Abstract: A diagnostic instrument distinguishes primary arcs from other electrical discharges in an electric power system based on pulse time density of radio frequency noise caused by the discharges. The instrument counts a maximum number of noise pulses in any small time window over a period, and identifies the discharges as primary arcs if the pulse time density is in a range characteristics of primary arcs.

Abstract: A diagnostic instrument for sources of electrical system discharges provides a map interface for controlling playback of collected signal traces. A map pane of the interface displays a map of an area illustrating a path along which signal data was collected. A double click input selecting a location on the path causes playback of a waveform for the recorded signal in a signal pane commencing from the selected location.

Abstract: An ultrasonic RFI source locator implements signal analysis to discriminate ultrasonic shocks emanating from power line equipment sources from ambient and other interference sources, as well as distinguish between specific type interference sources, such as corona and sparking discharge. The locator has a directional or contact ultrasonic sensor for receiving a signal representing the ultrasonic shocks from a targeted source, and includes signal processing circuitry to detect and compare the strengths of portions of the sensed signal that are modulated at whole integer multiples (harmonics) of an electrical power frequency (e.g., at 60 Hz and 120 Hz on a 60 Hz A/C power system, or 50 Hz and 100 Hz on a 50 Hz A/C power system) with each other, with the total signal and with selected non harmonic frequencies. The locator provides an operator indication of the result of this spectral analysis.

Abstract: Specific noise components in an input signal are identified and isolated for processing in a desired manner. The method comprises determining an interval during which the noise component is expected to occur and isolating a portion of the input signal occurring during that interval. Determination of the interval is made by sensing noise impulses in the input signal, temporally correlating the noise impulses, and estimating the time that the noise impulses are expected to recur. The input signal can then be passed during the interval to an output signal to enhance the noise component, or the input signal can be blanked from the output signal to reduce the noise component.

Abstract: When a fault in an energized power distribution cable flashes over, the surge draws charge from both sides of the line. The fault thus produces a pair of current surges that propagate from the fault in opposite directions along the line. These oppositely-directed current surges create pulsed electromagnetic fields of different directions which, in turn, induce voltages of different polarities in a receiving antenna positioned along the line. The polarity of the first such voltage pulse induced in the antenna indicates the direction from the antenna to the fault. In one embodiment, the line is repeatedly "thumped," causing flashovers to recur at the fault. By moving the antenna along the line until the polarity of the initial received pulse inverts, the precise location of the fault can be determined.

Abstract: Specific noise components in an input signal are identified and isolated for processing in a desired manner. The method comprises determining an interval during which the noise component is expected to occur and isolating a portion of the input signal occurring during that interval. Determination of the interval is made by sensing noise impulses in the input signal, temporally correlating the noise impulses, and estimating the time that the noise impulses are expected to recur. The input signal can then be passed during the interval to an output signal to enhance the noise component, or the input signal can be blanked from the output signal to reduce the noise component.

Abstract: A system is provided for mounting directional antennas on vehicles. The mounting system employs a conventional roof rack as a support base for the antenna mount. In one embodiment, a straight tubular frame member is attachable to the roof rack. An upwardly-extending rotatable shaft extends from adjacent one end of the frame, for supporting the antenna mast, and a downwardly-extending rotatable shaft, supporting a control handle, extends from adjacent the other end of the frame. The rotational movements of the shafts are tied together by a toothed belt which engages sprockets coupled to the shafts. In its preferred form, the control handle includes tactile positioning indicators on its surface which allow the user to sense the direction of the antenna without having to view it. A second embodiment is disclosed which uses a portion of a tubular horizontal bar on a conventional roof rack as part of the support frame of the device.