Abstract: In a GPS or GSM system using DSSS signals, accurate and robust time-of-flight signal processing is achieved by selection of leading-edge or correlation techniques based on a variety of tests and environmental conditions.

Abstract: A device includes an antenna for receiving an incoming signal. A multiplier multiplies the incoming signal with an output from a carrier generator in order to mix down signal the incoming signal. The output of the multiplier is provided to correlators for sequential correlation with a replica code of the mixed down signal provided from a code generator, in order to produce correlation data including I (imaginary) and Q (real) channels. The correlation data is then passed to a signal processor which adjusts appropriately both the code generator and the carrier generator to provide accurate position measurement in indoor environments with multiple diffuse reflections.

Abstract: In a GPS or GSM system using DSSS signals, accurate and robust time-of-flight signal processing is achieved by selection of leading-edge or correlation techniques based on a variety of tests and environmental conditions.

Abstract: A positioning method uses backscattered signals from a radio station (10, 20) to locate the radio station within an area, for example in a room in a building. The difference between the measured backscattered signals and the expected signals is then found, and the difference is compared with data stored in an object database (37) to identify objects in the vicinity of the radio station (10, 20).

Abstract: Radio stations (10, 20) include a variety of propagation models. A radio signal is transmitted from a first to a second radio station, and the received signal is fitted to a plurality of models. Alternatively, the correlation of the received signals is fitted to models. The received signals are processed based on the best fit model, and the corresponding propagation effects. In some cases, the model can be used to correct for propagation effects. In other cases, other techniques such as beam steering can be used.

Abstract: A radio system (10) and radio system (1, 2) in which the value of parameters for a model of a received multipath signal transmitted by a remote station (20) are estimated. A sounding signal transmitted and received by the radio station is used to derive data about the reflecting environment and this data is incorporated into the model after scaling it to represent the multipath signal received from a remote station. Optionally or alternatively the remote station may transmit a sounding signal and derive data about its reflecting environment and transmit this data to the radio station, The model may incorporate both sets of derived data, particularly if they are uncorrelated. The values of the resulting parameters are exploited in applications such as ranging, location or equalization.

Abstract: A method of, and apparatus for, determining position, comprises a receiver (14) receiving a signal from a remote transmitter (22) whose position has to be determined. The Fourier transform of a power spectrum density of the received signal is determined and a check is made to see if a line-of-sight (LOS) signal is present. If so, a multipath mitigation technique is implemented to identify the LOS signal and once identified the position of the remote transmitter is determined by deriving the propagation time of the LOS signal. Current can be saved by inhibiting the multipath mitigation technique in the absence of detecting a LOS signal. In one embodiment the presence or absence of the LOS signal is determined by dividing the magnitude of the peak at zero frequency by the maximum magnitude of all the other peaks and if the answer is less than unity, LOS is not present.

Abstract: A radio station (10) in which the value of parameters for a model of a received multipath signal are estimated, the model comprising a value representative of the perpendicular distance between the plane of the reflecting surfaces (40, 50) and the radio station. This perpendicular distance may be measured from the round trip delay of a sounding signal transmitted by the radio station. The amount of computation is reduced by applying constraints to the parameters, and these constraints may comprise this perpendicular distance. The constraints may also be a function of parameters such as the path length, angle of arrival or amplitude of the direct path signal, and the amplitude of reflections of the sounding signal. The values of the parameters may be estimated initially by analysis of the received signals, followed by a parameter estimation process. The values of the resulting parameters are exploited in applications such as ranging, location or equalisation.

Abstract: A radio system (10) and radio system (1, 2) in which the value of parameters for a model of a received multipath signal transmitted by a remote station (20) are estimated. A sounding signal transmitted and received by the radio station is used to derive data about the reflecting environment and this data is incorporated into the model after scaling it to represent the multipath signal received from a remote station. Optionally or alternatively the remote station may transmit a sounding signal and derive data about its reflecting environment and transmit this data to the radio station, The model may incorporate both sets of derived data, particularly if they are uncorrelated. The values of the resulting parameters are exploited in applications such as ranging, location or equalisation.

Abstract: A radio station (10) in which the value of parameters for a model of a received multipath signal are estimated, the model comprising a value representative of the perpendicular distance between the plane of the reflecting surfaces (40, 50) and the radio station. This perpendicular distance may be measured from the round trip delay of a sounding signal transmitted by the radio station. The amount of computation is reduced by applying constraints to the parameters, and these constraints may comprise this perpendicular distance. The constraints may also be a function of parameters such as the path length, angle of arrival or amplitude of the direct path signal, and the amplitude of reflections of the sounding signal. The values of the parameters may be estimated initially by analysis of the received signals, followed by a parameter estimation process. The values of the resulting parameters are exploited in applications such as ranging, location or equalisation.