Abstract: The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling device (204, 205, 206) for each transmitter (201, 202, 203), which sends to the computing device (208) a representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminal (207) with the representation sent back by the sampling device in the brightest transmitter is performed in the computing device (208), and an estimate of that brightest signal is subtracted from the representation sent back by the mobile terminal (207) in order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

Abstract: The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling device (204, 205, 206) for each transmitter (201, 202, 203), which sends to the computing device (208) a representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminal (207) with the representation sent back by the sampling device in the brightest transmitter is performed in the computing device (208), and an estimate of that brightest signal is subtracted from the representation sent back by the mobile terminal (207) in order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

Abstract: A method of calculating the position or state of motion of one or more terminals is proposed in which each has a receiver capable of making measurements of signals received from one or more transmission sources for use in calculating the unknown position or state of motion of the or each terminal. At least one transmission source has a known directional transmission pattern, and the bearing from one of the receivers of the or each of the transmission source having a known directional transmission pattern is estimated. Weights are assigned to the measurements made by the one receiver, the weights being calculated from the bearing or bearings and the known directional transmission pattern of the transmission sources.

Abstract: The invention concerns a method of determining the position or change in position or state of motion of a receiver or receivers, the position or change in position or state of motion of which is or are not already known, in a network of transmission sources some or all of whose positions are known. At a first time, the relative offsets in time, phase, frequency, or derivatives thereof with respect to each other, or with respect to a reference source, of the signals received by a first receiver from a plurality of the transmission sources are measured. At a selected second time, the respective offsets of the signals received by the same or a second receiver, whose position or state of motion is not already known, from the plurality of the transmission sources are measured.

Abstract: There is described a method of providing a positioning service for plural terminals operating in a communication network which may, for example be a GSM telephone network. The terminals have receivers for receiving signals from transmission sources. In the method measurements of the signals received from one or more of the transmission sources by the receivers are made and the measurements transferred to one or more data nodes. At the data node(s) one or more records of one or more of the measurements are created and at least some of the records are transferred to one or more computing nodes. At the computing node(s) a table of the records transferred to the computing node is maintained and a computation is carried out, using at least part of the table, from which the positions or states of motion or relative positions or relative states of motion of said plural terminals and the transmission time offsets of the transmission sources are extractable.

Abstract: The invention relates to a position determining system, for receiving digital telephone signals transmitted by a number of transmission sources BTS. The system has a pair of receiving stations, CBU and CRU, one at a known position O and another on a roving object R; a position determining processor CPP; and means for passing a link signal, L1 and L2, from each of the receiving stations to the position determining processor, the link signal containing information about the signals received at the receiving station from the transmission sources. Each of the receiving stations is arranged to receive the signals from the respective transmission sources substantially simultaneously. The position determining processor is arranged to compare the information received from the one receiving station with the information received at the other receiving station, and to determine the time delay between the respective signals received at both receiving stations in order to determine the position of the roving object.

Abstract: The invention relates to a position determining system, for receiving digital telephone signals transmitted by a number of transmission sources BTS. The system has a pair of receiving stations, CBU and CRU, one at a known position O and another on a roving object R; a position determining processor CPP; and means for passing a link signal, L1 and L2, from each of the receiving stations to the position determining processor, the link signal containing information about the signals received at the receiving station from the transmission sources. Each of the receiving stations is arranged to receive the signals from the respective transmission sources substantially simultaneously. The position determining processor is arranged to compare the information received from the one receiving station with the information received at the other receiving station, and to determining the time delay between the respective signals received at both receiving stations in order to determine the position of the roving object.

Abstract: A navigation and/or tracking system has a base station B and a roving receiver R both of which are capable of receiving signals from a plurality of transmission sources T.times.1,T.times.2. A link signal W,W' is passed between the base station and the roving receiver to enable the relative location of the roving receiver to be determined. The apparatus enables the determination of the position of the roving receiver within a space (such as a tunnel T) shielded from receipt of signals from the transmission sources and has equipment P,Q for producing substitute signals, each signal being locked in phase with a signal from a respective one of the transmission sources. A curvilinear transmission element or elements F,F',F", extend within the shielded space T for generating fields in the shielded space. The equipment P,Q propagates at least two of the substitute signals in opposite directions along the curvilinear transmission element or elements for receipt by the roving receiver R.