Abstract: Techniques for estimating distances to irregularities on a subscriber loop are described. A loop response is measured in the frequency domain. The loop response is weighted by a prolate spheroidal wave function to yield a weighted response. The weighted response is transformed to a spectral domain, and peaks in the spectral domain are identified as the distances to the irregularities.

Abstract: Techniques for estimating distances to irregularities on a subscriber loop are described. A loop response is measured in the frequency domain. The loop response is weighted by a prolate spheroidal wave function to yield a weighted response. The weighted response is transformed to a spectral domain, and peaks in the spectral domain are identified as the distances to the irregularities.

Abstract: Techniques for establishing a connection between a calling party and a called party using the processing of a controller located on a customer premises and served by two incoming telephone loops or ISDN-type channels so as to minimize telephone costs, preserve privacy, and provide heretofore unavailable services. After a first telephony connection is established with the calling party over the secondary loop/channel, the calling party provides control information to the controller. The controller utilizes the control information to establish a connection over the primary loop/channel, and the primary and secondary loops/channels are bridged so that the calling party may monitor the call progression on the primary loop/channel and provide supplemental control information, as needed.

Abstract: Techniques for establishing a connection with a calling party and a called party using the processing of an intermediary serving arrangement so as to minimize telephone costs and preserve privacy. During a first established telephony connection, the intermediary arrangement stores two telephone numbers as remotely provided by the calling party. The calling party and serving arrangement are connected during a second established connection using the first telephone number. The called party and serving arrangement are connected during a third established connection using the second telephone number. Upon successfully establishing the second and third connections, the calling party and called party are bridged for conversation.

Abstract: Circuitry for detecting and estimating the frequency of a tone signal comprises: sampler (20) to discretize the tone signal into samples; discrete-time filter means (21) for processing the samples; control means (30) including oscillator (31) for driving the sampler and clock generating means (32, 33 and 34) for developing a set of clocking signals to sequentially drive the filter means, this set comprising the frequency of the oscillator and preselected submultiples thereof; threshold signal (24) indicative of the strength of the tone signal; comparator (22) for providing a resultant indication of the comparison between the threshold signal and the output of the filter means; and decoder (23) for converting the set of resultant indications obtained sequentially during each clock signal to yield the output estimate. Thus, the circuitry relies on the use of a single discrete-time filter initially driven by a filter that is successively expanded in correspondence to a clock which is successively decimated.

Abstract: Apparatus and method (FIG. 1) for testing inductively loaded telephone transmission lines for immittance irregularities approximate a ladder network of series inductors and shunt capacitors equivalent to the input impedance of the transmission line from the pole and zero frequencies of the differential phase versus frequency characteristic thereof. The differential phase function is obtained (FIGS. 5 and 6 combined or FIGS. 5 and 7 combined) as the Hilbert transform of the logarithmic difference between a direct and delayed impedance measurement extending over a swept-frequency range in the voice-frequency band. Inductance values of the ladder network are proportional to the inductances of the line loads and the capacitor values are proportional to the distances between load inductors spaced along a transmission line.

Abstract: A fault on a nonloaded telephone subscriber loop is sectionalized by a frequency domain distance detection system. The derivative with respect to frequency of the phase angle of the complex input impedance of a cable pair is continuously monitored over a swept-frequency range beyond the voice-frequency band. The phase itself is obtained indirectly as the Hilbert transform of the logarithmic differences between the instantaneous impedance and a delayed version thereof. Thus, circuitry which is less sensitive to noise, parameter variation, and measurement error than prior techniques becomes practical for generating waves having energy peaks corresponding to the distance from the measurement end of a loop under test to impedance irregularities therealong.