Abstract: Apparatus for calculating the position of a receiver in dependence on the time it takes signalling events to travel from a plurality of satellites to the receiver, obtains an indication of a transit time for a signalling event to travel from each satellite to the receiver, and forms an indication of an expected transit time for a signalling event to travel from the satellite to the receiver. The obtained indication of the transit time and the indication of the expected transit time for each non-reference satellite are compared with the obtained indication of the transit time and the indication of the expected transit time for the reference satellite to form residuals that are representative of a combined error in those indications of expected transit time; and the position of the receiver is calculate without calculating the integer ambiguities in the obtained transit times, in dependence on the residuals.

Abstract: Apparatus for calculating the location of a receiver by means of a location algorithm that generates a receiver location in dependence on signalling events received by that receiver from a set of satellites, the apparatus being arranged to select, from a constellation of satellites visible to the receiver, the set of satellites to use in the location algorithm in dependence on an effect that it is estimated using that set of satellites will have on the capability of the location algorithm to generate an accurate location for the receiver.

Abstract: Apparatus for calculating the location of a receiver in a satellite navigation system, the apparatus being arranged to calculate a location of the receiver by means of an algorithm that utilizes an estimate of receiver location and/or an estimate of absolute time, the apparatus being arranged to perform the calculation in such a way as to extend a convergence zone within which the algorithm is capable of generating the correct location for the receiver despite an error in the estimate(s).

Abstract: An apparatus for determining a location of a receiver by using signals received by the receiver from a number of satellites, the apparatus being configured to, when the receiver has been unable to decode a time-of-transmission from the satellite signals, determine a location for the receiver by use of an algorithm that takes an estimate of the location of the receiver as an input, and, when an estimate of the location of the receiver is unavailable, determine an approximate location of the receiver in dependence on the satellite signals and input that approximate location into the algorithm as the estimate of the location of the receiver.

Abstract: A method of controlling a power spectrum of a navigation transmission signal in a navigation system is provided. The navigation transmission signal comprising a carrier signal, a navigation ranging signal, a data signal, and at least one subcarrier modulation signal. The method comprising modulating the navigation ranging signal with the at least one subcarrier modulation signal, wherein the at least one subcarrier modulation signal comprises a number, m, of amplitude levels, where m>2, to produce a modulated ranging signal. The amplitude levels having respective magnitudes and durations arranged to influence the power spectrum of the navigation signal in a predetermined manner. Modulating the carrier with the modulated ranging signal and the data signal to generate the navigation signal.

Abstract: Techniques for controlling a power spectrum of a navigation transmission signal in a navigation system are disclosed. In one particular embodiment, the techniques may be realized as a method of controlling a power spectrum of a navigation transmission signal in a navigation system, the navigation transmission signal comprising a carrier signal, a ranging code, a data signal, and at least one stepped subcarrier modulation signal. The method may comprise modulating the canier signal by the at least one stepped subcarrier modulation signal, the data signal, and the ranging code to generate the navigation transmission ranging signal, wherein the at least one stepped subcarrier modulation signal may comprise a number, m, of amplitude levels, where m>2. The amplitude levels may be arranged to constrain the power spectrum of the navigation transmission signal in a predetermined manner.

Abstract: Apparatus for calculating the location of a receiver in a satellite navigation system, the apparatus being arranged to calculate a location of the receiver by means of an algorithm that utilises an estimate of receiver location and/or an estimate of absolute time, the apparatus being arranged to perform the calculation in such a way as to extend a convergence zone within which the algorithm is capable of generating the correct location for the receiver despite an error in the estimate(s).

Abstract: An apparatus for determining a location of a receiver by using signals received by the receiver from a number of satellites, the apparatus being configured to, when the receiver has been unable to decode a time-of-transmission from the satellite signals, determine a location for the receiver by use of an algorithm that takes an estimate of the location of the receiver as an input, and, when an estimate of the location of the receiver is unavailable, determine an approximate location of the receiver in dependence on the satellite signals and input that approximate location into the algorithm as the estimate of the location of the receiver.

Abstract: Apparatus for calculating the position of a receiver in dependence on the time it takes signalling events to travel from a plurality of satellites to the receiver, obtains an indication of a transit time for a signalling event to travel from each satellite to the receiver, and forms an indication of an expected transit time for a signalling event to travel from the satellite to the receiver. The obtained indication of the transit time and the indication of the expected transit time for each non-reference satellite are compared with the obtained indication of the transit time and the indication of the expected transit time for the reference satellite to form residuals that are representative of a combined error in those indications of expected transit time; and the position of the receiver is calculate without calculating the integer ambiguities in the obtained transit times, in dependence on the residuals.

Abstract: An apparatus for determining the location of a receiver in dependence on signalling events transmitted to the receiver by a satellite constellation comprising a reference satellite and one or more other satellites, the apparatus being arranged to, for each of the one or more satellites, compare an indication of the transit time of the signalling event transmitted by that satellite and an indication of the transit time of the signalling event transmitted by the reference satellite and calculate the location of the receiver in dependence on those comparisons; the apparatus being further arranged to determine, for each of the satellites in the constellation, an indication of an error that would be incorporated in the comparisons if that satellite were selected as the reference satellite and to designate one of the satellites in the constellation as the reference satellite in dependence on those indications.

Abstract: Apparatus for calculating the location of a receiver by means of a location algorithm that generates a receiver location in dependence on signalling events received by that receiver from a set of satellites, the apparatus being arranged to select, from a constellation of satellites visible to the receiver, the set of satellites to use in the location algorithm in dependence on an effect that it is estimated using that set of satellites will have on the capability of the location algorithm to generate an accurate location for the receiver.

Abstract: A method of processing received satellite radio signals is disclosed in which signals are received the signals from plural satellites through a common antenna. The received signals are digitised to produce a time-series of digitised signal samples and a plurality of replicas representing the signals of each of the plurality of satellites are obtained. At least one sample is selected from each of the replicas and the elements of a register are set equal to the selected replica samples. Thereafter, in turn, for each one of said digitised signal samples, the value of the digitised signal sample is combined with each of the values of the elements of the register to produce corresponding modified values; and the modified values corresponding to each of said register elements are accumulated.

Abstract: A method of and system for calibrating un-calibrated time information within a mobile terminal 101 is disclosed. The terminal has a receiver 203 capable of receiving signals from which calibrated time information carried by a calibrated system (a satellite positioning system) can be extracted, and a receiver 200 capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system (a cellular communications system) may be extracted. The time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system is determined at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available.

Abstract: A navigation system is described which includes a mobile terminal 100 which has a transmission source receiver 204 for receiving the signals from one or more unsynchronised terrestrial transmission sources 102-105 and a satellite positioning receiver 200 for receiving signals from the satellite or satellites 107-110 of a satellite positioning system. The terminal also has a clock 208. A processor 209 is arranged to acquire a measurement vector having a list of values, each value representing a measurement made by a receiver 200,204, and the terminal clock's bias. It computes a state vector representing the current state of the system, using a previously-determined state vector, the measurement vector, and a dynamic model in order to derive a dynamic navigation solution.

Abstract: A method is described, for use with an SPS mobile terminal receiver 102, of providing a compact assistance vector to initialize and constrain the computation of the terminal's location within a region of validity. The compact assistance vector is provided to a computing node 108 able also to obtain measurements from a mobile terminal satellite positioning system receiver within said region. For a known reference point 104 within the region, the range or ranges from the reference point to one or more satellites 101 of the satellite positioning system are obtained. The range or ranges are represented by a number or numbers of ranging code repeat intervals in a limited resolution format. The compact assistance vector is created from the representation or representations of ranging code repeat intervals and transferred to the computing node 108. The compact assistance vector can then be used to initialize a location computation for the SPS mobile terminal receiver 102.

Abstract: A method of and system for calibrating un-calibrated time information within a mobile terminal 101 is disclosed. The terminal has a receiver 203 capable of receiving signals from which calibrated time information carried by a calibrated system (a satellite positioning system) can be extracted, and a receiver 200 capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system (a cellular communications system) may be extracted. The time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system is determined at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available.

Abstract: A method of associating a universal time with time of arrival information of an identified component of a signal at a terminal of a radio positioning system is disclosed. In the method a marker signal with an associated universal time tag is obtained from a timing device (or the marker signal is obtained from an independent oscillator and a universal time tag assigned to the marker signal), and the time or phase relationship between the marker signal (or between the time of arrival information of said identified component respectively) and the oscillator is measured. The time of arrival information of said identified component relative to the oscillator is determined and the universal time corresponding to the time of arrival information of said identified component is calculated from said universal time tag and said measured time or phase relationship, before the calculated universal time is associated with said time of arrival information.

Abstract: A method of and system for calibrating un-calibrated time information within a mobile terminal 101 is disclosed. The terminal has a receiver 203 capable of receiving signals from which calibrated time information carried by a calibrated system (a satellite positioning system) can be extracted, and a receiver 200 capable of receiving signals from which un-calibrated time information carried by an un-calibrated stable system (a cellular communications system) may be extracted. The time offset between calibrated time information extracted from the calibrated system and un-calibrated time information extracted from the un-calibrated stable system is determined at a first terminal position where the signals from the un-calibrated stable system are available, the travel times of the signals from the un-calibrated stable system are known or determined, and the signals from the calibrated system are available.

Abstract: A method of processing received satellite radio signals is disclosed in which signals are received the signals from plural satellites through a common antenna. The received signals are digitised to produce a time-series of digitised signal samples and a plurality of replicas representing the signals of each of the plurality of satellites are obtained. At least one sample is selected from each of the replicas and the elements of a register are set equal to the selected replica samples. Thereafter, in turn, for each one of said digitised signal samples, the value of the digitised signal sample is combined with each of the values of the elements of the register to produce corresponding modified values; and the modified values corresponding to each of said register elements are accumulated.

Abstract: The invention provides a method of combining satellite positioning system signals and position information derived from such signals in a mobile terminal, when these are available at a first location, with cellular communication signals and a method, system and apparatus for determining the approximate position information for the said mobile terminal when SPS signals are not available at a second location. The approximate position is determined in the mobile terminal only using a position difference vector derived from the cellular communication signals using time offsets in a method based on the observed time difference of arrival. The computations of cellular position and position difference information are made within the network infrastructure. The invention provides for the security of the user as only position difference information is communicated over the air interface, or transmission time offset measurements which require non-transmitted information to determine a solution.