Using A Comparison Or Difference Circuit Patents (Class 324/647)
  • Patent number: 5068614
    Abstract: An improved swept frequency domain reflectometry instrument has an input/output terminal coupled to one end of a cable. A radio frequency at the input/output terminal is converted to an intermediate frequency using a swept local frequency. The radio frequency is derived from the swept local frequency and a variable offset frequency. A controller controls the variable offset frequency, monitoring the amplitude of the intermediate frequency. A period counter counts the intermediate frequency at a first maximum response of the intermediate frequency and further counts the offset frequency at a second maximum response of the intermediate frequency. The location of a discontinuity in the cable is calculated from the counted frequencies.
    Type: Grant
    Filed: November 5, 1990
    Date of Patent: November 26, 1991
    Assignee: Tektronix, Inc.
    Inventors: Walter D. Fields, Linley F. Gumm
  • Patent number: 5066921
    Abstract: A radome diagnostic system comprises a rotatably mounted turntable having support memebers for supporting a radome in a radome support area on the turntable, and a scanning assembly on the turntable for supporting a probe antenna in the radome support area and for translating the probe antenna in perpendicular x and y directions to cover a predetermined planar scanning area. A reference antenna is mounted on the turntable to provide a reference signal, and both the reference antenna and the probe antenna are connected to a suitable receiver for receiving signals from them and for suitably analyzing the collected data. A transmitter is located at a position remote from the turntable to direct radiation towards a radome mounted on the turntable. The probe antenna will detect radiation as degraded or modified by the effect of the presence of the radome in the radiation path. The reference antenna receives unperturbed radiation.
    Type: Grant
    Filed: August 1, 1990
    Date of Patent: November 19, 1991
    Assignee: General Dynamics, Electronics Division
    Inventors: Eugene L. Rope, Dary R. Stewart, Gus P. Tricoles, Gary L. Vance, Jonathan Roussos, Roy S. Luoma
  • Patent number: 5057783
    Abstract: Apparatus (1) for performing an electrical test on a cable (3) used in local area networks (LAN's). A source (37) produces electrical signals transmitted through the cable. A resistance circuit (43) is interposed between the source and the cable. The amount of resistance interposed by the resistance circuit is adjusted using an adjustment circuit (67). A sensor (71) senses a characteristic of the signal and determines when that characteristic has a value representing an inpedance match between the source and the cable. The sensor circuit provides a command to the adjustment circuit to thereafter maintain the point of adjustment at which the impedances are matched.
    Type: Grant
    Filed: February 16, 1990
    Date of Patent: October 15, 1991
    Assignee: Beckman Industrial Corporation
    Inventor: Andrew Gubisch
  • Patent number: 5053712
    Abstract: A method for comparing the quality of RF absorbers uses a TEM cell which is provided with a low-reflection termination, in which cell the absorber wall (5) is equipped with reference absorbers (13). A steep-edged pulse wave is radiated in by means of a pulse generator (9) and a scattered wave reflected by the test absorber (14) is detected by means of a sensor (10). A reflection of the absorber wall is then determined by means of a first calibration measurement. The reference absorber is removed in a test area and a reflection of a metal wall (8) lying behind it is then determined by means of a second calibration measurement. Finally, a reflection of the test absorber (14) arranged in the test area is determined in a comparison measurement.
    Type: Grant
    Filed: November 8, 1989
    Date of Patent: October 1, 1991
    Assignee: Asea Brown Boveri LTD.
    Inventor: Diethard Hansen
  • Patent number: 5017910
    Abstract: A monitoring or control system includes a plurality of senders or sensors which are coupled to a central control unit by separate cables. The control unit includes a microprocessor which executes an intermittent fault detection algorithm while an operator manually flexes each cable in turn. When a cable with a fault is manipulated the algorithm responds by energizing a horn.
    Type: Grant
    Filed: August 24, 1989
    Date of Patent: May 21, 1991
    Assignee: Deere & Company
    Inventors: Arnold S. Farber, Stephen P. Lang, David C. Smart
  • Patent number: 4994749
    Abstract: A fuel or fluid level measurement arrangement for a spacecraft includes one or more electromagnetic transmission lines extending into the reservoir. The presence of fuel adjacent the transmission line changes the dielectric constant or loss characteristics of the transmission line(s) in a measurable manner. In one embodiment, strip transmission lines extend parallel to the fluid surface at various degrees of ullage, and the fuel level can be established to within the spacing between the transmission lines.
    Type: Grant
    Filed: December 16, 1988
    Date of Patent: February 19, 1991
    Assignee: General Electric Company
    Inventors: Keith Davies, William H. Meise
  • Patent number: 4977377
    Abstract: A petroleum stream microwave water cut monitor includes test cell means which contains a reference petroleum multiphase fluid sample and which has a sample stream of a petroleum stream passing through it. The test cell is maintained at a predetermined temperature. A source provides microwave energy to one of a first pair of antennae which provides the petroleum stream flowing in the test cell or the reference sample in the test cell with microwave energy. One of a second pair of antennae receives the microwave energy that has passed through either the petroleum stream or the reference sample. A detector detects the received microwave energy and provides a signal corresponding thereto. An indicator provides an indication of the water cut of the petroleum stream in accordance with the received signal power and a phase difference between the source provided microwave energy and the received microwave energy.
    Type: Grant
    Filed: April 13, 1989
    Date of Patent: December 11, 1990
    Assignee: Texaco Inc.
    Inventors: Michael G. Durrett, David A. Helms, Gregory J. Hatton, Earl L. Dowty, John D. Marrelli, Joseph D. Stafford, David J. Stavish
  • Patent number: 4975968
    Abstract: Dielectrometry monitoring method and apparatus for three-dimensional profiling and colorable imaging of the material contents of articles carried on a conveyor through an interrogation region are disclosed. In a preferred embodiment, the apparatus includes a plural, stationary, collimated, microwave transmitter/receiver antennae array and associated electronics for measuring the dielectric constant of the materials to produce data for interpretation in real time as to the article's dielectric material configuration and contents. High-speed, GaAs gates and switching devices, as well as microstrip delay lines, are used to perform the precisely timed, depth-wise sampling of data reflective of dielectric-constant material characteristics, with sampling periods in the sub-nanosecond range.
    Type: Grant
    Filed: October 27, 1989
    Date of Patent: December 4, 1990
    Assignee: Spatial Dynamics, Ltd.
    Inventor: Tex Yukl