Abstract: A device and method for locating a mobile station (MS) in a mobile communication system. In the MS locating device, a first antenna and a second antenna of a base station (BS) are spaced from each other by a distance equivalent to a wavelength of an MS transmission channel multiplied by a predetermined coefficient, such as one half. A first frequency downconverter and a second frequency downconverter convert signals received from the first and second antennas to baseband signals and digitize the baseband signals to chip sample data. A first channel demodulator and a second channel demodulator recover the chip sample data received from the first and second frequency downconverters and output information about the symbol start and PN code of a specific MS signal. A controller outputs a PN code for identifying the specific MS and finger position information based on the symbol start and PN code information received from the first and second demodulators.

Abstract: A pseudo random noise code is generated synchronously with a reference clock signal. A first forward electromagnetic wave is transmitted in response to the pseudo random noise code. A first echo wave is received which is caused by reflection of the first forward electromagnetic wave at an object. The received first echo wave is converted into a binary signal. A value of a correlation between the binary signal and the pseudo random noise code is repetitively calculated at a predetermined period having a synchronous relation with the reference clock signal. A time interval taken by the first forward electromagnetic wave and the first echo wave to travel to and from the object is measured in response to a timing at which the calculated correlation value peaks. Then, a second forward electromagnetic wave is transmitted in response to a transmitted pulse signal is transmitted. A second echo wave related to the second forward electromagnetic wave is received.

Abstract: A method for operating a radar system using at least two antennas provides an increased angular resolution for determining the angular position, radial velocity, and/or distance to a reflection object. A plurality of successive measuring phases are carried out in at least one measuring process. In each measuring phase, operation is repeatedly switched between a transmitting operation in which a transmitted signal pulse is emitted, and a receiving operation in which reflection signals are detected as received signals in the pulse pause interval between successive transmitted pulses. In at least one measuring phase, two different neighboring antennas of the radar system are used respectively as the transmitting antenna for emitting the transmitted signal and as the receiving antenna for detecting the reflected signal. In this manner, the respective receiving antenna monitors only the angular range of overlap between the emitted beam of the transmitting antenna and the field of view of the receiving antenna.

Abstract: A combined satellite positioning and electro-optical total station system including a satellite navigation receiver and a reference oscillator with a reference frequency output that can be related to precision time standards obtained from orbiting navigation-satellite transmissions. Such time standards are output by the satellite navigation receiver and are highly precise. An electronic distance meter (EDM) is included and has an EDM-transmitter for launching an out-bound signal to a distant target, and an EDM-receiver for receiving a reflected signal from the distant target. A phase measurement device is connected to the reference oscillator, and also to both the EDM-transmitter and EDM-receiver. It provides for a measurement of the difference in the number of cycles of the reference frequency between the out-bound signal and the reflected signal.

Abstract: A radar is provided, which enables determination of whether a detected target is a false image generated by a side lobe of the beam received by the antenna. In the radar, the first phase difference is obtained by actually calculating the target angle in the angle calculating section, and by supplying the calculated angle to a theoretical formula (with respect to the phase difference) in the first phase-difference calculating section. The second phase difference is directly calculated using actual received signals in the second phase-difference calculating section. These phase differences are compared with each other by the phase-difference calculating section, thereby determining whether the target exists at a side-lobe angle position of the beam received by the receiving antenna, based on a difference between two phase-difference characteristics.

Abstract: In a method for operating a radar system, the object is to determine by simple means and at low cost the distance and/or the radial velocity of at least one target object with high resolution. For this purpose, in each measuring phase of the measurement process in the "pulse FMCW radar system", switchover between a transmission mode and a receiving mode is effected a multiple number of times and at short intervals of time. In the transmission mode, all receiving units of the radar system are switched off, while a pulse-shaped (frequency-modulated) transmission signal with time-successive transmission pulses having a specific pulse-on time and a specific carrier frequency is emitted from at least one transmitter unit of the radar system.

Abstract: An automotive obstacle detecting system is provided which includes a radar to measure the distance to a target present within a detectable zone. The system monitors a distance limit measurable by the radar and determines a reduction in ability to measure the distance to the target by comparing the distance limit with a given reference value.

Abstract: A signal source produces a frequency-modulated signal. The signal is supplied to a transmit/receive unit and transmitted. A surface-wave element produces a signal delayed by a delay from the frequency-modulated signal. A mixer mixes the delayed signal with the received signal and outputs the mixed signal to an evaluation device. The delay is preferably equal to the propagation time of a signal on the measurement path. The coherence length of the ranging apparatus is thereby substantially improved.

Abstract: A distancing system comprising radio frequency transceivers and data processing circuits. The radio frequency transceivers allow data transmission via a high frequency radio signal. The transmission and receipt of these radio signals can be timed to estimate distance. But the data processing circuits operate at local clock frequencies, and one cannot be sure at what point a give radio frequency signal was received to a resolution greater than one-half cycle of the local clock signal. The data processing circuits periodically "skip" to resynchronize with incoming data streams. These skips occur at intervals corresponding to the frequency difference between the local clock frequencies. This frequency difference can be used to pinpoint fairly precisely when a given radio frequency signal was received in a previous half-cycle of the local clock.

Abstract: For measuring the level of a material in a vessel by a radar-based method an antenna arranged above the highest level anticipated radiates electromagnetic waves to the surface of the material contained in the vessel and receives reflected echo waves. The transit time of the wanted echo waves reflected by the material surface is measured from which the level is computed. Since this transit time corresponds to the group delay, for determining the reduction factor by which the group velocity of the electromagnetic waves differs from the velocity of propagation in the free space due to the geometry of the propagation space the phase difference of the wanted echo waves relative to a reference oscillation and the group delay are measured for various levels and the reduction factor is determined on the basis of the changes in the phase difference as a function of the group delay.

Abstract: A proximity sensor having a generator providing a signal of which a small portion is used as a reference signal and the remaining portion is radiated out towards a target. The radiation reflected from the target is equalized and/or normalized relative to the reference signal. The signals are compared in terms of relative phase relationship. This relationship implies the distance of the target from an antenna. An example target may be a rail wheel. A certain part of the wheel is measured in terms of distance from the sensor. This distance may determine wheel wear. Such wear is gauged relative to a threshold signal or reference distance. Also, speed and direction of the rail wheel can be determined from the signal reflected back to the proximity sensor.

Abstract: In an FMCW distance measurement process, a wave train of carrier frequency f.sub.0 is modulated with a time function f(t) and subdivided into a transmission signal and into a reference signal in deterministic phase relationship with the transmission signal; the transmission signal is sent on a transmission section to be measured and the reference signal is supplied to a phase difference-forming arrangement; the signal reflected in the transmission section with a delay that corresponds to propagation time .tau. is also supplied as a reception signal to the phase difference-forming arrangement that forms the time difference function .theta.(t) between the phases of reference and reception signals; the phase difference function .theta.(t) is separately evaluated in a continuous fraction .theta..sub.= that corresponds to the carrier frequency f.sub.0 and in an alternating fraction .theta..sub.- (t) that corresponds to the modulation time function f(t); and the propagation time .tau.

Abstract: To explore and analyze the structure of an object (O), the method according to the invention comprises transmission of at least one incident wave into said structure, reception of the waves retransmitted by the structure, by a plurality of independent detection elements (D1, Dn); memorization after digitization of the data supplied by the detection elements, in a field memory (MC); in respect of each point (Pij) of the object (O), computation of the positions occupied, in the field memory by the signals detected by the detection elements (D1, Dn) corresponding to the waves coming from said point (Pij); then reading of the field memory and addition of all the values contained in the memory positions corresponding to each point (Pij), the value (Vp) representative of the importance of the wave coming from said point (Pij) being obtained by multiplying the result of the addition by a correction factor (K).

Abstract: The distance to a target is determined by transmitting a radio frequency signal comprised of a plurality of pulses to a target from a transmitter at a given transmission time, receiving a plurality of return scans at a receiver, selecting a scan meeting a predetermined parameter that includes a reflected pulse; comparing the scan with a template of a reflected pulse at different locations to select the time at which the match between the scan and the template have the closest match; and calculating the distance to the target. The signal is transmitted and received through a wall of an aperture-free container that is transparent of said radio frequency pulses. The device also includes a barrier plate that is opaque to radio frequency pulses between the transmitter and receiver.

Abstract: A system is provided with a directional antenna having first and second antenna patterns oriented around an antenna boresight direction. The antenna boresight is oriented in a direction corresponding to a play determinative line on a playing field. Signals are emitted firm a playing object, used as a ball and detect using the two antenna patterns. Comparison of the detected signals provides an output indication when the playing object crosses the play determinative line.

Abstract: A phase difference measuring apparatus obtains a first receive signal by transmitting and receiving a to-be-measured material in a reference state and a second receive signal by transmitting and receiving a signal wave to and from that material in a measured state. The apparatus finds a reference phase difference .theta..sub.1 from the transmit wave and first receive signal and an apparent phase difference .theta..sub.2 ' from the transmit wave and second receive signal. The apparatus adds the apparent phase difference .theta..sub.2 ' to a product of the number of rotations, n, the apparent phase difference .theta..sub.2 ' passes through a given reference point and an angle of 360.degree. to find a true phase difference .theta..sub.2. The apparatus varies the number of rotations, n, to n+1 when the apparent phase difference .theta..sub.2 ', while being increased, passes through the reference point and that number of rotations, n, to n=n-1 when the apparent phase difference .theta..sub.

Abstract: In a method and device for frequency-modulated continuous-wave radar detection with removal of ambiguity between the distance and the speed, the radar sends out at least alternately two parallel and discontinuous frequency modulation ramps that are slightly offset by a frequency variation (.DELTA.F), the frequency switching from one ramp to the other at the end of a given duration (Tf), the distance from a detected target being estimated as a function of the difference in phase (.DELTA..phi.) between a received signal (S.sub.1 (t)) corresponding to the first ramp and a received signal (S.sub.2 (t)) corresponding to the second ramp, the speed of the target being obtained from the estimated distance and the ambiguity straight line associated with the target. The disclosed method and device can be applied especially to radars for automobiles.

Abstract: An object is to provide a cheap digital beamforming radar apparatus.

Abstract: Disclosed is a radar for the detection of obstacles. The radar uses at least four frequencies referenced F.sub.1, F.sub.2, F.sub.3, F.sub.4 such that:F.sub.1 -F.sub.3 =F.sub.2 -F.sub.4and such that:(F.sub.1 +F.sub.3)-(F.sub.2 +F.sub.4)=Cte where Cte represents a constant frequency value, the measurement of distance from the target being done on the basis of the difference in phase between two signals of which the first (r.sub.1 (t)-r.sub.3 (t)) is constituted by the difference between two received signals corresponding respectively to the frequencies F.sub.1 and F.sub.3 and the second (r.sub.2 (t)-r.sub.4 (t)) is constituted by the difference between two received signals corresponding respectively to the frequencies F.sub.2 and F.sub.4. Application in particular to automobile speed control.

Abstract: A low cost, real time, remote sensor device for accurately measuring distance to an object with a resolution of 1 millimeter or better using phase information from either electromagnetic or acoustic energy. The device repetitiously transmits a swept frequency and decodes the resulting echo to produce a phase gate which is then converted to an accurate measurement of the range from each sweep. A method for measuring the time between two known phase points on a return signal is employed to determine the range measurement. Since the phase of the signal is used to determine range, the resolution is not dependent on bandwidth.

Abstract: A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation.

Abstract: A displacement measuring method that measures phase changes between a reference and a phase-shifted signal from -.infin. to .infin. degrees (limited by the size of counters) in precise incremental steps using a method referred to as Digital Phase Signature Comparison. Digital Phase Signature Comparison uses an n-bit digital pulse train synchronized to a reference signal to sample a binary phase-shifted signal of a known duty cycle. This n-bit sampling creates a unique phase signature which is stored in a memory device. One digital n-bit phase signature is created for each synchronized pulse train. Each stored phase signature is compared with the previous phase signature to determine whether the phase of the phase-shifted signal has changed, the magnitude of that change, and the direction of displacement. Error detection can protect against unknown phase signatures and phase signature transitions, thus ehminating accumulated or incident inaccuracies.

Abstract: A method and system for determining an actual location of a sense antenna associated with a phased array communications satellite. A plurality of calibration carrier signals are transmitted at known frequencies. Each of the plurality of calibration carrier signals are received at a second frequency and compared with each of the plurality of transmitted calibration carrier signals. The actual location of the sense antenna is determined based on the comparison between the known frequency and the second frequency. The phased array communications satellite then broadcasts communication signals based on the actual location of the sense antenna rather than a desired location of the sense antenna.

Abstract: A phase difference measuring apparatus obtains a first receive signal by transmitting and receiving a to-be-measured material in a reference state and a second receive signal by transmitting and receiving a signal wave to and from that material in a measured state. The apparatus finds a reference phase difference .theta..sub.1 from the transmit wave and first receive signal and an apparent phase difference .theta..sub.2 ' from the transmit wave and second receive signal. The apparatus adds the apparent phase difference .theta..sub.2 ' to a product of the number of rotations, n, the apparent phase difference .theta..sub.2 ' passes through a given reference point and an angle of 360.degree. to find a true phase difference .theta..sub.2. The apparatus varies the number of rotations, n, to n+1 when the apparent phase difference .theta..sub.2 ', while being increased, passes through the reference point and that number of rotations, n, to n=n-1 when the apparent phase difference .theta..sub.

Abstract: Beat signals of respective receiver channels CH1 and CH2, produced by mixing their receiving signals with a transmission signal, are subjected to Fourier transformation to detect the frequency and phase of peak frequency components in both an ascending-section where the frequency of the transmission increases and a descending-section where the frequency of the transmission decreases. Based on peak frequency components derived from the same target, phase differences .DELTA..phi.u(i) and .DELTA..phi.d(j) between receiver channels CH1 and CH2 in the ascending- and descending-sections (steps 210-230). Relative relationship between the transmission signal and the receiving signal is judged based on the signs of the phase differences. Respective peak frequencies fu(i) and fd(j), detected as absolute values of frequency differences between the transmission signal and the receiving signal, are given sings in accordance with the judgement result.

Abstract: A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation.

Abstract: A radar system is designed to allow switched use of a pulse radar mode for detecting a target at a long distance away and a phase-difference radar mode for detecting a target at a short distance away, whereby target detection can be performed from a very close range to a long range with high accuracy. Also, the pulse radar mode enables detection of a plurality of targets in different ranges.

Abstract: The present invention provides an improved method for determining a coarse direction in an orientation system of a an autonomous device (10), for instance a dust cleaning robot together with a system of active beacons or transponders. A transmitter (20) for transmitting sensing signals is displaced in relation to the rotational center (25) of the the device (10). When the device is rotated around a vertical rotational axis in the rotational center, a minimum in the distance to the respective transponder or beacon is obtained when the transmitter of the device is positioned immediate to a point lying on a straight line between the rotational center of the device and a respective transponder, whereby an immediate coarse determination of the direction to each transponder is directly obtained.

Abstract: A radar system allows switched use of an FM-CW radar mode and a phase difference radar mode, the FM-CW radar mode being designed for use in sensing a target at a medium and long distance away and the phase difference radar mode being designed for use in sensing a target at a short distance away, whereby a target at an extremely short to long distance away can be sensed with high accuracy.

Abstract: A system has a plurality of transceiver units, including a parent unit and one or more portable and wearable child units, for generating an alarm when a child transceiver unit is more than a predetermined distance away from a parent transceiver unit. The distance is determined by the difference in the phase of a reference signal from the time it is transmitted on an rf signal by a parent unit, received and retransmitted by a child unit, and then received again by the parent unit.

Abstract: An apparatus for sensing the proximity of a moving target is provided which includes a sensor for sensing a range of distances between a reference point and a moving target. The sensor preferably has a detector for detecting a distance signal representative of a range of distances between a reference point and a moving target and a maximum and minimum generator responsive to the detector for generating a maximum distance range DC voltage signal representative of a maximum distance range value between a reference point and a moving target and for generating a minimum distance range DC voltage signal representative of a minimum distance range value between a reference point and a moving target.

Abstract: Method and device for reducing, in a radar system, the influence of distortion which has arisen in signals in signal-generating and signal-processing parts of the radar system by firstly applying a first random phase rotation to a signal before a first signal-processing. After the first signal-processing, the signal is phase-rotated with a second phase rotation which has the same phase rotation value as, but the opposite sign to, the first phase rotation. Thereafter, a transmission pulse, created from the signal, is emitted from the radar system and is reflected off targets or objects and is received by the radar system. A third random phase rotation with a second phase rotation value is applied to the received signal before a second signal-processing. After the second signal-processing, the received signal is phase-rotated with a fourth phase rotation which has the same phase rotation value as, but the opposite sign to, the third phase rotation.

Abstract: A method for measuring the position of at least one surface in a metallurgical process which includes the steps of providing a metallurgical melt, the metallurgical melt including at least a metal portion and a slag layer, providing a signal generator for generating signals at a plurality of frequencies over a frequency band, and providing an antenna for receiving the signals generated by the signal generator and for transmitting circularly polarized radio waves at the plurality of frequencies over the frequency band.

Abstract: An apparatus for detecting illegal tampering with an electricity meter which is adapted to record the amount of electricity supplied to the meter through cables has a first signal generating sensing coil situated externally of, and upstream of, the meter which generates a first signal representative of the current flowing through one of the supply cables and a second signal generating second sensing coil, located within the meter, which generates a second signal representative of the amount of electricity to be recorded by the meter. A Monitoring device monitors the first and second signals and produces a third actuation signal when one of the first and second signals differs from its correct value as a result of tampering.

Abstract: A system generates an alarm at one unit of the system when a second unit of the system is more than a predetermined distance from the first unit. The system has a first transceiver unit with a first transmitter for transmitting a first reference signal having a phase with respect to a reference source, and a first receiver for detecting a second reference signal having a phase which bears a relationship to that of the first reference signal. There is a second, portable, transceiver unit with a second transmitter for transmitting the second reference signal after receipt of the first reference signal. The first transceiver unit includes a distance resolver for determining the distance between the two transceiver units from the phases of the first and second reference signals, and an alarm, responsive to the distance resolver, for generating an alarm signal if the distance between the two transceiver units is more than a predetermined amount.

Abstract: The spatial separation of an object from a reference location is monitored utilizing a proximity alarm system which comprises a transceiver station mounted on the object and a repeater station at the reference location. Both stations function to generate and transmit an encoded rf signal in a half-duplex manner, with the transceiver station initiating the process. In one embodiment of the system, a phase delay is measured between a remote signal originating at the transceiver station and a corresponding decoded timing signal received from the repeater station. Correlation of the phase delay with a reference value ascertains the distance between the stations and an alarm at the transceiver station is actuated when the distance exceeds a predetermined value. A second embodiment of the system employs a clock driven counter that is stopped when a predetermined multiple of decoded timing signals is received at the transceiver station in response to iterative transmissions therefrom.

Abstract: A method and apparatus is disclosed for improved out-of-range rejection in pseudo-random noise (PN) coded systems by adjusting the relative phase difference between the two phase states of a bi-phase modulation. The energy in the spectral lines of the bi-phase modulated RF signal to generate a signal to be fedback to a voltage-controlled bi-phase modulator to adjust the relative phase difference between the two phase states. Sampled signals are mixed down to baseband using single sideband suppressed carrier modulation of the center frequency of the transmitted signal and the offset frequency. The offset frequency is chosen to be less than the PN code repetition frequency. The baseband signal is filtered and envelop detected producing a DC voltage proportional to the amplitude of the center line of the PN spectrum which is compared to either a fixed reference or to the amplitude of one or more of the remaining lines in the spectrum.

Abstract: A monostatic frequency modulator continuous wave radar for detecting and determining the distance to near range objects. A temperature compensated one port Z-network is provided to generate a voltage of equal magnitude and opposite sign to that of the voltage reflected from the antenna.

Abstract: A method and apparatus for sensing proximity of an object using near-field effects. Modulated radio frequency energy is fed to an antenna. The antenna radiates this modulated radio frequency energy to charge the surface of an object. When the position of the object changes, the impedance of the antenna due to near-field effects changes. This impedance change is detected to provide an indication of the object's movement. The sensing device may be packaged to be inserted into a wall to provide a sensor having a leak-free seal.

Abstract: A light beam encoder for measuring absolute distance over a linear path with an accuracy of at least that provided by incremental optical encoders, but over longer ranges than can readily be achieved with optical linear encoders due to the difficulty of providing a sufficiently long optical scale with the requisite accuracy and resolution. The resolution provided by the light beam encoder can be approximately 1-10 microns. A high frequency amplitude modulated light beam is reflected by a reflector disposed at the distance to be measured, and the phase lag of the reflected light beam is determined to provide an absolute measure of the distance. The encoder mixes a local oscillator signal generated by a phase locked loop with both a reference oscillator signal and the distance signal. Thus, the heterodyne mixers provide two low frequency signals preserving the phase lag between the two optical signals.

Abstract: A light wave distance measuring apparatus structured such that frequency dividing circuits create a base intermediate frequency outputted to a phase measuring circuit and a PLL reference frequency which is a multiple of an integer a (a.gtoreq.2) of the base intermediate frequency, and this PLL reference frequency is outputted to a PLL oscillation circuit, thereby preventing an error in the measurement of distance due to spurious components caused when measuring a phase in the light wave distance measurement.

Abstract: A method and apparatus for the measuring of a delay in a delay circuit by making a continuous frequency measurement is proposed. The phase-locking of a variable frequency signal applied to the delay circuit allows the user to significantly improve the precision and accuracy of the time delay measurement. A scheme to extract the number of cycles stored in the delay circuit is also disclosed.

Abstract: A phase modulated signal is split into quadrature components Savg+SaSin(.phi.(t)+kx(t)) and Cavg+CaCos((.phi.(t)+kx(t)). The average value for each signal is compared with the signal to produce a data bit whose meaning is that the average value was exceeded at a sampling instant. The bits at successive times (t.sub.0 and t.sub.1) are separated by an interval set by the Nyquist rate on the peak rate of change of the phase for the signal. Four bits at two sample times t.sub.0 and t.sub.1 are processed to determine the phase quadrants modulo 360 degrees to determine the direction of the phase change. The determination is used to produce a counter enable signal, counter direction control signal (up/down) and optionally an error signal if the phase change during one clock period is more than plus or minus one quadrant. A tracking counter counts the number of quadrants of change from those signals.

Abstract: A distance measuring system which may be used on a golf course in order for a golfer to accurately measure the distance between the present lie of his golf ball and the hole toward which he is currently advancing the golf ball. A master transceiver station is portably carried by the golfer to be disposed proximate the lie of his ball for measurement purposes, and a remote transceiver system is located in or on each hole's flag marker pole. The present system uses, as the basic measurement frequency, only the frequency of the remote carrier itself. Two separate and distinct phase measurements are made in rapid succession. The first measurement is made with the master RF carrier displaced above the remote carrier frequency by amount equal to the IF frequency, and the second measurement is made with the master carrier frequency displaced below the remote carrier frequency by the same amount.

Abstract: A lidar apparatus for detecting an object. The lidar apparatus includes a laser providing a visible light output signal over a first field of view and a photodiode having a second field of view. At least some of the first and second fields of view overlap. The photodiode provides electrical signals in response to received optical signals. A controller is coupled to the laser and to the photodiode. The controller for provides electrical signals to the laser, causing emission of visible light output signals. A time varying threshold generator is coupled to the controller. The time varying threshold generator provides a time varying threshold signal in response to signals from the controller. A threshold detector is coupled to the time varying threshold generator and to the photodiode. The threshold detector compares the time varying threshold signal to the electrical signals to provide signals indicating presence or absence of the object.

Abstract: A range finding system uses non-simultaneous measurements between two communicating and cooperating instruments such that a single carrier frequency is used to exchange information between the instruments with non-simultaneous transmission using the same transmission channel. The range finding system may be considered to be an interrogator/transponder arrangement in which the results of a phase measurement against a local clock is made at one transponder station during one time interval, and then the transponder transmits both a tone derived from the transponder's local clock and the measurement results back to the interrogator station during a second time interval. The interrogator then has everything it needs to accurately compute the range while eliminating local delays in clock differences, while permitting the interrogator and the transponder to share a single frequency intermittently.

Abstract: A ranging method for measuring the flight distance of a flight object is implemented by means of a simple system construction. The ranging method is also capable of continuing ranging even if an interruption occurs in data transmission. The ranging method comprises the steps of inserting ranging pulses in a telemeter signal transmitted from a transmitting apparatus provided on the flight object, separating and extracting a ranging pulse from a telemeter signal received by a receiving apparatus provided on the ground side, obtaining a time difference between the ranging pulse and a reference clock signal generated in the receiving apparatus on the basis of a time reference equal to that of the transmitting apparatus (clock signal periods t1 and t2 of both time references are equal), and calculating the flight distance.

Abstract: Time of transit of a propagated electric signal at lightspeed is used as a measure of distance from a transmitter (laser 32) to a receiver (photodetector 39) via a target (reflector 14). A continuous modulating signal of fixed frequency (10.700 MHz) is transmitted. The distance traversed is measured by a timer which compares the phase at transmission with that at reception. The invention involves a heterodyne down-conversion technique involving two crystal oscillators (30, 31), which are phase-locked to assure that one regulates the other to keep their frequencies in linear proportional relationship, both being at the transmitter location, which transfer the phase difference to a 10.45 kHz frequency, thereby facilitating high resolution and precision mesurement by extending the time measure representing distance.

Abstract: The range (R) to a target (12) is precisely determined by controlling the amplitude of the carrier before modulation using a feedback signal derived from the detected return. The amplitude of the carrier is adjusted (40) so that all return pulses have a constant amplitude. Hence, for any given range, all return pulses cross threshold at the same time, thereby eliminating ranging errors due to phase distortion. The return pulses are threshold detected (54) and converted to a CW signal, which is then down converted. The phase information, which is indicative of target range, is preserved in the down conversion process and is extracted by phase comparison (72) with a reference signal to determine the target range.

Abstract: A system for continuously and precisely measuring the positions of a generally symmetrical object, e.g., a tennis ball, in motion in a predefined three-dimensional region, e.g., a tennis court, which transmits multiple radar signals from first, second, and third, spaced antenna devices, respectively, into the three-dimensional region. Multiple return signals are sensed and are compared with the transmitted signals to determine the phases of the return signals, to thereby obtain ambiguous ranges of the object. Ambiguities are removed by using the Chinese Remainder Theorem to obtain less-ambiguous ranges. Time-of-arrival range information is used in conjuction with the less-ambiguous ranges to provide unambiguous ranges over the range of interest. The unambiguous ranges are used to compute three-dimensional coordinates of the object that are accurate to within approximately 0.1 inches.