# A Multimode Fusion-Based Aviation Communication System
## 3 Hardware Design
### Fusion Control Module  
The fusion control module is integral to the seamless interaction between external devices, such as optical lenses and flight control computers, within the multimode fusion communication system. This module is responsible for the sophisticated processing and distribution of critical data types, including image data, telemetry, and control signals. Additionally, it manages the comprehensive control and orchestration of various communication subsystems, which encompass the ad hoc network communication module, public network communication module, RTK differential high-precision positioning module, BeiDou satellite communication module, and ADS-B broadcast communication module.  
As depicted in Figure 13, the architecture of the integrated control module is designed for high efficiency and modularity. The system's core digital processing is managed by a field-programmable gate array (FPGA), which is responsible for executing tasks related to data manipulation and routing between various interfaces, such as RS232, RS422, SPI, and Ethernet. The FPGA also interfaces with external memory (DDR3) and flash storage to ensure rapid data processing and secure storage of critical information.  
A notable component of the system is the RTK high-precision positioning module, which is powered by a secondary power supply ensuring consistent operation at 12 V, with 3.3 V outputs managed by low-voltage TTL (LVTTL) interfaces. This module provides real-time, centimeter-level accuracy in positioning data, which is vital for flight safety and  
Figure 12: RNSS module composition diagram.  
Figure 13: Block diagram of an integrated communication module composition diagram.  
precise navigation. The integration of this module with the FPGA allows for real-time data processing and communication with other subsystems, such as the BeiDou satellite communication and ADS-B modules, thereby enhancing the reliability and precision of the entire system.  
The circuit layout also includes essential support systems, such as a power module and interfaces for JTAG and crystal oscillators, ensuring the system's stability and synchronization. The presence of multiple UART channels, Ethernet, USB 2.0, and LVTTL connections illustrates the system's versatility and ability to interface with a wide range of external devices, further enhancing its functionality in diverse aeronautical applications.  
The digital processing part of the integrated communication module is implemented by Xilinx's Z7 series FPGA chip XC7Z010. The power consumption of the fusion control module is about 5 W.  
The power module mainly converts the input 28 V primary power supply into 12 V to satisfy the power supply needs of other boards. The circuit diagram of the power module is shown in Figure 14. The power board adopts cooling conducting dissipation, with an input of 18-36 V DC for the power supply. After EMI filtering, two isolated DCDCs are generated into two paths of 12 V voltages. One channel has a rated power of 100 W and is in charge of supplying power to the other six modules, and the other channel has a rated power of 3.3 W, to provide power to the two cooling fans.