Underwater acoustic communication, as the only long-range wireless communication method underwater, is the primary means for achieving comprehensive underwater information sensing and interaction. However, the time delay, Doppler spread, and time-varying characteristics of underwater acoustic channels pose significant challenges for high-rate and high-reliability communication. Therefore, the research and development of high-speed underwater acoustic communication systems hold significant scientific and practical value. The fundamental idea of Software Defined Radio (SDR) technology is to use standardized hardware as a general-purpose platform to implement as many communication functions as possible through upgradeable and extensible software. Applying SDR technology to guide the top-level design of underwater acoustic communication systems can simplify the underlying hardware modules. At the same time, this reserves development interfaces for future software function upgrades of communication algorithms.

This paper integrates Software Defined Radio (SDR) technology and embedded technology to design and partially implement a general-purpose hardware platform for underwater acoustic communication systems. The main work of this paper involves studying the various process stages of the transmitter and receiver in an underwater acoustic communication system, providing communication parameters, and verifying the theoretical performance of the communication system through simulation. Furthermore, considering the need for extensive communication signal processing computations and data transmission control in underwater acoustic communication systems, the OMAPL138 was chosen as the embedded development platform. The OMAPL138 processor is a dual-core, low-power processor featuring a C6748 series DSP core and an ARM9 core. Its powerful data computation and information processing capabilities are highly suitable for high-speed underwater acoustic communication systems. In addition, based on the OMAPL138 embedded platform, driver software for the underwater acoustic communication system hardware platform was developed, and the system's operating modes were analyzed. Finally, through separate tests of the A/D module and the underwater acoustic transducer, as well as full-system sine wave transmission and reception tests in an anechoic pool, the basic information transmission capability and good operational reliability of this underwater acoustic communication system hardware platform were verified.

1 Evaluation Board Introduction

Based on TI OMAP-L138 (fixed-point/floating-point DSP C674x + ARM9) + Xilinx Spartan-6 FPGA processor;
OMAP-L138 and FPGA are connected via uPP, EMIFA, and I2C buses, with communication speeds up to 228 MByte/s; OMAP-L138 has a main frequency of 456MHz, offering computing power up to 3648 MIPS and 2746 MFLOPS;
FPGA compatible with Xilinx Spartan-6 XC6SLX9/16/25/45, providing strong platform upgradeability;
The development board provides abundant peripheral interfaces, including high-speed data transmission interfaces such as Gigabit Ethernet, SATA, EMIFA, uPP, USB 2.0, as well as common interfaces like GPIO, I2C, RS232, PWM, and McBSP;
Certified through high and low-temperature tests, suitable for various harsh working environments;
DSP + ARM + FPGA triple-core SOM (System-on-Module), with dimensions of 66mm*38.6mm, using industrial-grade B2B connectors to ensure signal integrity; Ø
Supports bare-metal, SYS/BIOS operating system, and Linux operating system.

Figure 1 Front and side views of the development board

The XM138F-IDK-V3.0 is a development board designed based on Shenzhen Xinmai's XM138-SP6-SOM core board. It features a 4-layer board design with immersion gold and lead-free process, providing users with a test platform for the XM138-SP6-SOM core board to quickly evaluate its overall performance.

The XM138-SP6-SOM exposes all CPU resource signal pins, making secondary development extremely easy. Customers only need to focus on upper-layer applications, significantly reducing development difficulty and time costs, enabling rapid product launch and timely capture of market opportunities. It provides not only rich demo programs but also detailed development tutorials and comprehensive technical support to assist customers with baseboard design, debugging, and software development.

2 Typical Application Areas

Data Acquisition, Processing, and Display Systems
Smart Power Systems
Image Processing Equipment
High-Precision Instrumentation
Mid-to-High-End CNC Systems
Communication Equipment
Audio and Video Data Processing

Figure 2 Typical application areas

3 Software and Hardware Parameters Schematic diagram of the development board's peripheral resource block

Figure 3 Schematic diagram of development board interfaces

Figure 4 Schematic diagram of development board interfaces