Abstract: A method of and system for rapidly locating all passive underground electronic marker types in an area under survey may locate various marker types simultaneously. In accordance with one aspect of the present invention, a marker locator may sequentially transmit and receive multiple frequencies very quickly; alternatively, the transmitter may transmit a broadband signal on multiple frequencies.

Abstract: A method of and system for locating a single passive underground marker type may distinguish false indications caused by other marker types. In accordance with aspects of the present invention, minimization or elimination of false marker indications may be accomplished by processing the response from a marker to determine which frequency has the largest response.

Abstract: A method and an apparatus for detecting signals in an electromagnetically noisy environment by detecting electromagnetic signals comprising a noise signal and a known signal, and compressing the electromagnetic signal to thereby generate a compressed signal. The compressed signal is filtered to generate a filtered signal comprising substantially the known signal, and the filtered signal is expanded.

Abstract: A method of and system for rapidly locating all passive underground electronic marker types in an area under survey may locate various marker types simultaneously. In accordance with one aspect of the present invention, a marker locator may sequentially transmit and receive multiple frequencies very quickly; alternatively, the transmitter may transmit a broadband signal on multiple frequencies.

Abstract: A method of and system for locating a single passive underground marker type may distinguish false indications caused by other marker types. In accordance with aspects of the present invention, minimization or elimination of false marker indications may be accomplished by processing the response from a marker to determine which frequency has the largest response.

Abstract: A pulse generator includes circuitry for starting a pulse in response to receipt of a pulse enable signal. The pulse enable signal is synchronous with a first time base. The pulse generator includes circuitry for ending the pulse after a predetermined, user selectable, number of clock cycles. The clock cycles have a second time base that is asynchronous with the first time base. Since the end pulse signal is not on the same time base as the pulse enable signal, there is up to one asynchronous clock cycle period random variation in width of pulses having the same nominal width.

Abstract: A time domain reflectometer transmission line interface includes a pulse driver for generating a transmitted pulse signal. A coupling transformer coupled to the pulse driver couples the transmitted pulse signal to a transmission line and receives a reflected pulse signal from the transmission line. A differential amplifier is coupled to the pulse driver and to the coupling transformer through a network configured such that said transmitted pulse is balanced at the inverting and non-inverting inputs of the differential amplifier.

Abstract: A method and an apparatus for detecting signals in an electromagnetically noisy environment by detecting electromagnetic signals comprising a noise signal and a known signal, and compressing the electromagnetic signal to thereby generate a compressed signal. The compressed signal is filtered to generate a filtered signal comprising substantially the known signal, and the filtered signal is expanded.

Abstract: An apparatus and method for characterizing a loading pattern of a twisted pair telecommunications transmission line includes a variable frequency signal generator and a measurement receiver connected to the twisted pair line. The signal generator applies a variable frequency signal to the twisted pair line and the measurement receiver acquires magnitude values representative of the impedance of the twisted pair line. A controller, operating under program control, models a plurality of baseline transmission line and twisted pair lines to generate magnitude values representative of the models. Error values are generated between the acquired magnitude values and the modeled magnitude values. The error values are compared to each other to determine the model with the minimum error value which is used as the model for charactering the twisted pair transmission line.

Abstract: A method and apparatus are provided for use in tracing transmission lines from a first location to a second location. The apparatus comprises a multi-channel speech synthesizer, a digital to analog convertor and a demultiplexer. The digital synthesized speech which can take any form is applied to a digital to analog convertor where it is transformed into an analog stream of distinct speech segments. In accordance with the corresponding method, the distinct speech segments are selectively connected by the multiplexer to one or more of the transmission lines to be traced. At the second location, the distinct speech segments are detected. As each distinct speech segment is associated with a particular transmission line, it is possible to distinguish between the many transmission lines which are being simultaneously traced.

Abstract: An apparatus and method are provided for use in tracing a cable; the apparatus and method allows a cable to be identified at any point along its length. The apparatus includes a transmitter for applying a unique waveform to a cable of interest, a line terminator for forming a cable loop through which current can flow, and a detector which is capable of detecting both voltage (electric field) and current (magnetic field). The unique waveform induces both a magnetic and an electric field in specifically identifiable patterns.

Abstract: An apparatus and method is disclosed for the location of faults occurring within transmission systems. The disclosed apparatus and method allows a user to adjust the center frequency of a pulse output by a standard narrow bandwidth time domain reflectometer, without altering the bandwidth of the output pulse. As a result, the detection of faults occurring at a wide range of frequencies is enabled--while the cost associated with widening the bandwidth of the transmitted pulse is not incurred. Moreover, due to the narrower bandwidth, efficient fault detection is achieved as well for high frequency systems as for low frequency systems.

Abstract: A sensor for permitting a signal carried on a tested conductor to be either inductive or capacitively coupled, in non intrusive manner, onto first or second output conductors includes a partially hollow material with high magnetic permeability wound by a first output conductor for permitting a signal carried on a tested conductor to be inductively coupled onto the first output conductor and a conductive material inserted partially within the hollow material and connected to the second output conductor for permitting a signal carried on a tested conductor to be capacitively coupled onto the second output conductor.

Abstract: An improved method and apparatus for detecting signals on a twisted pair of transmission lines includes a sensor for nonintrusively coupling a portion of the signal to the apparatus. A filter is coupled to the sensor and filters unwanted frequencies from the signal. The signal is then amplified and optionally passed to an identification circuit which identifies the presence of high and low frequency signals. The signal is rectified creating a DC signal proportional to the detected signal's strength. An audio tone proportional to signal strength is generated and the tone is amplified and output.

Abstract: An improved method and apparatus for achieving ping-pong communication over a single channel comprises a circuit (located at each communication station) which adjusts the transmission frequencies of two or more communicating stations such that each communicating station is transmitting at the same frequency as the other communicating stations. Additionally, the circuit provides a time delay between data receipt and data transmission at a given station such that data is not transmitted from the given station when data is being received by the given station. In the preferred embodiment cross coupled phase-lock loops are employed and the delay provided is such that a data pulse is transmitted half way between the receipt of two consecutive data pulses.

Abstract: An apparatus and method are provided for use in tracing transmission lines from a first location to a second location. The apparatus includes a signal generator, a timer/controller, a switching controller and a number of switches. In operation the switches are connected to transmission lines to be traced. The signal generator produces one or more unique signals. A unique signal pattern is applied to each transmission line by selectively opening and closing the switches connected to each transmission line, thereby allowing each transmission line to be traced from a first location to a second location by detection of the corresponding unique signal pattern.

Abstract: An improved method and apparatus for detecting signals on a twisted pair of transmission lines includes a sensor for nonintrusively coupling a portion of the signal to the apparatus. A filter is coupled to the sensor and filters unwanted frequencies from the signal. The signal is then amplified and optionally passed to an identification circuit which identifies the presence of high and low frequency signals. The signal is rectified creating a DC signal proportional to the detected signal's strength. An audio tone proportional to signal strength is generated and the tone is amplified and output.

Abstract: A device for measuring and isolating noise-creating imbalances in a paired telecommunications line has an internal circuit which includes a pair of substantially balanced ac current outlet pathways and a pair of high voltage bias pathways in parallel. An oscillator in the circuit generates a low voltage longitudinal ac signal that is transmitted across the balanced pathways and a dc power source simultaneously generates a high voltage dc signal that is transmitted across the high voltage bias pathways. Both signals are further transmitted to the paired line where it is the function of the high voltage dc signal to punch through any concealed faults in the line. In contrast, the low voltage ac signal travels the length of each conductor in the line and returns to the circuit as a metallic voltage signal. If there is any imbalance between the two conductors, the metallic voltage signals for the two conductors will be different.