Abstract: An underground marker and methodology for locating the same is discussed. The marker has a tuned circuit and an energy storage device. The marker also has a transponder that is coupled to the tuned circuit. When the tuned circuit receives electromagnetic energy at its tuned frequency, the tuned circuit resonates and provides power to the energy storage device, which in turn powers a transponder. The transponder has a memory containing a coded signal. The transponder transmits this coded signal using the tuned circuit. The transponder alters the impedance of the tuned circuit in accordance with the coded pattern. In this manner, an addressable underground marker can be used to locate particular types of buried structures. Nonaddressable markers can be used to locate addressable markers by providing a reference point for searches.

Abstract: The marker has a housing, an inner member and a tuned circuit. The housing has a spherical cavity therein. The inner member is located inside of the housing cavity and is rotatable therein. The tuned circuit has an inductance in the form of a coil as well as a capacitance. The tuned circuit is tuned to a particular frequency. A weight is coupled with the inner member and is eccentrically located within the spherical cavity. The eccentrically located weight seeks the lowest portion of the housing cavity. Thus, when the marker is manipulated so as to disorient the tuned circuit, the weight will rotate the inner member back to its stable position so as to properly orient the tuned circuit coil.

Abstract: A passive electrical marker has tuned circuits, each of which includes a coil and a capacitance. The tuned circuits are oriented with respect to each other in a predetermined arrangement so as to provide a broader spatial response. A foamed core inside of the tuned circuits maintains the tuned circuits in their respective orientations and protects the tuned circuits from mechanical shock. A shell or housing around the foamed tuned circuits provides environmental protection to the tuned circuits. The tuned circuits can be foamed together in a mold and then placed into the housing. Alternatively, the tuned circuits can be foamed together inside of a housing, which housing maintains the orientations between the tuned circuits during foaming. As still another alternative, the housing can be applied to the outside of the foamed tuned circuits as a coating.

Abstract: A probe for use in sampling signals from a pair of telephone wires has two conductors that are separated from each other by an insulating material such as a circuit board. Each of the conductors has an overall size and has plural nonconductive interstices therein so as to reduce the capacitance of the probe. In one embodiment, each of the conductors is shaped like a comb having conductive strips. Each of the conductors could alternatively be shaped in a zig zag manner. The telephone wires are oriented parallel to the strips so as to enhance coupling therebetween. The probe can have plural channels thereon, such as two conductors on each side of the insulating material. The strips of one conductor are located in the gaps of the other conductor which on the same side of the insulating material. The probe can reduce common mode noise by being balanced. A grounded guard trace on each side of the insulating material snubs homogeneous electric fields.

Abstract: In a jack that receives a "make with break" plug or jack, there is provided a "make without break" plug. The jack has a circuit with a set of contacts that are normally closed. The circuit is opened by displacing one of the contacts out of contact with the other contact. With the make without break plug, only a minimal displacement of the jack contacts occurs. The plug minimizes the displacement of the jack contacts by limiting the physical size of the plug. A preferred embodiment utilizes a reduced radius to form a notch in the plug. This notch receives the jack contacts with little or no displacement of these contacts. Another technique used to minimize the displacement of the jack contacts is to limit the amount of force exerted by the plug against the jack contacts. The plug itself is provided with displaceable and pliant contacts. Less force is required to displace the plug contacts than is required to displace the jack contacts.

Abstract: Resistive faults are analyzed on a conductor in a telephone line by first charging the conductor to an initial voltage. The conductor is allowed to float for a finite amount of time, allowing some of the charge on the conductor to leak through any resistive fault. Then, the voltage of the conductor is measured and compared to the initial voltage. Loss of voltage indicates a resistive fault. This information can be used to provide an indication of the accuracy of a capacitance measurement and can be used to correct the capacitance measurement to account for the error due to the resistive fault.

Abstract: The apparatus has a balanced capacitive probe for collecting a small portion of a carrier signal on a pair of wires. The collected portion of the carrier signal is mixed with a local oscillator signal so as to produce a heterodyned signal having a low frequency component and a high frequency component. The frequency of the local oscillator signal is selected to be within a few Kilohertz of the carrier signal so that the low frequency component is within an audible range. A low pass filter removes the high frequency component. The low frequency component is amplified and converted to sound. The audible signal is a representation of the carrier signal and allows a technician to determine the relative strength of the carrier signal and to identify the type of carrier signal on the wire pair. The probe enhances discrimination between uncoupled signals and coupled signals such as cross-talk.

Abstract: The apparatus has a probe for collecting a small portion of a carrier signal on a pair of wires. The collected portion of the carrier signal is mixed with a local oscillator signal so as to produce a heterodyned signal having a low frequency component and a high frequency component. The frequency of the local oscillator signal is selected to be within a few Kilohertz of the carrier signal so that the low frequency component is within an audible range. A low pass filter removes the high frequency component. The low frequency component is amplified and converted to sound. The audible signal is a representation of the carrier signal and allows a technician to determine the relative strength of the carrier signal and to identify the type of carrier signal on the wire pair.

Abstract: The apparatus of the present invention includes an audio encoder and decoder, a memory, a transmitter and a receiver that are optically coupled to an optical fiber, and a controller. The audio encoder produces samples of an audio input at a regular rate. The samples are accumulated in the memory. When enough samples have been accumulated, the transmitter begins to transmit the accumulated samples over the optical fiber in a burst. After transmitting, the apparatus pauses long enough to allow reflections on the optical fiber to attenuate to an undetectable level. Then, the receiver is actuated to receive any incoming bursts of data, which are stored in memory until sent to the audio decoder.

Abstract: There is provided a master station for transmitting data bursts at predetermined periods of time. A slave station receives the master station data bursts and transmits a replying data burst upon the receipt of each master station data burst. The transmissions of the data bursts from the master and slave stations are interleaved so that there may be data bursts transmitted by both stations on the channel at the same times. The data bursts are interleaved so that the master station receives the slave station's data bursts between transmissions of data bursts by the master station.

Abstract: The resistance of a cable conductor between a measuring point and a conductive fault is measured using an electronically regulated current source and a very high resistance voltmeter in such a way as to eliminate contact and fault resistance as a source of error. Distance to the fault is determined by calculation from the known resistance per unit length.

Abstract: The invention provides methods of communication between two locations along a cable where the only metallic conductor available is grounded at numerous points along its length, which methods utilize a "distributed earth referenced carrier system" and wherein a first transceiver is electrically coupled to the metallic conductor at a first location and a second transceiver is electrically coupled to the metallic conductor at a second location.