Abstract: An automatic steering system for a work vehicle comprises a position sensor for detecting a position of the vehicle, a memory for storing information about a nominal path of the vehicle and a control unit coupled to the position sensor, to the memory and to a steering actuator for steering the vehicle. The control submits control signals to the steering actuator that depend upon a feedback gain and a lateral offset between the actual position and the nominal path. The feedback gain depends upon a sensed payload of the vehicle.

Abstract: A microwave transmitting device for a level measuring device (1) having an electronic device, a microwave emitter and a waveguide (3). The inside of the waveguide is filled with a casting compound. A microwave transmitting device that is particularly compact and cost-effective is implemented by the microwave emitter and the electronic device being enclosed by a casting formed of a casting/potting compound.

Abstract: A portable hand held tank gauge for measuring a level or a volume of a fluid in a tank comprises a housing, a signal transceiver, a measurement activator, an adjustable arm, a processing element, and a display. The housing may house a portion of the other components. The signal transceiver may transmit a signal to the surface of the fluid, receive the signal reflected from the surface, and generate an output based on the difference in time between transmitting the signal and receiving the signal. The measurement activator may selectively initiate the signal transceiver to transmit the signal. The adjustable arm may couple to the housing and position the signal transceiver independently from the housing. The processing element may calculate the level or the volume of the fluid based on the output from the signal transceiver. The display may display the level or the volume of the fluid.

Abstract: A radar level gauge system for determination of a filling level of a product contained in a tank including first pulse generating circuitry for generating a transmission signal in the form of a first pulse train having a first pulse repetition frequency and second pulse generating circuitry for generating a reference signal in the form of a second pulse train having a second pulse repetition frequency. The second pulse repetition frequency differs from the first pulse repetition frequency by a predetermined frequency difference. A propagation device propagates the transmission signal towards a surface of the product inside the tank. Measurement circuitry forms a measurement signal based on a reflected signal and the reference signal. Processing circuitry determines a value indicative of a filling level based on the measurement signal.

Abstract: The invention relates to a system for determining relief on a granule filling surface in a petrochemical reactor, the filling direction in which the reactor is filled defining a vertical direction, the reactor having a central vertical axis, the system including a transmitter configured to be positioned above the filling surface in such a manner as to transmit a signal to various points of said surface. The system includes shift means for shifting the transmitter about the central axis of the reactor through an angle that is great than 60°.

Abstract: A radar level gauging system for determining at least one process variable related to a distance to a surface of a product in a tank comprising transceiver circuitry, processing circuitry, a wave guiding structure arranged guide measurement signals towards the surface, and a radiator connected to the transceiver circuitry and arranged to emit the measurement signal into the wave guiding structure. The system further comprises a mode generator adapted to convert electromagnetic waves emitted from the radiator from a first propagation mode to a second propagation mode, wherein the mode generator includes a lens in the form of a body transparent to electromagnetic waves in the operating frequency range. With this design, electromagnetic waves having the first propagation mode emitted by the radiator into the lens will be reflected at least twice within the lens (first in the bottom surface and then in the upper surface).

Abstract: A method for measurement of a distance to a surface of a product kept in a tank method comprises transmitting a pulse train of distinct carrier wave pulses having a duration greater than 1 microsecond and shorter than 100 milliseconds, the pulse train has an average duty cycle of less than 50 percent, each pulse has a defined center frequency, selected according to a frequency scheme within a predetermined frequency range, greater than 5% of an average center frequency. The method further comprises correlating actual phase properties of received pulses with expected phase properties to provide an updated estimation of the distance. The present invention is based on transmitting a set of carrier wave pulses, each having a distinct frequency selected within a frequency range. The method is therefore referred to as a Frequency Modulated Pulsed Wave (FMPW).

Abstract: A loop-powered field device for determining a process variable and providing a measurement signal indicative of the process variable to a remote location via a two-wire current loop, the loop-powered field device comprising: a measurement device for determining the process variable; and loop interface circuitry for providing the measurement signal to the two-wire current loop and for providing power from the two-wire current loop to the measurement device.

Abstract: A level sensing device with a high frequency radar system is provided. The radar system includes a radar high frequency module, a carrier board and a controller. The radar high frequency module is mounted on the carrier board using surface mount techniques. The controller includes a processor and the radar high frequency module has a plurality of components including one or more microwave integrated circuits, a radiating patch antenna, and coupling means for channeling a radiated signal from the patch antenna out of the module. The components are encapsulated to form the module and the coupling means includes a dielectric rod.

Abstract: A method for considering an echo amplitude profile as a result of convoluting a single echo with a channel response sequence, wherein for multiple echo detection, an estimation task is broken into three major steps comprising estimating a channel response, recovering a full shape of a single echo, and iteratively updating the channel response and echo shape to increase their accuracy. The estimation of the channel response is treated as a single echo detection problem and includes estimating the strongest echo for its position and amplitude, removing an echo corresponding to this recovered channel from the echo amplitude profile, and repeating the preceding steps for the next strongest echo.

Abstract: A method for ascertaining and monitoring fill level of a medium in a container by means of a field device by a travel time measuring method, wherein transmission signals are transmitted in the direction of the medium and reflection signals are received, wherein received reflection signals are registered as echo signals in an echo function dependent on travel time or travel distance, wherein position and/or amplitude at least of a wanted echo signal in the echo function are/is ascertained by means of an echo search algorithm and a continuous echo tracking of changes of position and/or of changes of amplitude of the wanted echo signal in the echo function is performed in a defined search window, wherein position and/or amplitude at least of a wanted echo signal is maintained, in case no wanted echo signal is ascertained in the search window, wherein from position and/or amplitude at least of a wanted echo signal, fill level is ascertained, and wherein a measured value of fill level is output.

Abstract: A method of monitoring operation of a radar level gauge system installed at a tank and arranged to determine a filling level of a product contained in the tank.

Abstract: Described is a radar-based method for measuring a level of material in a container. Microwaves are emitted to a surface of the material by a radar level gauge, echo waves reflected from the surface are received and the received echo waves are converted into an echo function which is stored and evaluated to establish a useful echo and to determine a position of the echo. The echo function is generated and stored with a first higher resolution for a selected first portion of the entire level measurement range of the radar level gauge. Further, the echo function is generated and stored with a second lower resolution or no echo function is generated and stored for the remaining second portion of the entire level measurement range.

Abstract: An antenna outputs query signals to a wireless tag, and receives response signals output from the wireless tag. An intensity detection circuit detects the signal intensity of the response signals. A control portion judges the type of toner housed in a cartridge, or whether the toner is a certified product or a non-certified product, from the detected signal intensity. Further, the control portion outputs to an output setting circuit an instruction signal to change the signal intensity of the query signals, such that normal wireless communication can be performed with the wireless tag.

Abstract: An ultra wide band (UWB) millimeter (mm) wave radar system includes a signal source having a control input, a GHz signal output and a frequency controlled output. A control loop is coupled between the GHz signal output and the control input including a frequency divider and a digitally controlled PLL that provides a locked output coupled to the control input of the signal source to provide frequency locked output signals that are discrete frequency swept or hopped. A frequency multiplier is coupled to the frequency controlled output of the signal source for outputting a plurality of mm-wave frequencies. An antenna transmits the mm-wave frequencies to a surface to be interrogated and receives reflected mm-wave signals therefrom. A mixer mixes the reflected mm-wave signals and mm-wave frequencies and processing circuitry determines at least one parameter relating to the surface from the mixing output.

Abstract: A radar level gauge system, for determining a filling level of a product contained in a tank, the radar level gauge system comprising: a transceiver for generating, transmitting and receiving electromagnetic signals; a propagating device electrically connected to the transceiver and arranged to propagate a transmitted electromagnetic signal towards a surface of the product contained in the tank, and to return echo signals resulting from reflections at impedance transitions encountered by the transmitted electromagnetic signal, including a surface echo signal resulting from reflection at the surface, back to the transceiver; processing circuitry connected to the transceiver and configured to determine the filling level based on the surface echo signal; and a bottom reflector arranged at a bottom of the tank.

Abstract: There is disclosed a process instrument comprising a housing and an antenna secured to the housing. A process adaptor is associated with the antenna and housing for securing the instrument to a process vessel to define a process seal. A control in the housing generates or receives a high frequency signal. The control comprises an electromagnetic radiating element. A body supports the radiating element in the housing proximate the antenna for rotation at any angular orientation without affecting the process seal.

Abstract: A radar level gauge system, for determination of a filling level of a product contained in a tank, the radar level gauge system comprising: first pulse generating circuitry for generating a transmission signal in the form of a first pulse train having a first pulse repetition frequency; second pulse generating circuitry for generating a reference signal in the form of a second pulse train having a second pulse repetition frequency, the second pulse repetition frequency differing from the first pulse repetition frequency by a predetermined frequency difference; a propagation device connected to the first pulse generating circuitry and arranged to propagate the transmission signal towards a surface of the product inside the tank, and to return a reflected signal resulting from reflection of the transmission signal at the surface of the product contained in the tank; measurement circuitry connected to the propagation device and connectable to the second pulse generating circuitry, the measurement circuitry being

Abstract: A sensor for detecting a substance in a physical space, having an RF energy emitter fed by a signal source on one side of the space and an RF energy receiving element coupled to a detector at an opposite side of the channel, spaced apart by a distance (r) selected so that when the signal wavelength (?) changes based on the value of the dielectric constant (?) of the particular substance in the physical space between the emitter and receiver, the mode of field type within the sensor channel changes between near field and intermediate or far field mode.

Abstract: The invention sets forth a method of determining a filling level of a product contained in a tank using a radar level gauge system. The steps include generating a transmission signal using first pulse generating circuitry outputting a first signal having a first oscillation frequency having a first pulse repetition frequency. The invention uses a second pulse generating circuitry having a resonator element having an input and an output, a reference signal in the form of a second pulse train having a second pulse repetition frequency which differs from the first pulse repetition frequency by a predetermined frequency difference. The invention forms a measurement signal including a sequence of values representing a time correlation between a pulse of the reference signal and the reflected signal, and determines the filling level based on the measurement signal.

Abstract: Method and apparatus for determining the thickness of material layers of a container-held substance comprising a first material disposed in an upper layer and a second material disposed in a lower layer, by transmitting a radio signal through the substance towards a container portion; receiving reflected signals from a surface of the upper layer, a surface of the second layer, and the container portion; varying the frequency of the transmitted signal to determine phase displacement between transmitted and reflected signals; determining optical distances to the surfaces and the container portion, dependent on the phase displacements; determining the thickness of one of said layers dependent on phase displacement through and index of refraction of that layer; and determining the thickness of the other layer dependent on the thickness of said one of said layers.

Abstract: An apparatus for ascertaining and/or monitoring fill level of a medium in a container. The apparatus includes an antenna, which transmits and receives high frequency signals in a predetermined oscillatory mode in a bounded space in a predetermined radiation direction, wherein, in front of the antenna in the radiation direction, an antenna protection element of a material transmissive for the high frequency signals is provided, and wherein a control/evaluation unit is provided, which evaluates the received high frequency signals and ascertains the fill level.

Abstract: In a pulse radar ranging system, directional coupling means are configured to convey transmit pulses to be transmitted via an antenna to a target and to convey target echoes received by the antenna to a signal mixer that generates an intermediate frequency signal. To embed a reference measurement into the target measurement, the directional coupling means include a four-port circulator with an additional port arranged between a port receiving the transmit pulses and a port coupled to the antenna. A reference line is coupled to the additional port for generating reference echo pulses in response to input pulses. The circulator is configured to split a portion of the transmit pulses to the reference line and to convey there reference echo pulses to the antenna.

Abstract: Pulse echo signals containing false echoes are processed by forming tracks of multiple received echoes and monitoring these tracks by a recursive filter such as a Kalman filter. A track velocity is estimated for each track, and the position of each the next echo on the track is predicted.

Abstract: A liquid characterization and level sensor with a coaxial probe attached to a closed loop servo circuitry combined with a DSP and novel algorithms to scan, lock and track signals to ascertain the level and purity of fluid in a container.

Abstract: A radar level gauge for determining the filling level of a product in a tank, comprising a transceiver for transmitting and receiving microwaves, processing circuitry connected to the transceiver and adapted to determine the filling level, an antenna connected to said transceiver and arranged to emit and receive microwaves through an opening of the tank, and a microwave transmissive sealing member adapted to cover said opening and to provide pressure sealing of the tank. The sealing member comprises a metal grid layer providing structural strength, which metal grid layer has sealed openings formed to allow transmission of microwaves. The tank opening is thus divided into a number of smaller openings by the metal grid, thereby improving the mechanical strength of the sealing member. At the same time, the sealing member is designed to maintain its pressure sealing properties, e.g. by suitable dielectric filling of the openings.

Abstract: A radar level gauge system using microwaves for measuring a level of a surface of a product in a container, comprising a waveguide arranged to extend into the product contained in the container, wherein a plurality of reference impedance transitions are arranged at known position along the waveguide and being configured to reflect a portion of transmitted electromagnetic signals back towards the transceiver. Preferably, each of the reference impedance transitions has a first reflection coefficient for the electromagnetic signals when the level of the surface is above the reference impedance transition and a second reflection coefficient for the electromagnetic signal when the level of the surface is below the reference reflector, the first reflection coefficient being substantially lower than the second reflection coefficient. According to this design, a higher accuracy of filling level measurements can be achieved.

Abstract: A level verification system for a radar level gauge utilizes a remotely positionable target. The target is positioned inside of a tank that is subject to level measurement, and stowed at a first position and selectively positionable to a second position to reflect emitted electromagnetic radiation in an amount indicative of a predetermined material level. The verification system can verify a high level alarm will be triggered when the material reaches a high level corresponding to the level of the target, by remotely positioning the target in front of the emitter of the radar gauge. The target reflects electromagnetic energy to the detector at approximately the same intensity that the material reaching the high level would reflect so as to provide an accurate verification.

Abstract: A fill level measuring device for ascertaining and monitoring fill level of a medium in the process space of a container by means of a microwave travel time measuring method. The device includes: measurement transmitter; and an antenna unit, which is constructed at least of a hollow conductor and a radiating element, wherein a process isolation element is inserted into the hollow conductor for process isolation between measurement transmitter and the process contacting, radiating element. The process isolation element is made of a ceramic material and includes at least one glass layer, via which the process isolation element is directly glass bonded in the hollow conductor in a glass bonding region.

Abstract: A method for lessening disturbances of a measurement signal in a radar unit for distance measurement by means of frequency-modulated radar in continuous wave operation. The method comprises steps of: registering, in a reference measurement, a reference signal as a function of time; deriving an error correction signal from the registered reference signal, wherein the error correction signal predominantly comprises spectral components caused or influenced by device-specific defects of the radar unit; registering a measurement signal; and correcting the measurement signal in accordance with the error correction signal by means of digital signal processing.

Abstract: The invention relates to a method for accurately determining the level L of a liquid by means of radar signals emitted to the liquid surface and radar signals reflected from the liquid surface. The invention further relates to a device for accurately determining the level of a liquid by means of the method according to the invention, which device comprises at least a radar antenna disposed above the liquid for emitting radar signals to the liquid and receiving radar signals reflected from the liquid surface, as well as means for determining the liquid level on the basis of the emitted radar signals and the reflected radar signals.

Abstract: A method of determining a filling level of a product contained in a tank using a radar level gauge system, the method comprising the steps of: generating a transmission signal using first pulse generating circuitry outputting a first signal having a first oscillation frequency, the transmission signal being in the form of a first pulse train having a first pulse repetition frequency; generating, using second pulse generating circuitry comprising a resonator element having an input and an output, a reference signal in the form of a second pulse train having a second pulse repetition frequency, the second pulse repetition frequency differing from the first pulse repetition frequency by a predetermined frequency difference; propagating the transmission signal towards a surface of the product contained in the tank; receiving a reflected signal resulting from reflection of the transmission signal at the surface of the product; forming a measurement signal comprising a sequence of values, each value representing a

Abstract: A radar level gauge system comprising power management circuitry for regulating operating power to be used by a microwave unit and a processing circuitry of the radar level gauge system. The power management circuitry comprises a DC-DC converter having an input terminal connected to the interface, an output terminal connected to the microwave unit and the processing circuitry, and a reference terminal connected to an electrical reference point, wherein a first voltage level at the input terminal and a second voltage level at the output terminal relates to a reference voltage level at the electrical reference point. The power management circuitry further comprises an energy storage capacitor connected between the input and output terminals of the DC-DC converter. According to this design, the capacitance of the power management circuitry gets reduced due to that the capacitance is originating from a series capacitance.

Abstract: A method for monitoring the surfaces of slag and molten metal in a mould of a continuous casting apparatus, using radar equipment is disclosed. The radar equipment emits a beam of electromagnetic waves having a bandwidth of at least 20 GHz. This also relates to an apparatus for using the method.

Abstract: A modular system is for assembling a fill-level radar antenna, a fill-level radar antenna, and o a fill level radar. The modular system comprises several modules that can be interconnected. In this way a host of different fill-level radar antennae may be produced that are optimally adapted to the corresponding conditions.

Abstract: An ultra wide band (UWB) millimeter (mm) wave radar system includes a signal source having a control input, a GHz signal output and a frequency controlled output. A control loop is coupled between the GHz signal output and the control input including a frequency divider and a digitally controlled PLL that provides a locked output coupled to the control input of the signal source to provide frequency locked output signals that are discrete frequency swept or hopped. A frequency multiplier is coupled to the frequency controlled output of the signal source for outputting a plurality of mm-wave frequencies. An antenna transmits the mm-wave frequencies to a surface to be interrogated and receives reflected mm-wave signals therefrom. A mixer mixes the reflected mm-wave signals and mm-wave frequencies and processing circuitry determines at least one parameter relating to the surface from the mixing output.

Abstract: A power management circuitry for a radar level gauge including a first voltage converter, having a low-voltage end for receiving a drive voltage from a power interface and a high-voltage end for supplying an intermediate voltage higher than the required operating voltage, a temporary energy store arranged to be charged by the intermediate voltage, a second voltage converter, having a high-voltage end for receiving an input voltage from the energy store, and a low-voltage end for providing the operating voltage lower than the input voltage. By storing energy at a higher voltage, a different type of energy store (e.g. low capacity capacitor) may be used. As a consequence, the cost and start-up time of the energy store is significantly reduced.

Abstract: A method of determining a filling level of a product contained in a tank, the method comprising generating and transmitting electromagnetic signals; propagating the transmitted electromagnetic signals towards a surface of the product contained in the tank; receiving echo signals resulting from reflections at impedance transitions encountered by the transmitted electromagnetic signals, including a surface echo signal resulting from reflection at a surface of the product; determining a position of a reference impedance transition using a reference echo signal resulting from reflection of the transmitted electromagnetic signals at the reference impedance transition; determining an update level located above the surface, based on the determined position of the reference impedance transition and a known position of the reference impedance transition; determining a disturbance echo profile using at least one of the echo signals resulting from reflection of the transmitted signals at at least one impedance transitio

Abstract: A radar level gauge system for determining a filling level of a product contained in a tank, comprising: a transceiver for generating, transmitting and receiving frequency-modulated electromagnetic signals; a transmitting propagating device electrically connected to the transceiver and arranged to propagate transmitted electromagnetic signals towards a surface of the product contained in the tank; and a receiving propagating device electrically connected to the transceiver and arranged to return echo signals resulting from reflections at impedance transitions encountered by the transmitted electromagnetic signals, including a surface echo signal resulting from reflection at the surface, back to the transceiver.

Abstract: A through air level measurement instrument for use in minimizing tank rattle comprises a housing and an antenna secured to the housing. A process adaptor is associated with the antenna and the housing for securing the instrument to a closed tank with the antenna directed into an interior of the closed tank. A control in the housing generates and receives a high frequency signal using an electromagnetic radiating element proximate the antenna. The control comprises an equivalent time sampling circuit including a main oscillator driving a timing circuit controlling timing between transmitted and sample pulses. A noise generator is operatively associated with the main oscillator to randomly modulate timing of the main oscillator. The control minimizes inaccuracies caused by tank rattle.

Abstract: A level measuring instrument has a variable transmitting power for measuring a filling level in a tank. The level measuring instrument includes a generator unit generating one of a first oscillator signal and a second oscillator signal. The generator unit generates a transmit signal from one of the first oscillator signal and the second oscillator signal. The level measuring instrument includes further a controller controlling the generator unit. The generator unit generates one of first and second transmitting powers for the transmit signal.

Abstract: The invention relates to an apparatus (1) for ascertaining and monitoring fill level (2) of a medium (3) in a container (4) by means of a travel-time measuring method of high-frequency measurement signals (6) with a horn antenna (7) having a waveguide section (8), a flared, horn section (9) and a cavity (11) filled, at least partially, with a dielectric filling body (12). Object of the invention is to provide a simple, temperature-stable, horn antenna filled with a dielectric material.

Abstract: A radar level gauge system comprising a transceiver for generating, transmitting and receiving electromagnetic signals; an antenna arranged to direct transmitted electromagnetic signals towards a surface of the product contained in the tank, and to return reflected electromagnetic signals resulting from reflections at impedance transitions encountered by the transmitted electromagnetic signals back to the transceiver; and a hollow waveguide connecting the transceiver and the antenna for guiding the electromagnetic signals therebetween. The radar level gauge system further comprises a leak indication member being movably arranged inside the hollow waveguide in such a way that a force resulting from leakage of the fluid at the sealing member causes a movement of the leak indication member which causes a change in at least one microwave propagation characteristic of the hollow waveguide.

Abstract: A radiometric measuring arrangement for measuring fill level of a fill substance in a container includes: arranged one above the other in measurement operation on a first side of the container, two or more radiometric radiators, which, in measurement operation, send radioactive radiation through the container, and which, in measurement operation, are arranged in a measuring position in the interior of the container in a pressure resistant, protective tube protruding laterally into the container; and, arranged on a second side of the container lying opposite to the radiators, at least one detector, which serves to receive radiation intensity penetrating through the container as a function of fill level and to convert such into a fill level dependent, electrical signal. The measuring arrangement permits achievement of a highly linear dependence of total detected radiation intensity on fill level.

Abstract: A narrowband radar arrangement having a radar transmitter and a radar receiver mounted above a targeted water surface to monitor and determine a sea state of the targeted water surface. Fixed frequency signals are transmitted by the transmitter and received by the receiver, via a direct path and via a forward scattered path off the targeted water surface. An interference pattern of interfering direct path signals and forward scattered signals is used to determine an instantaneous height of the water surface and also to determine the sea state of the targeted water surface.

Abstract: A radar level gauge for measuring a level of a surface of a product in a container has an antenna for transmitting microwaves to the surface and receiving microwaves reflected by the surface, a measurement circuitry for generating said microwaves to be transmitted and for evaluating said received microwaves, a hollow waveguide between the antenna and the measurement circuitry, said waveguide being separated by a gap into a first waveguide member coupled to the antenna and a second waveguide member coupled to the measurement circuitry, and a dielectric barrier arranged in said gap. A dielectric barrier which is simpler in construction and less critical with respect to the wavelength of the microwaves is obtained in that the dielectric barrier comprises a shaft member inserted into the hollow waveguide and extending through at least a portion of the first waveguide member, through the gap and through at least a portion of the second waveguide member.

Abstract: A radar level gauging system for determining a level of a surface of a product in a tank, comprising a propagation device arranged to allow microwave signals to propagate towards the surface, and to return a reflection of the microwave signals from the surface and at least two radar level gauge (RLG) units. Each RLG unit includes transceiver circuitry, processing circuitry connected to the transceiver circuitry and adapted to determine the level based on a relation between transmitted and received signals, and a communication interface. The system further comprises a communication link interconnecting the RLG units, for communicating control data between the RLG units, the communication link comprising an isolating interface, ensuring galvanic isolation between the RLG units. One unit may communicate configuration data to the other RLG units which results in a simplified configuration of the sensor system and thus more cost effective compared to the prior art solutions.

Abstract: A method and apparatus for optimally loading and conditioning materials for transport is provided. Specially, the invention, in a preferred embodiment, relates to loading ash-like materials which require treatment prior to loading onto a truck or vehicle to avoid slurry spillage, overload or airborne particulate during loading or transport. The system conditions the ash-like materials by liquid additions proportional to material flow rate, truck information, slump height and/or slump weight. The system further includes a slump height or weight indicator and a communication and integration system.

Abstract: The invention relates to a device for loading solid particles into a vessel comprising: particle feed means (24); means (26) for dispersing the particles from the top to the bottom of the vessel; at least one means (17) for measuring the height of the filling bed; and at least one automated system for controlling the feed means (24) and/or the dispersion means (26), and also to a process and uses implementing the device.

Abstract: A broadband radar arrangement having a radar transmitter and a radar receiver mounted above a targeted water surface to monitor and determine a sea state of the targeted water surface. Spectrally spaced signals are transmitted by the transmitter and received by the receiver, via a direct path and via a forward scattered path off the targeted water surface. An interference pattern of interfering direct path signals and forward scattered signals is used to determine an instantaneous height of the water surface and also to determine the sea state of the targeted water surface.