Abstract: A system for preventing the distortion of data signals in a return frequency band by a laser on a return path of bidirectional communication network. The distortion of data signals is prevented by minimizing strong noise energy in the return band. The return frequency band is divided into a lower return frequency band and an upper return frequency band. The lower return band contains frequencies overlapping a noise floor with strong noise signals. The splitting of the upper and lower return frequency bands allows the upper return frequency band to be unaffected by the strong noise signals. The distortion by the strong noise signals on data signals at adjacent frequencies is minimized by transforming signals in the lower return frequency band to another form of signals that are not affected by strong noise energy.

Abstract: A system and method for demodulation of an RF signal on a transmission channel is provided. The RF signal is demodulated to baseband as an in-phase (I) data signal and a quadrature (Q) data signal. A first block of I data is captured and a first block of Q data is captured. A time domain guard interval is provided in the captured first blocks of I and Q data. A complex discrete Fourier transform is performed on the captured first I and Q data blocks. An inverse frequency response for the transmission channel is determined. The inverse frequency response is multiplied by the complex discrete Fourier transform of the guard-interval protected first I and Q data blocks to generate a frequency domain product signal. An inverse Fourier transform on the product of the multiplying step is performed to generate a first equalized time domain signal. In a preferred embodiment, the method also includes using an overlapped Fourier transform and discarding a first portion of each equalized time domain signal.

Abstract: Noise energy and other undesirable signals are suppressed in a return frequency band of a return path of a bidirection cable network. Data signals in a third frequency band and a prybar signal are transmitted on a user site to a mixing tap. The mixing tap contains a filter for eliminating signals in the return frequency band generated at the user site. The prybar signal is received by the mixing tap and activates a local oscillator. The third band signals and oscillation signals are applied to a mixer in the mixing tap and the third band signals are converted to return band signals. This mixing tap then applies the return band to the return path of the cable network.

Abstract: A bi-directional cable network having a hybrid return gate system that prevents undesirable energy in the bi-directional cable network's return path from adversely effecting the entire network whether the network is operating as a contention based network, a reservation based network, or combination of contention and reservation. The hybrid return gate system comprises a solid state radio frequency switch used to connect and disconnect the return path of a bi-directional communication path in conjunction with a transmission from one of a plurality of remote points. Transmissions from a remote point occur in one of a plurality of dynamically defined contention time slots or reservation time slots. At least one network monitoring time slot can also defined to monitor and/or test the bi-directional cable network. In one embodiment each return gate services a plurality of remote points downstream from the return gate. In a second embodiment each remote point has a dedicated return gate.

Abstract: A table for forming trusses that includes channels that do not unduly deform or bend during truss construction comprises: a support frame; first and second substantially horizontally-disposed elongate panels; a first channel having a generally horizontal floor and opposed side walls extending upwardly therefrom; and a locator stop. Each of the panels has an upper surface, a lower surface, and opposing lateral edge portions, and the panels are positioned so that their respective upper surfaces are substantially coplanar and so that a first of the lateral edge portions of the first panel is in adjacent, non-contacting relationship with a first of the lateral edge portions of the second panel, thereby forming a gap therebetween. One of the side walls of the channel supports the lower surface of the first panel, and the other of the side walls supports the lower surface of the second panel.

Abstract: A modulation and demodulation scheme for video signals may be used for HDTV signals using VSB-PAM, analog NTSC signals using VSB-AM and digital video signals using QAM. VSB-PAM modulation and demodulation may be performed using in-phase and quadrature baseband filters. By adjusting the filter taps, a single modulator structure may be used for QAM and VSB-PAM modulation. Similarly, a single demodulator structure may be used for QAM and VSB-PAM demodulation. This demodulator may also be used for VSB-AM modulation.

Abstract: A communication method enables a plurality of remote locations to transmit data to a central location. The remote locations simultaneously share a channel and there is a high degree of immunity to channel impairments. At each remote location, data to be transmitted is coded by translating each group of one or more bits of the data into a transform coefficient associated with a frequency in a particular subset of orthonormal baseband frequencies allocated to each remote location. The particular subset of orthonormal baseband frequencies allocated to each location is chosen from a set of orthonormal baseband frequencies. At each remote location, an electronic processor performs an inverse orthogonal transform (e.g., an inverse Fourier Transform) on the transform coefficients to obtain a block of time domain data. The time domain data is then modulated on a carrier for transmission to the central location.

Abstract: A bidirectional cable network having a signal distribution system that prevents undesirable energy in the bidirectional cable network's return path from adversely effecting the entire network. The signal distribution system a first signal transmitted in a forward path direction over the bidirectional communication path from a headend to a plurality of remote points. Signals transmitted in a return path direction are time division multiplexed on a series of cyclically reoccurring time slots where at least one of the cyclically reoccurring time slots is assigned to each of the plurality of remote points.

Abstract: A table for forming trusses comprises a support frame and first and second substantially horizontally-disposed elongate panels wherein each of the panels has an upper surface, a lower surface, and opposing lateral edge portions with a gap being formed between the panels. A first channel is also included and has a generally horizontal floor and opposed side walls extending upwardly therefrom. One of the side walls supports the lower surface of the first panel, and the other of the side walls supports the second panel. The floor is supported by the frame and is positioned beneath the gap. The table also includes magnetic positioning indicia mechanism located within the channel and magnetically attached to the first channel floor.

Abstract: A system for protecting software from copying wherein the software to be protected is placed on the computer system in two parts. A first part is stored in non-volatile storage, such as a hard disk or floppy disk within the computer system, and a second part is stored and executed in a "hardware key", which is attached to the computer system. The second part is stored in volatile RAM and will be erased when electrical power is removed from the hardware key, or when the software stops execution. This requires that the second part of the software be reloaded each time the hardware key is powered up. Typically, the second part of the software will be loaded from a network, or from a cable network, thus reloading of the second part into the hardware key is a trivial matter, so long as the user is an active subscriber to the network or cable network.

Abstract: An undesirable energy suppression system in a contention based communications network having a shared communication path between a plurality of remote points and a headend in a simplex network or a bidirectional network. The system includes a method and apparatus for transmitting a signal on the shared communication path from any one of the plurality of remote points contending for the shared communication path, to the headend. The signal includes a gate enabling signal also known as a prybar signal. The shared communication path includes a gate where the gate connects the shared communication path when the gate is closed, and the gate disconnects the shared communication path when the gate is open. The system controls the gate in response to receiving the gate enabling signal. Absent a gate enabling signal, any signal or other energy on the shared communication path will not propagate through the network because the shared communication path is disconnected.

Abstract: A table for forming trusses that includes channels that do not unduly deform or bend during truss construction comprises: a support frame; first and second substantially horizontally-disposed elongate panels; a first channel having a generally horizontal floor and opposed side walls extending upwardly therefrom; and a locator stop. Each of the panels has an upper surface, a lower surface, and opposing lateral edge portions, and the panels are positioned so that their respective upper surfaces are substantially coplanar and so that a first of the lateral edge portions of the first panel is in adjacent, non-contacting relationship with a first of the lateral edge portions of the second panel, thereby forming a gap therebetween. One of the side walls of the channel supports the lower surface of the first panel, and the other of the side walls supports the lower surface of the second panel.

Abstract: Disclosed is a method for treating asbestos to minimize the formation of airborne particulate of asbestos by applying to the asbestos an aqueous composition containing certain water-dispersible polymers. The method is especially useful when used in conjunction with the removal of asbestos from asbestos-coated objects.

Abstract: A set-up jig for a truss table is disclosed. The jig comprises (a) a body portion having a recessed portion on its lower surface configured to receive and slide upon a rail and further including a securing apeture and (b) stop means for constraining the movement of truss planks. A truss table suitable for use with such jigs is also disclosed.

Abstract: A system is disclosed which provides a significantly enhanced transmission rate for digital data transmitted over a channel, while also providing immunity to signal interference caused by multipath reception. One embodiment of the system transmits a signal containing digital data in the vertical blanking interval of a television signal. Before being transmitted, the digital data is modulated by a process called orthogonal frequency division multiplexing, or OFDM. A guard interval is optionally prefixed to the front end of the data signal to provide additional immunity to multipath interference. A further feature of the present system is the optional inclusion in the transmitted signal of an error correcting code which allows detection and correction of multiple sequential data transmission errors.

Abstract: Novel reciprocating engines which feature conversion units each formed of an expansion cylinder, a compression cylinder and a passageway connecting the two. Pistons in the cylinders are preferably connected via a four-bar or other linkage to the crank so that the compression piston remains at substantially top dead center for a substantial portion of the stroke of the expansion piston, and vice versa. Communication between the cylinders via the passageway may thus be continuously open with no substantial pressure drop between cylinders. Fuel may be injected into the air or other gas moving between cylinders giving an internal combustion engine, or the gas may be heated by external means. Devices according to this concept limit peak pressure and temperatures, resulting in the formation of fewer nitrous oxides.

Abstract: In order to facilitate the installation of off-premises equipment which distributes CATV signals from a distribution cable to subscribers and to allow different subscribers to receive different classes of service (basic service alone or with one or more premium or pay-per-view channels), a pair of housings are used, one containing circuits for tapping the signals from the cable and the other for electronics hardware which processes the signals and distributes them to subscribers in accordance with the class of service which is ordered by the subscribers. The housing containing the tapping circuits is permanently connected to the cable and need not be removed or replaced when connecting additional subscribers or changing the class of service. The housing containing the electronics hardware for processing the signals may be attached to or along side of the first housing. The first housing may be suspended from the strand which supports the cable in an aerial mount configuration.

Abstract: A method for treating fiber insulation to minimize the formation of dust and airborne particulate and waterproofing calcium silicate by applying to the insulation an aqueous composition containing certain water-dispersible polymers. The method is especially useful when used in conjunction with the removal of installed insulation.

Abstract: Mounts for satellite tracking antennas or other devices. Mounts according to the invention aim antennas or other devices at various satellites along the geosynchronous satellite arc by creating a mechanical analog of that arc and forcing the axis of the antenna or device to rotate through the analogous arc. This is accomplished by fixing an Earth center analog point and mechanically constraining the axis of the antenna or device to rotate about a site-analog point which is located vertically a predetermined distance from the Earth center analog point. A rotating arm through which the axis of the antenna or device may pass swings the axis through an arc which is in a plane parallel to the Earth's equatorial plane and which has the Earth center analog point at its center and a radius of 6.611 times the predetermined distance between the Earth center analog point and the site-analog point. The arm may be rotated to aim the antenna or device at various satellites along the geosynchronous satellite arc.