Abstract: Techniques for processing a navigation signal are disclosed. In one particular embodiment, the techniques may be realized as a method processing a navigation signal, the method comprising the steps of: receiving, using a receiver, the navigation signal, the navigation signal comprising a carrier signal, a data signal and at least one ranging code modulated by at least one stepped subcarrier modulation signal, the at least one stepped subcarrier modulation signal comprising a number, m, of amplitude levels, where m>2, and wherein the amplitude levels have respective magnitudes and durations arranged to influence the power spectrum of the navigation signal is constrained in a predetermined manner, processing the navigation signal to recover the modulated at least one ranging code; and processing the recovered at least one modulated ranging code to recover at least one demodulated ranging code.

Abstract: Embodiments of the present invention provide a method to produce a modulation signal comprising combining at least two modulation signals, for example, BOCs or derivatives thereof, having portions (chip or a number of chips) thereof with respective relative phases or states ({++,??} and {+?,?+}) selected such that the average of a plurality of said portions at least reduces cross spectral terms of the composite complex spectrum of said at least two modulation signals.

Abstract: Embodiments of the present invention provide a method to produce a modulation signal comprising combining at least two modulation signals, for example, BOCs or derivatives thereof, having portions (chip or a number of chips) thereof with respective relative phases or states ({++,??} and {+?,?+}) selected such that the average of a plurality of said portions at least reduces cross spectral terms of the composite complex spectrum of said at least two modulation signals.

Abstract: The present invention relates to a modulation system in which an m-level, m>2, digital subcarrier is used to modulate a signal.

Abstract: Embodiments of the present invention provide a method to produce a modulation signal comprising combining at least two modulation signals, for example, BOCs or derivatives thereof, having portions (chip or a number of chips) thereof with respective relative phases or states ({++, ??} and {+?, ?+}) selected such that the average of a plurality of said portions at least reduces cross spectral terms of the composite complex spectrum of said at least two modulation signals.

Abstract: A method of generating a subcarrier modulation signal for modulating a further signal, the method involving multiplexing or selectively combining portions of first and second subcarriers to produce the subcarrier modulation signal.

Abstract: Embodiments of the present invention provide a method to produce a modulation signal comprising combining at least two modulation signals, for example, BOCs or derivatives thereof, having portions (chip or a number of chips) thereof with respective relative phases or states ({++, ?} and {+?, ?+}) selected such that the average of a plurality of said portions at least reduces cross spectral terms of the composite complex spectrum of said at least two modulation signals.

Abstract: In a mobile unit housing a two-way communications subsystem and a satellite positioning system (SPS) receiver subsystem, the communications subsystem includes a training signal generator for generating a training signal mimicing a positioning signal transmitted by a remote SPS transmitter. The training signal is frequency-coupled to a reference frequency source contained within and used by the communications subsystem, which source is, itself, stabilized by means of communication with a remote station, e.g. a base station in a cellular telephone system. In a training sequence, the training signal is activated and coupled into the SPS receiver subsystem, and a replica signal generator for generating a carrier replica signal for position-fixing purposes is controlled so as to bring the carrier replica signal into aliment with the training signal. Information representative of the control setting of the replica signal generator corresponding to such alignment is stored.

Abstract: Apparatus for receiving ranging signals (e.g. signals from Global Positioning System satellites) has a receiver coupled to a plurality of spaced antennas. The receiver includes a signal combiner which receives, from a processing circuit, signal components individually representative of a characteristic of the received ranging signals (e.g. signal-to-noise ratio) at a respective antenna and weights the said components to produce a range estimate of improved accuracy in difficult reception conditions. In one embodiment receiver includes a common i.f. channel which filters a combination signal representative of all the incoming signals in order substantially to maintain phase coherence between the incoming signals, yielding improvements in carrier phase measurement and discrimination.

Abstract: Positioning apparatus for use in a moving vehicle includes circuitry arranged to process signals received from GPS satellites, and to provide signals in response thereto from which the position of the apparatus can be calculated at a remote station. The apparatus provides, for each satellite in view, carrier frequency estimation signals, samples of the carrier signals and code tracking signals to a data transmission device, which modulates the signals onto a carrier prior to transmission to the remote station. A carrier loop reconstruction device and a location processor in the remote station co-operate to determine the location of the positioning apparatus. A memory device may record signals received over a period of time, from which mission replay may be performed.

Abstract: In a mobile unit housing a two-way communications subsystem and a satellite positioning system (SPS) receiver subsystem, the communications subsystem includes a training signal generator for generating a training signal mimicing a positioning signal transmitted by a remote SPS transmitter. The training signal is frequency-coupled to a reference frequency source contained within and used by the communications subsystem, which source is, itself, stabilized by means of communication with a remote station, e.g. a base station in a cellular telephone system. In a training sequence, the training signal is activated and coupled into the SPS receiver subsystem, and a replica signal generator for generating a carrier replica signal for position-fixing purposes is controlled so as to bring the carrier replica signal into aliment with the training signal. Information representative of the control setting of the replica signal generator corresponding to such alignment is stored.

Abstract: Positioning apparatus for use in a moving vehicle includes circuitry arranged to process signals received from GPS satellites, and to provide signals in response thereto from which the position of the apparatus can be calculated at a remote station. The apparatus provides, for each satellite in view, carrier frequency estimation signals, samples of the carrier signals and code tracking signals to a data transmission device, which modulates the signals onto a carrier prior to transmission to the remote station. A carrier loop reconstruction device and a location processor in the remote station co-operate to determine the location of the positioning apparatus. A memory device may record signals received over a period of time, from which mission replay may be performed.

Abstract: Apparatus for receiving ranging signals (e.g. signals from Global Positioning System satellites) has a receiver coupled to a plurality of spaced antennas. The receiver includes a signal combiner which receives, from a processing circuit, signal components individually representative of a characteristic of the received ranging signals (e.g. signal-to-noise ratio) at a respective antenna and weights the said components to produce a range estimate of improved accuracy in difficult reception conditions. In one embodiment receiver includes a common i.f. channel which filters a combination signal representative of all the incoming signals in order substantially to maintain phase coherence between the incoming signals, yielding improvements in carrier phase measurement and discrimination.

Abstract: A tufting machine has a reciprocating needle bar which may be shifted laterally by a drive which includes at least one linear motor. Each linear motor has two major elements which may be coupled together electromagnetically. One of the elements is connected to a fixed portion of the tufting machine and another of the elements is connected to the needle bar. When electrical power is supplied to the motor, the element connected to the needle bar moves relatively to the other thereby moving the needle bar.