1. Overview
Traditional weapon data link testing methods primarily focus on static performance parameter detection of the transmission system, making it difficult to accurately identify transient anomalies in the data link, let alone perform dynamic simulation testing under normal operating conditions. Ultimately, this fails to effectively guarantee the reliable and fault-free operation of the data link. Dynamic simulation testing of weapon data links, as a crucial component of distributed parallel testing developed using SDP (Structured Distributed Programming) technology in next-generation weapon systems, not only completes the testing of the data link itself but also provides supporting functions for simulation testing of other units within the weapon system. ADLINK's PCI-9846 high-resolution, high-speed data acquisition card, with its wide dynamic range, onboard 512MB memory, and lack of PCI bus speed limitations, significantly contributes to weapon data link testing in weapon data link testing systems. It meets the complex application requirements of parallel, dynamic, and simulation testing, becoming a technological highlight of the testing system and enhancing the overall testing technology level.
This testing system has advantages such as small size, high quantitative testing accuracy, high level of automation, and reliable operation. It meets the requirements of modularization, generalization, and serialization, and has significant characteristics in terms of military and economic benefits.
2. Data Link Simulation Testing Technology
The weapon data link testing system is centered on a computer and a weapon data link simulation module. It features advanced performance, compact structure, and strong operability. It has unique advantages in simulation application testing and protocol testing, and meets the requirements of dynamic testing and intelligent testing.
The performance indicators of the tested weapon's data link system cover aspects such as radio frequency performance, time synchronization, signal format, image processing, electromagnetic compatibility, and antenna tracking. The test system realizes functions such as data link system integration and debugging, technical site testing, production calibration, and fault detection, achieving the goal of integrated dynamic testing of the entire system.
In terms of testing technology, based on electromagnetic wave propagation theory, a testing method using a microanechoic chamber and near-field simulation of the actual open space environment is proposed. Microwave network system identification technology is used to determine the transfer function between near-field transmitting and receiving antennas, realizing real-time online quantitative measurement of radio frequency channels, reducing passive intermodulation, and solving high-power protection and electromagnetic compatibility issues. Protocol testing technology for weapon-specific data link testing systems is proposed, performing protocol statistical analysis and data processing. Through this protocol testing technology, the consistency, interoperability, and robustness of weapon data link protocols are tested.
3. Composition of the data link testing system
3.1 Hardware Components
The data link testing system mainly consists of an industrial control computer and a weapon data link simulation module, as shown in Figure 1.
The industrial control computer internally expands with multiple RS-422 serial interfaces and USB 2.0 interfaces. The external RS-422 interfaces are used to transmit bidirectional serial control data with the weapon testing system, receive command information, and transmit data link status information to the weapon testing system via the internal RS-422 interfaces. It can also control the weapon data link simulation equipment. The USB 2.0 interfaces are used to transfer or receive externally specified image and information files for image and information data restoration processing. The industrial control computer is also used for test control, receiving commands from the weapon testing system or generating commands locally to control the programmable attenuator via the I/O digital interface for testing the receiver sensitivity of the data link. A PCI-9846 high-speed data acquisition card is plugged into the industrial control computer to complete image data acquisition and image analysis processing, and to realize image storage and playback.
Figure 1. Composition of the data link test system
The weapon data link simulation equipment completes the transmission of command information and the reception of image and status information. Commands are generated by the weapon test system or the local industrial control computer, and the generated commands are processed, modulated, and transmitted through the module's command baseband. At the same time, the module's image receiver receives the signal, demodulates it, and performs baseband processing before inputting it to the PCI-9846 high-speed data acquisition card. The industrial control computer then analyzes and processes the received images.
The application test flowchart of the data link test system is shown in Figure 2.
Figure 2. Block diagram of data link test application
3.2 Test Software Architecture
The test software architecture mainly includes the following parts, as shown in Figure 3:
1. Application
It provides a user-friendly human-machine interface, enabling functions such as command sending, status information display, image data storage, playback, status and record display, and image monitoring. It can also receive control from weapon testing systems and perform functions under remote control conditions.
2. Database
It stores image data records and allows for querying.
3. Application Programming Interface Service Layer
Applications interpret API functions from the API service layer into user applications by calling them.
4. Software Service Layer
Dynamic link libraries and system configuration files constitute the main components of the software service layer. This layer manages and schedules drivers for hardware boards and performs the conversion between the interface service layer and the hardware interface, making the application independent of the board's hardware type.
5. Board Hardware Driver Layer
The board hardware driver layer implements the specific function calls.
Figure 3 Software architecture of the data link testing system
3.2 Test Software Design
The system utilizes the Delphi programming language and a Chinese-language graphical user interface to implement the required operational functions of the testing system. A local Access database is established, and database access is achieved through the ADO (Active Data Objects) object model. ADO's main advantages are its ease of use, speed, low memory consumption, and small disk footprint. When developing database applications using Delphi, database components (ADOQuery or Query) can be combined with SQL statements to implement functions such as data browsing and deletion.
1. Application API Interface
Based on the low-level drivers and data read/write routines of the various provided interface cards, write DLL files and further encapsulate them into API functions suitable for Delphi programming language calls. Implement image data storage and output playback, attenuation control, and image window control.
2. Database Operations
Delphi provides visual controls for data access and data control, enabling the easy and quick creation of powerful database applications with user-friendly interfaces. It also utilizes non-visual controls, such as TTable, TQuery, and TDatabase, to implement database data management functions.
3. Human-computer interface
Develop a user-friendly human-computer interface by making full use of the interface function controls, button controls, menu and data display controls provided by Delphi, so as to achieve the requirements of simple operation and powerful functions. Provide dynamic prompts on the interface to facilitate the operation of various functions, and use clear status indicator controls to indicate various states and processes.
4. Testing key technologies
4.1 Microaneous Chamber Near-Field Simulation Open Space Testing Technology
The test antenna anechoic chamber shield is placed on the weapon under test with the antenna already installed. It receives the high-power signal emitted by the weapon under test and also provides a certain degree of shielding for the emitted signal.
The test antenna anechoic chamber shield is designed with a square cross-section, with the top surface parallel to the ground. Considering structural dimensions and strength, it is made of aluminum to ensure shielding performance in the operating frequency band. To ensure that the test antenna anechoic chamber shield does not affect the normal operation of the weapon antenna, wedge-shaped absorbing material is added inside to mimic an anechoic chamber. Since the power to be absorbed is high, the space occupied by the absorbing material is small. To avoid excessive heat generation and potential danger, rubber material with wedge-shaped protrusions on the surface is selected for the absorbing material. The bottom of the test antenna anechoic chamber shield needs to be conformally designed with the boundary curve of the weapon body, and the bottom is covered with a thick layer of absorbing rubber material, which can both absorb electromagnetic waves and further realize the conformal design. The internal antenna design adopts a broadband circular monopole antenna, which can meet the requirements of size, weight, and bandwidth. The test antenna anechoic chamber shield is shown in Figure 4.
1. Test antenna interface; 2. Absorbing rubber; 3. Aluminum plate shielding; 4. Broadband monopole antenna; 5. Conformal absorbing rubber; 6. Antenna interface of the weapon under test.
Figure 4. Shielding cover for the test antenna in the anechoic chamber.
4.2 Simulation Scenarios and Computer Integration Testing Technology
The data link testing system simulates the actual application scenario of the weapon system's data link under ground environment conditions. Following its workflow, it uses computer technology to simulate the functions of the supporting equipment and tests the function and performance of the target module. The simulation scenario needs to be close to the actual use conditions to ensure that the test results are comprehensive, safe, reliable, and trustworthy.
The data link test system adopts computer control technology, expands multi-channel synchronous and asynchronous communication interfaces, image acquisition, programmable attenuator, simulates external equipment conditions and data information, and builds a simulation test platform. The test software also has intelligent and modular features, and modular combinations are made for the workflow of weapon systems under different states, which fully realizes the integrated testing of weapon systems under computer conditions.
The data link testing system adopts a centralized measurement and control approach with a modular structure, utilizing industrial control computer technology. The entire system has a compact structure and reliable operation, making it highly suitable for equipment testing and support under technical conditions. Simultaneously, the testing software employs a hierarchical and modular structure, significantly improving testing efficiency and facilitating software maintenance and expansion.
The data link testing system adopts a standardized design, with unified test interface standards, unified test standards, and test items. This is intended not only to standardize the testing system and enhance its versatility, but also to improve its scalability. In the future, the testing system will be compatible with different types of weapons and equipment, and will be serialized to further broaden its application scope, reduce redundant investment in the testing system, and ensure that the development of the testing system keeps pace with the development of weapons and equipment.
4.3 Data Link Protocol Testing Techniques
This testing system employs protocol testing technology to test the functionality of weapon data links. The data link testing system is a crucial component of the overall weapon system functional testing. Protocol testing is a vital step in utilizing data link functionality for comprehensive weapon functional testing. Its purpose is to ensure that the protocol is implemented and operates stably and reliably according to its description, which is of great significance for ensuring the quality of the data link. The protocol testing technology primarily includes conformance testing, performance testing, and robustness testing. For example, protocol conformance testing was mainly used for data link self-checks and command control functions; protocol performance testing was mainly used for transmission delay performance testing of command control and status information; and protocol robustness testing was used for receiver sensitivity performance testing.
In the series of control process tests of weapon data links, black-box testing of software is carried out in a specific test environment using pre-compiled test cases. By comparing the actual output of the tested weapon equipment with the expected output, it is determined whether the function or process implementation of the tested equipment is consistent with the protocol description, thereby achieving protocol consistency testing.
4.4 Object-Oriented Testing Techniques and Test-Driven Development
Given the scale and complexity of the data link testing system, traditional development methods—developing the test software based on the existing system under test—are no longer adequate. Therefore, the data link testing system adopts Test-Driven Development (TDD). The data link testing system starts synchronously with the data link device. During the implementation of each function of the data link device, considerations are given to how to test that function, and test code is written. This allows for continuous improvement of the device's code based on test results, reusing development workload while ensuring software quality. Related test case code is continuously optimized, and other functions are added iteratively until all functions are developed. Code efficiency is a key objective of TDD. This approach has proven highly effective in practice, making data link test development an integral part of the project design and seamlessly integrating development and testing into a unified whole.
Data link testing system development (TBD) is a fine-grained goal management method in project development management. It drives software development by setting clear objectives. The TDD approach ensures that the data link testing system is developed from the bottom up, implementing a series of solutions sequentially, ultimately evolving into the overall design.
4.5 Image ROI Processing Technology Based on PCI-9846
ADLINK PCI-9846 is a 4-channel 16-bit 40MS/s sampling digitizer designed for high-frequency and high dynamic range signals with input frequencies up to 20MHz. The analog input range can be programmed to ±1V/±0.2V or ±5V/±0.4V. It features up to 512MB of onboard memory, freeing it from the constraints of the PCI bus and enabling longer data storage times. The PCI-9846 is equipped with four high-linearity 16-bit A/D converters.
Compared to other sampling digitizers, the PCI-9846 has the following key features:
Standard height, half-length PCI specification;
Supports 5V and 3.3V PCI signals;
Supports 32-bit/66MHz PCI interface;
16-bit high-resolution A/D converter;
Maximum sampling rate of 40MS/s per channel;
Onboard 512MB shared quad-channel memory for data storage;
Programmable input voltage range ±0.2V/±1V or ±1V/±5V;
Analog input bandwidth can reach 20MHz;
Supports scatter-gather DMA transfer.
4.5.1 Image Storage Based on PCI-9846
The process of an image storage system based on PCI-9846 can be composed of the following parts:
The analog image signal is converted into a digital signal via PCI-9846 and then enters the receiving device (such as a computer).
The digital signal is divided and segmented into Regions of Interest (ROIs) in the receiving device.
Perform noise reduction, resolution increase, and anti-aliasing operations on the ROI signal to increase clarity;
Compress non-ROI signals to reduce storage capacity;
The signals are integrated and compressed.
Create a database and store the final data.
4.5.2 Region of Interest Image Coding Techniques
Region of Interest (ROI) image coding technology has become a key research focus in the field of digital image compression coding in recent years. It can better guarantee the quality of the reconstructed ROI under high compression ratios, and is an important means to effectively resolve the contradiction between image quality and compression ratio. The basic principle of ROI coding algorithms is: perform wavelet transform on the input image, generate an ROI mask based on the ROI, move the wavelet coefficients within the ROI mask to a higher bit plane, and achieve priority encoding and transmission in subsequent embedded coding, so that the decoded and reconstructed ROI has better quality than the background region. However, this type of algorithm requires increasing the number of bit planes, and the moved bit planes must also be inversely shifted during decoding, increasing complexity. Another type of ROI coding method is based on the code block distortion calculation in the Embedded Block Coding with Optimized Truncation (EBCOT) algorithm. A representative example is the implicit ROI algorithm proposed by Taubman, which increases the weight of the ROI code block distortion metric, so that the encoded bitstream contains more ROI information, thereby improving... This method achieves high-quality reconstructed image ROIs. Its advantages include not changing the number of bit planes, not requiring additional ROI shape information, and low complexity due to the lack of extra decoding operations. However, since encoding is done in blocks, some ROI blocks may contain a large number of wavelet coefficients from the background region, with only a few ROI information. Therefore, this algorithm affects encoding efficiency to some extent; at low bit rates (not greater than 0.5 bits/pixel), the improvement in ROI quality relative to the background region is not significant. A corresponding processing method has emerged that reduces the weight of wavelet coefficients from the background region in the ROI block to minimize their impact on encoding, thus significantly improving the ROI quality of the reconstructed image. However, this method is a lossy operation, affecting the quality of the background region at higher bit rates. Adjusting the weights by the proportion of wavelet coefficients from the region of interest in the ROI block achieves better results.
5. Conclusion
Currently, foreign military data link automated test systems (ATS) are moving towards generalization, standardization, networking, and intelligence. This data link test system is also progressing towards building a generalized automated test system. By sharing test hardware and software resources and adopting open technical and testing standards, it aims to reduce the development and upgrade costs of test system hardware and software, standardize the hardware and software development process, improve the interchangeability and versatility of various functional modules in the test equipment, achieve the portability and reusability of the test case set (TPS), and ultimately achieve the reconfigurability of the entire test system. A high-performance test system can achieve continuous upgrades by optimizing and enriching test cases; furthermore, in building a networked test system, a dedicated IP bearer network can be used to achieve remote control and remote fault diagnosis of the testing process.
