Abstract: A radar system is disclosed for forming a scanning receive beam from signals received by a phased array having a plurality of sub arrays. An exemplary radar system includes a plurality of phase units each configured to receive a signal from one or more sub arrays. Each phase unit includes a waveform generator configured to generate an analog waveform having a frequency corresponding to a time-varying phase shift. Each waveform generator is arranged to digitally generate the analog waveform, and output a comparison of the received signal with the waveform, incorporating the time-varying phase shift. The system further includes a combining unit configured to combine the outputs from the plurality of phase units to form a scanning receive beam.

Abstract: A positioning system (1) comprising one or more transmitters configured to transmit transmissions including positioning data, wherein the system is configured to synchronize the transmission with a reference time. The transmissions are formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips. The system (1) is configured to determine a timing bias (44;54) between the first transmission and the reference time. The system (1) is configured to change the number of chips in one or more of said transmissions such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.

Abstract: A positioning system (1) comprising one or more transmitters configured to transmit transmissions including positioning data, wherein the system is configured to synchronise the transmission with a reference time. The transmissions are formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips. The system (1) is configured to determine a timing bias (44;54) between the first transmission and the reference time. The system (1) is configured to change the number of chips in one or more of said transmissions such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.

Abstract: A radar system is disclosed for forming a scanning receive beam from signals received by a phased array having a plurality of sub arrays. An exemplary radar system includes a plurality of phase units each configured to receive a signal from one or more sub arrays. Each phase unit includes a waveform generator configured to generate an analog waveform having a frequency corresponding to a time-varying phase shift. Each waveform generator is arranged to digitally generate the analog waveform, and output a comparison of the received signal with the waveform, incorporating the time-varying phase shift. The system further includes a combining unit configured to combine the outputs from the plurality of phase units to form a scanning receive beam.

Abstract: A method of operating synthetic aperture radar in a low PRF mode, comprising generating a stream of radar pulses, imposing onto said stream a predetermined modulation of the Pulse Repetition Frequency (PRF), directing said stream to a target area, and processing received pulses, comprising separating the received pulses as a sequence of sets, and superposing received radar pulses of said sets, whereby to enhance the central received lobe and to attenuate side lobes.

Abstract: A method of operating synthetic aperture radar in a low PRF mode, comprising generating a stream of radar pulses, imposing onto said stream a predetermined modulation of the Pulse Repetition Frequency (PRF), directing said stream to a target area, and processing received pulses, comprising separating the received pulses as a sequence of sets, and superposing received radar pulses of said sets, whereby to enhance the central received lobe and to attenuate side lobes.