Abstract: The invention relates to an integrated antenna node (22) for use in wireless communication in a communication system (20), the wireless communication involving uplink and downlink physical-layer processing. The integrated antenna node (22) is adapted to perform, for at least one set of corresponding uplink and downlink physical-layer processing functions, only the uplink physical-layer processing functions or the corresponding downlink physical-layer processing functions. The invention further relates to a main node (21), a radio base station (28), computer programs and computer program products.

Abstract: The present invention provides an antenna control method and an antenna device. The method includes (A1) defining a plurality of rough scanning sectors in a signal region; (A2) rotating the antenna to each rough scanning sector to measure a first evaluation signal; (A3) selecting one of the plurality of rough scanning sectors in accordance with the first evaluation signals; (A4) defining a plurality of fine scanning sectors; (A5) rotating the antenna to the plurality of fine scanning sector corresponding to the selected rough scanning sector to measure a second evaluation signal; (A6) selecting one of the plurality of fine scanning sectors in accordance with the second evaluation signals; (A7) rotating the antenna to the selected fine scanning sector.

Abstract: A method of determining the position of an underwater node. The positions of three or more transmitters are determined. Each transmitter transmits at least four pulses, wherein a time difference between each pulse and a previous one of the pulses is proportional to a respective co-ordinate of the position of the transmitter. The pulses are received at the underwater node and decoded by measuring the delays between them, thereby determining the co-ordinates of the transmitters. The range of each transmitter relative to the underwater node is also determined. Finally the position of the underwater node is determined in accordance with the co-ordinates and ranges. Any errors in the measurements of the delays between the pulses only translate into small errors in the determined position because of the proportionality between the delays and the coordinates. Therefore if there is a gradual decrease of signal-to-noise ratio then the accuracy of the position estimate also degrades gradually.

Abstract: Methods and systems for determining a position and an orientation utilize a radio frequency signal transmitted from an effective source location which moves along a first closed, non-planar path. The closed, non-planar path has a plurality of local extreme points with respect to a predetermined axis. The radio frequency signal is received at an effective receiving location which may, optionally, move along a second closed, non-planar path. A phase signal representative of the phase of the received radio frequency signal is detected. The phase signal is filtered and processed to form at least one signal quantity representative of elevation, bearing, and/or orientation.

Abstract: RF energy received by an antenna (10) of a radio direction finding system is evaluated for determining the presence of a RF signal transmission source at bearing values at which the received RF energy is statistically strong (33) and which have a relatively stable signal strength (35). The scanning pattern (sequence) ( 12, 15) of the antennae is altered to increase the dwell time of the antennae at bearings having a statistically strong and relatively stable signal strength combination, and decrease the percentage of time spent scanning the remainder of the 360 degree search spectrum. External sensors (30) are used to sense changes in antennae orientation with respect to a fixed reference to thereby reduce bearing errors (27) during changes in the attitude and heading of the platform carrying the radio direction finding system.

Abstract: A radio system for determining the range and bearing of mobile equipment, such as an aircraft, relative to reference equipment such as an aircraft carrier, with low probability of interception (LPI). The aircraft remains equipped with high power range and bearing determination equipment, such as TACAN equipment. Reference equipment transmits a LPI beacon, such as a pseudo noise code spread spectrum signal through a rotating beam antenna to amplitude modulate the beacon as a function of antenna orientation. The PN code is inverted as the antenna passes through a reference bearing. Mobile LPI equipment determines bearing and generates a high power signal, such as an emulated TACAN beacon signal. High power range and bearing equipment extracts bearing information from the emulated signal and display it. Range can be determined in a cooperative mode. Mobile LPI equipment transmits a LPI interrogation signal. Reference LPI equipment returns a LPI reply signal.

Abstract: A method and apparatus of deriving a directional polar diagram from the signals R received by a synthetic-aperture aerial (in direction-finding applications), or P from such an aerial (in radio-beacon applications), these signals including a carrier of frequency .omega. which is phase-modulated at the scanning frequency .omega..sub.m of the individual aerials. The method comprises generating an "estimated" signal (26) of frequency .omega. phase-modulated at frequency .omega..sub.m, and multiplying (25) the generated signal by the received signal to derive an output which includes a selectable Bessel Function (J.sub.O) representing the directional polar diagram. The phase (with circular aerial arrays) (27) or amplitude (with linear aerial arrays) of .omega..sub.m as applied to phase-modulate the generated signal is controlled to maximize or minimize, as appropriate, the selected Bessel Function and thereby control the bearing direction of the polar diagram. The zero-order Function J.sub.

Abstract: A microwave radiometer reconstructs images by fanbeam inversion. True time delay (100), frequency (600, 700) and mechanical scanning systems (200) are disclosed. The mechanically scanning radiometer includes a fanbeam antenna (210) to scan a scene so that the antenna output is a projection of the scene taken along the direction of scan. The mechanical scanning motion is provided by a rocking motor (254) controlled by a computer (214). Projections are obtained for successive orientations as the antenna is rotated by another motor (212). By application of an inverse Radon transform, the scene scanned is reconstructed by the computer.In one frequency scanning system (600), a filter bank spectrometer is implemented to obtain the projections, and in the other frequency scanning system (700), a transform spectrometer implemented. In the delay scanning system (100), a beam forming computer is used in the reconstruction process.