Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-02-23
2002-02-05
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S543000, C324S538000
Reexamination Certificate
active
06344748
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a coaxial cable testing and, more particularly, to a coaxial cable testing methods and apparatus that detect intermittent and continuous opens and shorts at junctions between a coaxial cable and terminating coaxial cable connectors. The present invention is generally applicable to all types of connectors for coaxial cables including bayonet coaxial cable (BNC) connectors, threaded connectors and other currently available coaxial cable connectors and connectors which may become available in the future.
BACKGROUND OF THE INVENTION
Currently almost all customers of cable installation require the testing of every coaxial cable connector terminated in the field. To test coaxial cable connectors in the field, an installer can use a simple battery device with current running through the cables including the connector actuating a buzzer, LCDs, LEDs or a combination thereof to indicate opens or shorts. However, with a simple battery device it is very difficult or impossible to catch intermittent fault conditions because intermittent errors are often too short in duration for the buzzer or LCDs/LEDs to give any indication. Further, field installed cables to be tested often extend over hundreds of feet so that some prior art field testing devices require an installer at each end of the cable, one installer on one end of the cable with the testing device in hand in order to see or hear fault indications and the other installer at the other end of the cable to manipulate the coaxial cable connector on the other end of the cable.
In order to reduce this double testing effort, users can use a Bit Error Rate Test Set (BERT) to detect intermittent or continuous problems at the coaxial cable connector coaxial cable junctions. However, a BERT is very expensive and relatively bulkier than the above describe hand held testers making it difficult to transport in the field.
The prior art discloses a number of coaxial cable testing devices. U.S. Pat. No. 4,553,085 to Canzano discloses a coaxial cable tester device which detects shorts and opens in either the center conductor or the ground conductor of a coaxial cable and indicates the defective conductor. U.S. Pat. No. 5,391,991 to Tuttle discloses a cable shield resistance test set that measures degradation in cable shield without the need to disconnect the cable from the circuit. U.S. Pat. No. 5,477,152 to Hayhurst discloses a cable testing device that tests continuity and/or short circuits automatically in a cable. U.S. Pat. No. 5,565,784 to DeRenne discloses a coaxial cable testing and tracing device that allows the continuity of a plurality of coaxial cables to be tested and to individually locate a coaxial cable.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not disclose, teach or suggest a coaxial cable connector tester that checks for intermittent and continuous opens and shorts at the junction of the coaxial cable connector and coaxial cable.
In this respect, the coaxial cable connector tester device according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of testing for intermittent and continuous opens and shorts at the junction of the coaxial cable connector and the coaxial cable.
Therefore, it can be appreciated that there exists a continuing need for a new and improved coaxial cable connector testing device which can test for intermittent and continuous opens and shorts at the junction between a coaxial cable connector and a coaxial cable.
SUMMARY OF THE INVENTION
This need is met by the coaxial cable connector tester according to the present invention wherein a terminator plug is connected to one connector of a coaxial cable and the connector tester is connected to the other connector. The connector tester applies a voltage to the center conductor of the coaxial cable and a ground to the shield with the voltage at the center conductor being monitored for open and short fault conditions while the cable adjacent first one and then the other connector of the cable are wiggled to test the integrity of the connection of the connectors to the cable. The voltage level on the center conductor changes if either a short or open is present or intermittently occurs during the wiggle operation. To detect shorts and opens, the voltage on the center conductor is monitored by two comparator circuits with one detecting short faults, short comparator, and the other detecting open faults, open comparator. The outputs of the comparator circuits are combined to generate an OK signal if no faults are detected. If open faults are detected, the signals from the open comparator are clocked into a flip-flop and if short faults are detected, the signals from the short comparator are clocked into a flip-flop. Outputs from the flip-flops are counted by respective open and short fault counters and displayed so that the number of intermittent open and short faults, if any, are displayed up to the capacity of the counter and a display used for the tester, 0-8 for the illustrated embodiment. A buzzer can also be used selectively to provide an audible fault signal if desired. A power management circuit provides power to circuitry of the tester as demanded by a user and also monitors a battery so that an indication of low battery power can also be signaled to the user of the tester.
In accordance with one aspect of the present invention, a tester for junctions between a coaxial cable and coaxial cable connectors connected to the coaxial cable to test for intermittent and continuous open circuit and short circuit faults at the junctions comprises a cable terminator plug having a characteristic impedance and being coupled to a first end of a coaxial cable whose junctions are to be tested. An electronic testing circuit having a coaxial cable connector coupled to a second end of the coaxial cable to be tested comprises a test circuit coupled to the coaxial cable connector for detecting open and short circuit faults at one or both of the junctions. The electronic testing circuit generates open fault signals indicating detected open circuit faults, short fault signals indicating detected short faults and a no shorts
o opens signal indicating no detected short or open faults. An open counter coupled to the test circuit counts the open fault signals and a short counter coupled to the test circuit counts the short fault signals. A display circuit displays the counts accumulated in the open counter and the short counter to indicated to a user the number of each type of fault up to the capacity of the counters and the display.
The test circuit may comprise a first comparator coupled to the coaxial cable connector for detecting the open circuit faults and a first storage device responsive to the open circuit faults generates the open fault signals. A second comparator is coupled to the coaxial cable connector for detecting the short circuit faults and a second storage device responsive to the short circuit faults generates the short fault signals. Combination circuitry is coupled to the first and second storage devices for generating the no shorts
o opens signal. The storage devices may comprise flip-flop circuits and the tester may further comprise a battery with the tester being powered by the battery and a power management circuit for controlling power coupled from the battery to the electronic testing circuit. The power management circuit further monitors power of the battery and generates a visual warning displayed by the display circuit if a low power condition exists. Preferably, the power management circuit provides a first low power warning if the power is detected below a first threshold level and a second lower power warning if the power is detected below a second threshold level. For a three volt battery, the first threshold level is approximately 2.6 volts and the second threshold level is approximately 2.45 volts. T
Metjahic Safet
Nguyen Vincent Q.
Stevens & Showalter LLP
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