Abstract: A carrier phase-based relative positioning apparatus includes a plurality of antennas fixedly mounted on a moving body for receiving positioning signals from satellites, an inertial measurement unit (IMU) for measuring accelerations and angular velocities of the moving body, a reference attitude calculator for calculating attitude information about the attitude of the moving body from observables of the IMU at least before an integer ambiguity candidate is initially determined, an integer ambiguity estimator for estimating integer ambiguity candidates from the positioning signals received by the antennas, and an integer ambiguity validator for evaluating correctness of the integer ambiguity candidates estimated by the integer ambiguity estimator.

Abstract: A multilevel symbol timing signal detector is provided, which is used for reliably detecting the symbol timing of a multilevel QAM signal. When an oversampling I signal is inputted to I-Signal Histogram Generator 610, the signal is subjected to 1-symbol length buffering by computing absolute values. Sampling times corresponding to an oversampling frequency and amplitude data for these times are extracted from the buffered data and the amplitude data is buffered for each sampling time over predetermined intervals. Histograms of the amplitude data for each sampling time are generated based on these buffered amplitude data. Symbol timing is acquired by detecting a sampling time corresponding to the amplitude data with the highest frequency of detection based on the histograms of amplitude data.

Abstract: An underwater sounding apparatus includes a transducer transmitting an acoustic sounding beam along a plurality of directional surfaces that intersect in three-dimensions and receiving echoes returning from within a fish school using receiving beams. The transducer can form the receiving beams in directions generally along a substantially vertical planar directional surface and in directions generally along a substantially umbrella-shaped directional surface formed around the ship, the umbrella-shaped directional surface intersecting both a horizontal plane and the vertical, planar directional surface. A signal processing section calculates fish quantity information about the fish school by constructing pseudo-three-dimensional data from data obtained by the receiving beam. Also, the signal processing section may binarize the data obtained by the receiving beams and calculates an approximate value of the volume of the fish school by constructing pseudo-three-dimensional data from the binarized data.

Abstract: An easy-to-fabricate and relatively strong circularly polarized loop antenna of a simple construction is built. A circularly polarized loop antenna 1 has a loop section 11, which is made up of a loop-shaped conductor whose length is equal to 1 wavelength (?) of the transmitted and received signals, and a coupling section 12, made up of a conductor, is connected thereto at a prescribed point. The coupling section 12 is shaped such that it is connected to the loop section 11 at a connection point 201 at one end and extends along the loop section 11 throughout a length equal to ?/4. A reflective plate 2 is placed in a predetermined position in the vertical direction from the circumferential plane of the loop section 11, in parallel to the circumferential plane. In addition, the other end of the loop section 11 is connected to external circuitry carrying out the processing of signals transmitted and received via a first feed conductor 13 and a second feed conductor 14 and operates as a feed point, 200.

Abstract: A navigational aid for use as an AIS apparatus includes a memory for storing information about previous use of individual time slots synchronized with transmission schedules of other stations and a signal detector for judging whether an information signal exists in a time slot specified in accordance with a synchronization timing signal based on the information stored in the memory and a result of monitoring of the behavior of a baseband signal obtained from a received signal on an IQ-plane. The navigational aid transmits information about own station based on a result of judgment by the signal detector. The monitoring of the behavior of the received baseband signal plotted on the IQ-plane can be accomplished by performing pattern recognition operation, for which a carrier sense technique, such as a support vector machine, subspace method or neural network, can be used.

Abstract: A quantitative echo sounder includes delay circuits, phase correction circuits, an incidence angle calculator and a directivity correction unit. The delay circuits adjust transmission start timing or phases of acoustic waves radiated by individual vibrating elements based on pitch and roll angles measured by a motion sensing device so that the direction of an acoustic axis of a transmitting beam matches a sounding direction. The phase correction circuits adjust phases of received echo signals based on the pitch and roll angles so that the direction of an acoustic axis of a receiving beam matches the sounding direction. The incidence angle calculator calculates echo signal incidence angle with respect to the sounding direction from phase differences among receiving beam signals obtained by four vibrating element groups. The directivity correction unit corrects a measured target strength by using the echo signal incidence angle calculated by the incidence angle calculator.

Abstract: A carrier phase-based relative positioning apparatus includes a plurality of antennas fixedly mounted on a moving body for receiving positioning signals from satellites, an inertial measurement unit (IMU) for measuring accelerations and angular velocities of the moving body, a reference attitude calculator for calculating attitude information about the attitude of the moving body from observables of the IMU at least before an integer ambiguity candidate is initially determined, an integer ambiguity estimator for estimating integer ambiguity candidates from the positioning signals received by the antennas, and an integer ambiguity validator for evaluating correctness of the integer ambiguity candidates estimated by the integer ambiguity estimator.

Abstract: An attitude sensing apparatus for determining the attitude of a mobile unit is provided that can reliably estimate an alignment angle between a GPS antenna coordinate system and an IMU coordinate system with good accuracy regardless of the magnitude of the alignment angle. Based on observation of the difference between a GPS angular velocity and an IMU angular velocity, an alignment angle estimating section estimates an alignment angle and sensor errors. An alignment angle adder and a sensor error adder cumulatively add and update the estimated alignment angle and sensor errors, respectively. The estimated alignment angle is fed back to an inertia data converter while the estimated sensor errors are fed back to an inertia data correcting section. The apparatus repeatedly performs estimation until the estimated alignment angle gradually approaches a true alignment angle by successively feeding back estimated values to a flow of alignment angle estimation process.

Abstract: An automatically tracking scanning sonar alternately performs horizontal scanning and vertical scanning and a target lock processor calculates a predicted position of a target based on an echo signal previously received from the target when the echo signal from the target is interrupted. A selector sets a range, tilt angle and sounding direction and outputs them to a transmit-receive controller such that the scanning sonar can scan the predicted target position. As the depth of the target is determined by performing the vertical scanning, the tilt angle of an umbrellalike beam pattern produced by the horizontal scanning can be varied to follow the target by controlling the tilt angle based on target depth information even when the target moves in vertical directions. It is therefore possible to automatically track the target in a reliable fashion.

Abstract: A receiving beam is formed using 60 elements arranged in a 90° sector area of a cylindrical receiving array. Receiving beam 0 is formed with elements 0-59 divided into two (front and rear) groups. Specifically, the elements 0-59 are divided into rear group 1 (elements 0-8, 51-59) and front group 2 (elements 9-50) in the beam direction, and the receiving beam is formed by using sample data obtained from the transducer elements 0-8, 51-59 of group 1 in a current scanning cycle as well as sample data obtained from the transducer elements 9-50 of group 2 in a preceding scanning cycle. This approach makes it possible to form the receiving beam such that incoming waves of a short-pulse signal would simultaneously hit the relevant transducer elements of the receiving array and thereby improve directivity and sensitivity of the receiving beam for the reception of short-pulse waves.

Abstract: A small and light helical antenna, with a high gain, includes arranging the dielectric cylinder with a helix conductor on the conductive plate and arranging a thin rectangular conductive plate between the lower end of the helix conductor and the feed point in a predetermined position of the conductive plate. The impedance matching is between the input impedance of the helix conductor and a power feeder. The upper and lower conductive plates constitute parallel plate waveguide space, and the probe which comes into the parallel plate waveguide space is in the lower conductive plate side, and the lower end of a thin rectangular conductive plate is connected with the lower end of a probe.

Abstract: An electric reel is furnished with an information communication unit is adapted for transmitting first information concerning the reel to an external fishing information display device. The information communication unit is adapted for receiving second information concerning fishing from a fish finder or a GPS through a fishing information display device and an information coordinating unit. A second display unit of the fishing information display device can display the first information concerning the reel obtained from the reel and the second information concerning fishing with one of the first and second information being superimposed on the other. In this fishing reel, a large amount of information can be displayed while the size of the reel is kept small. Also, information concerning fishing can be obtained quickly.

Abstract: In a cylindrical transducer constructed of a plurality of ultrasonic transducer arrays arranged in a circular form, the ultrasonic transducer arrays is divided into a plurality of groups, and tilt angles of transmitting and receiving beams are controlled to compensate for swing motions of the cylindrical transducer depending on which group the individual ultrasonic transducer arrays belong. Provided that the uncompensated tilt angle of the beam is a and the angle of inclination of the cylindrical transducer in a particular direction is b, the tilt angle of the beam formed by a transducer array in the inclining direction should be adjusted to &agr;−&bgr; and the tilt angle of the beam formed by a transducer array in the opposite direction should be adjusted to &agr;+&bgr;.

Abstract: A radar apparatus can supervise a target easily and can enlarge a display showing a target. The target is one of a group of multiple targets and the positions of the multiple targets are detected from radar data. The relative position of a target of interest to a radar location is determined and the display reset to enable the target of interest to be within a display window.

Abstract: A display apparatus for a navigational aid displays an own ship mark and a barge assembly mark representing respectively the shapes of own ship and a barge assembly, which are coupled to each other, in which the barge assembly mark includes segments arranged in columns by rows corresponding to individual barges within the barge assembly. The display apparatus reads information on a choice of a location within the barge assembly mark entered by an operator using a pointer and shows a mark indicating the presence or absence of a barge at the selected location, thereby enabling the operator to set the barge assembly mark of a desired shape to match the shape of the actual barge assembly.

Abstract: The present invention relates to a raster scanning radar display apparatus which is capable of improving the display of echo signals from objects in the vicinity of a ship on the display surface of an indicator. The raster scanning radar display apparatus includes a memory for storing echo signals based on one search signal, a sweep scanning device for drawing a plurality of imaginary sweeps which are parallel with each other in a display memory each time the pointing bearing of the antenna is varied and for generating signals representative of addresses of memory elements in a display memory scanned by the sweeps. The apparatus whites echo signals into the memory elements of the display memory scanned by one sweep and writes predetermined signals into the memory elements of the display memory scanned by other sweeps. The signals in the disply memory are read and displayed on an indicator.

Abstract: A detection system forms a plurality of reception beams successively in angular directions by receiving incoming signals from various directions in a manner that the Doppler effect is produced to vary the carrier frequency of the incoming signals. The detection system displays underwater conditions on an indicator. To determine the underwater conditions, the detection system uses a plurality of ultrasonic transducers for receiving incoming signals, a plurality of preamplifiers for amplifying the reception signals produced by the ultrasonic transducers. A first coupling device which connects at least two of the ultrasonic transducers to a single preamplifier, and a matched filter for pulse-compressing reception signals produced by the ultrasonic transducers. A second coupling device successively couples the output terminals of the preamplifiers to an input terminal of the matched filter. The indicator displays output signals from the matched filter.

Abstract: An underwater detection system display underwater conditions on an indicator comprised of a monochrome cathode ray tube with two groups of different degrees of brightness. One group of different degrees of brightness is related to the amplitude of echo signals in such a way that degrees of brightness are in direct proportion to the amplitude of an echo signal. The other group of different degrees of brightness has another relationship with the amplitude of an echo signal.