Multipath simulation test apparatus

Abstract

The utility model discloses a kind of multipath simulation test devices, comprising: standard open test field, the standard open test field includes the measured system on the turntable and multiple transmission systems in the measured system periphery, further comprising radio frequency signal source and the power divider connected with the radio frequency signal source, the power divider is connected with the transmission antenna of the transmission system by multi-path optical fiber transmission network;The utility model is mainly used for the multipath simulation test of the multi-scale multipath compression and direction reconstruction of standard open test field OATS.

Description

Technical Field

[0001] This utility model relates to the field of radio monitoring and direction finding technology, and in particular to a multipath simulation test device. Background Technology

[0002] Multipath propagation is a major source of interference in wireless communication and direction finding systems, especially in complex electromagnetic environments (such as cities, canyons, and seas). Signals reach the receiver after being reflected and diffracted through different paths, leading to a decrease in direction finding accuracy. Particularly in shortwave communication, UAV telemetry and control, and maritime radar, the system faces severe multipath interference from constant-mode signals and low direction finding accuracy. Traditional direction finding algorithms experience significant performance degradation in high multipath delay (1-6.67 μs) scenarios, and the root cause of inaccurate direction finding lies in the multipath propagation of the signal. Figure 1 As shown, multipath signals with path differences of 300m-2000m or more are very likely to be generated in high mountains, canyons, and ocean surfaces. In the field of radio monitoring and direction finding, the standard open test field with a diameter of 200m used still adopts the traditional method of simulating multipath signals with long cables. Due to the difficulties of large attenuation, large cable volume, and high cost of cables with a length of 300m-2000m or more, large-scale multipath signals cannot be simulated in the standard open test field for radio monitoring and direction finding to date.

[0003] To address the inaccuracy of multipath signal testing in the field, there is an urgent need to develop direction-finding methods and testing systems that are resistant to multipath interference. However, existing testing methods mostly rely on field tests at product installation sites or general channel simulators, which have the following problems: 1) High cost of field testing at product installation sites: frequent deployment in real-world scenarios is required, and the tests are limited by weather and terrain differences at different installation sites, resulting in poor repeatability. 2) Does not meet the requirements of existing radio monitoring direction-finding tests, which must be conducted in open test sites that meet relevant standards. 3) Traditional simulators lack flexibility: it is difficult to accurately control the multipath delay, amplitude, and phase characteristics, especially lacking the ability to specifically simulate constant-mode multipath (constant amplitude, variable delay).

[0004] In addition, the traditional layout for testing the direction finding accuracy of two multipath signals is as follows: Figure 2 As shown, according to Figure 3 The requirements are as follows: Arrange the turntable, the system under test, transmitting system 1, and transmitting system 2. The input signals of transmitting system 1 and transmitting system 2 are evenly distributed to the transmitting antennas of the two transmitting systems from the same signal source system via a power divider. The transmitting systems are connected as follows: Figure 2As shown. Existing traditional long-cable multipath simulation solutions have the following problems: 1) High cost of field testing at product installation sites: Frequent deployment of real-world scenarios is required, and test repeatability is poor due to weather and terrain differences at different installation sites. 2) Does not meet existing radio monitoring direction finding requirements, which necessitate open test sites that meet relevant standards. 3) Low-cost alternatives: Traditional multipath simulation requires multiple signal sources and cables. Delay control methods typically include using long cables, digital delay line ICs (non-analog delay), and surface acoustic wave (SAW) devices, but these methods are characterized by large size, narrow bandwidth, high loss, unstable phase, and high cost, making it difficult to simulate and test the required multipath signals in standard open test sites. 4) Insufficient flexibility of traditional simulators: It is difficult to accurately control the multipath delay, amplitude, and phase characteristics, especially lacking the ability to specifically simulate constant-mode multipath (constant amplitude, variable delay). Traditional open test sites, with a diameter of 200m, cannot simulate multipath distances. Utility Model Content

[0005] To address the problems existing in the prior art, the purpose of this utility model is to provide a multipath simulation testing device. This utility model is mainly used for multi-scale multipath compression and orientation reconstruction multipath simulation testing in the standard open test field OATS.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a multipath simulation test device, comprising: a standard open test field, wherein the standard open test field includes a system under test set on a turntable and multiple transmitting systems set around the system under test, characterized in that it further includes a radio frequency signal source and a power divider connected to the radio frequency signal source, wherein the power divider is connected to the transmitting antenna of the transmitting system through a multi-path optical fiber transmission network.

[0007] As a further improvement of this utility model, each of the optical fiber transmission networks includes an E / O electro-optic converter, a tunable optical fiber, an O / E opto-converter, and a gain controller, which are sequentially connected between the power divider and the transmitting antenna of the transmitting system.

[0008] As a further improvement of this utility model, the power divider and the transmitting antenna of the transmitting system are also equipped with a vector network analyzer.

[0009] As a further improvement of this utility model, the distance between the transmitting antenna of the transmitting system and the receiving antenna of the system under test is D, and the distance between the transmitting antenna of the transmitting system and the edge of the standard open test field is d, where D≥10λ, d≥5λ, and λ refers to the wavelength of the lowest test frequency of the system under test.

[0010] As a further improvement of this utility model, the polarization mode and the mounting height of the transmitting antenna of the transmitting system and the receiving antenna of the receiving system are the same.

[0011] As a further improvement of this utility model, the center point of the receiving antenna of the system under test coincides with the center point of the turntable.

[0012] To simplify testing and improve the testability of multipath propagation, this invention designs a multipath simulation test device for multi-scale multipath compression and orientation reconstruction in the standard open test range (OATS). It can simulate the multipath effects generated when radio waves propagate through mountains, canyons, urban high-rises, and ocean surfaces at altitudes ranging from hundreds to thousands of meters. Furthermore, it can perform orientation reconstruction at any angle within the limited OATS standard open test range with a fixed diameter of 200 meters. Ultimately, this enables precise multipath effect testing at any distance and angle within the limited OATS standard open test range, while ensuring test repeatability and compliance.

[0013] The beneficial effects of this utility model are:

[0014] This invention provides a system for multi-scale multipath compression and direction reconstruction multipath simulation testing, primarily used in standard open test ranges (OATS). This multipath simulation device is the first of its kind in the field of radio monitoring and direction finding. It meets the requirements of both military and national standards for open test range testing. Furthermore, due to the small size and low cost of the photoelectric conversion module and optical fiber, it reduces the cost of modifying standard open test sites by more than 90% (the cost of the photoelectric conversion kit in this solution is significantly lower than that of the cable solution). It can be widely used for performance testing of multipath signal monitoring and direction finding receiver systems in standard open test ranges (OATS), and can also be used for testing various combinations of multipath elevation angles. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a multipath generation system.

[0016] Figure 2 This is a schematic diagram of a traditional two-way multipath signal transmission system;

[0017] Figure 3 A schematic diagram of the general test site layout for a standard open test range;

[0018] Figure 4 This is a system block diagram of the multipath simulation test device in the embodiments of this utility model. Detailed Implementation

[0019] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0020] Example

[0021] This embodiment aims to design a multipath simulation test device for multi-scale multipath compression and orientation reconstruction, primarily used in standard open-field test ranges (OATS). Multipath effects occur when radio waves propagate through mountains, canyons, urban high-rises, and ocean surfaces at altitudes of hundreds to thousands of meters. Traditional multipath effect testing can only be performed on-site.

[0022] This embodiment designs a method to directly modulate radio signals into optical signals, delay them through optical fibers, and then convert the optical signals back into radio signals. These radio signals are then transmitted via cable and antenna at different angles. The time delay of the radio signals at different distances is simulated using optical fibers of varying lengths. The direction of arrival of the multipath signals at different angles is simulated by using a turntable in an existing standard open test area corresponding to the transmission point. The signal amplitude is adjusted by an adaptive amplifier that performs electro-optical and photoelectric conversions to ensure amplitude stability. This allows for the simulation of multipath effects at the required standard angles and with different time delays within a fixed-diameter 200-meter OATS standard open test area. Ultimately, this enables precise multipath effect testing at any distance and angle within a limited OATS standard open test area, ensuring test repeatability and compliance.

[0023] Standard open test range orientation finding test layout as follows Figure 3 As shown, according to Figure 3 Set up the turntable, the system under test (DUT), and the transmitting system, ensuring that the center point of the DUT's antenna coincides with the center point of the turntable. The distance between the transmitting system's antenna and the DUT's antenna should be D (D not less than 10λ, where λ refers to the wavelength of the lowest test frequency of the DUT), and the distance from the edge of the testing area should be d (d not less than 5λ). The polarization and mounting height of the transmitting system's antenna should be consistent with those of the DUT.

[0024] The system block diagram of the multi-path simulation test device designed in this embodiment, primarily for multi-scale multipath compression and orientation reconstruction in standard open-field OATS, is as follows: Figure 4 As shown, the core requirement of multipath simulation testing is the precise control of the amplitude, phase, and time delay of signals from multiple paths. This embodiment designs a distributed radio frequency optical signal ROF conversion via an optical fiber transmission network to precisely control the time delay, phase synchronization, and power distribution of multiple signals (simulating direct waves and reflected waves) in an open field. The solution of this embodiment is as follows... Figure 4 As shown, to address the requirements of large-scale deployment and long-distance phase stability assurance solutions in open areas, the following approaches are abandoned: Figure 2 This embodiment supports analog multipath transmission via long cables after RF signal power division, or analog multipath transmission using long cables with common-phase reference for multiple signal sources. Figure 3The standard open test field direction finding test layout simulates multipath signals using a single signal source power divider. It simplifies traditional long RF cable multipath simulation equipment by using ROF (Radio Frequency Optical) technology. It uses ROF direct RF modulation technology for fiber optic transmission. It sets fixed combinations of different fiber lengths according to the limits of multipath testing capabilities and develops a 1-n multipath distribution topology combination scheme for the fiber length requirements of commonly used multipath signals. Different multipath channels are calibrated for the entire independent link before testing using vector network analysis, so as not to add expensive delay fine-tuning equipment. A gain controller is set to ensure that the amplitude meets the variable test requirements. The system architecture adopts a distributed coverage transmission network to facilitate the synthesis of multipath test signals of different angles and directions in a standard open test field.

[0025] The embodiments described above merely illustrate specific implementations of this utility model, and while the descriptions are detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A multipath analog test apparatus comprising: A standard open test range, comprising a system under test (SUT) mounted on a turntable and multiple transmitting systems located around the SUT, characterized in that it further includes a radio frequency (RF) signal source and a power divider connected to the RF signal source. The power divider is connected to the transmitting antenna of the transmitting system via a multi-path fiber optic transmission network. Each path of the fiber optic transmission network includes an E / O electro-optic converter, a tunable fiber, an O / E opto-converter, and a gain controller sequentially connected between the power divider and the transmitting antenna of the transmitting system.

2. The multipath simulation testing device according to claim 1, characterized in that, The power divider and the transmitting antenna of the transmitting system are also equipped with a vector network analyzer.

3. The multipath simulation testing device according to claim 1, characterized in that, The distance between the transmitting antenna of the transmitting system and the receiving antenna of the system under test is D, and the distance between the transmitting antenna of the transmitting system and the edge of the standard open test field is d, where D≥10l, d≥5l, and l refers to the wavelength of the lowest test frequency of the system under test.

4. The multipath simulation testing device according to claim 3, characterized in that, The polarization and mounting height of the transmitting antenna and the receiving antenna of the transmitting system are the same.

5. The multipath simulation testing device according to claim 1, characterized in that, The center point of the receiving antenna of the system under test coincides with the center point of the turntable.

Images