WO2006068604A1 - Système de jauge de niveau radar - Google Patents

Système de jauge de niveau radar Download PDF

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Publication number
WO2006068604A1
WO2006068604A1 PCT/SE2005/001987 SE2005001987W WO2006068604A1 WO 2006068604 A1 WO2006068604 A1 WO 2006068604A1 SE 2005001987 W SE2005001987 W SE 2005001987W WO 2006068604 A1 WO2006068604 A1 WO 2006068604A1
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WO
WIPO (PCT)
Prior art keywords
propagation properties
signals
difference
echo
time
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SE2005/001987
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English (en)
Inventor
Tomas Wennerberg
Olov Edvardsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rosemount Tank Radar AB
Original Assignee
Rosemount Tank Radar AB
Saab Rosemount Tank Radar AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from SE0403165A external-priority patent/SE0403165D0/sv
Application filed by Rosemount Tank Radar AB, Saab Rosemount Tank Radar AB filed Critical Rosemount Tank Radar AB
Priority to JP2007548152A priority Critical patent/JP2008525796A/ja
Priority to DE112005003220T priority patent/DE112005003220T5/de
Publication of WO2006068604A1 publication Critical patent/WO2006068604A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/284—Electromagnetic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/284—Electromagnetic waves
    • G01F23/2845—Electromagnetic waves for discrete levels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
    • G01S13/103—Systems for measuring distance only using transmission of interrupted, pulse modulated waves particularities of the measurement of the distance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications

Definitions

  • the present invention relates to a radar level gauge system for determining the filling level of a filling material in a tank, comprising a transmitter for emitting measuring signals towards the surface of the filling material; a receiver for receiving echo signals from the tank; and processing circuitry for determining the filling level of the tank based on said echo signal. More specifically the invention relates to a radar level gauge system to be used in tanks having at least one interfering structure which reflects the emitted measuring signals. Further, the invention also relates to a corresponding method for determining the filling level of a filling material in a tank.
  • Radar level gauging to measure the level of a filling material, such as a liquid or a solid like a granulate is an increasingly important method for level gauging in tanks, containers, etc.
  • the process of radar level gauging quite general can be divided into three steps:
  • Present RLGs typically use the information in FFT spectra to distinguish what echo that corresponds to the surface to be measured.
  • the FFT spectra reflects the reflected energy at different distances. Consequently, the FFT spectra is normally a rather inaccurate means for distinguishing between e.g. a stationary object, a turbulent filling material surface and a moving agitator structure arranged in the tank. Further, it is normally difficult to distinguish the filling material surface when the tank is essentially empty and is starting to be filled. At this time, the filling material surface is also rather turbulent. Still further, strong echoes from stationary objects and structures in the tank would intervene in the measurement, and the tracking functionality could easily be fooled to lock on an erroneous echo, or loose the filling material surface echo when close to a disturbing echo.
  • the tank spectrum is a detected tank signal where the amplitude is only used in combination with suitable logical decisions. Still further, a function for measuring the amplitude and a related threshold is conventionally needed to discriminate noise or irrelevant echoes from the true surface echo. This is also mainly a software function but need certain calibration of amplifications etc. in order to tell the system what a "normal" echo should be. A more or less sophisticated echo logic could also be used in processing the echoes which have passed the test with sufficient amplitude and sufficient similarity to already verified echoes. However, there is still a need for improved radar level gauging, especially for tanks having interfering structures generating reflecting signals.
  • Receiving the echo in two polarizations is one method to increase the ability to distinguish a surface echo from less symmetric disturbing echoes.
  • the time variation of the echo amplitude is another way which may be combined with the polarization and which is useful for a turbulent surface.
  • a third method is to use a still more complicated antenna for creating a few different antenna lobes (or a slightly non-vertical lobe rotating around the plumb-line) all in the ideal case giving the same surface echo but greatly different echoes from disturbing structures which typically are non-symmetric located.
  • US 6 759 977 These methods may be efficient but unfortunately they require extra hard- ware, and is therefore normally more expensive and more cumbersome to produce and install. Further, such system will normally require more time and development resources.
  • a method for microwave signal based gauging of a distance to a surface with reflective properties at a filling level of a filling material in a tank having at least one interfering structure having a surface with reflective properties comprising: transmitting at a first time first transmit signals towards the surfaces; receiving at essentially said first time first receive signals including a first surface echo; recording first propagation properties of the first transmit and receive signals associated with the first surface echo; transmitting at a second time second transmit signals towards the surfaces; receiving at essentially said second time second receive signals including a second surface echo; recording second propagation properties of the second transmit and receive signals associated with the second surface echo; wherein the first time and the second time are temporally separated by a first separation time; calculating a first difference between the first and second propagation properties; transmitting at a third time third transmit signals towards the surfaces; receiving at essentially said third time third receive signals including a third surface echo; recording third propagation properties of the third transmit and receive signals associated with the third surface echo
  • the determining of said distance to the selected surface of the filling material is preferably based on at least one of the recorded propagation properties. However, additionally or alternatively it is also feasible to use other propagation properties, e.g. from a different set of transmitted and received signals. It is notable that the first and third times may occur essentially simultaneously.
  • the first transmit signals may be identical to the third transmit signals, even though it may also be possible to use separate transmit signals, having e.g. different polarization.
  • the second and fourth times may occur essentially simultaneously, wherein the second transmit signals may be identical to the fourth transmit signals. However, the times may also be temporally separated.
  • measurements could be added at one or more further time moments creating a set of measurements enabling more reliable conclusions when e.g. the level and amplitude values are fluctuating due to turbulence, etc.
  • the temporally separation between the first and second times and/or the third and fourth times is less than a maximum separation time.
  • said temporally separation is less than one hour, and preferably less than one minute and most preferably less than 10 seconds.
  • the new method of microwave signal or radar level gauging is especially suited for process applications with complicated tank situations.
  • the invention includes means enabling even small movements of the liquid surface to be used to distinguish the surface echo from non wanted echoes caused by disturbing objects.
  • the present invention makes use of a difference based on the same measurement, but at different times, in order to distinguish events and changes that has occurred.
  • Previously known difference signals such as the one discussed in EP 1 128 169, are normally concentrated on the difference between different measurement situations, such as the difference between measurements performed in different medias, etc.
  • the difference analysis of the present invention provides a number of advantages, since the echoes corresponding to the filling material surface could be detected more easily and accurately.
  • the present invention is usable as a complement to conventional RLG logics, to identify the surface during start-up, during the situation where the empty-tank condition is left, and the tank is starting to be filled, when the filling level passes reflecting structures in the tank, etc.
  • the difference analysis is also useful for distinguishing between the echoes from moving objects, such as agitators, from stationary objects, such as baffles and beams.
  • the method may further comprise the steps of calculating, based on the recorded propagation properties, distances to reflective surfaces in the tank, wherein the difference between the propagation properties are preferably calculated as the difference between said calculated distances.
  • the recorded propagation properties comprises at least one of phase information and amplitude information from the transmitted and received signals.
  • the calculation of a difference between the recorded propagation properties involves identification of at least one of a phase difference or an amplitude difference between the recorded propagation properties.
  • phase information in the signals has proven very efficient and accurate. However, the use of the amplitude information is, even though not as extensive as the phase information, fully adequate for most situations and applications. Amplitude could in the context of this application generally be comprehended as signal strength.
  • the method to search for the echoes exhibiting the greatest change over time can alternatively be described in the following way, in particular suited for the case where measurements at more than two time moments are used. From the gradual temporal change of the level or phase of two echoes it is possible to conclude whether the two echoes will coincide in the future or if they have been at the same level earlier, both conclusions taken from a linear extrapolation of the change based on two or more time moments.
  • the event of predicted or passed coincidence is called intercept, and in the case of an intercept below the present average level of the two surfaces the upper level is the liquid surface while an intercept above the average present level indicates that the lower level is the liquid surface.
  • the method comprises repeating at least three temporally separated times the transmitting, the detecting and the calculating; wherein the distance to the surface of the filling material is determined as the calculated distance that exhibits the greatest change between said different time moments.
  • ⁇ is the wavelength of the radar waves, and for a 5.8 GHz frequency ⁇ will be 52 mm, etc.
  • the method is particularly useful for high-level or overfill alarm systems, since the new method is particularly useful for identifying moving surfaces, and since only moving surfaces are of interest for overfill considerations.
  • Such systems could be dedicated to this single use, or be a functionality incorporated in a general RLG system.
  • the high-level or overfill alarm functionality could involve comparing the determined distance to the filling material to at least one predetermined threshold level value.
  • the calculating of a difference between the propagation properties is preferably based on a comparison between distances calculated from said propagation properties.
  • the distances to the surface levels are continuously monitored, and the surface level changing most rapidly over time is automatically considered to be the surface level of the filling material.
  • the method is usable both when continuous signals are emitted, and wherein the distances are calculated based on a phase difference between the received echo signal and a reference signal, as in FMCW systems, and when pulsed signals are emitted, and wherein the distances are calculated based on the time between the emission of a pulsed signal and the reception of the echo of said signal. It is preferred that the received signals are filtered for reducing noise related changes before recording of the propagation properties, or before using said recorded propagation properties for calculating a difference.
  • the method may further comprise the step of initially assuming that certain of the received surface echoes origins from the surface of the filling material, i.e. that the first and second surface echoes or the third and fourth surface echoes are reflected from the surface of the filling material.
  • the assumption is thereafter preferably changed to the now selected surface echoes.
  • the initial assumption is further preferably regularly tested and if necessary corrected within a limited time period, said time period being less than one hour, and preferably less than half an hour.
  • said time period is less than one minute, and most preferably less than 10 seconds.
  • Association of echo signals from temporally separated received signals with the assumption that they originate from the same reflective surface could be made in various ways, which are per se known in the art. This association between echo signals could be made directly upon reception of the signals, or subsequently based on the recorded propagation properties.
  • a method for microwave signal based gauging of a distance to a surface with reflective properties at a filling level of a filling material in a tank having at least one interfering structure comprising: transmitting at at least two temporally separated times transmit signals into the tank, and subsequently receiving receive signals including surface echoes; recording propagation properties of the transmit and receive signals in association with at least two distinguishable reflective surfaces; calculating for each distinguishable reflective surface a difference in the recorded propagation properties between the at least two temporally separated times; comparing the calculated differences for the at least two distinguishable reflective surfaces; selecting the greatest of said differences as the difference associated with the surface of the filling material; and determining said distance to the selected surface of the filling material based on propagation properties of transmitted and received signals.
  • a radar level gauge system for determining a distance to a surface with reflective properties at a filling level of a filling material in a tank having at least one interfering structure, comprising: a transmitter for transmitting measuring signals towards the surface of the filling material; a receiver for receiving echo signals from the tank; a storage for recording propagation properties of the transmit and receive signals in association with at least two distinguishable reflective surfaces; processing circuitry for calculating for each distinguishable reflective surface a difference in the recorded propagation properties between at least two temporally separated times, and selecting the greatest of the calculated differences for the at least two distinguishable reflective surfaces as the difference associated with the surface of the filling material, and determining said distance to the selected surface of the filling material based on propagation properties of transmitted and received signals.
  • the present invention is useful for level gauging in tanks having a filling material having a surface with reflective properties as well as at least one interfering structure having a surface with reflective properties.
  • the invention is useful when said reflective surfaces are separated, i.e. not on essentially the same level, and thus independently distinguishable in the reflected echo signals.
  • the possibility of distinguish the surfaces could depend on various parameters, such as one or several of: the separation distance, the level resolution of the measurement equipment, the signal strength, etc.
  • a method for microwave signal based determination of a high-level or overfill situation for the filling level of a filling material in a tank having a surface with reflective properties comprising: transmitting at a first time first transmit signals towards the surfaces; receiving at essentially said first time first receive signals including a first surface echo; recording first propagation properties of the first transmit and receive signals associated with the first surface echo; transmitting at a second time second transmit signals towards the surfaces; receiving at essentially said second time second receive signals including a second surface echo; recording second propagation properties of the second transmit and receive signals associated with the second surface echo; wherein the first time and the second time are temporally separated by a first separation time; calculating a first difference between the first and second propagation properties; determine a distance to the surface of the filling material; identifying if the difference exceeds a predetermined difference level and if the determined distance is within a predetermined high level zone, and if so setting the alarm.
  • Fig 1 is a schematic cross-sectional side view of a container, in which an antenna device according to the embodiment is arranged;
  • Fig 2 is a schematic block diagram illustrating the radar level gauge system of fig i; Fig 3 are some schematic diagrams representing different signal spectra for an exemplary tank situation; and
  • Fig 4 illustrates a possible signal processing for use in the invention.
  • Fig 1 shows schematically a radar level gauge system 1 in which the invention may be advantageously incorporated.
  • the system in fig 1 comprises an electronic unit 3 for transmitting and receiving radar signals and processing the received signals in order to detennine the level in the tank, an antenna 4 arranged inside the tank for transmitting and receiving radar waves into the tank, and a radar wave guide assembly 5 for guiding signals between the electronic unit 3 and the antenna 4.
  • the same antenna could preferably be used both as a transmitter for emitting the output radiation and as a receiver for receiving the reflected echo signal, even though it is also possible to use separate antennas for these functions.
  • the exemplifying embodiments of the invention uses radar antennas providing a free radar beam, in which case disturbing echoes are particularly frequent, but it is also possible to use the invention in guided radar systems, using a waveguiding structure for forwarding the emitted radar beam to and/or from the tank.
  • the radar level gauge 2 transmits radar energy along the waveguide, 5 through the tank roof port and receives reflected energy from the liquid surface 8 to provide an indication of the level of the liquid within the tank.
  • the radar level gauge 2 could be coupled to a remote location (for example a control room) via a signal wire or the like.
  • the system may use pulsed or continuously emitted radiation.
  • the signals can be DC pulses with a length of about 2 ns or less, with a frequency in the order of MHz, at average power levels in the nW or ⁇ W area.
  • the pulses are modulated on a carrier wave of a GHz frequency.
  • the tank is provided with a sealing, arranged to allow the electromagnetic signals to pass through the wall of the tank while maintaining an air tight seal, so as to prevent tank contents from escaping from the tank.
  • the circuitry 20 includes a signal processor 21, a transmitter 23, a receiver 28 and signal processing circuits 29 preparing the received signals to the processor 21.
  • the circuitry further includes a transmit/receive (TR) coupler 25 which connects the transmitter 23 and the receiver 28 with the antenna 4 which is directing signals towards the surface 28 of the material the level of which is to be measured.
  • TR-coupler 25 can be a directional coupler, a ferrite circulator, a switch or any other conventional component.
  • the circuitry also includes at least power circuits 22 and communication circuits 24 which both can be of many types.
  • the signal processor 21 is preferably a microprocessor based circuit adapted to receive the incoming signal, as discussed above, and provide as an output a signal or information indicative of the level of material 8.
  • the functions and algorithms implemented by signal processor 110, some of which can be embodied in hardware and some of which can be embodied in software, are per se known from the art will not be discussed further in this application.
  • the electromagnetic signals are received by the antenna 12, and forwarded back to the transceiver 10, where they are sampled and digitalized in a process controlled by a processing circuitry, such as a processor 11.
  • the processor is provided with software for analyzing the signal in order to determine a the filling level in the tank, i.e. the level of the surface 2.
  • the processor 11 is preferably a microprocessor based circuit adapted to receive the incoming signal, as discussed above, and provide as an output a signal or information indicative of the level of material 3.
  • the functions and algorithms implemented by signal processor 11, some of which can be embodied in hardware and some of which can be embodied in software, are per se known from the art and will not be discussed further in this application.
  • the method preferably comprises the, per se well- known functionality of searching in order to identify surface echoes among possible disturbing echoes, and tracking in order to follow the found surface echo during various changing conditions.
  • Several surfaces generating reflecting signals could be monitored simultaneously, and typically the processing circuitry is arranged to manage monitoring of 5-10 such surface echoes simultaneously.
  • the processing circuitry is arranged to manage monitoring of 5-10 such surface echoes simultaneously.
  • Two fairly close echoes generally appear as two echoes, whereas when they are very close they will not be able to be distinguished but will appear as one single echo at an average distance, and between these two cases there is a transition region where the accuracy may be low.
  • the limit is determined by the pulse time or the inverted bandwidth and is around 150 mm for a system having 1000 MHz bandwidth or 1 ns pulse time fairly independent of the type of system.
  • the embodiments to be discussed resolve the echo situation at distances outside of this zone of less accuracy.
  • means for assisting in case several reflecting surfaces exist in the tank, which part of the received signal, and which calculated distance, that represents the surface of the filling level.
  • This functionality is preferably mainly soft-ware related, and can in many cases be implemented on existing (or reasonably extended) hard- ware, and will work for FMWC as well as for pulsed systems. It can be used alone but also in combination with the methods mentioned above or with many other methods.
  • the phase information in the received signals is used.
  • a memory function is provided, where the raw tank-signal including the phase information is saved at suitable points of time.
  • the information in one "snapshot" (a sweep for a FMWC system or the corresponding interval for a pulsed system) is a few kbyte so the storage of a few "snapshots" is compatible with even a modest but modern processor with its RAM.
  • a difference is formed between the most recent "snapshots" and one of the older ones and an essentially normal signal processing is performed on the difference.
  • a few different "snapshots" are preferably saved and the interval for savings is supposedly matched to the movement so the best comparison can be made.
  • the sampling is preferably done before any detection (which is commonly applied in present pulsed systems).
  • the signal is treated linearly and that the phase is preserved.
  • One standard way to do so is to save two signals 90 degrees out of phase, generally referred to as I and Q-channel.
  • the upper echo is a disturbing echo (e.g. a tank structure) with a dotted trend line and the lower the echo from changing liquid surface with a solid trend curve.
  • the intercept point between the two trend lines gives the level where two echoes will coincide (in the future) or were at the same level (in the past).
  • the "intercept level” is now close to the upper end of the level interval between said two echoes and the significance of this will be discussed further in the following.
  • the disturbing echo is below the surface, and the corresponding set of measured levels at four different times will have a slightly different appearance.
  • the disturbing echo is now measured through a variable thickness of at least partly radar transparent liquid and both the levels will have a variation but in opposite directions.
  • the intercept level can still be defined but is now below the average between the two measured levels. This will hold both at increasing and decreasing level but the hypothetical moment of intercept will be different.
  • a multiple echo from the tank roof i.e. twice the distance
  • the level of the intercept point will be higher than both the two measured levels and the multiple echo is revealed. It is obvious that at very smooth signals the result of this simple trend analysis in fig 4a and 4b provide the same result as evaluation at greater change, but with a noise like disturbance the trend analysis will provide a safer result.
  • the position of the intercept level could be used in the following way:
  • the system must be able to measure under a non-moving surface too, and then the tank signal could be used in a conventional way.
  • this only applies when the surface is neither moving nor turbulent and then the amplitude of the echo is at least 10-20 dB stronger than during turbulent conditions.
  • the standard method is used during the most favorable conditions only.
  • the methods could be operated continuously and in parallel, whereby the information from both could be extracted and compared for a more accurate determination of the surface. When no turbulence or movement is at hand, the result from the standard method will be used as it is, and when movements occurs the standard method could be used as a verification.
  • the method allows the disturbing echoes with their phase to be stored so the especially strong echoes can be subtracted from the tank signal even for a steady surface echo.
  • the subtraction of two echo signals recorded at two fairly close points of time is however more efficient as the disturbing echoes are "fresh" and this have the same influence from sediments, temperature variations etc.
  • the above-discussed method can be applied to different kinds of RLG systems, among them the commonly used pulsed systems and FMWC systems.
  • With a pulsed system short pulses are transmitted which each may be a 1 ns long pulse of a few 6 GHz periods. After reflection in the surface the pulses are received and mixed with a similar pulse train having a slightly different PRF (such as 1.00000 MHz compared to 1.00001 MHz) and then, after low-pass filtering, the received pulses
  • the IF signal ideally is a sum of sinusoidal signals, one for each echo with preserved phase and amplitude and with a length equal to the length of one sweep (e.g. 100 ms).
  • the signal processing in a modern system can be supposed to include one or more FFTs and at this stage the difference in signal processing between a pulsed and a FMCW system can be said to be reduced to weather an odd or even number of FFTs are applied.
  • the term "generic IF signals" is used for both pulsed systems, FMCW systems or other radar systems giving a linear combination of echoes from possibly many echoes with preserved amplitude, phase etc.
  • the snapshots from the generic IF signals at one or more points of time are preferably stored in a storage in the described system.
  • one snapshot is well preserved by taking around 1000 samples with 8-16 bits of amplitude resolution.
  • a few or up to 10 kbytes of storage space is required for each snapshot making the storage of a few snapshots easy to obtain even with a limited storage space in a modern digital processor.
  • 1000 samples is a typical amount so the hardware requirements are compatible with the industrial RLG standard today.
  • the difference signal for a moving echo will obviously be similar to the original echo but with another amplitude and phase which in the normal type of signal processing will not have any influence on the calculated distance.
  • the difference will be very similar to supposing the time difference is small as compared to the pulse time (which in terms corresponds to a distance in the order of 100 mm). Even in a pulse the most information is in the phase.
  • the signal before video detection is used (where the two pulses have different phase) as the two detected signals from slightly different points of time are very similar and will not form any usable difference.
  • any echo from any structure above the liquid surface will virtually disappear while the surface echo will remain with a likely change in amplitude which can be chosen by having a limited choice of snapshots.
  • the surface echo will be much cleaner and even more important it will become the closest non-zero echo even in situations where there are many strong disturbing echoes present.
  • the described method is well suited for this task as it will enable the detection of even weak but somewhat moving echoes in a accurate defined near vicinity of the radar level gauge.
  • the echo situation in the near vicinity of the gauge is fairly static so the instrument can be made sensitive to any change which in this part of the tank most likely is caused by the rising liquid surface.
  • phase information in the received signals were used to distinguish a moving surface from a non-moving surface, and thereby to identify reflective signal from the surface of the filling material from disturbing echoes.
  • signals without phase information it is also possible to use signals without phase information to essentially the same end.
  • a difference spectrum is formed for the amplitude in each position, and comparing signals received at different times, from which the echo characteristics are determinable.
  • the difference in amplitude for a position n at a time t could be determined as:
  • AmplDiff(n) t Ampl(n) t - Ampl(n) t-1
  • AmplDiff(n) t Abs(Ampl(n) t - Ampl(n) t-1 )
  • the amplitude difference is further preferably filtered, in order to avoid noise generated disturbances, e.g. in the following way:
  • FiltAmplDiff(n) t FiltFactor x FiltAmplDiff(n) t-1 + (1 -FiltFactor) x Am ⁇ lDiff(n) t
  • the difference analysis will generate a clear indication of moving surfaces, such as a turbulent surface, a surface that is raised or lowered, or moving agitators.
  • moving surfaces such as a turbulent surface, a surface that is raised or lowered, or moving agitators.
  • stationary surface will essentially not be visible, such as beams, baffles, etc. The same is true for a totally still filling material surface.
  • the difference analysis makes use of received signals from at least two, and preferably several previous times, and preferably with different timely separation.
  • this extended analysis makes it possible to avoid the situation where the difference between two received signals corresponds to exactly a multiple of ⁇ /2, which would make even a moving echo disappear.
  • the difference analysis for signals received at a time t could be made based on a e.g. measurements at t-1, t-10 and t-100.
  • the above-discussed method and system is particularly useful for overfill applications.
  • the determined surface level could be compared with one or several threshold values, and e.g. a set of the following three threshold values:
  • OFA_AmpThreshold which is a threshold value for an amplitude that could generate the alarm within the range.
  • threshold values are chosen properly, so that no surface echoes are missed, but at the same time that false alarms due to other reflections, noise etc, are avoided as far as possible.
  • overfill alarm functionality has previously been difficult to realize in practice, and have normally required substantial and cumbersome configuration for each individual use situation.
  • a threshold value for the amplitude would normally be needed even when the differential analysis discussed above is used.
  • this threshold value could be set as a general parameter, independent of the filling material, the tank environment, etc. Consequently, a constant threshold could be used regardless where and how the system is installed.
  • the gauge system could further comprise an alarm (not shown), which is activated by said alarm signal.
  • the alarm could e.g. be arranged in a control unit for the system.
  • the alarm system may be distributed, whereby the alarm could be arranged at a distance from the gauge system.
  • the alarm signal could be sent to a separate system, such as to a general control system.
  • the alarm may be arranged close to the measuring equipment, or at a remote location (for example in a control room), wherein the alarm signals could be transferred via a signal wire or the like.
  • the alarming unit can be designed in several ways to alert an operator about the current situation.
  • an acoustic signal can be activated
  • alarming lamps can start to light or twinkle or some kind of signaling can be activated on a control board
  • alarms on a computer screen or a remote unit could be activated, etc.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • General Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L’invention concerne un procédé et un système de jaugeage radar de niveau de remplissage pour matériau de remplissage, où le réservoir possède au moins une structure interférente. Le procédé consiste à : transmettre à un premier moment dans le temps un signal micro-onde vers la surface du matériau de remplissage ; recevoir des signaux micro-ondes tels qu’ils sont réfléchis contre la surface du matériau de remplissage et tels qu’ils sont réfléchis contre ladite au moins une structure interférente ; calculer sur la base des temps de propagation des signaux micro-ondes transmis et réfléchis, au moins deux distances par rapport à des surfaces réfléchissantes dans le réservoir ; et répéter à un second moment dans le temps la transmission, la détection et le calcul, où ledit premier moment dans le temps est séparé de manière opportune dudit second moment dans le temps. Sur la base des différentes mesures répétées, la distance par rapport à la surface du matériau de remplissage est déterminée comme distance calculée présentant le changement le plus important entre ledit premier moment dans le temps et ledit second moment dans le temps. Sur la base de cette analyse de différence temporelle, il est possible de distinguer des surfaces mobiles de manière très facile et très précise. Le procédé est spécifiquement avantageux pour les systèmes d’alarme de trop-plein ou de niveau élevé.
PCT/SE2005/001987 2004-12-23 2005-12-21 Système de jauge de niveau radar Ceased WO2006068604A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2007548152A JP2008525796A (ja) 2004-12-23 2005-12-21 レーダ液面計システム
DE112005003220T DE112005003220T5 (de) 2004-12-23 2005-12-21 Radarlevelmesssystem

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SE0403165-4 2004-12-23
SE0403165A SE0403165D0 (sv) 2004-12-23 2004-12-23 A radar level gauge system
US11/038,836 2005-01-20
US11/038,836 US7284425B2 (en) 2004-12-23 2005-01-20 Radar level gauge system

Publications (1)

Publication Number Publication Date
WO2006068604A1 true WO2006068604A1 (fr) 2006-06-29

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Country Status (3)

Country Link
KR (1) KR20070086633A (fr)
DE (1) DE112005003220T5 (fr)
WO (1) WO2006068604A1 (fr)

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EP2148219A1 (fr) 2008-07-22 2010-01-27 Siemens Milltronics Process Instruments Inc. Traitement de signaux de mesure par impulsion-écho
EP2527801A1 (fr) * 2011-05-27 2012-11-28 VEGA Grieshaber KG Dispositif et procédé de détermination de caractéristiques de milieux et de récipients
US20140083184A1 (en) * 2012-07-26 2014-03-27 Vega Grieshaber Kg Tracking taking account of a linear relationship
US9068876B2 (en) 2011-05-27 2015-06-30 Vega Grieshaber Kg Device and method for determining media and container properties
US10416021B2 (en) 2013-04-09 2019-09-17 Endress+Hauser Se+Co.Kg Method for fill level measurement using the travel time principle
CN112050901A (zh) * 2019-06-05 2020-12-08 罗斯蒙特储罐雷达股份公司 雷达物位计系统及其填充物位确定/验证操作的方法
CN113627283A (zh) * 2021-07-23 2021-11-09 中冶南方工程技术有限公司 基于雷达回波信号的料面测量方法、终端设备及存储介质
CN118960903A (zh) * 2024-10-17 2024-11-15 齐翔华利新材料有限公司 一种储罐液位自动计量方法、装置及系统
WO2025201910A1 (fr) * 2024-03-25 2025-10-02 Vega Grieshaber Kg Agencement de capteur radar sans contact ayant une électronique de niveau limite

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US10012721B2 (en) * 2015-02-19 2018-07-03 Teradyne, Inc. Virtual distance test techniques for radar applications
US10145720B2 (en) * 2016-06-29 2018-12-04 Rosemount Tank Radar Ab FMCW radar level gauge with enhanced timing control
KR102037132B1 (ko) 2019-02-27 2019-10-28 안민헌 분리형 레이더 수위 측정 장치

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DE10260962A1 (de) * 2002-12-20 2004-07-01 Endress + Hauser Gmbh + Co. Kg Füllstandsmeßgerät und Verfahren zur Füllstandsmessung nach dem Laufzeitprinzip
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WO2004010093A1 (fr) * 2002-07-19 2004-01-29 Vega Grieshaber Kg Procede et dispositif permettant de determiner une plage de valeurs escomptees pour un echo de niveau et un echo parasite
US20040036617A1 (en) * 2002-08-22 2004-02-26 Ola Hall System for level gauging and alarms
DE10260962A1 (de) * 2002-12-20 2004-07-01 Endress + Hauser Gmbh + Co. Kg Füllstandsmeßgerät und Verfahren zur Füllstandsmessung nach dem Laufzeitprinzip
US6759976B1 (en) * 2002-12-20 2004-07-06 Saab Marine Electronics Ab Method and apparatus for radar-based level gauging

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2148219A1 (fr) 2008-07-22 2010-01-27 Siemens Milltronics Process Instruments Inc. Traitement de signaux de mesure par impulsion-écho
US8022862B2 (en) 2008-07-22 2011-09-20 Siemens Milltronics Process Instruments, Inc. Processing of pulse-echo measurement signals
EP2527801A1 (fr) * 2011-05-27 2012-11-28 VEGA Grieshaber KG Dispositif et procédé de détermination de caractéristiques de milieux et de récipients
US9068876B2 (en) 2011-05-27 2015-06-30 Vega Grieshaber Kg Device and method for determining media and container properties
US9354100B2 (en) 2011-05-27 2016-05-31 Vega Grieshaber Kg Device and method for determining media characteristics and container characteristics
US20140083184A1 (en) * 2012-07-26 2014-03-27 Vega Grieshaber Kg Tracking taking account of a linear relationship
US10416021B2 (en) 2013-04-09 2019-09-17 Endress+Hauser Se+Co.Kg Method for fill level measurement using the travel time principle
CN112050901A (zh) * 2019-06-05 2020-12-08 罗斯蒙特储罐雷达股份公司 雷达物位计系统及其填充物位确定/验证操作的方法
CN113627283A (zh) * 2021-07-23 2021-11-09 中冶南方工程技术有限公司 基于雷达回波信号的料面测量方法、终端设备及存储介质
CN113627283B (zh) * 2021-07-23 2024-05-24 中冶南方工程技术有限公司 基于雷达回波信号的料面测量方法、终端设备及存储介质
WO2025201910A1 (fr) * 2024-03-25 2025-10-02 Vega Grieshaber Kg Agencement de capteur radar sans contact ayant une électronique de niveau limite
CN118960903A (zh) * 2024-10-17 2024-11-15 齐翔华利新材料有限公司 一种储罐液位自动计量方法、装置及系统

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DE112005003220T5 (de) 2008-04-30

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