Radar level gauge system and method for determining / verifying filling level thereof

Abstract

A radar level gauge system and a method for performing a fill level determination and / or verification operation on the radar level gauge system. A storage tank includes a tank top supporting the radar level gauge system, a tank wall, and a tank environment in a space defined by the surface of a product in the tank, the tank top, and the tank wall. The method performed using the radar level gauge system includes: generating and transmitting an electromagnetic first transmit signal; propagating the first transmit signal through the tank environment toward a corner reflector formed by the surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being at a known horizontal distance from the radar level gauge system; receiving an electromagnetic first reflection signal caused by reflection of the first transmit signal at the corner reflector; and performing a fill level determination and / or verification operation on the radar level gauge system based on a timing relationship between the first transmit signal and the first reflection signal and the known horizontal distance between the radar level gauge system and the corner reflector.

Description

Technical Field

[0001] The invention relates to a radar level measurement method and system. Background Art

[0002] Radar level gauges are often used to determine the fill level of a product in a storage tank. Fill level determination depends on the propagation speed of an electromagnetic signal through the tank environment above the surface of the product inside the tank. Therefore, at least for some applications, it can be beneficial to be able to correct the determined fill level for variations in the characteristics of the tank environment. It can also be beneficial to be able to verify that the fill level determination and / or the radar level gauge system is operating as expected. Summary of the Invention

[0003] In view of the above, a general object of the present invention is to provide an improved radar level gauge.

[0004] Aspects of the present invention are based on the realization that the surface of the product in the tank and the tank wall form a corner reflector where the surface of the product contacts the tank wall, and that analysis of the reflected signal due to reflection of the transmitted signal at the corner reflector can be used in various ways to improve radar level gauges in tanks.

[0005] According to a first aspect of the present invention, there is provided a method for determining a signal propagation velocity compensation factor in a tank using a radar level gauge system, the tank having a tank wall and a tank environment above a surface of a product in the tank, wherein the method comprises: generating and transmitting a first electromagnetic transmit signal; propagating the first transmit signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being at a known horizontal distance from the radar level gauge system; receiving a first electromagnetic reflection signal caused by reflection of the first transmit signal at the corner reflector; generating and transmitting a second electromagnetic transmit signal; propagating the second transmit signal vertically toward the surface of the product through the tank environment; receiving a second electromagnetic reflection signal caused by reflection of the second transmit signal at the surface of the product; and determining the signal propagation velocity compensation factor based on a first timing relationship between the first transmit signal and the first reflection signal, a second timing relationship between the second transmit signal and the second reflection signal, and the known horizontal distance between the radar level gauge system and the corner reflector.

[0006] According to a second aspect of the present invention, there is provided a radar level gauge system for determining a fill level of a product in a tank, the tank having a tank wall and a tank environment above the surface of the product in the tank, wherein the radar level gauge system comprises: a transceiver for generating, transmitting and receiving electromagnetic signals; a signal propagation device coupled to the transceiver for propagating an electromagnetic first transmit signal through the tank environment towards a corner reflector formed by the surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being at a known horizontal distance from the radar level gauge system and reflecting the first transmit signal at a position above the surface of the product in the tank; a first electromagnetic reflection signal caused by reflection at the corner reflector and returned to the transceiver; and a second electromagnetic transmission signal from the transceiver propagating through the tank environment toward the surface of the product and returning the second electromagnetic reflection signal caused by reflection of the second transmission signal at the surface of the product to the transceiver; and a processing circuit coupled to the transceiver and configured to determine the fill level based on a first timing relationship between the first transmission signal and the first reflection signal, a second timing relationship between the second transmission signal and the second reflection signal, and a known horizontal distance between the radar level gauge system and the corner reflector.

[0007] In these aspects, the known geometry, combined with the ability to make two measurements of geometrically related distances through the tank environment, allows for the determination of a signal velocity compensation factor and the true fill level to be determined.

[0008] In particular, using simple geometry, the known horizontal distance can be expressed as an exemplary signal velocity compensation factor multiplied by the square root of the difference between the square of the measured distance to the corner reflector and the square of the measured vertical distance to the surface. After determining the signal velocity compensation factor, the true or compensated vertical distance to the surface of the product can be determined by dividing the measured vertical distance to the surface of the product by the signal velocity compensation factor.

[0009] Additionally, a signal velocity compensation factor may be used to estimate the total amount of product in the gas phase to achieve an improved estimate of the total amount of product in the tank.

[0010] According to a third aspect of the present invention, there is provided a method for determining a fill level of a product in a tank using a radar level gauge system, the tank having a tank wall and a tank environment above the surface of the product in the tank, the method comprising: generating and transmitting a first electromagnetic transmit signal; propagating the first transmit signal through the tank environment toward a corner reflector formed by the surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being a known horizontal distance from the radar level gauge system; receiving a first electromagnetic reflection signal caused by reflection of the first transmit signal at the corner reflector; determining a measurement result indicative of a propagation direction of the first reflection signal; and determining the fill level based on the measurement result indicative of the propagation direction of the first reflection signal and the known horizontal distance between the radar level gauge system and the corner reflector.

[0011] In this regard, the true vertical distance to the surface of the product in the tank can be determined based on known geometry and a measurement of the direction of a line from a reference position at the radar level gauge system to a corner reflector formed by the product surface and the tank wall. For example, the direction can be expressed as the angle of the transmitted signal that causes the strongest reflection from the corner reflector. The true vertical distance between the reference position at the radar level gauge system and the surface of the product in the tank can then be determined based on this determined angle and the known horizontal distance.

[0012] According to an embodiment, the vertical distance determined based on the direction of the line from the reference position at the radar level gauge system to the corner reflector formed by the surface of the product and the tank wall and the known horizontal distance can be compared with the uncorrected vertical distance determined using the second transmitted signal propagating perpendicularly toward the surface. Such a comparison can verify the correct operation of the radar level gauge system and / or provide an indication of the reliability of the radar level gauge system.

[0013] According to a fourth aspect of the present invention, there is provided a radar level gauge system for determining a fill level of a product in a tank, the tank having a tank wall and a tank environment above a surface of the product in the tank, wherein the radar level gauge system comprises: a transceiver for generating, transmitting and receiving electromagnetic signals; a signal propagation device coupled to the transceiver, for propagating a first electromagnetic transmission signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being at a known horizontal distance from the radar level gauge system, and returning a first electromagnetic reflection signal caused by reflection of the first transmission signal at the corner reflector to the transceiver; and propagating an electromagnetic second transmission signal from the transceiver through the tank environment toward the surface of the product, and returning an electromagnetic second reflection signal caused by reflection of the second transmission signal at the surface of the product to the transceiver; and a processing circuit coupled to the transceiver and configured to: determine a first measurement result of the filling level based on the propagation direction of the first reflection signal and a known horizontal distance between the radar level gauge system and the corner reflector; determine a second measurement result of the filling level based on a timing relationship between the second transmission signal and the second reflection signal; and verify the operation of the radar level gauge system based on a comparison between the first measurement result of the filling level and the second measurement result of the filling level.

[0014] The tank may be any container or vessel capable of containing the product and may be metallic or partially or completely non-metallic, open, semi-open or closed.

[0015] Thus, the tank may have a tank roof supporting the radar level gauge system, and the tank environment may be in a space defined by the surface of the product in the tank, the tank roof and the tank walls.

[0016] A "transceiver" may be one functional unit capable of transmitting and receiving electromagnetic signals, or may be a system comprising separate transmitter and receiver units.

[0017] It should be noted that the processing circuitry may be provided as one device or as several devices working together.

[0018] By "horizontal distance" is meant the distance along a horizontal line between the corner reflector defined above and a vertical line passing through a reference point of the radar level gauge system. For example, such a reference point may be defined by an antenna of the radar level gauge system.

[0019] The horizontal distance can be assumed to be constant across the range of allowable fill levels of the tank, or it can be provided as a function of the approximate fill level in the tank. Such horizontal distances can be pre-stored in a memory, for example, in a lookup table or the like, and can be based on previous measurements and / or a computational model of the tank. When a computational model of the tank is used, the horizontal distance can be estimated based on various parameters, such as the approximate fill level, temperature, and / or a profile of the tank wall measured using other measurement methods. For example, the tank wall can be scanned from the inside or outside while the tank is empty and / or at different fill levels.

[0020] According to various embodiments of aspects of the present invention, the signal propagation device may include that the radiating antenna is configured to propagate the first transmission signal in a plurality of directions relative to a line perpendicular to a surface of the product.

[0021] In an embodiment, the radiating antenna, which may advantageously be a patch antenna, may be controllable to continuously propagate the transmit signal in each of a plurality of directions.

[0022] The first transmit signal and the second transmit signal may advantageously be propagated as horizontally polarized electromagnetic signals to minimize power lost when striking the surface of the product at an oblique angle.

[0023] It should be noted that the embodiments and variations of the various aspects of the invention are largely similar.

[0024] In summary, the present invention therefore relates to a method performed using a radar level gauge system, the tank having a tank wall and a tank environment above the surface of a product in the tank, wherein the method comprises: generating and transmitting an electromagnetic first transmit signal; propagating the first transmit signal through the tank environment towards a corner reflector formed by the surface of the product and the tank wall where the surface of the product contacts the tank wall, the corner reflector being a known horizontal distance from the radar level gauge system; receiving an electromagnetic first reflection signal caused by reflection of the first transmit signal at the corner reflector; and performing a fill level determination and / or verification operation for the radar level gauge system based on a timing relationship between the first transmit signal and the first reflection signal and the known horizontal distance between the radar level gauge system and the corner reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings which show a currently preferred embodiment of the invention, in which:

[0026] Figure 1 schematically illustrates an exemplary tank arrangement comprising a radar level gauge system according to an embodiment of the present invention;

[0027] Figure 2 yes Figure 1 Schematic diagram of the radar level gauge system in FIG;

[0028] Figure 3 is a schematic block diagram of a transceiver and a measurement processor included in a radar level gauge system according to an embodiment of the present invention;

[0029] Figure 4 is a flow chart schematically illustrating an example embodiment of the method according to the first aspect of the present invention;

[0030] Figure 5 is a schematic diagram of how to position the corner reflector by scanning the propagation direction of the first transmission signal; and

[0031] Figure 6 is a flow chart schematically illustrating an example embodiment of the method according to the second aspect of the present invention. DETAILED DESCRIPTION

[0032] In this detailed description, various embodiments of the present invention are primarily discussed with reference to a radar level gauge system having a signal propagation arrangement comprising a patch antenna that is controllable to direct a radiation lobe in a plurality of desired directions.

[0033] It should be noted that this in no way limits the scope of the present invention, and the present invention also covers radar level gauge systems with other types of signal propagation devices. For example, the signal propagation device may include separate signal propagation devices for propagating toward a corner reflector formed where the surface of the product contacts the tank wall and for vertical signal propagation toward the surface of the product. In this case, it may not be necessary to set the signal propagation device for vertical signal propagation as a radiating antenna, but the signal propagation device can be set as a transmission line probe. In addition, the communication interface of the radar level gauge system does not need to be wireless, and the radar level gauge system can be configured for wired communication, for example, using a 4mA to 20mA current loop and / or other wired means for communication.

[0034] Figure 1 An exemplary radar level gauge system 1 is schematically shown, mounted at a tank 3 having a tubular mounting structure 5 (commonly referred to as a "nozzle") extending substantially vertically from a top 7 of the tank 3. The tank 3 contains a product 9 to be measured, and a tank environment 11 is present in the space defined by a surface 13 of the product 9, the tank top 7, and a tank wall 15. Figure 11 and 2. Additionally indicated are a corner reflector 16 formed by the surface 13 of the product 9 and the tank wall 15 where the surface 13 of the product 9 contacts the tank wall 15, a vertical distance A between a reference position at the radar level gauge system 1 and the surface 13 of the product, a horizontal distance B between a vertical line passing through the reference position and the tank wall 15 at the corner reflector 16, and a straight-line distance C between the reference position at the radar level gauge system 1 and the corner reflector 16.

[0035] Depending mainly on the characteristics of the product 9 in the tank 3, the tank environment 11 can affect the electromagnetic emission signal and the reflected signal S T1 、S R1 、S T2 、S R2 Furthermore, tank environment 11 may not have uniform propagation characteristics throughout its entirety, but may, for example, be stratified. In the case of product 9 containing hydrocarbons, evaporation may be quite slow, and thus, during a relatively long transition period, a stratification of hydrocarbon vapor density may exist in the tank environment. This transition period may be on the order of several days. During this transition period, correctly compensating for variations in signal propagation velocity based on the assumption of a steady-state vapor concentration in tank environment 11 may be extremely difficult or even impossible.

[0036] By implementing various aspects of the present invention, the first transmission signal S may be transmitted along a propagation path exhibiting the same vertical layered profile. T1 and the second transmission signal S T2 To deal with the effects of this stratification, etc.

[0037] Figure 2 yes Figure 1 FIG1 is an enlarged view of the radar level gauge system 1 in FIG1 , schematically indicating the functional components of the radar level gauge system 1. Figure 2 The radar level gauge system 1 comprises a transceiver 17, a signal propagation device 19, here in the form of a patch antenna, a processing circuit 21, a communication interface 23 and a communication antenna 25 for enabling wireless communication between the radar level gauge system 1 and an external unit, such as a control system (not shown).

[0038] exist Figure 2In the exemplary embodiment, communication from / to the radar level gauge system 1 is indicated as wireless communication. Alternatively, for example, communication can be performed via an analog and / or digital wired communication channel. For example, the communication channel can be a two-wire 4mA to 20mA loop, and the filling level and / or leak detection signal can be transmitted by providing a specific current corresponding to the filling level on the two-wire 4mA to 20mA loop. Digital data can also be sent via such a 4mA to 20mA loop using the HART protocol. In addition, a purely digital communication protocol such as Modbus or Foundation Fieldbus can be used.

[0039] Figure 3 yes Figure 2 A partial and simplified schematic block diagram of the radar level gauge system 1 is shown in FIG. Figure 2 , the block diagram shows the Figure 2 The transceiver 17, the signal propagation device 19 and the measurement channel of the processing circuit 21 are provided.

[0040] The transceiver 17 is shown here as comprising a microwave source 27, a power splitter 29 and a mixer 31. The processing circuitry 21 is shown as comprising a timing circuit 33, a sampler 35, an FFT block 37 and a processing and control block 39.

[0041] like Figure 3 As schematically indicated in FIG, the timing circuit 33 is coupled to the microwave source 27 to control the microwave source 27 to generate the transmission signal S T The microwave source 27 is connected to the antenna 19 via a power splitter 29 and thus transmits a signal S T1 、S T2 Provided to antenna 19. The reflected signal S from antenna 19 R1 、S R2 The power divider 29 is routed to the mixer 31, which is also connected to receive the signal from the microwave source 27. The transmission signal S provided by the microwave source 27 is T1 、S T2 and the reflected signal S from antenna 19 R1 、S R2 Combined to form the corresponding intermediate frequency signal S IF1 、S IF2 .

[0042] like Figure 3 As schematically shown in FIG, the intermediate frequency signal S is sampled by the sampler 35. IF1 、S IF2 The sampler 35 can be controlled by the timing circuit 33 to be in accordance with the corresponding transmission signal S T1 、S T2 Synchronous. The sampled intermediate frequency signal S IF1、S IF2 is further processed by the FFT block 37. The processing and control block 39 controls the operation of the radar level gauge system 1 including the operation of the timing circuit 33 and the operation of the signal propagation device 19. For example, the processing and control block 39 can control the signal propagation device 19 (here, a patch antenna) to change the propagation direction of the transmission signal provided to the signal propagation device 19. In addition, the processing and control block 39 can analyze the sampled and frequency-converted intermediate frequency signal S IF1 、S IF2 to determine the filling level and / or to verify the operation of the radar level gauge system 1 .

[0043] While the elements of the transceiver 17 are typically implemented in hardware and form part of an integrated unit often referred to as a microwave unit, at least some parts of the processing circuitry 21 may typically be implemented by software modules executed by an embedded processor. The invention is not limited to this particular implementation and it is contemplated that any implementation may be found suitable for implementing the functionality described herein.

[0044] Now refer to Figure 4 An exemplary embodiment of the method according to the first aspect of the present invention is described with reference to the flowchart in FIG. In a first step 100, a first transmit signal S is generated and transmitted. T1 In step 101, the first transmission signal S is received. T1 The reflected signal S is caused by the reflection at the corner reflector 16. R1 .

[0045] Now briefly refer to Figure 5 , Figure 5 How to scan the first transmitted signal S T1 Schematic diagram of positioning the corner reflector 16 in the propagation direction. Figure 5 As indicated in FIG, the signal propagation device 19 can be controlled to propagate the first transmission signal S in a plurality of different directions. T1,1 To S T1,5 The same antenna 19 can be used to transmit the first transmission signal S in sequence. T1,1 To S T1,5 , or depending on the capabilities of the transceiver 17 and the signal propagation device 19, the first transmission signal S T1,1 To S T1,5 . As from Figure 5 As can be understood from the schematic diagram in the figure, only one S T1,3 A strong reflection will be caused at the corner reflector 16. This reflection is the first reflection signal S R1 Of course, it is possible and often desirable to propagate a larger number of first transmit signals and / or to propagate the first transmit signals in smaller directional increments, particularly near the direction to the corner reflector 16 .

[0046] return Figure 4 , in step 102, a second transmission signal S is generated and transmitted T2 In step 103, the second transmission signal S is received. T2 The reflection signal S is caused by the reflection at the surface 13 of the product 9. R2 Again, briefly refer to Figure 5 , the second transmission signal S T2 Propagates vertically towards the surface 13 of the product 9 .

[0047] Alternatively, or in combination with the angular scanning process described above with respect to step 101, the direction from the radar level gauge system 1 to the corner reflector 16 can be estimated based on a previous (most recent) filling level determination (measurement of the vertical distance A to the surface 13). Based on at least an approximate estimate of the vertical distance A and the known horizontal distance B, the direction to the corner reflector 16 can be estimated and used to define a narrow scanning range. For example, the second transmission signal S can be emitted T2 , the second reflected signal S can be received R2 and can propagate the first transmission signal S T1 The approximate vertical distance to the surface 13 of the product 9 is previously determined. This alternative or supplementary procedure is equally relevant for all aspects of the invention.

[0048] In the following step 104, a signal speed compensation factor is determined, which is specific to the tank environment 11. T1 With the first reflected signal S R1 The first timing relationship between the second transmission signal S T2 and the second reflected signal S R2 The compensation factor is determined based on the second temporal relationship between the two and the known horizontal distance B between the radar level gauge system 1 and the corner reflector 16 .

[0049] For example, the first timing relationship can be represented by the first intermediate frequency signal S IF1 For example, the second timing relationship can be realized by the second intermediate frequency signal S IF2 Based on the first intermediate frequency signal S IF1 , under the assumption that signal propagation occurs in the air, the measurement distance C' between the reference position at the radar level gauge system 1 and the corner reflector 16 can be determined, and based on the second intermediate frequency signal S IF2 , a measured distance A′ in the vertical direction between a reference position at the radar level gauge system 1 and the surface 13 of the product 9 can be determined.

[0050] because Figure 1In the geometry of the measurement configuration, the actual distances A and C are related to the known horizontal distance B according to the following relationship:

[0051]

[0052] If the tank environment 11 consists of air, the same relationship will be valid for the measured distances A' and C'. When the tank environment 11 is not composed of air, but contains hydrocarbon vapors, etc., the signal speed is generally reduced, resulting in a longer flight time, so that the measured distances A' and C' appear longer than they actually are.

[0053] The signal propagation speed compensation factor to compensate for this effect can therefore be obtained from the following relationship:

[0054]

[0055] In this relationship, ε real is the actual average dielectric constant of the tank environment, and ε cal is the dielectric constant used during factory calibration (usually the dielectric constant of air).

[0056] Finally, in step 105, the filling level L is determined based on the measured vertical distance A', the compensation factor k and the known dimensions of the tank 3. In particular, the true vertical distance A can be determined as A' / k. The true vertical distance A can then be used to determine the filling level L in a manner known per se.

[0057] Now refer to Figure 6 An exemplary embodiment of the method according to the second aspect of the present invention is described with reference to the flowchart in FIG.

[0058] In the first steps 200 and 201, a first transmission signal S is generated and transmitted. T1 , and as above about Figure 4 The first steps 100 and 101 of the method described above receive the first reflected signal S R1 .

[0059] In the following step 202, it is determined that the first reflected signal S R1 For example, several first transmission signals S T1,1 To S T1,5 It can propagate in different directions, and the first reflected signal S that causes the strongest R1 The first transmission signal S T1,3 The direction corresponds to the first reflected signal S R1 For example, the first reflected signal S R1The direction of may be represented by an angle α relative to a vertical line passing through a reference position at the radar level gauge system 1 (eg a symmetry line passing through the antenna 19). Figure 1 and Figure 5 This angle α is indicated in .

[0060] Based on this angle α and the known horizontal distance B, the vertical distance A to the surface 13 of the product 9 can be determined as follows:

[0061] A=B cot α

[0062] Obviously, a high-precision determination of the vertical distance A requires a high-precision determination of at least the direction (represented by the angle α). This can be achieved, for example, by first performing a rough direction scan, e.g. Figure 5 , to find the approximate direction to the corner reflector 16 and then perform a fine directional scan around this approximate direction. It may also be advantageous to configure the antenna 19 to have a narrow antenna lobe at least in a cross section having a vertical plane ( Figure 5 The exemplary and enlarged lobe widths indicated in FIG have a cross section in a vertical plane).

[0063] In step 203 , the filling level L is determined based on the vertical distance A and the known dimensions of the tank 3 .

[0064] Optionally, the method may continue with steps 204 to 207 to verify the operation of the radar level gauge system 1 .

[0065] In step 204, a second transmission signal S is generated and transmitted. T2 In step 205, the second transmission signal S is received. T2 The reflection signal S is caused by the reflection at the surface 13 of the product 9. R2 Again, briefly refer to Figure 5 , the second transmission signal S T2 The second transmission signal S is transmitted vertically toward the surface 13 of the product 9. In step 206, based on the second transmission signal S T2 and the second reflected signal S R2 The uncompensated filling level measurement result L' is determined by the timing relationship between them.

[0066] Finally, in step 207, based on the first reflected signal S R1The operation of the radar level gauge system 1 is verified by comparing the filling level L determined in step 203 with the filling level L′ determined in step 206. If the comparison indicates that the two measurements of the filling level differ by more than would be expected based on known measurement tolerances and the predicted approximate signal propagation delays in the tank environment 11, a signal may be provided from the radar level gauge system 1 indicating that correct operation cannot be verified. The operator may then take appropriate action to perform a more thorough check of the functionality of the radar level gauge system 1.

[0067] Those skilled in the art will appreciate that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Claims

1. A method for determining the fill level of a product in a tank using a radar level gauge system, the tank having a tank wall and a tank environment above the surface of the product in the tank, wherein: The method comprises: generating and transmitting a first electromagnetic transmission signal; propagating the first transmit signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product meets the tank wall, the corner reflector being a known horizontal distance from the radar level gauge system; receiving a first electromagnetic reflection signal caused by reflection of the first transmission signal at the corner reflector; generating and transmitting a second electromagnetic transmission signal; propagating the second transmission signal vertically toward the surface of the product through the tank environment; receiving a second electromagnetic reflection signal caused by reflection of the second transmission signal at a surface of the product; determining a signal propagation speed compensation factor based on a first timing relationship between the first transmit signal and the first reflected signal, a second timing relationship between the second transmit signal and the second reflected signal, and a known horizontal distance between the radar level gauge system and the corner reflector; and A fill level of the product in the storage tank is determined based on the second timing relationship between the second transmitted signal and the second reflected signal and the signal propagation speed compensation factor.

2. The method according to claim 1, wherein The first transmit signal propagates in a plurality of directions relative to a line perpendicular to a surface of the product.

3. The method according to claim 1 or 2, wherein The first transmission signal is one of a plurality of transmission signals propagating in a plurality of directions.

4. A radar level gauge system for determining a filling level of a product in a tank, the tank having a tank wall and a tank environment above the surface of the product in the tank, wherein: The radar level gauge system comprises: a transceiver for generating, transmitting, and receiving electromagnetic signals; a signal propagation device, coupled to the transceiver, for: propagating an electromagnetic first transmit signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product contacts the tank wall, and returning an electromagnetic first reflected signal caused by reflection of the first transmit signal at the corner reflector to the transceiver, the corner reflector being a known horizontal distance from the radar level gauge system, and a second electromagnetic transmit signal propagating vertically from the transceiver toward the surface of the product through the tank environment and returning a second electromagnetic reflected signal caused by reflection of the second transmit signal at the surface of the product to the transceiver; and a processing circuit coupled to the transceiver and configured to determine the fill level based on a first timing relationship between the first transmit signal and the first reflected signal, a second timing relationship between the second transmit signal and the second reflected signal, and a known horizontal distance between the radar level gauge system and the corner reflector.

5. The radar level gauge system according to claim 4, wherein: The signal propagation device includes a radiating antenna configured to propagate the first transmission signal in a plurality of directions relative to a line perpendicular to a surface of the product.

6. The radar level gauge system according to claim 5, wherein: The radiating antenna is controllable to continuously propagate a transmit signal in each of the plurality of directions.

7. A method of determining a fill level of a product in a tank using a radar level gauge system, the tank having a tank wall and a tank environment above a surface of the product in the tank, the method comprising: generating and transmitting a first electromagnetic transmission signal; propagating the first transmit signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product meets the tank wall, the corner reflector being a known horizontal distance from the radar level gauge system; receiving a first electromagnetic reflection signal caused by reflection of the first transmission signal at the corner reflector; determining a measurement result indicative of a direction of propagation of the first reflected signal; as well as The filling level is determined based on a measurement result indicating a propagation direction of the first reflected signal and a known horizontal distance between the radar level gauge system and the corner reflector.

8. The method according to claim 7, wherein: The first transmission signal is one of a series of transmission signals that continuously propagate in a plurality of directions relative to a line perpendicular to a surface of the product.

9. The method according to claim 8, wherein The propagation direction of the first reflected signal is determined based on the propagation direction of the first transmitted signal.

10. The method according to any one of claims 7 to 9, further comprising the steps of: determining a distance along a straight line between the radar level gauge system and the corner reflector based on a timing relationship between the first transmit signal and the first reflected signal; as well as The presence of product in the tank environment is determined based on the distance along a straight line between the radar level gauge system and the corner reflector, the direction of the first reflected signal, and the known horizontal distance between the radar level gauge system and the corner reflector.

11. A method of verifying the operation of a radar level gauge system, comprising the steps of any one of claims 7 to 10, and additionally comprising the following steps: generating and transmitting a second electromagnetic transmission signal; propagating the second transmission signal vertically toward the surface of the product through the tank environment; receiving a second electromagnetic reflection signal caused by reflection of the second transmission signal at a surface of the product; determining a measurement result indicative of the filling level based on a timing relationship between the second transmit signal and the second reflected signal; as well as The operation of the radar level gauge system is verified by comparing a filling level determined based on a measurement indicating the propagation direction of the first reflected signal and a known horizontal distance between the radar level gauge system and the corner reflector with a filling level determined based on a timing relationship between the second transmitted signal and the second reflected signal.

12. A radar level gauge system for determining a fill level of a product in a tank, the tank having a tank wall and a tank environment above a surface of the product in the tank, wherein: The radar level gauge system comprises: a transceiver for generating, transmitting, and receiving electromagnetic signals; a signal propagation device, coupled to the transceiver, for: propagating an electromagnetic first transmit signal through the tank environment toward a corner reflector formed by a surface of the product and the tank wall where the surface of the product contacts the tank wall, and returning an electromagnetic first reflected signal caused by reflection of the first transmit signal at the corner reflector to the transceiver, the corner reflector being a known horizontal distance from the radar level gauge system, and a processing circuit coupled to the transceiver and configured to: A first measurement result of the filling level is determined based on the propagation direction of the first reflected signal and a known horizontal distance between the radar level gauge system and the corner reflector.

13. The radar level gauge system according to claim 12, wherein: The signal propagation device is further configured to: propagating a second electromagnetic transmission signal vertically from the transceiver toward the surface of the product through the tank environment, and returning a second electromagnetic reflection signal caused by reflection of the second transmission signal at the surface of the product to the transceiver, and The processing circuit is further configured to: determining a second measurement result of the filling level based on a timing relationship between the second transmission signal and the second reflection signal, and The operation of the radar level gauge system is verified based on a comparison between the first measurement of the filling level and the second measurement of the filling level.

14. The radar level gauge system according to claim 12 or 13, wherein: The signal propagation device includes a radiating antenna configured to propagate the first transmission signal in a plurality of directions relative to a line perpendicular to a surface of the product.

15. The radar level gauge system according to claim 13, wherein: The transceiver comprises: a first measurement channel, configured to generate and transmit the first transmit signal and receive the first reflected signal; and The second measurement channel is configured to generate and transmit the second transmission signal and receive the second reflection signal.

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