ZYNQ + ADC-based Multi-channel Ship Noise Acquisition System

With the advancement of electronic communications and automation technologies across various sectors, ships, while ensuring fundamental maritime safety and transportation security, are increasingly emphasizing the provision of a more comfortable and healthier navigation environment for crew and passengers. Against this backdrop, effective acquisition and control of ship noise have become an indispensable path to address these concerns. This paper proposes a multi-channel ship noise acquisition system based on the ZYNQ platform, tailored to the demands of ship automation and intelligence. The ZYNQ architecture, combining the collaborative capabilities of its soft and hard cores, high-speed data processing, compact size, and low power consumption, is highly suitable for such applications. This system can achieve real-time, high-speed, and accurate acquisition of ship noise, thereby providing reliable data support for subsequent noise processing and control, enhancing ship navigation safety, and improving passenger comfort. This system design not only improves the efficiency of noise management but also contributes to elevating the overall quality of ship operations, offering a superior navigation environment for those on board.

Ships house a wide variety of machinery and possess complex hull structures. During operation, power machinery vibrations directly radiate into the air, generating airborne noise. These vibrations also propagate along the ship's structure throughout the hull, subsequently radiating outwards as structural noise. Furthermore, the hull's vibrations radiate into the water, producing underwater noise [2~3].

Real-time, high-speed, and accurate acquisition of ship noise signals is the starting point and most fundamental step for ship vibration reduction, noise control, and fault diagnosis. To address the three distinct types of noise found in ships—airborne noise, underwater noise, and vibration noise—corresponding sensors can be selected for precise measurement. Specifically, microphones can be used to measure airborne noise, accelerometers are suitable for capturing noise generated by vibrations, and hydrophones are dedicated to detecting underwater noise. By utilizing these three specialized sensors, various types of ship noise can be effectively measured and analyzed in detail [4]. Subsequently, an acquisition system is designed to convert these electrical signals, after conditioning, acquisition, quantization, and encoding, into computer-recognizable digital signals [5].

ZYNQ series chips integrate two core components: the Processor System (PS) and the Programmable Logic (PL). The processor component is an ARM dual-core processor, and the programmable logic component utilizes Xilinx's 7-series FPGA architecture, enabling the construction of a full-featured System-on-Chip. This combination not only optimizes hardware processing capabilities but also enhances system flexibility and versatility, making the ZYNQ series an ideal choice for various complex digital computing requirements [10]. The ARM processor offers powerful software programmability, while the FPGA provides robust hardware programmability. ZYNQ cleverly and efficiently integrates these, and it also supports high-speed interfaces, allowing for efficient implementation in applications requiring high-speed data transfer. Compared to traditional separate ARM and FPGA configurations, ZYNQ adopts a "baseboard + core board" hardware design, achieving higher integration. This optimizes the acquisition system's volume while offering flexibility and expandability [11]. When designing an efficient data acquisition and processing system, especially during the multi-channel input signal acquisition and pre-processing stages, the FPGA's high-speed parallel processing capability is leveraged to execute real-time tasks. The ARM processor acts as the central control core, responsible for scheduling the entire system, including issuing acquisition commands, receiving data, and uploading data. Furthermore, the flexibility of the ARM processor allows the entire system to be configured according to specific requirements, making it easy to extend with new functionalities. This paper combines the advantages of ZYNQ with system requirements, proposing a design scheme that applies the ZYNQ platform to a multi-channel ship noise acquisition system, enabling multi-channel acquisition and transmission of ship noise.

2 Overall Design Scheme of the Multi-channel Ship Noise Acquisition System

As shown in Figure 1, the overall system structure primarily consists of four parts: noise detection sensors, a signal conditioning unit, a signal acquisition and transmission unit, and a host computer. In this configuration, the noise sensors are responsible for real-time monitoring of noise levels within the cabin and transmitting the acquired signals to the signal conditioning unit. The signal conditioning unit performs gain switching, low-pass filtering, and pre-amplification on the signal amplitudes provided by different sensors, preparing them for appropriate pre-processing before analog-to-digital converter (ADC) sampling. Subsequently, the ADC is responsible for converting continuous analog signals into discrete digital signals. The converted digital signals are received by the ZYNQ's PS (Processor System) side. After parsing instructions from the PC, these instructions are transmitted via the ZYNQ's internal AXI bus to the ZYNQ's PS, which then controls the ADC and receives the sampled data. Upon completion of these steps, the acquired data is sent to the PC via an Ethernet communication interface for further analysis and processing. This design not only ensures efficient and accurate data acquisition but also enhances the system's responsiveness to different noise types and its processing speed, allowing it to operate reliably in various application environments.

4 System Software Design

Upon system power-up, the ARM processor first performs self-initialization to ensure that all system modules are operating correctly. After initialization, the ARM processor enters a standby state, ready to receive acquisition control commands from the PC. Whenever the ARM processor receives a command from the PC, it first performs a detailed parsing of the command content. Based on the parsing result, it controls analog switches to adjust the gain for the specified channel, thereby meeting the processing requirements of different input signals. Next, the ARM generates corresponding sampling control commands and sends them to the FPGA. Subsequently, the ARM continues to wait for the next command from the PC. If no commands are received from the PC during this process, the ARM needs to check if the FPGA is transmitting data. If the ARM receives data from the FPGA, it forwards this data to the host computer via the Ethernet interface for further processing. This ensures that data can be promptly transmitted to the host computer for subsequent analysis and processing. If no data is received, the ARM will continue to wait for acquisition control commands from the PC.

On the FPGA side, upon receiving acquisition control commands from the ARM, it performs corresponding protocol parsing. These protocols include key parameters such as the specified acquisition channel and data output rate. Based on these parameters, the FPGA will perform necessary initialization configurations for the AD7768 as required, ensuring it operates normally according to predefined parameters and requirements to begin data acquisition tasks. Concurrently, it starts receiving data acquired from the AD7768, and this data is stored in SDRAM for subsequent processing and access. This ensures that data is properly preserved after reception, facilitating subsequent operations and usage. Once the accumulated data volume reaches a predetermined magnitude, the FPGA transmits the data back to the ARM via an interface, thus completing the entire data acquisition and control process. The configuration and data flow for this process are detailed in Figure 5.

5 Conclusion

The multi-channel noise acquisition system developed in this study is designed based on the ZYNQ platform, combining the high hardware programmability of an FPGA with a complete ARM processor system. A significant feature of this system is the fast and highly stable data transfer speed between the ARM processor and the FPGA. This efficient interaction mechanism not only simplifies the development process and reduces complexity but also significantly shortens the overall project development time, making the system easier to implement and optimize. Furthermore, the design supports convenient expansion of various peripherals. The collaborative operation of the Processor System (PS) and Programmable Logic (PL) within the ZYNQ platform ensures efficient instruction parsing and data transmission, thereby providing robust assurance for the rapid and reliable transfer of noise data to the PC. In practical applications, this system demonstrates broad potential, not only advancing noise detection technology but also opening up more possibilities for engineering applications in related fields. These advantages make this system particularly valuable in noise-intensive industries such as shipping, effectively helping engineers and researchers conduct more precise noise analysis and control.

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