Abstract: The system has two units for transferring a telephone circuit from an old pair to a new pair between two locations. Each unit has a carrier amplitude measuring circuit to determine which location has the larger carrier amplitude and therefore which is the upstream location. Each unit has a charge switch, two transfer switches in the form of an old pair switch and a new pair switch and a controller for controlling the switches. One of the units closes its charge switch to charge the new pair to the dc level of the old pair. Then, the upstream unit operates its two transfer switches at the same time to switch from the old pair, by opening the old pair switch, to the new pair, by closing the new pair switch. The upstream unit transmits a signal to the downstream unit on a third pair. When the downstream unit receives the signal, it operates its two transfer switches at the same time to complete the transfer from the old pair to the new pair.

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 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 an improved method of testing conductor pairs in a telephone cable to determine presence or absence of a customer phone, its location relative to a cable throw or test location and the type of service. Certain types of trouble shooting tests can also be made. The improved method involves utilization of a Wheatstone bridge type connection wherein first and second legs have a common connection at one end to the central office direct current voltage source and consist respectively of a conductor of a pair in a first cable and its corresponding half tap conductor in a second cable; wherein a meter is connected between the first and second legs at the cable throw or test location; wherein a third leg comprises a customer telephone or a test pair; and wherein the fourth leg comprises either an open, or selectably either a variable resistance or a variable reactance, or both.