A total temperature phosphor measurement method and system that is insensitive to incoming flow angle

Abstract

The application relates to a total temperature phosphor measurement method and system which is insensitive to the angle of the incoming flow, and the method comprises the following steps: generating an excitation light signal and irradiating a sensing sheet provided with a temperature-sensitive phosphor material layer on a fluid passage to be measured; acquiring image data of the temperature-sensitive phosphor material layer after excitation; obtaining temperature distribution information of the sensing sheet based on the image data by using a preset relationship between phosphor lifetime and temperature; and selecting the highest temperature from the temperature distribution information as the measured total temperature. Compared with the prior art, the total temperature is obtained by extracting the maximum temperature value, the sensitivity to the angle of the incoming flow is further reduced by adopting an optimized air inlet hole and air outlet hole design, and the influence of the environment is reduced by adopting a temperature measurement method of phosphor lifetime.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature measurement, and in particular to a total temperature phosphor measurement method and system which is not sensitive to the angle of incoming flow. BACKGROUND

[0002] A total temperature probe is a sensor used to measure the total temperature of a fluid, such as air or gas. Existing total temperature probes are very sensitive to the angle of incoming flow during measurement. During the measurement process, the angle of incoming flow often changes, making it difficult to ensure that the incoming flow is always positive relative to the probe. Therefore, the existing total temperature probe has poor adaptability when facing variable airflow directions. Especially in high-speed aircraft, wind tunnel tests and other dynamic environments, the airflow direction may change rapidly, which puts higher requirements on the measurement accuracy of the total temperature probe. However, due to the sensitivity of the existing probe to the angle of incoming flow, its performance in these applications is often not ideal. In addition, since the measurement results of the probe depend on the relative angle of the airflow and the probe surface, this angle dependence will increase the measurement error. Specifically, when the airflow impacts the probe at different angles, the temperature distribution on the surface of the probe will change, affecting the accuracy of temperature measurement.

[0003] The above errors may come from the following aspects: (1) Aerodynamic heating effect: due to different airflow impact angles, the degree of aerodynamic heating is different, causing the measured temperature to deviate from the actual temperature. (2) Uneven heat dissipation: different angles of airflow impact may cause different heat dissipation on the surface of the probe, further increasing the uncertainty of temperature measurement. (3) Flow field disturbance: changes in the angle of incoming flow may cause disturbances in the flow field around the probe, causing fluctuations in the measurement results. Due to the sensitivity to the angle of incoming flow, the existing total temperature probe is subject to certain limitations in installation and deployment. The probe must be installed at a specific angle to ensure that the airflow can impact the surface of the probe directly. This installation limitation may affect the application of the probe in complex environments, especially in scenarios where the position of the probe needs to be adjusted flexibly. In order to reduce the influence of the angle of incoming flow on the measurement results, the existing total temperature probe needs to be calibrated and corrected in a complex manner, which not only increases the complexity of data processing, but also may introduce additional uncertainties.

[0004] In summary, there is currently a lack of a total temperature measurement probe to solve or partially solve the aforementioned problems. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a total temperature phosphor measurement method and system which is not sensitive to the angle of incoming flow, to solve or partially solve the problem of inaccurate measurement results caused by sensitivity to the angle of incoming flow.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] In one aspect of the present application, a total temperature phosphor measurement method insensitive to incoming flow angle is provided, comprising the following steps:

[0008] In step S1, an excitation light signal is generated and irradiated on a sensor sheet with a temperature-sensitive phosphor material layer arranged on a fluid passage to be measured;

[0009] In step S2, image data of the temperature-sensitive phosphor material layer after excitation is obtained;

[0010] In step S3, based on the image data, a preset relationship between phosphor lifetime and temperature is used to obtain temperature distribution information of the sensor sheet;

[0011] In step S4, the highest temperature is selected from the temperature distribution information as the measured total temperature.

[0012] As a preferred technical solution, the process of obtaining the relationship between phosphor lifetime and temperature comprises:

[0013] The temperature is measured, the phosphor signal is collected and recorded, and the lifetime is calculated. The collected temperature and phosphor lifetime are one-to-one corresponding, and the calibration curve of phosphor lifetime and temperature is obtained.

[0014] As a preferred technical solution, the excitation light signal is ultraviolet laser with a wavelength of 260-410 nm and a power of 0.1-15 W.

[0015] In another aspect of the present application, a total temperature phosphor measurement system insensitive to incoming flow angle is provided for implementing the aforementioned total temperature phosphor measurement method insensitive to incoming flow angle, and the total temperature phosphor measurement system comprises:

[0016] A probe head is provided with a channel in the axial direction inside, and the probe head is provided with an air inlet hole and an air outlet hole;

[0017] A sensor sheet is located in the channel and connected with the probe head, the sensor sheet is provided with a sensor sheet through hole, one side of the sensor sheet is provided with a temperature-sensitive phosphor material layer, and the air inlet hole, the sensor sheet and the air outlet hole form a fluid passage;

[0018] A lens is located in the channel and opposite to the temperature-sensitive phosphor material layer of the sensor sheet;

[0019] A signal transmitting unit is used to generate an excitation light signal and excite the temperature-sensitive phosphor material layer;

[0020] A signal receiving unit is used to receive image data of the temperature-sensitive phosphor material layer after excitation captured by the lens;

[0021] The data processing unit is used for obtaining temperature distribution information of the sensing sheet based on the image data by using a preset relationship between phosphorescent lifetime and temperature, and selecting the highest temperature as the total temperature of measurement.

[0022] As a preferred technical scheme, the probe head comprises a plurality of air inlet holes, and the air inlet holes are arranged at intervals along the circumference of the probe head, the diameter of the air inlet hole is 0.6-5mm, the distance between the center line of the air inlet hole and the top end of the probe head is 1-5mm, the center line of the air inlet hole is perpendicular to the axis of the channel and intersects the center of the circumferential cylindrical surface, and the angle between the axes of adjacent air inlet holes is 15-60°.

[0023] As a preferred technical scheme, the diameter of the channel is 1.5-10mm.

[0024] As a preferred technical scheme, the probe head comprises a plurality of air outlet holes, and the air outlet holes are arranged at intervals on the opposite side of the air inlet hole, the diameter of the air outlet hole is 0.3-3mm, the center line of the air outlet hole is parallel to the axis of the channel, and the distance between the center line of the air outlet hole and the top end of the probe head is 6-18mm.

[0025] As a preferred technical scheme, the temperature-sensitive phosphorescent material layer is MFG, Y2O3:Eu, YSZ:Eu, YVO4:Dy or YAG:Dy, and the thickness is 0.001-0.01mm.

[0026] As a preferred technical scheme, the signal transmitting unit comprises a light source, an optical fiber and a collimating lens.

[0027] As a preferred technical scheme, the signal receiving unit comprises a filter.

[0028] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0029] (1) The total temperature is obtained by extracting the maximum temperature to reduce the sensitivity to the flow angle: the present application collects image data after the temperature-sensitive phosphorescent material layer is excited, obtains the temperature distribution information of the sensing sheet by using the preset relationship between the phosphorescent lifetime and the temperature, selects the highest temperature as the total temperature of measurement, and records the maximum temperature, thereby effectively reducing the influence of the flow angle.

[0030] (2) The temperature measurement method based on the phosphorescent lifetime is used to reduce the environmental influence: the present application uses the temperature measurement method based on the phosphorescent lifetime, thereby avoiding the influence of the measurement environment and the emission coefficient of the surface gray body of the measured object and the influence of the measurement angle.

[0031] (3) Further reduce the sensitivity to the angle of the incoming flow by optimizing the design of the inlet holes and outlet holes: the present application is by making a plurality of inlet holes along the circumferential direction of the probe head, the center line of the plurality of inlet holes is perpendicular to the axis of the channel and intersects the circumferential cylindrical center, the angle between the axes of adjacent inlet holes is 15°-60°, a plurality of outlet holes are arranged on the opposite side of the inlet holes along the circumferential direction, and the center lines of the outlet holes are parallel and perpendicular to the cylindrical axis respectively, by optimizing the angle of the incoming flow, the influence of the angle of the incoming flow is further reduced. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Flow chart of the total temperature phosphor measurement method which is not sensitive to the angle of the incoming flow in the embodiment;

[0033] Figure 2 Schematic diagram of the total temperature phosphor measurement system which is not sensitive to the angle of the incoming flow in the embodiment;

[0034] Figure 3 Structural schematic diagram of the total temperature phosphor measurement probe which is not sensitive to the angle of the incoming flow in the embodiment;

[0035] Figure 4 Is Figure 3 Schematic diagram of the sensing sheet, sensing sheet through hole and temperature sensitive phosphor material layer;

[0036] Figure 5 Is Figure 3 The left view of;

[0037] Figure 6 Is Figure 3 The right view of;

[0038] Figure 7 Is Figure 3 The A view of;

[0039] Figure 8 Is Figure 3 The B view of;

[0040] Figure 9 Is Figure 3 The C view of;

[0041] Figure 10 The graph of the total temperature measured by the probe with the change of the angle of the incoming flow (total temperature 373K) in the embodiment;

[0042] Wherein, 1-probe head, 2-probe stem, 3-inlet hole, 4-outlet hole, 5-channel, 6-sensing sheet, 7-sensing sheet through hole, 8-temperature sensitive phosphor material layer, 9-lens. DETAILED DESCRIPTION

[0043] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present application.

[0044] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0045] Embodiment 1

[0046] In view of the problems of the prior art described above, the present embodiment provides a total temperature phosphor measurement method which is not sensitive to the angle of the incoming flow, see Figure 1 The method comprises the following steps:

[0047] Step S1, generating an excitation light signal and irradiating a sensor sheet provided with a temperature-sensitive phosphor material layer on the fluid passage to be measured.

[0048] In the present embodiment, the excitation light signal is ultraviolet laser with a wavelength of 260-410 nm and a power of 0.1-15 W.

[0049] Step S2, obtaining image data after excitation of the temperature-sensitive phosphor material layer.

[0050] Step S3, based on the image data, using the preset relationship between phosphor lifetime and temperature to obtain temperature distribution information of the sensor sheet.

[0051] The process of obtaining the relationship between phosphor lifetime and temperature is to measure the temperature, collect and record the phosphor signal and calculate the lifetime, and correspond the collected temperature and phosphor lifetime to obtain a calibration curve of phosphor lifetime and temperature.

[0052] Step S4, selecting the highest temperature from the temperature distribution information as the measured total temperature.

[0053] In addition, the present embodiment also provides a total temperature phosphor measurement system which is not sensitive to the angle of the incoming flow, see Figure 2The system mainly comprises a probe 01 comprising a fisheye lens and a temperature-sensitive phosphor layer, a signal transmitting unit 02, a signal receiving unit 03 and a data processing unit 04.

[0054] Referring to Figure 3 The probe 01 comprises a probe head 1, a probe stem 2, air inlet holes 3, air outlet holes 4, a channel 5, a sensing sheet 6, sensing sheet through holes 7, a temperature-sensitive phosphor layer 8 and a lens 9. The probe shell is made of high-temperature-resistant and corrosion-resistant materials to adapt to various complex environments. The parts will be described separately below.

[0055] The probe head 1 is combined by a cylinder and a fast converging curve rotating body. The probe head 1 is provided with the air inlet holes 3 on the side facing the main flow and the air outlet holes 4 on the side facing away from the main flow. The probe head 1 is internally provided with a circular channel 5 along the axial direction, which penetrates the entire probe. The channel 5 is internally provided with the sensing sheet 6, and the lower surface of the sensing sheet 6 is sprayed with the temperature-sensitive phosphor layer 8. The circular channel 5 below the sensing sheet 6 is internally provided with the fisheye lens 9.

[0056] Preferably, the diameter d of the cylinder of the probe head 1 is 3-10 mm, and the length is 10-45 mm. In the embodiment, 7 mm and 20 mm are selected, respectively. The curve rotating body is formed by double torsion wire rotation. The diameter of the channel 5 in the probe head 1 is 1.5-10 mm, and 6 mm is selected in the embodiment.

[0057] Referring to Figure 5 The cylinder of the probe head 1 is provided with the air inlet holes 3 on the side facing the main flow. The diameter of the air inlet hole 3 is 0.6-5 mm, and 1.5 mm is selected in the embodiment. The number of the air inlet holes 3 is 3-8, and 3 is selected in the embodiment. The air inlet holes 3 are arranged in a straight line along the circumferential direction. The distance from the center line of the air inlet hole 3 to the top end of the probe head 1 is 1-5 mm, and 4.5 mm is selected in the embodiment. Figure 7 The center line of the circumferentially arranged hole is perpendicular to the cylinder axis and intersects the circumferential cylinder surface center. The angle between the adjacent circumferential holes is 15°-60°, and 30° is selected in the embodiment.

[0058] Referring to Figure 6 and Figure 9 The cylinder of the probe head 1 is provided with the air outlet holes 4 on the side facing away from the main flow. The diameter of the air outlet hole 4 is 0.3-3 mm, and 0.9 mm is selected in the embodiment. The number of the air outlet holes 4 is 1-3, and 2 is selected in the embodiment. The air outlet holes 4 are arranged in a straight line along the circumferential direction. The center lines of the air outlet holes 4 are parallel and perpendicular to the cylinder axis. The distance from the center line of the air outlet hole 4 to the top end of the probe head 1 is 6-18 mm, and 11 mm is selected in the embodiment.

[0059] The probe stem 2 is a cylinder. The diameter D of the cylinder is 4-12 mm, and 8 mm is selected in the embodiment.

[0060] Referring to Figure 4 The material of the sensing sheet 6 is selected to be copper or silver, the diameter is the same as the circular channel 5, and the thickness is 0.02mm-0.2mm, and in this embodiment, the thickness is selected to be 0.1mm. The distance between the sensing sheet 6 and the top end of the probe head 1 is 3.5-12mm, and in this embodiment, the distance is selected to be 7.5mm. Referring to Figure 8 A plurality of sensing sheet through holes 7 are arranged on the outer side of the sensing sheet 6. The diameter of the sensing sheet through hole 7 is 0.2mm-3mm, and in this embodiment, the diameter is selected to be 0.8mm. The number of the sensing sheet through holes 7 is 8-12, and in this embodiment, the number is selected to be 8.

[0061] The temperature-sensitive phosphor material layer 8 is sprayed on the entire lower surface of the sensing sheet 6 by mixing with a high-temperature adhesive. The temperature-sensitive phosphor material layer 8 can be selected to be MFG, Y2O3:Eu, YSZ:Eu, YVO4:Dy or YAG:Dy, and in this embodiment, Y2O3:Eu is selected. The spraying thickness is 0.001mm-0.01mm, and in this embodiment, the spraying thickness is selected to be 0.005mm.

[0062] The lens 9 is a 180-degree panoramic fisheye lens for measuring the large-range signal inside the probe. The diameter of the lens 9 is 1.3mm-9mm, and in this embodiment, the diameter is selected to be 5.5mm.

[0063] The signal transmitting unit 02 includes a light source and an optical fiber connected to the light source, and is used for exciting the temperature-sensitive phosphor material layer. The excitation light of the light source is collimated by a collimating lens and then irradiated onto the temperature-sensitive phosphor material. The light source can be an ultraviolet LED, a blue LED or other suitable light source, and the wavelength range is 260-410nm. In this embodiment, the light source is selected to be an ultraviolet LED, the wavelength is 355nm, the power of the light source is 10w, the width of the pulse light is 20ms, and the pulse period is 1000ms.

[0064] The signal receiving unit 03 includes an optical fiber and a light detector connected behind the fisheye lens, and is used for detecting the temperature-related phosphor signal emitted by the temperature-sensitive phosphor material. The light source and the light detector are connected to the fisheye lens through the optical fiber, and the light detector passes through a filter to filter out background light and non-phosphor signals. The photoelectric detector can be a photodiode, a photomultiplier tube or other suitable photoelectric detector, and in this embodiment, a photomultiplier tube is selected.

[0065] The data processing unit 04 is used for processing the signal output by the light detector and calculating the phosphor decay time to determine the temperature. The measurement area is the temperature distribution on the entire sensing sheet, and the highest temperature value on the entire sensing sheet is selected as the output result in the measurement process.

[0066] Referring to Figure 10 The total temperature of the probe measured as a function of the flow deflection angle.

[0067] The process of measuring by using the total temperature phosphor measurement system insensitive to the angle of the incoming flow includes:

[0068] (1) Place the total temperature phosphor measurement probe insensitive to the angle of the incoming flow in the measured flow field, so that the inlet hole 3 is directly opposite the incoming flow direction;

[0069] (2) The light emitted by the signal transmitting unit 02 excites the temperature-sensitive phosphor material layer 8 through the fisheye lens 9;

[0070] (3) The high-speed airflow completely converts the kinetic energy into heat energy at the sprayed temperature-sensitive phosphor material layer 8, the temperature-sensitive phosphor material layer 8 is excited by the input light, generates excitation light carrying temperature information, and is output through the lens 9, and then transmitted to the data processing unit 04 through the signal receiving unit 03;

[0071] (4) The data processing unit 04 processes the optical signal carrying temperature information, and then obtains the total temperature information of the flow field.

[0072] In summary, the embodiment utilizes the temperature-sensitive characteristics of phosphor materials, and calculates the temperature by detecting the phosphor decay time, which has the characteristics of high sensitivity and high precision. By using a fisheye lens, it has the characteristics of extremely wide viewing angle and can realize a viewing angle coverage of up to 180 degrees or even more under the connection of small optical fibers. The embodiment designs the inlet structure of the total temperature probe, combines the fisheye lens and the phosphor temperature measurement technology, and significantly reduces the influence of the angle of the incoming flow on the total temperature phosphor measurement.

[0073] The method and system have the following beneficial effects:

[0074] By opening several inlet holes circumferentially on the surface of the total temperature probe, airflow under different incoming flow angles can flow into the probe. A temperature-sensitive area is placed downstream of the inlet hole to capture all temperature information of the airflow. After the airflow enters the total temperature probe, it impacts on the temperature-sensitive area, and there must be a maximum temperature area in the temperature-sensitive area inside the probe. The fisheye lens records all temperature information of the temperature-sensitive area, so even if the highest temperature area changes with the incoming flow angle, it can be effectively captured. By extracting the maximum temperature, the total temperature is obtained, and the total temperature of the airflow is obtained regardless of the incoming flow angle.

[0075] By fisheye measurement, all temperatures inside the probe can be measured, and in the form of recording the maximum temperature, the influence of the incoming flow angle can be avoided. Since phosphor materials are used as the carrier for temperature measurement, temperature measurement can be performed in the range of-100-1500℃, the temperature measurement range is wide, and the spatial resolution is high. At the same time, using the temperature measurement method based on phosphor lifetime avoids the influence of the emission coefficient of the measured environment and the surface of the measured object and the influence of the measurement viewing angle. The method / system can be used for measuring the total temperature of high-temperature fluid of an aero-engine or a gas turbine component, and provides a solution for high-precision evaluation of flow conditions.

[0076] Embodiment 2

[0077] This embodiment provides an electronic device comprising: one or more processors and memory storing one or more programs comprising instructions for performing a total temperature phosphor measurement method that is insensitive to incoming flow angle as described in embodiment 1.

[0078] Embodiment 3

[0079] This embodiment provides a computer-readable storage medium comprising one or more programs for execution by one or more processors of an electronic device, the one or more programs comprising instructions for performing a total temperature phosphor measurement method that is insensitive to incoming flow angle as described in embodiment 1.

[0080] The above description is merely that of a specific implementation of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be encompassed within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. A total temperature phosphorimetry method that is insensitive to the angle of the incoming flow, characterized in that, It comprises the following steps: Step S1, generating an excitation light signal and irradiating a sensor sheet with a temperature-sensitive phosphor layer arranged on a fluid passage to be measured; Step S2, acquiring image data of the temperature-sensitive phosphor layer after excitation; Step S3, based on the image data, using a preset relationship between phosphor lifetime and temperature to obtain temperature distribution information of the sensor sheet; Step S4, selecting the highest temperature from the temperature distribution information as the measured total temperature, The process of obtaining the relationship between the phosphor lifetime and the temperature comprises: Measuring the temperature, recording the phosphor signal and calculating the lifetime, and corresponding the collected temperature and the phosphor lifetime to obtain the calibration curve of the phosphor lifetime and the temperature.

2. A total temperature phosphorimetry method according to claim 1, wherein The excitation light signal is ultraviolet laser with a wavelength of 260-410 nm and a power of 0.1-15 W.

3. A total temperature phosphor measurement system that is insensitive to incoming flow angle, characterized by, The total temperature phosphor measurement system for realizing the total temperature phosphor measurement method of the flow angle insensitivity according to any one of claims 1-2 comprises: A probe head (1) with a channel (5) inside along the axial direction, the probe head (1) is provided with an air inlet hole (3) and an air outlet hole (4); A sensor sheet (6) is located in the channel (5) and connected with the probe head (1), the sensor sheet (6) is provided with a sensor sheet through hole (7), one side of the sensor sheet (6) is provided with a temperature-sensitive phosphor layer (8), the air inlet hole (3), the sensor sheet (6) and the air outlet hole (4) form a fluid passage; A lens (9) is located in the channel (5) and directly opposite the temperature-sensitive phosphor layer (8) of the sensor sheet (6); A signal transmitting unit (02) is used to generate an excitation light signal and excite the temperature-sensitive phosphor layer (8); A signal receiving unit (03) is used to receive the image data of the temperature-sensitive phosphor layer (8) after excitation captured by the lens (9); A data processing unit (04) is used to obtain the temperature distribution information of the sensor sheet (6) based on the image data, using a preset relationship between phosphor lifetime and temperature, and select the highest temperature from the temperature distribution information as the measured total temperature, The system comprises a plurality of air inlet holes (3), and the plurality of air inlet holes (3) are arranged at intervals along the circumference of the probe head, the diameter of the air inlet hole (3) is 0.6-5 mm, the distance from the center line of the air inlet hole (3) to the top end of the probe head (1) is 1-5 mm, the center lines of the plurality of air inlet holes (3) are perpendicular to the axis of the channel (5) and intersect at the center of the circumferential cylindrical surface, and the angle between the axes of adjacent air inlet holes (3) is 15-60°.

4. A total temperature phosphor measurement system that is insensitive to incoming flow angle according to claim 3, wherein, The diameter of the channel (5) is 1.5-10 mm.

5. A total temperature phosphor measurement system that is insensitive to incoming flow angle according to claim 3, wherein, A plurality of air outlet holes (4) are arranged on the opposite side of the air inlet hole (3) along the circumference, the diameter of the air outlet hole (4) is 0.3-3 mm, the center lines of the air outlet holes (4) are parallel and respectively perpendicular to the cylindrical axis, and the distance from the center line of the air outlet hole (4) to the top end of the probe head (1) is 6-18 mm.

6. A total temperature phosphor measurement system that is insensitive to incoming flow angle according to claim 3, wherein, The temperature-sensitive phosphor layer (8) is MFG, Y2O3:Eu, YSZ:Eu, YVO4:Dy or YAG:Dy, and the thickness is 0.001mm to 0.01mm.

7. A total temperature phosphor measurement system that is insensitive to incoming flow angle according to claim 3, wherein, The signal emitting unit (02) comprises a light source, an optical fiber and a collimating lens.

8. A total temperature phosphor measurement system that is insensitive to incoming flow angle according to claim 3, wherein, The signal receiving unit (03) comprises a filter.

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