Abstract: A method of despreading a target spread spectrum signal containing pseudorandom noise (PRN) code sequences modulated by a data message is disclosed. The method comprises the steps of providing data message information relating to the timing of an epoch of at least one data bit; and performing a correlation of the target signal and a replica signal containing corresponding PRN code sequences using the data message information to minimise degradation of the correlation caused by variations in the PRN code sequences in the target signal attributable to modulation by the data message.

Abstract: GPS receiver (1) is disclosed together a mobile unit especially in the form of a mobile cellular telephone (30) incorporating the same. The GPS receiver (1) comprises a GPS signal antenna (10) for receiving externally transmitted GPS signals; an analogue-to-digital converter (11) coupled to the antenna for sampling the received GPS signals; a memory (12) for storing the GPS signal samples; and a digital GPS signal processor (13, 14) for retrieving pseudorange information from the GPS signal samples stored in the memory (12). The receiver (1) has a dormant mode of operation in which received GPS signals are sampled and stored in the memory (12) but the signal processor (13, 14) is not operative for retrieving pseudorange information, and an active mode of operation in which the signal processor (13, 14) is operative for retrieving pseudorange information.

Abstract: TV receiver apparatus (1) and a related method are disclosed, the TV receiver apparatus comprising a video signal receiver (2) for receiving video signals transmitted from an external video signal transmitter, a GPS signal receiver (3) for receiving GPS signals transmitted from an external GPS signal transmitter and signal coupling means (4) connected to both receivers. The signal coupling means is adapted to provide both receivers with respective video and GPS signals via a common antenna (5) where the antenna is adapted to receive terrestrially broadcasted video signals.

Abstract: A mobile unit (1) is disclosed for use with a cellular radio transmission system in the form of a plurality of base stations (BS1 to 7) adapted for two-way radio communication and situated at respective geographical locations to define a corresponding plurality of overlapping service areas (SA1 to 7) constituting one or more regions. The mobile unit comprises a receiver (5), control means (2) for controlling the mobile unit and a user interface (6, 9, 10) wherein the control means is adapted whereby, in use and having pre-programmed the control means with information identifying a predetermined service area, the control means recognizes entry of the mobile unit into that service area from an adjacent service area and notifies a user of the mobile unit of said entry via the user interface. The mobile unit may further comprising a transmitter (5) and be adapted to communicate by two-way radio with the base stations. The user may be notified with an audible, visible or mechanical alarm by the user interface.

Abstract: A selective call system comprises at least one base station which transmits address code words at a predetermined data rate. High rate telescript information having a length of more than 500 characters, for example, an E-mail message, is transmitted at a data rate greater than that used for sending address code words. In the event of the system comprising a simulcast system, intersymbol interference (ISI) may occur and in order to reduce the effects of ISI on the decoding the telescript information while avoiding an unnecessarily large drain on a secondary station's batteries, the telescript information as received for a specific secondary station is stored and subsequently equalized in non-real time. The secondary station can comprise a mobile terminal unit and may include a transmitter for transmitting acknowledgement or other response signals, for example, such as spread spectrum signals. The acknowledgement signals may be used for locating the mobile terminal unit.