Abstract: A guided wave radar level gauge comprising a housing providing explosion proof protection and having an intrinsically safe output, a transmission line probe connected to the IS output. The housing encloses radar level gauge circuitry which is incompatible with intrinsic safety requirements, a microwave unit connected to the IS output, an electrical barrier connected between the RLG circuitry and the microwave unit, the electrical barrier having a barrier ground potential which is independent from the grounded housing wall, and a set of blocking capacitors connected between the microwave unit and the IS output.

Abstract: A pulsed radar level gauge comprising a pulse generator configured to generate a transmit signal (ST) in the form of a pulse train, a propagation device connected to direct the transmit signal (ST) into a tank and return a microwave return signal (SR), a receiver, sampling circuitry configured to provide a time expanded tank signal, and processing circuitry for determining said filling level based on the time expanded tank signal. The gauge further comprises impedance increasing circuitry arranged to ensure that an input impedance of the receiver is at least 2 k? and a delay line arranged between said receiver and said propagation device, the delay line configured to introduce a delay greater than said pulse duration, such that said time expanded signal includes a transmitted pulse.

Abstract: A guided wave radar level gauge comprising an explosion proof housing with an intrinsically safe (IS) output, a resistor having a first terminal connected to the IS output and a second terminal connected to the housing ground potential, and a transmission line probe connected to the IS output. The housing encloses radar level gauge (RLG) circuitry and a microwave unit having a floating ground potential, and a set of blocking capacitors connected between the microwave unit and the IS output. The microwave unit includes a differential receiver, having a first terminal connected to the IS output via the set of blocking capacitors, and a second terminal connected to the housing ground potential via the set of blocking capacitors, a voltage between the first and second terminals forming an input signal to the differential receiver.

Abstract: A method of determining a filling level of a product in a tank, comprising, for each transmit pulse repetition frequency in a sequence of different transmit pulse repetition frequencies: generating and transmitting an electromagnetic transmit signal in the form of a pulse train of transmit pulses, the pulse train exhibiting the transmit pulse repetition frequency; propagating the transmit signal towards a surface of the product in the tank; returning an electromagnetic reflection signal resulting from reflection of the transmit signal at the surface back towards the transceiver; receiving the reflection signal; determining a measure indicative of signal disturbance of the reflection signal; evaluating the measure indicative of signal disturbance of the reflection signal in view of a predefined signal disturbance criterion; and determining the filling level based on at least one of the reflection signals fulfilling the signal disturbance criterion.

Abstract: A guided wave radar level gauge comprising a housing providing explosion proof protection and having an intrinsically safe output, a transmission line probe connected to the IS output. The housing encloses radar level gauge circuitry which is incompatible with intrinsic safety requirements, a microwave unit connected to the IS output, an electrical barrier connected between the RLG circuitry and the microwave unit, the electrical barrier having a barrier ground potential which is independent from the grounded housing wall, and a set of blocking capacitors connected between the microwave unit and the IS output.

Abstract: A pulsed radar level gauge comprising a pulse generator configured to generate a transmit signal (ST) in the form of a pulse train, a propagation device connected to direct the transmit signal (ST) into a tank and return a microwave return signal (SR), a receiver, sampling circuitry configured to provide a time expanded tank signal, and processing circuitry for determining said filling level based on the time expanded tank signal. The gauge further comprises impedance increasing circuitry arranged to ensure that an input impedance of the receiver is at least 2 k? and a delay line arranged between said receiver and said propagation device, the delay line configured to introduce a delay greater than said pulse duration, such that said time expanded signal) includes a transmitted pulse.

Abstract: A guided wave radar level gauge comprising an explosion proof housing with an intrinsically safe (IS) output, a resistor having a first terminal connected to the IS output and a second terminal connected to the housing ground potential, and a transmission line probe connected to the IS output. The housing encloses radar level gauge (RLG) circuitry and a microwave unit having a floating ground potential, and a set of blocking capacitors connected between the microwave unit and the IS output. The microwave unit includes a differential receiver, having a first terminal connected to the IS output via the set of blocking capacitors, and a second terminal connected to the housing ground potential via the set of blocking capacitors, a voltage between the first and second terminals forming an input signal to the differential receiver.

Abstract: A radar level gauge system comprising a first transceiver; a second transceiver; an antenna arranged to radiate a first transmit signal generated by the first transceiver and a second transmit signal generated by the second transceiver, and to receive a first reflection signal and a second reflection signal; a tubular waveguide to guide the transmit signals towards the interface, and to guide the reflection signals back towards the antenna; a plurality of signal interacting structures arranged at different levels along a the tubular waveguide, to selectively interact with the second transmit signal to contribute to the second reflection signal; and processing circuitry to determine a level of the interface between liquid phase product and vapor phase product based on a relation between the first transmit signal and the first reflection signal, and a density distribution based on a relation between the second transmit signal and the second reflection signal.

Abstract: A radar level gauge system comprising a first transceiver; a second transceiver; an antenna arranged to radiate a first transmit signal generated by the first transceiver and a second transmit signal generated by the second transceiver, and to receive a first reflection signal and a second reflection signal; a tubular waveguide to guide the transmit signals towards the interface, and to guide the reflection signals back towards the antenna; a plurality of signal interacting structures arranged at different levels along a the tubular waveguide, to selectively interact with the second transmit signal to contribute to the second reflection signal; and processing circuitry to determine a level of the interface between liquid phase product and vapor phase product based on a relation between the first transmit signal and the first reflection signal, and a density distribution based on a relation between the second transmit signal and the second reflection signal.

Abstract: The present invention relates to a field device adapted to determine a process parameter value related to a tank, the field device comprising a terminal block with: a first interface configured to connect to two wires of a loop; a first electrical conductor and a second electrical conductor for connecting the first interface with field device electronics, the second electrical conductor having a voltage drop generating element; a first power supply conductor connected to said second electrical conductor upstream of the voltage drop generating element and a second power supply conductor connected to said second electrical conductor downstream of the voltage drop generating element; and a second, auxiliary interface adapted for wired connection to an external device and configured at least for communication with said external device, wherein the second auxiliary interface comprises a communications connector which is galvanically isolated from the field device electronics.

Abstract: The present invention relates to a field device adapted to determine a process parameter value related to a tank, the field device comprising a terminal block with: a first interface configured to connect to two wires of a loop; a first electrical conductor and a second electrical conductor for connecting the first interface with field device electronics, the second electrical conductor having a voltage drop generating element; a first power supply conductor connected to said second electrical conductor upstream of the voltage drop generating element and a second power supply conductor connected to said second electrical conductor downstream of the voltage drop generating element; and a second, auxiliary interface adapted for wired connection to an external device and configured at least for communication with said external device, wherein the second auxiliary interface comprises a communications connector which is galvanically isolated from the field device electronics.

Abstract: The present invention relates to a method of controlling a pulsed radar level gauge system, comprising the steps of: acquiring a signal indicative of a present operating temperature; determining an initial frequency control parameter for control of at least one of transmission signal generating circuitry and reference signal generating circuitry based on the present operating temperature and a plurality of data sets each comprising data indicative of a previous operating temperature and a previously determined frequency control parameter for the previous operating temperature; and controlling, starting from the initial frequency control parameter, at least one of the transmission signal generating circuitry and the reference signal generating circuitry to achieve the known frequency difference between the first pulse repetition frequency and the second pulse repetition frequency at the present operating temperature.

Abstract: The present invention relates to a 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 field device comprises a measurement device for determining the process variable; a current control device electrically connected in series with the measurement device and controllable by the measurement device to provide the measurement signal to the two-wire current loop; and voltage regulation circuitry electrically connected in series with the current control device and the measurement device for controlling a voltage across the current control device towards a desired voltage by varying a voltage across the voltage regulation circuitry.

Abstract: A method for powering a radar level gauge, comprising an initial frequency stabilization procedure, ensuring a stable separation frequency between a first and a second clock frequencies, during which frequency stabilization procedure said radar level gauge is not powered to provide a level output, and a subsequent measurement cycle, performed only when a stable separation frequency has been established, during which said radar level gauge is powered to provide a level output. The present invention allows a radar level gauge system to save power by not providing power to and operating the radar level gauge circuit during such times when the frequency separation would not enable the radar level gauge to provide proper level measurements.

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: The present invention relates to a 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 field device comprises a measurement device for determining the process variable; a current control device electrically connected in series with the measurement device and controllable by the measurement device to provide the measurement signal to the two-wire current loop; and voltage regulation circuitry electrically connected in series with the current control device and the measurement device for controlling a voltage across the current control device towards a desired voltage by varying a voltage across the voltage regulation circuitry.

Abstract: A method for powering a radar level gauge, comprising an initial frequency stabilization procedure, ensuring a stable separation frequency between a first and a second clock frequencies, during which frequency stabilization procedure said radar level gauge is not powered to provide a level output, and a subsequent measurement cycle, performed only when a stable separation frequency has been established, during which said radar level gauge is powered to provide a level output. The present invention allows a radar level gauge system to save power by not providing power to and operating the radar level gauge circuit during such times when the frequency separation would not enable the radar level gauge to provide proper level measurements.

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 of determining a filling level of a product contained in a tank using a level gauge system, comprising the steps of: transmitting a first signal towards a surface of the product; receiving a first echo signal; determining a present echo characteristic value based on the first echo signal; and comparing the present echo characteristic value and a stored echo characteristic value. If a difference between the present echo characteristic value and the stored echo characteristic value is greater than a predefined value, the method further comprises transmitting at least a second transmit signal towards the surface; receiving at least a second echo signal; and determining the filling level based on the at least second electromagnetic echo signal.

Abstract: The present invention relates to a method comprising providing an activation signal from a wireless communication unit to a measurement unit to switch the measurement unit from its inactive state to its active state; providing a measurement request signal to the measurement unit to request measurement of a filling level of a product in a tank; and thereafter switching the wireless communication unit from its active state to its inactive state. The measurement unit measures the filling level and provides a measurement ready signal to the wireless communication unit; the wireless communication unit is switched from its inactive state to its active state in response to the measurement ready signal received from the measurement unit; the wireless communication unit retrieves the value indicative of the filling level from the measurement unit; and wirelessly transmits the value indicative of the filling level to the remote device.