Abstract: A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Abstract: A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Abstract: A method of communicating datagrams between terminals (nodes) of a communications system. In systems operating over unreliable media, redundancy check data can be included in a datagram for use in verifying the integrity of the datagram when received by a terminal; and satisfactory receipt of the datagram can be confirmed by the receiving terminal issuing a response datagram to the originating terminal, for example an acknowledgement. The redundancy check data of a received original datagram (which redundancy check data includes information on the identity of the originating terminal and the content of the datagram) is utilized in the generation of new redundancy check data for the acknowledgement (or other type of response) datagram. The originating terminal receives and processes the response datagram in conjunction with its own local record of the redundancy check data of the original datagram.

Abstract: A method of communicating datagrams between terminals (nodes) of a communications system. In systems operating over unreliable media redundancy check data (136) can be included in a datagram for use in verifying the integrity of the datagram when received (112) by a terminal; satisfactory receipt of the datagram can be confirmed by the receiving terminal issuing (128) a response datagram to the originating terminal, for example an acknowledgement. The present invention utilises the redundancy check data (116) of a received original datagram (which redundancy check data includes information on the identity of the originating terminal and the content of the datagram) in the generation (122) of new redundancy check data for the acknowledgement (or other type of response) datagram. The originating terminal receives (130) and processes (134, 138) the response datagram in conjunction with its own local record of the redundancy check data (136) of the original datagram.

Abstract: A time-of arrival(TOA) method of determining the position of a cellular handset, for example a phone or a PDA, comprises causing the wireless terminal (MWT) to adapt to operate on a first network (GSM) having a plurality of first base stations (GSM 1 to GSM 3) and effecting position measurements with respect to ranging signals transmitted by one or more of the first base stations and causing the wireless terminal to adapt to operate on a second network (UMTS) having a plurality of second base stations (UMTS 1 to UMTS 3) and effecting position measurements with respect to ranging signals transmitted by one or more of the second base stations. The position measurements are combined and the position of the wireless terminal is determined from the combined measurements. The position fix may be determined by the wireless terminal (MWT) or a remote station to which the position measurements are relayed by the wireless terminal.

Abstract: A digital communication system including a transmitter and a receiver and wherein transmitted digital signal samples are modulated in accordance with a first constellation of modulated signal values. The receiver includes a phase locked loop for synchronizing digital sampling at the receiver with the received signal samples. The synchronism adjustment error is formed from a pseudo-error function which is a weighted combination of first and second errors, the first error being a function of the distance between received samples and the decisions made with respect thereto in the first constellation, the second error being a function of the distance between received samples and the decisions made with respect thereto in a second simplified constellation derived from the first constellation. A weighting is assigned to the second error which may, in one embodiment, be proportional to the first error.

Abstract: A receiver for use in a synchronous digital communication system wherein transmitted digital signal samples are modulated in accordance with a first constellation of modulated signal values. The receiver includes a phase locked loop for synchronizing digital sampling at the receiver with the received signal samples. The synchronism adjustment error is formed from a pseudo-error function which is a weighted combination of first and second errors, the first error being a function of the distance between received samples and the decisions made with respect thereto in the first constellation, the second error being a function of the distance between received samples and the decisions made with respect thereto in a second simplified constellation derived from the first constellation. A weighting is assigned to the second error which may, in one embodiment, be proportional to the first error.

Abstract: A decoder for a series of received digital signal samples which are encoded as points in a 2-dimensional constellation of points corresponding to authorized code values, which constellation is sub-divided into a plurality of subsets. The branch length .mu. between a received point and the closest authorized point in a subset is calculated as a function of the magnitude and sign of the error distance between the received point and the closest authorized point of the constellation, and of the displacement between successive authorized points in the subsets. It is thus possible to determine branch length without calculation of squared values and without employing any approximations.

Abstract: A predistortion arrangement (9) for a digital transmission system transmits complex input data of a constellation by means of a modulator (14) and a power amplifier (15) which distorts the data. The arrangement comprising a predistortion circuit (11) which predistorts the input data in opposite sense before they pass through the amplifier and a transmit filter (10) which applies oversampled filtered data encoded with 2N bits to the predistortion circuit (11) at the rate k/T. The predistortion circuit (11) is formed from an encoder (20) transforming the filtered 2N-bit encoded data into data encoded with 2M bits (M<N) which address a memory (51) that stores complex predistortion coefficients, and a complex multiplier (52) that multiplies for each data element the 2N bits of the filtered data element by the selected predistortion coefficient for producing predistorted data.

Abstract: A circuit for recovering the carrier of a digitally modulated wave having a phase symmetry 2.pi./M, wherein M is the order of the symmetry, includes means for automatic and fast acquisition comprising a voltage-controlled oscillator having an output supplying said carrier and a control input to which an error signal .epsilon.(.phi.) is applied in order to change the oscillator phase and to adjust it to the phase of the digital modulated wave. This wave is introduced in two channels, one being in phase and the other being in quadrature with the carrier, each comprising the series arrangement of: a demodulator, a low-pass filter, reconstruction means for reconstructing a signal and for determining the error between the filtered and reconstructed signals, the quadrature channel comprising in addition a 90.degree. phase shifter, the two channels being joined together with the aid of a phase comparator arrangement which produces a comparison signal and a variable-rate sampling clock.

Abstract: An adaptive equalizer arrangement for digital transmission system comprises at the output of the transmission channel a first in-phase path and in parallel with this first path, a second quadrature path, both paths being of the non-recursive transversal filter type having n branches and (n-1) delay circuits between the inputs of these branches, each of these n branches comprising, arranged in series, a mixer, a low-pass filter, a multiplier, and having their outputs connected to an adder which is followed by a sampling circuit and thereafter by a comparator circuit to decide the symbols to be transmitted from the outputs of these paths. The arrangement also comprises a third control path which comprises two subtracting circuits to determine the differences between the signals before and after decision and a control circuit of a voltage-controlled oscillator, 2n phase shifters and 2n multipliers.