Abstract: A system that provides live television programming to passengers by integrating direct broadcast satellite services into an in-flight aircraft entertainment system. The present invention is a satellite television system that has an antenna disposed on the aircraft that is pointed at a plurality of satellites that are part of a direct broadcast satellite system. The antenna is controlled by an antenna controller and antenna interface unit that send control signals and process status signals to steer the antenna. The antenna is steered to lock it onto RF signals transmitted by the satellites. The antenna interface unit downconverts the received RF signals to provide left hand circularly polarized RF signals and right hand circularly polarized RF signals that contain different sets of television channels. The downconverted RF signals are processed by a receiver/decoder that decodes them to provide video signals corresponding to different television channels.

Abstract: A satellite television system that provides live television programming to passengers by integrating direct broadcast satellite services into an in-flight aircraft entertainment system. The system has an antenna disposed on the aircraft that is pointed at a plurality of satellites that are part of a direct broadcast satellite system. The antenna is controlled by an antenna controller and antenna interface unit that send control signals and process status signals to steer the antenna. The antenna is steered to lock it onto RF signals transmitted by the satellites. The antenna interface unit downconverts the received encoded RF signals to provide encoded left hand circularly polarized RF signals and right hand circularly polarized RF signals that contain different sets of television channels. The downconverted encoded RF signals are processed by a receiver to provide encoded video and audio signals of different television channels. The receiver does not decode or D/A convert the downconverted signals.

Abstract: The invention discloses several computation and control techniques which use historic information as well as other cues in order to enhance the accuracy of a radio position fix. These computational techniques include neural networks, mapped grid coefficients as input to a set of simultaneous or differential equations, and table lookup of correction coefficients for known low accuracy positions. The invention further discloses techniques for receiver array synchronization so that all system elements in a particular coverage area obtain a time reference appropriate for time of flight radio location measurements. The invention further teaches techniques to enhance the accuracy of a position fix by use of both fixed references, which are located in a coverage area, as well as a mobile reference carried by a search team. The invention also discloses techniques to provide information appropriate to guide a search team to an unknown positioned transmitter that is located within a building or structure.

Abstract: An adaptive polarization diversity system for radio link communication. The system includes a base station antenna for transmitting either a clockwise polarized transmission or a counterclockwise polarized transmission, the transmission including a training pilot signal. The system further includes at least one subscriber unit for receiving the transmission, the unit including a first subscriber unit antenna for receiving a clockwise polarized transmission, a second subscriber unit antenna for receiving a counter-clockwise polarized transmission, and a dual channel receiver for adaptively combining the clockwise polarized transmission with the counterclockwise polarized transmission in proportion to first and second weights, respectively, the dual channel receiver determining the first and second weights so as to substantially optimally receive the training pilot signal.

Abstract: In accordance with the present invention, a traveling wave coupler generates tracking signals from a circularly polarized microwave signal and includes a waveguide manifold for exciting circular TM.sub.01 and TM.sub.11 modes of said circularly polarized microwave signal. The waveguide manifold includes an input port, a propagation length, and an output port. A coupling arm waveguide includes an auxiliary input port and an auxiliary output port and is aligned and connected to the waveguide manifold along a portion of the propagation length. A coupler located between the waveguide manifold and the coupling arm transforms microwave energy of a TM.sub.01 mode of the circularly polarized microwave signal into a rectangular TE.sub.10 mode in the coupling arm waveguide. The coupling arm waveguide and the coupler generate a difference signal, used to generate the tracking signals, at the auxiliary output port related to the coupled TE.sub.10 mode.

Abstract: An interference nulling system is provided which nulls out all types of interference signals received in different lobes of the receiving antenna. The data to be received is transmitted from a high quality circular polarized transmitter antenna having the same polarization as the data receiving port of the receiving antenna. The receiving antenna also has a receiving port whose circular polarization is orthogonal to the antenna port receiving the data so that this latter channel contains only interference signals. The interference signals in this latter channel are correlated with the interference components in the data channel. A control loop is employed to adaptively adjust the phase (or delay) and amplitude of the sample of the interference signal and the adaptively adjusted interference signal is subtracted from the data signal which contains some of the interference signals, thus, providing a clean data signal.

Abstract: An adaptive interference canceller for use in a dual polarized radar system for receiving cross-polar and like-polar signals and generating an output signal corresponding to the received cross-polar signal with a like-polar interfering component cancelled therefrom. A modified adaptive filter is provided with a self-adjusting impulse response conforming to a least means square adjustment cancelling the influence of the like-polar signal, which is generally much stronger on the cross-point signal. The resulting output has a high target-to-clutter ratio and therefor a high probability of detection.

Abstract: A radar apparatus transmits right circular polarized signals and selects the right circular polarized components of the corresponding returns. It also transmits left circular polarized signals and selects the left circular polarized components of the corresponding returns. The selected left and right circular polarized compoments are processed by, for example, averaging them, producing a weighted average of them, or selecting the component of larger value.

Abstract: A radio wave receiving system comprises an antenna having at least two antenna elements, a phase shifter connected to at least one of the antenna elements, and a combiner for combining signals passed through the phase shifter and other signals not passed through the phase shifter. Through proper control of the mutual phase difference between signals from the aforementioned antenna elements by using the phase shifter, the system alters the polarization characteristic of the antenna in the direction of incidence of undesired reflected waves and consequently supresses the fading due to undesired reflected waves.

Abstract: A system for receiving signals from spatial objects comprising an array fed aperture antenna for producing multiple beam patterns covering a predetermined spatial volume a corresponding feed port for each beam pattern coupled to said array for producing an output when a signal is generated by an object within a corresponding beam pattern, a receiver for receiving the antenna array feed port outputs, and means coupled between the antenna array feed ports and the receiver for automatically coupling only the output of the feed port producing the greatest power to the receiver whereby automatic and continuous reception of signals from an object within the multiple beam pattern is accomplished. In addition, the invention relates to coherent summing of various combinations of the feed port outputs to provide a variable beam width pattern.