Abstract: A radar fill-level sensing device has a high-frequency unit that serves to generate and process radar signals of a predefined frequency and wavelength, an antenna for transmitting and/or receiving the radar signals, as well as circuitry, provided on a circuit board. That circuitry includes a microstrip circuit for connecting the high-frequency unit to the antenna, that microstrip circuit featuring a ground conductor. The ground conductor encompasses a first segment, a radial stub and a second segment, the length of the first segment corresponding essentially to one quarter of the predefined wavelength. The radial stub is positioned at the end of the first segment, the second segment connects to the end of the first segment and to the radial stub, and the second segment is grounded. Based on this design, a radar fill-level sensing device is obtained that can easily and reproducibly be implemented within the requirements of “intrinsically safe” ignition protection.

Abstract: The invention relates to a method for determining the filling level of a medium in a container. A mixer that has at least one mixer blade and a mixer frequency (f<1>R</1>) is disposed in the container. Measuring signals are emitted at a predetermined measuring frequency (f<1>M</1>) towards the medium. The measuring signals reflected on the surface of the medium are received and evaluated by a run time method. The aim of the invention is to provide a device which allows for a reliable measurement of the filling level of a medium in a container provided with a mixer. To this end, the measuring frequency (f<1>M</1>) of the measuring signal having the mixer frequency (f<1>R</1>) of the mixer is synchronized (f<1>M</1>=n f<1>R</1>with n ? N) and that the measuring frequency (f<1>M</1>) is shifted by a defined phase (?) with respect to the mixer frequency (f<1>R</1>).

Abstract: An antenna device for determining the filling level of a filling material in a container (tank) comprising an essentially flat array antenna with an emitting area for emitting measuring signals towards the surface of the filling material and a holder for holding the array antenna over an opening of the container and to be connected to the rim of the opening in at least two points of attachment. Further, a protective dielectric cover covers the emitting area, the dielectric cover having an extension larger than the opening in order to extend over the rim of the opening. The antenna device provides several advantages, such as a very efficient sealing of the container opening, a very clean solution towards the container and a very effective protection of the array antenna.

Abstract: A method and system is disclosed for enabling quantities of bulk-type products to be determined using RFID tags that can also be used to determine the existence of product or packaging containing RFID tags. Packaging and/or containers for the bulk products are configured so that the RFID tags contained thereon provide an indication of an approximate relative quantity of the bulk material. More specifically, the position and/or shielded or unshielded state of RFID tags are utilized to identify a quantity of the bulk-type material.

Abstract: A level of liquid of pulverent solids in a container (or volume of a liquid in the absence of gravity) is detected by using radio frequency identification (RFID) tags or similar transponders located inside or outside the container. The interrogation signal and/or the return signal is attenuated by the material and the signal strength of the return signal, if any, is evaluated either directed or in a binary fashion by imposing a threshold to determine whether or not material in contained in a portion of the container corresponding to the location of a particular RFID tag or transponder. Volume, pressure and container orientation can also be derived in accordance with one or more return signals.

Abstract: The present invention relates to a radar level gauge (1) comprising an antenna (2), a tank sealing (3), an electronics unit (4) and a waveguide feed (5) between the electronics unit (4) and the antenna (2). The waveguide (5) is essentially straight and has a 90°-symmetric cross section and is further arranged to accommodate two essentially orthogonal waveguide modes. The waveguide (5) further has a length (I) below two times the range resolution of said radar level gauge (1). The present invention further relates to a method for improved radar level gauging using a radar level gauge (1) as above.

Abstract: A process control instrument comprises a control for generating or receiving a high frequency signal. A waveguide comprises a cylindrical housing closed at one end by a rear wall. A loop launcher is operatively connected to the control and comprises a wire having a first straight leg electrically connected at one end to the control and extending into the waveguide a first select length. A second straight leg is connected at one end to the rear wall and extends into the waveguide a second select length, greater than the first select length. A curved middle section connects the other ends of the first and second straight legs. An antenna is operatively coupled to the waveguide.

Abstract: A transceiver unit, particularly for measuring applications, comprising a transmitter (1) for generating a signal, an acquisition antenna (5) for emitting the signal in an acquisition volume and for picking up an effective echo signal reflected by the acquisition volume, as well as a receiver (2) for evaluating an echo signal supplied by the acquisition antenna (5). The echo signal is composed of the effective echo signal and an unwanted echo signal generated by the acquisition antenna (5). In order to compensate for the unwanted echo signal, an antenna simulation (6) is connected via a coupler (3) to the transmitter (1) and the receiver (2) which, after having received the signal, supply an correction signal in proportion to the unwanted echo signal. The coupler so heterodynes the correction signal and the echo signal that the correction signal and the unwanted echo signal cancel out each other.

Abstract: A radar level gauge system for determining the filling level of a filling material in a tank is disclosed. The system comprises an antenna device for emitting measuring signals towards the surface of the filling material and a receiver device for receiving echo signals from the tank. Further, the system comprises processing circuitry for determining the filling level of the tank based on said echo signal, wherein said processing circuitry is adapted to amplify the received echo signals in dependence of the distance from which the echo signals originates, in such a way that an echo signal from a lower filling level is more amplified than an echo signal from a higher filling level. The processing circuitry is adjustable to optimize the amplification of the echo signal based on the height of the tank. A corresponding processing circuitry and method of operation is also disclosed.

Abstract: The invention relates to an apparatus for monitoring a field device for determining and/or monitoring a physical and/or chemical process parameter of a process medium with a first sealing stage facing toward the process and at least one housing with a predetermined interior volume. The housing is located on the side of the first sealing stage facing away from the process, wherein energy is transferable through the first sealing stage 4 in the direction of the process medium. This energy interacts with the process medium, wherein at least one detector unit is provided in the housing, which unit monitors at least one condition parameter of the interior volume of the housing.

Abstract: A test apparatus for a waveguide that senses levels in a container. The test apparatus includes a bridge with a test position where the bridge bridges the waveguide to simulate a simulated level. The bridge also has a storage position. The test apparatus also has an actuator coupled to the bridge that moves the bridge between the test and storage positions.

Abstract: Described is a radar filling level measuring device for non-contact measurement of a filling level of a filling matter in a vessel. A radar filling level measuring device including an electronics unit for generating transmission signals and for evaluating receiving signals reflected for a filling matter, an antenna unit connected to the electronics unit and adapted to radiate the transmission signals generated by the electronics unit in the direction of the filling matter and to receive the receiving signals reflected from the filling matter surface and to pass them on to the electronics unit, and a housing forming a cavity which is at least tight with respect to the atmosphere within the vessel and in which the electronics unit and antenna unit are acommodated. By this structure both the antenna unit and the electronics unit are protected in a technically simple and cheap way against aggressive ambient conditions and against chemical and mechanically abrasive aggression.

Abstract: A method and a device for measuring, by means of radar, in an enclosed space (1) in which a liquid (2) is stored, the level of a liquid surface (6), where the method involves the steps: a radar unit (3) mounted on the roof (4) of the enclosed space transmits a microwave signal downwards into the enclosed space (1) through a waveguide (7) that communicates with the liquid in the enclosed space; the transmitted microwave signal's polarization alters according to a predetermined time sequence in such a way that the signal is propagated alternatively at least in a first and a second plane of polarization; the signal transmitted in the first plane of polarization is reflected by the liquid surface (6) back to the radar unit (3); the signal in the second plane of polarization is reflected by at least one reference transmitter placed at a known distance from the radar unit; a calculating unit calculates the level of the liquid surface based partly on the propagation time for the microwave signal, i.e.

Abstract: The invention relates to a microwave-operated level meter with a small blind zone, comprising an antenna for transmitting or for transmitting and receiving microwaves, a microwave generator directly located on said antenna, and a transmitter or transmitter and receiver element pointing into the antenna and directly linked with the microwave generator, said transmitter or said transmitter and receiver element being an extension of the connection.

Abstract: A radar level gauge for measuring the level of a surface of a product stored in a tank by use of radar. The radar transmits microwaves towards the surface and receives microwaves reflected by the surface and is adapted to transmit and receive microwaves within two widely separated frequency bands. Widely separated frequency bands are chosen to utilize the differences in attenuation due to foam on the surface and the differences in beam-width or other disturbances. The ratio between the center frequencies of the two widely separated frequency bands can be quantified as at least greater than 1.5:1 or preferably greater than 2:1.

Abstract: A fill level measuring device for measuring a fill level of a fill substance in a container and a method for fill level measurement using this fill level measuring device are provided. The fill level measuring device can perform fill level measurements upon re-start immediately on its own and reliably, and includes: at least one antenna, which issues transmitted signals (S) and receives echo signals (E); a signal processor, which serves for deriving from the received echo signals (E) an echo function containing the amplitudes (A) of the echo signals (E) as a function of travel time; a memory for storing data in a table whose columns serve for storing the echo functions in the columns in a sequence which corresponds to the fill levels associated with the individual echo functions; and an evaluation unit, which accesses the table for determining the fill level.

Abstract: A method, an arrangement and a radar level gauging system for preventing interference, which radar level gauging system comprises at least two radar level gauges arranged to measure a filling level of a product kept in a container. Microwave pulses are transmitted towards the surface of said product and microwave pulses reflected by said surface are received by said at least two radar level gauges. Information is provided with said microwave pulses and said information is used for controlling the measurement pulses of said at least two radar level gauges.

Abstract: The present invention relates to a radar filling level measuring device capable of generating and receiving an elliptically polarized wave and, as a special case, a circularly polarized wave, using a directional coupler which, according to a particular embodiment, may be configured as a 3 dB coupler. By simultaneously using a 3 dB coupler the necessary separation into transmitting and receiving functions can be achieved. Moreover, the present invention relates to a use of a directional coupler for generating an elliptically polarized wave and, as a special case, a circularly polarized wave, as well as to a method for generating and receiving an elliptically polarized wave.

Abstract: A method for processing a time domain reflectometry (TDR) signal used to determine at least one process variable for a material in a tank, wherein said TDR signal has been generated by a radar level gauge system comprising a pulse generator, a probe extending into the tank for guiding the pulse, and a receiver for receiving said TDR signal, and wherein the TDR signal comprises at least a surface reflection pulse caused by an interface between different materials in the tank, and an interfering pulse caused by a transition between the pulse generator and the probe.

Abstract: There is provided a radar level gauge using microwaves for measuring a level of a surface of a product in a tank, comprising an antenna for transmitting microwaves to the surface and receiving microwaves reflected by the surface, a measurement circuitry feeding said antenna through a hollow wave guide and said wave guide including at least an antenna wave guide member, at one end couplable to the antenna and at its other end having an opening in an intersection across the wave guide, wherein the radar level gauge further comprises: a dielectric barrier extending along said intersection across the opening of said antenna wave guide member for non-conductively separating said antenna wave guide member from the measurement circuitry, said dielectric barrier having a first side facing the wave guide in a direction towards the antenna wave guide member and said dielectric barrier having a second side facing a direction substantially away from said antenna wave guide member.

Abstract: A device for establishing and/or monitoring a predetermined fill level in a container is provided, which also operates stably in liquids with surface waves, which includes: a mechanical oscillatory structure placed at the height of the predetermined fill level, an electromechanical transducer, which in operation excites the oscillatory structure to resonance oscillations, and a receiver- and evaluation-unit, which serves for determining from the resonance oscillation whether the predetermined fill level has been reached, or not, in which a shape of the oscillatory structure is so constructed that the resonance frequency changes only slowly with immersion depth in the case of immersion in the region of the predetermined fill level.

Abstract: The invention relates to a method and a device for determining the level of a filling (1) in a container (2). The aim of the invention is to provide a method and a device for measuring said level which are economical to carry out/produce and which offer an especially high degree of measuring accuracy.

Abstract: The invention concerns a device for determining and/or monitoring the fill level of a fill material in a container with a transmitting-/receiving-unit, which produces and receives high frequency measurement signals, and an evaluation/control-unit, which determines the fill level of the fill material in the container on the basis of the travel time of the high frequency measurement signals. High frequency measurement signals are guided along a conductive element. The coupling onto, and from, element is done by a coupling unit. The device is secured at the container using an attachment part placed above the maximum fill level to be measured and/or monitored in the upper region of the conductive element, a horn-shaped element is arranged such that its lower opening area facing in the direction toward the surface of the fill material lies approximately in the plane of the attachment part.

Abstract: A dielectric rod antenna assembly for a level measurement system. The antenna assembly includes a transition structure housed within a coupling sleeve. The transition structure includes a short-circuited waveguide filled with a dielectric material and an exciter element projecting through the waveguide into the material. The transition structure directs electromagnetic energy through the bottom of the dielectric material into a rod antenna attached to the bottom of the coupling sleeve for propagation within the container. The dielectric material includes a longitudinal axial bore having a tapered tip to provide a dielectric-lined waveguide. The bottom end of the dielectric is encircled with a metal ring of a diameter larger than the dielectric to smooth the transition into the rod antenna.

Abstract: Method and device for calculating the level of the surface of a product in a storage room by a radar level gauging system, which includes a first gauging device for calculating a first value of level and functionally separated from the first gauging device a second gauging device for calculating a second value of said level, wherein: a first signal is produced being dependent of a preset first threshold value of the level in the first gauging device, a first current level value signal is output from the first gauging device, a second signal is produced in dependence of a preset second threshold value of the level in the second gauging device, a second current level value signal is output from the second gauging device and the value of the current level of said surface is presented by an indicating unit adapted to receive at least one of the first level value signal and the second level value signal for evaluation of the current level value.

Abstract: An antenna assembly for use with a level measurement device for measuring the level of a material held in a container is provided. The antenna assembly includes an upper section for coupling to the level measurement device, and an antenna for transmitting energy pulses emitted by the level measurement device and receiving energy pulses reflected by the material in the container. A transducer module is disposed between the upper section and the antenna. A controller is operably connected to the transducer module, the transducer module being responsive to control signals of the controller for activating the transducer module such that the transducer module, when activated by the controller, vibrates the antenna to dislodge or remove material adhering to the antenna.

Abstract: A sensor for detecting contact of a fluid delivery probe with a fluid surface and for detecting fluid flow through the probe includes a first electrode disposed along a fluid flow path of the probe upstream from a distal tip of the probe and a second electrode longitudinally spaced and electrically isolated from the first electrode and disposed at the distal tip of the probe. An oscillating signal is transmitted through the first electrode, and at least a portion of the signal is received through the second electrode. Through changes in the received signal due to the distal tip of the probe coming into contact with a fluid surface or due to fluid flow through the conduit between the first and second electrodes, fluid surface contact and fluid flow can be detected. A pressure sensor can be employed to monitor internal fluid pressure within the fluid conduit of the fluid delivery probe as a secondary, redundant mechanism for detecting fluid flow through the conduit.

Abstract: A microwave-based level measurement system having a planar microwave antenna configuration. According to another aspect, the microwave-based level measurement devices are field interchangeable with ultrasonic based level measurement devices.

Abstract: Described is a method and an apparatus of directly digitizing microwave signals reflected at a filling product surface of a filling product present in a receptacle, in which method the microwave signals reflected at the filling product surface are sampled unmodified in their frequency, and the therefrom resulting analog values are converted into digital values, with successive digital values being stored in various intermediate memories, and the intermediately stored digital values are read out from the intermediate memories and are stored in a terminal memory unit, to which accesses an evaluation arrangement which determines the filling level height.

Abstract: A method and apparatus for estimating a communication channel in a wireless communication system having multiple transmitter antennas using reduced rank estimation. The method exploits redundant and/or a priori knowledge within a system to simplify the estimation calculations. In one embodiment, a covariance matrix is calculated and analyzed to determine if the channel parameters may be reduced for channel estimation. If not, all parameters are used, otherwise a reduced rank matrix is used for the calculation.

Abstract: A time domain reflectometry measuring instrument uses a microprocessor that provides added functionality and capabilities. The circuit electronics and probe are tested and calibrated at the factory. Installation and commissioning by the user is simple. The user installs the probe. The transmitter is attached to the probe. The user connects a standard shielded twisted pair to the electronics. Power is applied and the device immediately displays levels. A few simple parameters may need to be entered such as output characteristics and the process material dielectric constant.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.

Abstract: A guided wave radar transmitter comprises a probe defining a transmission line including a relatively low impedance target marker above an expected sensing region of the probe. A pulse circuit is connected to the probe for generating pulses on the transmission line and receiving a reflected signal from the transmission line. The reflected signal selectively includes a target pulse representing the target marker and a level pulse representing material along the length of the probe. A controller is operatively connected to the pulse circuit. The controller normally operates at a relatively low gain to determine a level time to the level pulse to determine material level, and periodically operates at a relatively high gain to determine a target time to the target pulse. The target time is used to compensate the level time for properties of vapor above the material level.

Abstract: A time-base generator with a self-compensating control loop. The time-base generator is suitable for use in level measurement and time-of-flight ranging systems. The time-base generator includes a pulse generator stage, a delay stage, a control loop and a references voltage module. The pulse generator generates a transmit pulse train and a receive or sampling pulse train with a delayed timing relationship. The control loop functions with the delay stage to maintain the desired delay between the first pulse train and the second pulse train. According to another aspect, the time-base generator includes a calibration module. The calibration module generates calibration pulses which are used by the controller in the level measurement system to calibrate operation.

Abstract: An antenna device in a radar-based level gauge mounted at an opening in a roof of a tank, the antenna device comprising at least one elongated radiating structure, which has a length that is substantially larger, preferably more than 3-5 times longer, than a maximum cross-sectional length dimension of the opening; is oriented in a non-vertical position; and is configured and fed to produce an essentially vertical radiation beam directed downwards in the tank. Preferably, the antenna device is foldable and is inserted into the tank through the opening and oriented in the non-vertical position by means of folding the radiating structure.

Abstract: The invention relates to a device for determining and/or monitoring filling of a product or the position of the boundary surface between two media or phases in a container. The device comprises a signal generating unit that generates high-frequency measuring signals, an injection unit and a surface waveguide, wherein the measuring signals are injected into the surface waveguide by means of the injection unit and directed toward the filling product via the surface waveguide. The device also comprises a receiver/evaluation unit, which directly or indirectly determines filling of the product or the position of the boundary surface in the container during the running time of the measuring signals reflected on the surface or boundary surface of the filling product. The invention aims at providing a device which is configured in such a way that parasitic voltages are effectively diverted. This is achieved in that the surface waveguide is connected to a frame potential by means of a coupling.

Abstract: Calibrating the measurement of a distance between a transceiver and an object such as a radiating element (antenna) or a target by continuously changing the wavelength (frequency) of the transmitted wave and observing the rate of phase shift as a function of change in wavelength. The rate of phase shift change as a function of wavelength can be mathematically related to the total displacement to the reflecting object. This calibration technique is applicable to a sensing device comprising a transceiver configured to transmit a signal toward an object, detectors offset in phase to receive the transmitted signal and a reflected signal, and a processor configured with logic to measure a rate of phase shift proportional to the change in wavelength between the transmitted signal and the reflected signal at the detectors. The processor can be further configured with logic to relate the phase shift to displacement between the transceiver and the reflecting object.

Abstract: A separation frequency detector circuit and a method for detection of a separation frequency in a radar level gauge. A first circuit element (1) is arranged to receive a first clock frequency, and a second clock frequency. An instantaneous value of the first clock frequency will be transferred to and held at an output Q of the first circuit element (1) once each period of the second clock frequency. A predetermined value will be transferred to and held at an output Q of a second circuit element (3) triggered by the output Q of the first circuit element (1), and the predetermined value will be cleared from the output Q of the second circuit element (3) a predetermined time period after being triggered. An output is obtainable as a short pulse with a leading edge which will be synchronized with the first change of the leading signal edge of the first circuit element (1).

Abstract: The invention relates to a method of determining expectancy ranges to which echoes from a filling level envelope curve are assigned, which curve has been generated by a filling level measurement device. The determination of these expectancy ranges takes place in consideration of the temporal behavior of past echo data. Since these expectancy ranges exhibit a predeterminable range width, a statement can be made with a predeterminable probability whether an echo—be it at filling level echo or a false echo—assigned to such a range, has been assigned erroneously to this range. When, for example, an expectancy range for a filling level echo has been prognosticated, then it may be assumed with a predeterminable probability that an echo falling within this expectancy range, actually is a filling level echo. The invention moreover relates to an evaluation means configured for carrying out this method and a level gauge.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.

Abstract: The present invention relates to the field of radar level gauging systems, in which a level of a surface of a product stored in a container is measured. The gauging system comprises: a radar level gauge arranged above the surface of the product which is arranged to transmit a microwave signal towards the product surface and receive a reflected microwave signal from the product surface; a calculation unit arranged to determine a measured value of the product level based upon the received signal; means for comparing the measured value of the product level with a predetermined value; and a second level gauge arranged closed to the bottom of the container and arranged to determine the product level when the measured value is below the predetermined value.

Abstract: An antenna assembly suitable for use with a microwave-based level measurement system mounted on a vessel. The antenna assembly includes an installation thread, a shielded extension, and a rod antenna. The antenna assembly is screwed into a threaded portion in the opening of the vessel. The antenna assembly may be formed as a single integral unit molded from a polymer material. The antenna assembly may also be constructed with the installation thread, the shielded extension and the rod antenna comprising individual polymeric components which are welded together to form a unitary assembly. The polymer material is selected based on chemical resistant properties according to the application.

Abstract: The present invention relates to a radar filling level measuring device capable of generating and receiving an elliptically polarized wave and, as a special case, a circularly polarized wave, using a directional coupler which, according to a particular embodiment, may be configured as a 3 dB coupler. By simultaneously using a 3 dB coupler the necessary separation into transmitting and receiving functions can be achieved. Moreover, the present invention relates to a use of a directional coupler for generating an elliptically polarized wave and, as a special case, a circularly polarized wave, as well as to a method for generating and receiving an elliptically polarized wave.

Abstract: A radar fill level measurement sensor for measuring the level of material in a container, includes a transmit/receive circuit that transmits an electromagnetic pulse, and detects reflected electromagnetic pulses and provides an intermediate frequency signal indicative of the reflected electromagnetic pulses. A logarithm detector circuit receives the intermediate frequency signal and provides a logarithmic output signal indicative of the logarithm of the intermediate frequency signal. An evaluation unit receives and processes the logarithmic output signal, to determine the fill level of the material within the container, and provides a fill level measurement signal indicative thereof.

Abstract: A time-base generator with a self-compensating control loop. The time-base generator is suitable for use in level measurement and time-of-flight ranging systems. The time-base generator includes a pulse generator stage, a delay stage, a control loop and a references voltage module. The pulse generator generates a transmit pulse train and a receive or sampling pulse train with a delayed timing relationship. The control loop functions with the delay stage to maintain the desired delay between the first pulse train and the second pulse train. According to another aspect, the time-base generator includes a calibration module. The calibration module generates calibration pulses which are used by the controller in the level measurement system to calibrate operation.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.

Abstract: The present invention relates to the field of radar level gauging systems, in which a level of a surface of a product stored in a container is measured. The gauging system comprises: a radar level gauge arranged above the surface of the product which is arranged to transmit a microwave signal towards the product surface and receive a reflected microwave signal from the product surface; a calculation unit arranged to determine a measured value of the product level based upon the received signal; means for comparing the measured value of the product level with a predetermined value; and a second level gauge arranged closed to the bottom of the container and arranged to determine the product level when the measured value is below the predetermined value.

Abstract: A bottom reflector for a radar-based level gauge, which measures a level of a liquid stored in a tank by means of transmitting a microwave signal towards the surface of the liquid from the top of the tank, receiving the microwave signal as reflected against the surface of the liquid, and calculating the level of the liquid from the propagation time of the transmitted and reflected microwave signal, wherein the bottom reflector is adapted to be mounted close to the bottom of the tank and comprises a reflecting structure having a first reflection coefficient for the microwave signal when the level of the liquid is above the reflecting structure and a second reflection coefficient for the microwave signal when the level of the liquid is below the reflecting structure, wherein the first reflection coefficient is substantially lower than the second reflection coefficient.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.