Spx Corporation

General Signal Corporation

William A DeCormier

Brett J Grandchamp

Cole Nason Plummer

John L Schadler

Andre Skalina

Jeffrey M Brown

David B Folsom

Philip C Noll

A monitoring system for an transmission line, such as a multi-channel television broadcasting antenna feed line, gathers data about the physical and electrical condition of the line in real time. The system can detect and localize deterioration and other time-dependent faults in the transmission line by the tendency of faults to produce reflections back to the transmitter that were not part of the original characterization of a particular installation. Some kinds of faults, identified early enough, can be corrected without replacing components, and especially without shutting down the transmission line during prime viewing hours. Other faults can be detected in time to order replacement parts before the underlying problem becomes severe, and to allow servicing during periods of low demand.

Apparatus and method for monitoring transmission systems using off-frequency signals

An apparatus and method stabilizes a pair of parallel coaxial lines for an antenna having a tower. An upper portion of each coaxial line is suspended from the tower. A lower end of the coaxial lines is free to move vertically relative to the tower. The apparatus has an expandable element disposed along a first portion of the length of one coaxial line and a frame which rigidly ties together the two coaxial lines at a second portion of each of the lines below the expandable element. One type of expandable element includes telescoping inner conductors and telescoping outer conductors.

Coaxial line phase stabilization assembly and method

A apparatus for joining coaxial line sections for high-power RF signals includes a feature that permits the impedance and the electrical profile of the inner joining element to remain comparatively uniform as the sections of coaxial conductor change dimensions with temperature. The apparatus for joining coaxial line sections further includes a feature in the outer joining element that compensates for impedance lumps caused by the nonuniform profile of the inner element at the joints.

Coaxial line section assembly and method with VSWR compensation

A signal mutiplexer that combines the NTSC and DTV signals of adjacent television channels into a composite signal for transmission on a common transmission line or wave guide. Separate hybrid couplers and band pass filters produce quadrature phase signals that are combined in a signal combiner to produce a pair of quadrature phase multiplexed signals. A notch filter reflects the aural component of the NTSC signal. An output hybrid coupler combines the pair of multiplexed quadrature phase signals with the reflected aural component to produce the composite signal.

Multiplexer for adjacent NTSC and DTV channels

An apparatus and method stabilizes a pair of parallel coaxial lines for an antenna having a tower. An upper portion of each coaxial line is suspended from the tower. A lower end of the coaxial lines is free to move vertically relative to the tower. The apparatus has a flexible section disposed along a first portion of the length of one coaxial line and a frame which rigidly ties together the two coaxial lines at a second portion of each of the lines below the flexible section.

A signal multiplexer for N channel signals of different frequency bands that utilizes only N&plus;1 hybrid couplers and presents a constant impedance to the transmitters that supply the N channel signals. The channel signals are coupled by separate ones of N of the N&plus;1 hybrid couplers to N pairs of matched band pass filters. The outputs of the filters are combined in a signal combiner to form a pair of quadrature phase multiplexed channel signals that are converted to a single multiplexed output signal by the remaining hybrid coupler. A selector mechanism operates to select one of the N inputs for connection to a load for test purposes.

Signal multiplexer and method

A sharp-cutoff VHF elliptic filter includes a folded signal path and internally coupled feedback in a conductive enclosure. Sized for the power requirements of commercial television broadcast transmission, the filter implements the elliptic filter equation through use of cavities, resonators, and couplers. The negative feedback required by the elliptic filter equation is implemented by folding the RF signal path and coupling the feedback energy through a gap in an internal septum to sum negatively with the signal in the main signal path. The elliptic filter can have an interdigital configuration, which puts successive resonators on opposite walls of the enclosure and couples the signal at half-wavelength spacing. The elliptic filter can alternatively have a comb line configuration, which places all resonators on one wall and employs full-wavelength spacing.

Very high frequency (VHF) sharp tuned elliptic filter and method

A signal multiplexer for N channel signals of different frequency bands that utilizes only N&plus;1 hybrid couplers and presents a constant impedance to the transmitters that supply the N channel signals. The channel signals are coupled by separate ones of N of the N&plus;1 hybrid couplers to N pairs of matched band pass filters. The outputs of the filters are combined in a signal combiner to form a pair of quadrature phase multiplexed channel signals that are converted to a single multiplexed output signal by the remaining hybrid coupler.

A broadcast switching system includes at least two sources, such as power amplifiers or transmitters; a waste or dummy load; and an antenna. A non-contacting switching arrangement for such a system includes directional or hybrid couplers for suitably cross-coupling portions of the signals from each of the sources. The present system is such that at least two couplers of nominally identical value may be employed regardless of input power ratios and yet, required power levels can be obtained at the outputs by reason of the deployment of phase shifters providing controlled phase delays over the entire range, which phase delays are precisely selectable for a full range of input power ratios. Although a nominal coupling value of -3 dB for the couplers may be utilized, the invention is not necessarily restricted to this value.

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Poland, ME, United States of America

William A DeCormier