Abstract: A self-diagnosing FMCW radar level gauge and a method for providing self-diagnosing with a radar level gauge is provided in a radar level gauge comprising a transceiver, a mixer, a signal propagating device and a signal propagation path connecting the transceiver and the signal propagating device, a filter arrangement and processing circuitry. The filter arrangement provides a filtered intermediate frequency signal. The transceiver outputs either a diagnostic sweep configured such that a reference echo from the signal propagation path is detectable in said filtered intermediate frequency signal, or a measurement sweep configured such that the reference echo is suppressed in the filtered intermediate frequency signal and that a surface echo is detectable. The processing circuitry is configured to self-diagnose the radar level gauge based on the reference echo, and to determine the distance to the surface based on the surface echo.

Abstract: A GWR level gauge system for determining a filling level in a tank. The system comprises a tank, a transceiver, a surface waveguide comprising a single conductor transmission line probe, connected to the transceiver, arranged extending vertically into the tank and configured to guide the electromagnetic transmission signals towards the surface and to guide the reflected electromagnetic signals back to the transceiver; processing circuitry connected to the transceiver and configured to determine the filing level based on received reflected electromagnetic signals; a plurality of retaining elements arranged in fixed positions in relation to an inside of the tank and spaced apart along the probe, wherein each of the retaining elements circumscribes the probe, and is configured to allow movement of the probe in a vertical direction relative the retaining element, and to restrict movement of the probe in a horizontal direction relative the retaining element.

Abstract: The present invention relates to a guided wave radar level gauge system comprising a transceiver for generating an electromagnetic transmit signal within a predetermined frequency range having a center frequency, a flexible single conductor probe having a first end connected to the transceiver and extending towards and into the product to a second end of the flexible single conductor probe; and a probe aligning member attached to the second end of the flexible single conductor probe for keeping the flexible single conductor probe substantially vertically extending from the first end to the second end. The probe aligning member exhibits a horizontal extension that increases with increasing distance from the first end of the flexible single conductor probe along a vertical distance greater than one half of a wavelength of the transmit signal at the center frequency. Hereby, determination of filling levels close to the bottom of the tank is improved.

Abstract: A radar level gauge system comprising a single conductor probe extending through a tubular mounting structure towards and into the product in the tank, a shielding structure radially spaced apart from the single conductor probe and extending along a top portion of the probe inside the mounting structure and past the lower end of the mounting structure, and processing circuitry connected to the transceiver for determining the filling level of the product in the tank. The shielding structure at least partly encloses the top portion of the single conductor probe, and is open in a radial direction to allow entry of the product. The shielding structure exhibits a total enclosing arc angle around the single conductor probe greater than 180° inside the tubular mounting structure, and a total enclosing arc angle around the single conductor probe that decreases with increasing distance from the lower end of the mounting structure.

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: An FMCW type radar level gauge configured to transmit an electromagnetic transmit signal and receive an electromagnetic return signal reflected from the surface, the electromagnetic transmit signal having a bandwidth of at least 1 GHz, a relative bandwidth (max frequency/min frequency) of less than 2.5 and an upper frequency limit less than 4 GHz. The gauge comprises a single conductor probe mechanically suspended in the tank and extending into the product in the tank, and a matching arrangement providing an electrically matched connection between an electrical feed-through and the single conductor probe. According to the present invention, the relatively expensive still-pipe is replaced with a relatively inexpensive a single conductor acting as a surface wave-guide (SWG).

Abstract: The present invention relates to a radar level gauge system comprising a signal propagation device; a microwave signal source; a microwave signal source controller; a mixer configured to combine a transmit signal from the microwave signal source and a reflection signal from the surface to form an intermediate frequency signal; and processing circuitry coupled to the mixer and configured to determine the filling level based on the intermediate frequency signal. The microwave signal source is configured to exhibit a phase noise greater than or equal to ?70 dBc/Hz @ 100 kHz offset from a carrier frequency for the transmit signal.

Abstract: The present invention relates to a radar level gauge system comprising a signal propagation device; a microwave signal source; a microwave signal source controller; a mixer configured to combine a transmit signal from the microwave signal source and a reflection signal from the surface to form an intermediate frequency signal; and processing circuitry coupled to the mixer and configured to determine the filling level based on the intermediate frequency signal.

Abstract: The present invention relates to a guided wave radar level gauge comprising a transceiver, processing circuitry and a single conductor probe comprising at least two elongate probe sections. A connector extending from a first end of the probe section comprises: an abutment portion having a diameter smaller than a diameter of the probe section, an intermediate portion, having a diameter smaller than the abutment portion, arranged between the probe section and the abutment portion and an outside threaded portion. A second end portion of the probe section comprises a sleeve comprising an inside threaded receiving portion receiving the connector; a passage through a sidewall of the sleeve being located off-center in relation to a longitudinal central axis of the probe section. The probe further comprises a locking pin to be arranged in the passage locking two assembled probe sections by limiting movement of the abutment portion in a longitudinal direction.

Abstract: System for monitoring a floating roof of a tank containing a liquid, wherein the system determines a local status of the floating roof in spaced apart sensing element locations. In a hazardous or potentially hazardous environment, there is an on-roof subsystem including a sensing element in each sensing element location, intrinsically safe measuring circuitry coupled a sensing elements and arranged for determining said local status, intrinsically safe radio communication on-roof circuitry coupled for communicating externally of the on-roof subsystem the local, an intrinsically safe power supply circuitry connected to an intrinsically safe and interchangeable energy storage unit for powering the on-roof subsystem. The system further includes monitoring circuitry for receiving the indication of local status and for determining an overall monitored status of said floating and further radio communication circuitry. The on-roof subsystem is wireless in its power supply and communication.

Abstract: The present invention relates to a radar level gauge comprising a reference reflector arranged at a known reference reflector level in a tank. The radar level gauge is controllable between a filling level measuring state and a proof test state. In the proof test state, the radar level gauge is configured to determine a first verification level based on a reference reflector echo resulting from reflection of an electromagnetic transmit signal at the reference reflector; determine a second verification level based on a surface echo resulting from reflection of an electromagnetic transmit signal at the surface of the product; and provide the first verification level and the second verification level to allow determination of a proof test result based on at least the first verification level, the known reference reflector level and the second verification level.

Abstract: The present invention relates to reflector arrangement for proof test of a radar level gauge and to a radar level gauge system comprising such a reflector arrangement. The reflector arrangement comprises a pliable elongated member for attachment to a fixed structure in the tank; a weight attachable to the pliable elongated member; and a reflector member for reflecting an electromagnetic signal impinging on the reflector plate. The weight is configured to be coupled to the reflector member in such a way that an orientation of the weight determines an orientation of the reflector member.

Abstract: A gauging installation for a tank with a long narrow nozzle providing access to an interior of the tank. The gauging system includes a GWR level gauge with a probe, and a first rigid extension member providing an interior probe mounting position at the end of the nozzle. The probe is configured to guide an electromagnetic transmit signal from a transceiver towards the product inside the tank, and to return the electromagnetic echo signal resulting from a reflection of the electromagnetic transmit signal by a surface of the product. A microwave transmission line connects the transceiver and the probe. With this design the beginning of the probe of the GWR level gauge will be located at the lower end of the nozzle, i.e. at the upper interior of the tank.

Abstract: The present invention relates to a radar level gauge system comprising PLL circuitry for generating an output signal. The PLL circuitry is configured to indicate a lock state of the PLL circuitry; and signal modifying circuitry is connected to the PLL circuitry for receiving the output signal and for modifying at least one property of the output signal for forming the transmit signal. The signal modifying circuitry is arranged and configured to receive a PLL status signal indicative of the lock state of the PLL circuitry, and to modify the at least one property of the output signal in response to the PLL status signal indicating that the PLL circuitry is in a locked state.

Abstract: A radar level gauge using electromagnetic waves for determining a filling level of a product in a tank, comprising a transceiver, processing circuitry, a signal propagating device and a tank feed through structure. The tank feed through structure includes a fixed tank connection arranged to be secured to the tank, a tank connection adaptor arranged in a through hole of the fixed tank connection, a coupling arrangement arranged in the through hole and resting against the tank connection adaptor, and a fastening member attached to the fixed tank connection and securing the coupling arrangement between the tank connection adaptor and the fastening member.

Abstract: A radar level gauge and a method for measurement of a distance to a surface of a product in a tank are disclosed. The radar level gauge comprises transceiver circuitry configured to transmit and receive electromagnetic signals, the transceiver circuitry comprises a frequency stabilizing feedback loop configured to generate the electromagnetic transmit signal in the form of a frequency sweep. The frequency stabilizing feedback loop is configured to generate an oscillation, forming a sinusoidal modulation of the frequency sweep. The radar level gauge further comprises a second mixer configured to mix an intermediate frequency signal and an integer multiple of the frequency of the sinusoidal modulation to provide an adjusted intermediate frequency signal, and processing circuitry configured to determine the distance based on the adjusted intermediate frequency signal. By providing a frequency sweep comprising a sinusoidal modulation, an improved sensitivity is achieved by the radar level gauge and method.

Abstract: The present invention relates to a method of determining a filling level of a product contained in a tank by propagating a first transmitted electromagnetic signal in a first frequency range and a second transmitted electromagnetic signal in a second frequency range different from the first frequency range along a transmission line probe towards a surface of the product in the tank, receiving a first reflected electromagnetic signal in the first frequency range and a second reflected electromagnetic signal in the second frequency range, and determining the filling level based on a time-of-flight of the first reflected electromagnetic signal and a difference in time-of-flight of the first reflected electromagnetic signal and the second reflected electromagnetic signal.

Abstract: A radar level gauge using comprising a transceiver, processing circuitry, a signal propagating device, and a wave guide arrangement connecting the transceiver with the signal propagation device. The wave guide arrangement includes a hollow wave guide, a first filling member made of a first dielectric material, which first filling member is arranged inside the hollow wave guide, and a second filling member made of a second dielectric material, which second filling member is arranged inside the hollow wave guide outside the first filling member with respect to the tank. The second filling member is fixed in the wave guide at least in a direction out from the tank, and is configured to withstand temperatures up to 250 degrees Celsius. During conditions of temperatures sufficiently high to soften the inner filling member, the outer filling member will thus serve to prevent the first filling member from being forced out of the wave guide.

Abstract: The present invention relates to a pulsed level gauge system comprising frequency control circuitry. If an acquired signal indicates that the time between the previous filling level determination and the present filling level determination is shorter than a predefined time, the frequency control circuitry controls at least one of a transmit signal generating circuitry and a reference signal generating circuitry comprised in the pulsed level gauge system using previous frequency control settings stored in memory.

Abstract: A method for identifying an undesired condition in the function of a floating roof of a tank, the method comprising determining a filling level of a product in the tank, detecting a reference distance between a reference position on the roof and the surface using a level gauge mounted on the roof, forming a reference distance deviation as a difference between the reference distance and an expected value, and comparing the reference distance deviation with a specified range. If the reference distance deviation is outside the specified range, a data set including the reference distance deviation and the filling level is stored. These steps are repeated for a plurality of points in time, and the undesired condition is then identified based on stored data sets of reference distance deviations and filling levels. The present invention thus provides an economical method to provide diagnostics of a floating tank roof.