable may be comprised of many conductors to permit simultaneous parallel transmission of multiple digital signals, control signals, DC power levels, and the like. For instance, one typical multiconductor cable has a standard one hundred conductor construction with suitable connectors on either end. Depending on the type of installation, multiconductor cables may extend distances several hundred feet long. Many types of problems may arise with such cables including but not limited to, miswirings such as miswiring of appropriate pins on the plugs of opposite ends of the cable, open circuits or lack of continuity, shorts, and the like. In some cases, the multiconductor cable may be provided in standard sections, such as twenty-five foot sections, so that suitable lengths require connecting several different sections of the cable together.
During fabrication, closed loop testing of the multiconductor cable is facilitated because both ends of the uninstalled multiconductor cable are readily available for connection to a closed loop multiconductor cable tester. In this situation, it is possible to easily connect the closed loop multiconductor cable tester to automatically comprehensively test the cable because the plugs of opposite ends of the multiconductor cable are normally readily available for connection to the cable tester. The closed loop tester is able to test and measure test signals on each conductor in the multiconductor cable separately while monitoring all other conductors for miss-wires and other problem conditions.
After installation of the cable, the closed-loop multiconductor cable tester requires the use of an extender cable that must be temporarily installed between the closed-loop cable tester and the far end of the cable under test. Such temporary extender cables tend to be heavy. Storage, maintenance, relocation, set up, and the like, of these extender cables for testing purposes tends to be cumbersome, time consuming, and costly. Such cable may comprise twenty-five foot lengths with generic 100-pin connectors on each end. The extender cables are prone to damage when they are temporarily installed, removed, and reinstalled as a system installation progresses. The extender cables are usually laid out in general passageways where they are subject to abuse from foot traffic and other construction activities. The extender multiconductor cables inherently have a rather high susceptibility to damage due to the large number of conductors and connections therein as compared to, for instance, single conductor cable. The extender cables therefore frequently become a subject of test and repair, making tracing of the cause of problems more difficult. Damaged extender cables can significantly lengthen the system checkout process due to the introduction of additional errors during testing.
While the automated closed loop multiconductor cable tester has been preferred in the past, due to the difficulties of closed loop testing of installed multiconductor cables, an automated open loop multiconductor cable tester has also been developed. The open loop tester utilizes a shorting plug at the far end of the cable under test. The shorting plug connects all pins together. The open loop tester uses one pin (usually pin 1) as a return path. Then logic level signals are applied in sequence to each remaining pin in the connector as determined by a pre-stored wiring list. The open loop multiconductor cable tester senses if there is continuity in each individual conductor, records the results, and then sequences to the next pin. However, the open loop multiconductor cable tester does not detect all problems. For instance, if there is a miswiring problem, where the continuity of the incorrectly connected wires is otherwise good, the open loop multiconductor cable tester will not sense the error.
Various inventors have attempted to solve related problems as evidenced by the following patents, without providing the solutions taught hereinafter.
U.S. Pat. No. 3,986,106 issued Oct. 12, 1976, to Shuck et al, discloses a portable cable test set that includes a master unit connected to one end of a cable made up of multiple wire pairs and a remote unit connected to the other end. The master unit generates a series of digital pulses, a pulse being applied to a first wire of each wire pair in a predetermined sequence. The remote unit interconnects the wire pair with a resistor of predetermined resistance which differs from every other resistor and which is much greater than the resistance of the wire pair undergoing testing. A corresponding resistor of like value is included in the master unit and receives the same pulse that is applied to the wire undergoing testing. A comparator in the master unit compares the magnitude of the pulse sent over the wire pair with the magnitude of the pulse sent through the reference resistance in the master unit and a sequencer applies the next pulse to the next wire and next corresponding resistance when the preceding pulse magnitudes are equivalent. An interrupter stops the test sequence when the compared pulses are unequal in magnitude, and an indicator then identifies the wire pair having conditions activating the sequence interrupter.
U.S. Pat. No. 4,389,694, issued Jun. 21, 1983, to R. Cornwell, Jr., discloses a monitoring system for insuring the continuity and integrity of a power distribution system comprising a plurality of trailing cables, each trailing cable connected at a central station to a common power source and transmitting a power energizing signal to a load disposed at a remote location. In particular, the monitoring system comprises a transmitter and receiver for each trailing cable of the power distribution system whereby a monitoring signal is transmitted from the central station to the remote location and returned for detection by the receiver. If there is a fault condition within the trailing cable, the receiver provides a signal indicative thereof to be applied to a circuit breaker or coupling switch actuating the coupling switch to its open position thereby disconnecting the power from the trailing cable and its load. When a monitoring signal is successively transmitted and detected, the receiver provides a manifestation indicating the integrity and continuity of its trailing cable and actuates its coupling switch to its closed position, thus applying an energizing signal via its conductor to the load. The transmitter dedicated to each trailing cable includes means responsive to the frequency or frequencies of the previously generated monitoring signals, even from other transmitters, for generating a monitoring signal of substantially the same frequency whereby the monitoring signals as applied via the common AC power bus will be of substantially the same frequency. As a result, the monitoring system of this invention tends to eliminate the production of difference or beat signals and the resultant false indications of a fault condition within one or more of the trailing cables.
U.S. Pat. No. 5,027,074, issued Jun. 25, 1991, to E. C. Haferstat, discloses a cable tester for testing the individual conductors of a multiconductor cable. The cable tester includes a transmitter for connection to one end of the cable and a receiver for connection to the opposite end of the cable. The receiver includes a microprocessor having an EPROM memory. The receiver also includes an LCD display and a keypad for data input. In use the transmitter sequentially generates voltage pulses through each conductor of the cable and to the receiver. The receiver monitors these pulses at the opposite end of the cable and feeds this data in
Huot Raymond U.
Pereira Fernando J.
Kasischke James M.
Nasser Jean-Paul A.
Nolan, Jr. Charles H.
Oglo Michael F.
The United States of America as represented by the Secretary of
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