Abstract: Improved telephone cable conductor pair identifier apparatus incorporates an "Expander" which is interposed at an appropriate location in the amplifier and filtering circuitry between the pick up probe and the audio signal emitter, or speaker. The "Expander" acts to accentuate the differences in the amplitudes of signals present, thereby significantly enhancing the effective sensitivity of a human operator to signal amplitude differences, with a resulting remarkable improvement in the ability of the human operator to readily and accurately locate and select a telephone cable conductor being sought. Switch means may be provided to permit the "Expander" to be bypassed at the will of the human operator, since it may be desirable to use the "Expander" only in the more difficult cases of conductor pair identification.

Abstract: Passive type electronic marker device is hoop shaped, with the hoop thickness in the radial direction being substantially less than the hoop width in the axial direction and with a tuned circuit disposed within the hoop. Improved structure and the method involves a mandrel portion on which the tuned circuit coil is wound, a mating cover band, and special peripheral hermetic seals.

Abstract: Systems and methods for locating re-access points along an underground conductor wherein tuned passive marker elements are disposed adjacent and alongside the conductor at the re-access points, a transmitted signal is coupled to the conductor to create a field about same such that a receiver that is swung to and fro laterally of the conductor by an operator traversing same will normally have a peak-null-peak output, but as a marker is approached the receiver will have a peak output in the normally null region due to a field generated by the passive marker element, thus permitting the location of the passive marker element to be precisely determined.

Abstract: Improved method and apparatus for measuring the capacitance of telephone cable pairs utilizes the technique of charging and discharging the cable pair being measured to respective predetermined voltage levels and integrating the discharge current while observing certain specified parameter requirements. This technique provides an output which is a linear function of the capacitance of the cable pair being measured and has the property of substantially infinite rejection of a predetermined (interference) frequency and its harmonics, and yet permits the apparatus to have requisite simplicity and economy.