Abstract: A balance device comprises first, second and third components. The first, second and third components include substantially cylindrical first, second and third central portions, respectively, and which are coaxial with one another. The balance device further comprises a first set of connectors for coupling the first component to the third component and a second set of connectors for coupling the second component to the third component. The connectors accommodate axial movement in response to relative axial forces between the first and second components and minimise rotational movement about the axial direction in response to relative axial torque between the first and second components.

Abstract: A method of obtaining oceanographic and meteorological data from high frequency radar spectral information including the steps of transmitting a plurality of signals to a remote geographic location, recording signals backscattered from the said location, generating a family of Doppler clutter spectra from the recorded backscattered signal and analyzing the Doppler clutter spectra in terms of a model or models to generate oceanographic and meteorological data estimates. The Doppler spectra are categorized according to Suitability for Deatiled Analysis (SDA). The SDA takes account of the clutter-to-noise ratio in the spectrum, the amplitudes of the Bragg-lines, multimode propagation, spectral broadening and other spectral parameters. Spectra with a low SDA are inappropriate for extracting directional wave spectrum estimates of reasonable accuracy but are useful for obtaining wind direction estimates.

Abstract: A frequency surveillance method for monitoring background atmospheric noise evels in unoccupied channels in an operating frequency band of a high frequency communication system. In the method, the unoccupied channels are scanned a number of times to obtain analogue signals. The obtained signals are transformed to a digital form and averaged. The averaged digital signals are filtered to remove substantially all radio frequency interference. Absolute signals are then produced by scaling or comparing the filtered signals with a known noise level. The background noise levels are obtained by further averaging the absolute signals. A visual display unit is used to display the background noise levels as a function of frequencies. A frequency surveillance apparatus is also disclosed.

Abstract: A method of co-ordinate registration for Over-the-Horizon Radar comprising he steps of generating a geographic auto correlation function to determine one or more geographic beacons in a coverage area of the Over-the-Horizon Radar, the auto correlation function being in polar co-ordinates, comparing the return radar signal with the geographical map of the coverage area in the general region of the one or more geographic beacons and finding the best fit of the geographic map with return radar signal to enable registration of co-ordinates of the return radar signal. The auto correlation function indicates the amount of correlation between a neighbourhood and a slight displacement from that neighbourhood. A geographic beacon is an area in which there is a substantial difference between the neighbourhood and its surroundings thereby producing a low auto correlation function.

Abstract: A plasma generator utilizing two magnetrons preferably acting out of phase with each other and each comprising one part of the other magnetic mirror. There may be included a thermal fragmenter to produce gas atoms directly into the plasma for ionization before being drawn onto a substrate. The use of a thermal fragmenter separate from the magnetrons produces ionized atoms directly where they are needed and allows quicker changeover to alternative atoms for multilayer coating.