Radio height simulation device and method

Abstract

The invention relates to the field of radio measurement, in particular to a radio height simulation device and method. The radio height simulation device comprises a fixed attenuator, a photoelectric conversion module Tx, a first optical path control member, a second optical path control member, a photoelectric conversion module Rx, a numerical control attenuator and a host. One end of the fixed attenuator is connected with the radio altimeter, one end of the photoelectric conversion module Tx is connected with the fixed attenuator, the other end of the photoelectric conversion module Tx is connected with the first optical path control element, the first optical path control element is externally connected with at least one optical fiber, and the optical fiber is connected with the second optical path control element; according to the invention, the dependence on a digital signal processor and a long-distance radio frequency cable is reduced, the hardware cost is reduced, the radio altimeter can be tested according to the radio height simulation device, the device can be calibrated by using a vector network analyzer, and the accuracy of height simulation is further ensured.

Description

Technical Field

[0001] The present invention relates to the field of radio measurement, and in particular to a radio altitude simulation device and method. Background Art

[0002] Radio altimeters are commonly used altitude measurement equipment in aircraft. During the development and testing phase of radio altimeters, radio altitude simulators are used to simulate signal environments at different altitudes, thereby conducting comprehensive performance testing and calibration of the altimeter. Currently, mainstream radio altitude simulators in the industry are mainly based on the following technologies: Digital delay simulators: After receiving the signal from the altimeter, these simulators precisely delay the signal according to preset altitude simulation parameters and then transmit the delayed signal back to the altimeter's receiver. The length of the delay directly corresponds to the simulated altitude value, and by adjusting the delay, different flight altitudes can be simulated. However, digital delay simulators typically rely on digital signal processors and complex algorithms, resulting in high procurement costs, which are often unaffordable for projects with limited budgets or those in the early stages of development and verification.

[0003] RF cable simulation: Using a certain length of RF cable, the altimeter's transmitting and receiving ports are directly short-circuited. The physical length of the cable is then used to simulate the signal's transmission distance in space. Because the propagation speed of RF signals in a cable is similar to that in free space, varying altitudes can be accurately simulated by adjusting the cable length. However, long-distance RF cables are not only bulky, heavy, and expensive, but signal attenuation also increases significantly with cable length, limiting their feasibility in long-distance simulation applications.

[0004] A photoelectric conversion altimeter simulator converts the radio frequency signal emitted by the altimeter into an optical signal through a photoelectric conversion module. This optical signal is then transmitted via optical fiber to a specified distance. Another photoelectric conversion module then converts the optical signal back to a radio frequency signal, which is then transmitted back to the altimeter's receiving end. However, existing photoelectric conversion altimeter simulators still have many shortcomings in practical applications, such as the excessive number of photoelectric conversion modules leading to high system complexity, the inability to effectively test the altimeter's sensitivity, and the difficulty in implementing an automated testing process. Summary of the Invention

[0005] In response to the problems mentioned in the prior art, the present invention proposes a radio altitude simulation device and method, which can effectively reduce the testing cost of radio altimeters.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a radio altitude simulation device, comprising a fixed attenuator, a photoelectric conversion module Tx, a first optical path control component, a second optical path control component, a photoelectric conversion module Rx, a digitally controlled attenuator, and a host; One end of the fixed attenuator is connected to the radio altimeter, one end of the photoelectric conversion module Tx is connected to the fixed attenuator, and the other end is connected to the first optical path control component, the first optical path control component is externally connected to at least one optical fiber, and the optical fiber is connected to the second optical path control component, one end of the photoelectric conversion module Rx is connected to the second optical path control component, and the other end is connected to the digitally controlled attenuator, wherein the digitally controlled attenuator is also connected to the radio altimeter; The host is connected to the radio altimeter, the first optical path control component, the second optical path control component and the digitally controlled attenuator respectively.

[0007] As a further improvement of the present invention, the operating frequency of the fixed attenuator meets the frequency band range of the signal transmitted by the radio altimeter.

[0008] As a further improvement of the present invention, the first light path control component and the second light path control component include optical switches or optical switch matrices.

[0009] As a further improvement of the present invention, the optical fiber wavelength matches the photoelectric conversion module Rx and the photoelectric conversion module Tx.

[0010] As a further improvement of the present invention, the host is equipped with testing software, wherein the host also includes a main control board.

[0011] As a further improvement of the present invention, the radio altimeter is connected to the fixed attenuator via a first radio frequency cable, and the radio altimeter is connected to the digitally controlled attenuator via a second radio frequency cable.

[0012] A method of a radio altitude simulation device, comprising the steps of: Preset the required optical fiber length; Connect the optical fiber to the radio altitude simulator and calibrate it; Connect the radio altitude simulation device, optical fiber and radio altimeter to test the sensitivity and ranging accuracy of the radio altimeter.

[0013] As a further improvement of the present invention, the length of the preset optical fiber is shown as follows:

[0014] Where: H is the simulated height; n is the refractive index of the optical fiber, which is 1.46; L1 is the calibrated electrical length of the first RF cable; L2 is the calibrated electrical length of the second RF cable.

[0015] As a further improvement of the present invention, the calibration process is: Connect the radio height simulator to the vector network analyzer and access a preset length of optical fiber; Initially set up the vector network analyzer to measure the loop length and the loop attenuation corresponding to the loop length; Adjust the digitally controlled attenuator to compensate for the loop attenuation.

[0016] As a further improvement of the present invention, it is necessary to verify whether the loop length meets a preset error.

[0017] Compared with the prior art, the present invention has achieved the following technical effects: The present invention replaces traditional radio frequency cables with optical fiber transmission, and combines optical path control components with digitally controlled attenuators to achieve low-cost, high-precision, and high-flexibility radio altimeter testing. This device realizes an efficient testing process through the coordinated work of a fixed attenuator, a photoelectric conversion module Tx, a photoelectric conversion module Rx, a first optical path control component, a second optical path control component, and optical fibers of preset lengths. The fixed attenuator can control signal attenuation and simulate signal strength at different flight altitudes. The photoelectric conversion modules Tx and Rx ensure seamless conversion between optical and electrical signals. The first optical path control component and the second optical path control component can flexibly switch between optical fibers of different lengths according to test requirements, quickly simulating a variety of flight altitude environments to meet the requirements of complex test scenarios.

[0018] The present invention reduces dependence on digital signal processors and long-distance radio frequency cables, cuts hardware costs, combines test software with a main control board to implement an automated process, and can also measure the fiber loop length and attenuation value through a vector network analyzer, further ensuring the accuracy of altitude simulation. While simplifying the system structure and reducing manufacturing costs, the present invention takes into account both test efficiency and accuracy. It is particularly suitable for projects in the early stages of development or with limited budgets, and provides efficient and reliable technical support for performance verification of radio altimeters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural diagram of the radio altitude simulation device of the present invention; Figure 2 This is the interface diagram of the test software of the present invention; Figure 3 It is a schematic diagram of the altitude calibration of the radio altitude simulation device of the present invention.

[0020] Figure numerals: 1. fixed attenuator; 2. photoelectric conversion module Tx; 3. first optical path control component; 4. second optical path control component; 5. photoelectric conversion module Rx; 6. digitally controlled attenuator; 7. host; 8. radio altimeter; 9. vector network analyzer. DETAILED DESCRIPTION

[0021] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0024] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0025] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0026] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0027] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0029] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 As shown, the present invention proposes a radio altitude simulation device, including a fixed attenuator, a photoelectric conversion module Tx, a first optical path control component, a second optical path control component, a photoelectric conversion module Rx, a digitally controlled attenuator and a host; one end of the fixed attenuator is connected to the radio altimeter, one end of the photoelectric conversion module Tx is connected to the fixed attenuator, and the other end is connected to the first optical path control component, the first optical path control component is externally connected to at least one optical fiber, and the optical fiber is connected to the second optical path control component, one end of the photoelectric conversion module Rx is connected to the second optical path control component, and the other end is connected to the digitally controlled attenuator, wherein the digitally controlled attenuator is also connected to the radio altimeter; the host is respectively connected to the radio altimeter, the first optical path control component, the second optical path control component and the digitally controlled attenuator.

[0032] In the embodiment, the radio altitude simulation device includes a fixed attenuator, a photoelectric conversion module Tx, a first optical path control component, a second optical path control component, a photoelectric conversion module Rx, a digitally controlled attenuator, and a host.

[0033] The fixed attenuator is used to attenuate the strength of the radio frequency signal transmitted by the radio altimeter to prevent signal overload and damage and is used in the subsequent photoelectric conversion module. Its operating frequency needs to cover the signal frequency band of the radio altimeter (for example, 4.2 to 4.4 GHz) to ensure that the signal is not distorted or attenuated. In the embodiment, the fixed attenuator is connected to the transmitting end of the radio altimeter through a first RF cable, and the other end is connected to the photoelectric conversion module Tx.

[0034] In the embodiment, the photoelectric conversion module Tx is used to convert the attenuated radio frequency signal into an optical signal, and the wavelength is usually selected to be 1550nm or 1310nm to match the optical fiber transmission characteristics; in the embodiment, the photoelectric conversion module Rx restores the optical signal transmitted through the optical fiber into a radio frequency signal, and feeds it back to the receiving end of the radio altimeter through a digitally controlled attenuator.

[0035] In this embodiment, the first and second optical path control components preferably employ optical switches or optical switch matrices to support multi-path fiber switching. Specifically, the first optical path control component distributes the optical signal from the photoelectric conversion module Tx to a preset optical fiber length; the second optical path control component receives the optical fiber signal and transmits it to the photoelectric conversion module Rx. By switching optical paths, different optical fiber lengths can be quickly selected to simulate various heights.

[0036] In the embodiment, the digitally controlled attenuator is used to attenuate the echo signal power and adjust the loop gain, thereby controlling the signal strength entering the altimeter receiving end, and realizing the sensitivity test of the radio altimeter; the host is connected through a digital interface, and the attenuation value is adjusted in real time to dynamically adapt to the test requirements.

[0037] In the embodiment, the hardware of the host is a main control board, which is responsible for controlling the communication of the first optical path control component, the second optical path control component, the digitally controlled attenuator and the radio altimeter.

[0038] like Figure 2 The figure shows the test software interface. The host test software is used to calibrate the altitude of the radio altitude simulation device and read the information of the module under test.

[0039] In this embodiment, the refractive index of the optical fiber is 1.46, and the wavelength matches the photoelectric conversion module Tx and the photoelectric conversion module Rx. The signal transmission distance is simulated by adjusting the length of the optical fiber. The relationship between the physical length of the optical fiber and the simulated height (H) is:

[0040] Where: H is the simulated height; n is the refractive index of the optical fiber, which is 1.46; L1 is the calibrated electrical length of the first RF cable; L2 is the calibrated electrical length of the second RF cable.

[0041] During connection, the radio altimeter's transmitter connects to a fixed attenuator via a first RF cable. The receiver connects to a digitally controlled attenuator via a second RF cable. The fixed attenuator's output is connected to a photoelectric conversion module Tx, whose output is connected to a first optical path controller. The first optical path controller is connected to multiple optical fibers of preset lengths (e.g., 10m, 50m, 100m), the other ends of which are connected to a second optical path controller. The output of the second optical path controller is connected to a photoelectric conversion module Rx, which is then connected to the digitally controlled attenuator. The host computer preferably controls the switching logic between the first and second optical path controllers via an RS-485 bus. The digitally controlled attenuator communicates with the host computer via a USB interface, and the radio altimeter communicates with the host computer as well.

[0042] like Figure 3 As shown, the present invention provides a method for a radio altitude simulation device, which includes three stages: presetting the optical fiber length, calibration process and sensitivity test. The specific implementation method, parameter setting principle and effect of each step are described in detail below to ensure that the system can achieve comprehensive testing of the radio altimeter within a low-cost and high-precision framework.

[0043] The following steps are involved: Initialization settings: Enter the first RF cable calibration electrical length L1 and the second RF cable calibration electrical length L2 in the test software, select the fiber refractive index, set it to 1.46, and the simulation height H.

[0044] Fiber selection: Calculate the required fiber length (L) based on the formula and select the fiber closest to the required length to ensure that the signal transmission delay is consistent with the actual flight altitude.

[0045] In the embodiment, it is assumed that the first RF cable's nominal electrical length L1 and the second RF cable's nominal electrical length L2 are both 0.5 m, and the simulated height is 100 m. Therefore, the optical fiber length L is approximately 136.3 m, and a 136 m optical fiber is selected.

[0046] In the embodiment, the system can preset multiple optical fibers of different lengths according to actual needs. In order to avoid bending loss, the optical fibers need to be evenly wound on a disk, and each optical fiber is marked with a unique ID and corresponding simulated length. Calibration process: The test software controls the first optical path control component to switch to the target optical fiber, and starts the vector network analyzer to measure the loop length and attenuation value.

[0047] In the embodiment, the output end of the device is connected to the first port of a vector network analyzer, and the input end is connected to the second port, the actual length and attenuation value of the optical fiber loop are calibrated, and whether the simulated height is consistent with the optical fiber loop is calculated.

[0048] Initialize the parameters of the vector network analyzer, set the vector network analyzer to time domain reflectometry mode, measure the loop length and loop attenuation, and record the fiber length and simulated height in the software; verify the loop length, for example: Theoretical value of loop length: L 理论 =H×2=200 m; Actual value of loop length: L 实际 =136×1.46+0.5+0.5≈200.06 m; If the error between the two is too large, for example, the preset error is 0.1 m, it is necessary to check the optical fiber connection or recalibrate the first RF cable electrical length and the second RF cable electrical length.

[0049] Adjust the digitally controlled attenuator: In the embodiment, the loop attenuation is recorded. Assume that the loop attenuation is -32dB, while the target attenuation is -30dB. Therefore, the host controls the digitally controlled attenuator to achieve adjustment, manually adding 2dB compensation to match the adjusted loop attenuation with the target attenuation to compensate for the fiber loss.

[0050] After calibration, connect the transmitting end of the radio altimeter to the fixed attenuator through the first RF cable, connect the receiving end to the CNC attenuator through the second RF cable, and switch to the calibrated 136m optical fiber through the first optical path control component and the second optical path control component; adjust the parameters of the radio altimeter and perform the test. The test software will display the calibration height information of the current optical fiber, the height information sent by the module under test and other parameter information. In addition, the sensitivity test of the radio altimeter can be achieved by adjusting the loop attenuation.

[0051] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0052] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A radio altitude simulation device, characterized in that: It includes a fixed attenuator, a photoelectric conversion module Tx, a first optical path control component, a second optical path control component, a photoelectric conversion module Rx, a digitally controlled attenuator and a host; One end of the fixed attenuator is connected to the radio altimeter, one end of the photoelectric conversion module Tx is connected to the fixed attenuator, and the other end is connected to the first optical path control component, the first optical path control component is externally connected to at least one optical fiber, and the optical fiber is connected to the second optical path control component, one end of the photoelectric conversion module Rx is connected to the second optical path control component, and the other end is connected to the digitally controlled attenuator, wherein the digitally controlled attenuator is also connected to the radio altimeter; The host is connected to the radio altimeter, the first optical path control component, the second optical path control component and the digitally controlled attenuator respectively.

2. A radio altitude simulation device according to claim 1, characterized in that: The operating frequency of the fixed attenuator meets the frequency band range of the signal transmitted by the radio altimeter.

3. A radio altitude simulation device according to claim 1, characterized in that: The first optical path control component and the second optical path control component include optical switches or optical switch matrices.

4. A radio altitude simulation device according to claim 1, characterized in that: The optical fiber wavelength matches the photoelectric conversion module Rx and the photoelectric conversion module Tx.

5. The radio altitude simulation device according to claim 1, characterized in that: The host is equipped with testing software, and the host also includes a main control board.

6. A radio altitude simulation device according to claim 1, characterized in that: The radio altimeter is connected to the fixed attenuator via a first radio frequency cable, and the radio altimeter is connected to the digitally controlled attenuator via a second radio frequency cable.

7. A method according to any one of claims 1 to 6, characterized in that: The following steps are involved: Preset the required optical fiber length; Connect the optical fiber to the radio altitude simulator and calibrate it; Connect the radio altitude simulation device, optical fiber and radio altimeter to test the sensitivity and ranging accuracy of the radio altimeter.

8. A radio altitude simulation device according to claim 7, characterized in that: The preset optical fiber length is as follows: Where: H is the simulated height; n is the refractive index of the optical fiber, which is 1.46; L1 is the calibrated electrical length of the first RF cable; L2 is the calibrated electrical length of the second RF cable.

9. A radio altitude simulation device according to claim 7, characterized in that: The calibration process is: Connect the radio height simulator to the vector network analyzer and access a preset length of optical fiber; Initially set up the vector network analyzer to measure the loop length and the loop attenuation corresponding to the loop length; Adjust the digitally controlled attenuator to compensate for the loop attenuation.

10. A radio altitude simulation device according to claim 9, characterized in that: During the calibration process, it is necessary to verify whether the loop length meets the preset error.

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