AIS signal simulation testing device

Abstract

The utility model discloses an AIS signal simulation testing device, include: standard open test field, the standard open test field includes the measured system of being located on the rotating platform and a plurality of sending system located in the measured system periphery, still include a plurality of AIS signal source, every AIS signal source all is connected with the transmitting antenna of sending system through the optical fiber transmission network, the utility model discloses mainly for the AIS signal simulation test 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 an AIS signal simulation test device. Background Technology

[0002] Time-division duplexing (TDD) signals are widely used in AIS, 4G, and 5G. TDD systems are often used in communications to share the same frequency band for uplink and downlink, enabling bidirectional communication through time division. However, the dynamic time slot switching characteristics of TDD signals (such as rapid uplink / downlink switching and multi-user time-division access) pose serious challenges to the real-time performance, synchronization accuracy, and anti-interference capabilities of direction-finding systems.

[0003] Ocean surface AIS system schematic diagram as follows Figure 1 As shown, AIS receivers must be located at the seaside or riverbank to receive AIS messages transmitted from ships, resulting in high on-site testing costs: vessels must be leased for testing in waterways, with a single test costing over 100,000 yuan. Signal reliability is low: commercial AIS simulators lack independent verification mechanisms, leading to a message error rate >10⁻³. Azimuth efficiency is low: manually moving the transmitting antenna takes >30 minutes per attempt, failing to meet the needs of intensive multi-azimuth testing. Time slot dynamics are insufficiently adapted: while AIS time slot length is fixed (26.67ms), competition among multiple ships leads to high randomness in time slot switching, making it difficult for traditional direction-finding equipment to capture transient signals. Standardized testing methods are lacking: existing radio monitoring direction-finding tests must be conducted in open test sites that meet relevant standards, and the industry lacks a direction-finding performance evaluation system specifically for AIS-TDD characteristics. Utility Model Content

[0004] To address the problems existing in the prior art, the purpose of this utility model is to provide an AIS signal simulation test device, which is mainly used for AIS signal simulation testing in standard open test fields (OATS).

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: an AIS signal 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, and also includes multiple AIS signal sources, each of which is connected to the transmitting antenna of the transmitting system through an optical fiber transmission network.

[0006] 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 transmitting antenna of the AIS signal source and the transmitting system.

[0007] As a further improvement of this utility model, the AIS signal source and the transmitting antenna of the transmitting system are also equipped with a vector network analyzer.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] To simplify testing and improve the testability of multipath propagation, this invention designs an AIS signal simulation test device primarily for standard open test ranges (OATS). It can simulate the transmission effects of marine AIS signals over distances ranging from hundreds to thousands of meters, and can perform directional reconstruction at arbitrary angles within a limited OATS standard open test range with a fixed diameter of 200 meters. This ultimately enables precise testing of AIS composite effects at any distance and angle within a limited OATS standard open test range, while ensuring test repeatability and compliance.

[0012] The beneficial effects of this utility model are:

[0013] This invention provides an AIS signal simulation test device mainly used in standard open test ranges (OATS). This AIS simulation device and test method are the first of their 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. At the same time, due to the small size and low cost of the photoelectric conversion module and optical fiber, it reduces the cost of standard open test range modification by more than 95% (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 AIS signal monitoring and direction finding receiver systems in standard open test ranges (OATS), and can also be used for testing various combinations of AIS elevation angles. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of an AIS system for the ocean surface.

[0015] Figure 2 A schematic diagram of the general test site layout for a standard open test range;

[0016] Figure 3This is a system block diagram of the receiver test of the AIS simulation test device in the embodiments of this utility model. Detailed Implementation

[0017] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0018] Example

[0019] This embodiment designs an AIS signal simulation test device mainly used in standard open-field test ranges (OATS). The transmission effect of marine AIS signals over distances of several hundred to several thousand meters requires on-site testing, as is the traditional method for assessing AIS effects.

[0020] In this embodiment, the AIS signal source is selected by purchasing a low-cost commercially available beacon transmitter that transmits fixed-position and marine MMSI information, and an AIS simulator capable of simulating various AIS signals with variable information such as speed, heading, and latitude / longitude. These two AIS signal sources together form the test system, simulating the AIS transmission signals of multiple ships. Both types of AIS signal sources have the capability to simulate continuous AIS signal transmission and can be designed for stress testing of the equipment under test. By simulating marine AIS signals at different distances using fiber optic cables, the constructed test setup can perform AIS TDD signal testing in a standard test site.

[0021] The general test site layout of a standard open test range is as follows: Figure 2 As shown, according to Figure 2 Set up a turntable, the system under test (DUT), and transmitting systems 1, 2, 3, and n. The center point of the DUT antenna should coincide with the center point of the turntable. The distance between the transmitting system 1 antenna and the DUT antenna is 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 is d (d not less than 5λ). The polarization and mounting height of the transmitting system antenna should be consistent with those of the DUT.

[0022] To address the five problems encountered in testing commercial AIS receivers—namely, the requirement that they can only receive AIS messages from ships at seaside or riverbanks, and the limitations of commercial AIS simulations such as high cost, low signal reliability, low azimuth efficiency, insufficient time slot dynamics adaptation, and difficulty in simulating large-scale AIS scenarios using standardized settings—this embodiment designs the transmission system as follows: Figure 3 As shown.

[0023] Transmission system 1, transmission system 2, transmission system 3, and transmission system n, each of which can be used for the arrangement of AIS signal sources. The system design connection for each transmission system in this embodiment for AIS testing is as follows: Figure 3As shown, the transmitting system first converts the radio frequency signal from the AIS signal source into an optical signal through a radio frequency to optical conversion module. By adjusting the length of the optical fiber, the equivalent transmission distance from the ship emitting the AIS signal to the monitoring and direction finding receiving system can be simulated. After the optical signal is transmitted through the optical fiber, it is converted into a radio frequency signal again through the optical to radio frequency conversion module, and then the signal is transmitted to the system under test through the transmitting antenna of the standard open test site.

[0024] To address the difficulty in obtaining actual AIS signals, a combination of low-cost AIS beacon transmitters, low-cost AIS (A / B) class vessel automatic identification systems, and AIS signal simulators was used in a standard open test range for land-based radio monitoring and direction finding to simulate the effects of waterway testing. Independent calibration of the AIS beacon transmitters, AIS (A / B) class vessel automatic identification systems, and AIS signal simulators ensured that the signal-to-noise ratio of the AIS signal met relevant standard requirements, thus resolving the issue of low signal reliability in the field. The AIS signal simulator was configured with randomized vessel speed, heading, and latitude / longitude information to address the problem of low efficiency and difficulty in repeating on-site tests. Simultaneous and repeated signal transmission at fixed time slots (30s / 26.67ms, etc.) by the AIS beacon transmitters, low-cost AIS (A / B) class vessel automatic identification systems, and AIS signal simulators resolved the issue of high randomness in time slot switching caused by simulated multi-ship competition, making it difficult for traditional direction finding equipment to capture transient signals. The radio frequency signal is converted into an optical signal by a radio frequency to optical conversion module. By adjusting the length of the optical fiber, the equivalent transmission distance from the ship emitting the AIS signal to the monitoring and direction finding receiving system can be simulated. After the optical signal is transmitted through the optical fiber, it is converted into a radio frequency signal by the optical to radio frequency conversion module. Thus, the test of AIS signals emitted by ships at different distances within a radius of tens of kilometers can be simulated in a standard open test field with a diameter of 200m.

[0025] The simulation of AIS incoming wave direction at different angles is achieved by transmitting from the turntable corresponding to the transmission point in the existing standard open test field. The amplitude of the signal is adjusted by an adaptive amplifier that performs electro-optical and photoelectric conversion to ensure the stability of the signal amplitude. Thus, the standard angle and different time delays of AIS effects that need to be tested can be simulated in the OATS standard open test field with a fixed diameter of 200 meters. Ultimately, it is possible to conduct accurate AIS effect tests at any distance and angle in a limited OATS standard open test field, and to ensure the repeatability and compliance of the test.

[0026] 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. An AIS signal simulation test device, 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 comprises multiple AIS signal sources, each of which is connected to the transmitting antenna of the transmitting system via an optical fiber transmission network.

2. The AIS signal simulation test device according to claim 1, characterized in that, 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 transmitting antenna of the AIS signal source and the transmitting system.

3. The AIS signal simulation test device according to claim 1, characterized in that, The AIS signal source and the transmitting antenna of the transmitting system are also equipped with a vector network analyzer.

4. The AIS signal simulation test 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≥10λ, d≥5λ, and λ refers to the wavelength of the lowest test frequency of the system under test.

5. The AIS signal simulation test device according to claim 4, characterized in that, The polarization and mounting height of the transmitting antenna and the receiving antenna of the transmitting system are the same.

6. The AIS signal simulation test 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.

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