Abstract: A system and method measures the time offsets of a plurality of acoustic sensor nodes relative to a reference time. The system includes an acoustic transceiver arranged to transmit a first signal to each acoustic sensor node and a processing resource arranged to record the transmission time of the first signal relative to the reference time. The acoustic sensor nodes receive the first signal and transmit a return second signal to the acoustic transceiver after a predetermined time delay, the second signal including the current acoustic sensor node internal time. The acoustic transceiver receives the second signal, and the processing resource records the time at which the second signal was received relative to the reference time and records also the combined time of flight of the first and second signal. From this data the time offset between the sensor node internal time and the reference time is calculated.

Abstract: A system and method measures the time offsets of a plurality of acoustic sensor nodes relative to a reference time. The system includes an acoustic transceiver arranged to transmit a first signal to each acoustic sensor node and a processing resource arranged to record the transmission time of the first signal relative to the reference time. The acoustic sensor nodes receive the first signal and transmit a return second signal to the acoustic transceiver after a predetermined time delay, the second signal including the current acoustic sensor node internal time. The acoustic transceiver receives the second signal, and the processing resource records the time at which the second signal was received relative to the reference time and records also the combined time of flight of the first and second signal. From this data the time offset between the sensor node internal time and the reference time is calculated.

Abstract: Measuring apparatus for providing information on the relative location of a target site which is radiating a target signal that includes a predetermined pulse signal, comprises receiver means for providing a pair of temporally spaced output pulses in response to a single received said predetermined pulse signal and cross-correlation means coupled to said receiver means for cross-correlating said pair of output pulses or signals derived therefrom.

Abstract: An aerofoil has a body, and at least one flow control device, the flow control device including a passage within the body of the aerofoil, and a passage outlet at an upper aerofoil surface of the aerofoil, whereby in use, air from the passage passes through the passage outlet to affect airflow over the upper surface of the aerofoil over at least a range of incidence angles, wherein the passage outlet is provided by an outlet fitting which is secured relative to the upper surface of the aerofoil, the outlet fitting including a surface part which lies contiguously with the surrounding upper aerofoil surface so there is no or only a minimal discontinuity where the surface part and the surrounding upper aerofoil surface interface, the surface part of the fitting further including an opening which communicates with the passage within the body of the aerofoil.