AIS Data Collection, Storage and Display System

In an automatic identification system (AIS) receiver, after frequency down conversion and carrier separation, the frequency of AIS signals becomes 9.6 KHz. The design of AIS data collection, storage and display system based on ARM9 is presented for the data storage and playback of waveform in the paper. First, analog AIS signals are converted into digital signals by the analog-digital (AD) module of mini2440. Then, the digital signals are saved into the NandFlash. Next, the data can be displayed on the liquid crystal display (LCD). Furthermore, data from the NandFlash could send to the computer for handling later. Introduction The automatic identification system (AIS) is the communication system, which is widely used in the in the maritime domain. In the rapid development of electronic measurement and digital technology, the data collection technology is an important means of obtaining data information. Data collection is an interface which collects data from the outside of the system. It collects non-electric quantity or power signals from the sensors and other equipment automatically for handling later, such as analog and digital measured unit[1]. The data storage technology records the data stream in the processing with a specified format in the internal or external storage medium of the computer. Data playback technology reproduces the data by reading the data in a storage medium[2]. The experiments based on AIS in the sea are not convenient. The AIS data collection, storage and display system is developed, whose function includes the data collection, the data storage, the data playback, the serial port communication and the spectrum analysis. It is comprised of the AD, the NandFlash, the serial port and the LCD based on ARM2440. With the advantage of the small size and convenient operation, it is portable used for the collection and processing of AIS analog modulation signal, which frequency is 9.6 KHz. Thus, it has great application value. System Structure This paper designed the AIS data collection storage system based on ARM2440 of Samsung. The function includes AIS data collection, storage and playback. Meanwhile, the stored data can be sent to the computer via a serial port for the spectrum analysis or AIS message analysis. ARM is the main controller, which controls the entire system and assigns the clock of crystal oscillator of the AD, the NandFlash, the serial port and the LCD. The transformed data are saved in the NandFlash. Then the AIS data can be read from the NandFlash by the LCD module for the display. Furthermore, the data can also be sent to the computer via the serial port. These data can be used for spectrum analysis or AIS message analysis. The structure of the system is illustrated in Fig. 1. Joint International Mechanical, Electronic and Information Technology Conference (JIMET 2015) © 2015. The authors Published by Atlantis Press 349 Fig. 1 System Composition Structure System Function Realization The whole system is comprised of the data collection module, the control module, the data storage module, the data transmission module and the data display module. The software design consists of five modules to complete the data collection, storage and display. The AIS data is collected by the data collection module by AD. The control module and the data storage module are used for data storage by the NandFlash. The data transmission module and the data display module are used for the data dynamic display by the LCD and handling later, such as the spectrum analysis, AIS message analysis. The implementation and the design of these modules are explained as following. Design of Control Module. For the realization of the AIS data collection and storage and display, the ARM needs to coordinate all these five modules. The software design of the control module based on the ARM is shown in Fig. 2. First, the collected data is converted by AD. And high and low 8 bits are written into NandFlash in the proper order. And then determine whether the capacity reaches the value that has been set. If it does, the LED will light and it will stop writing data. If it does not, it will continue to write data. Finally, the AIS data is displayed on the LCD after the storage. Meanwhile, the data can also be transmitted to the computer by the serial port. Fig. 2 Software Design of Control Module Data Collection Module. The collected AIS data of 9.6 KHz is the AIS signal after frequency down conversion and carrier separation. The AD of S3C2440 has a maximum conversion frequency of 500 KHz, which meets the requirement of AIS data collection. The AD of S3C2440 can collect 4 channels of external input signals to process. The main features include the resolution of 10, the analog input range of 0 to 3.3 V; maximum switching frequency of 500 KSPS. The data collection module is mainly complete the AIS data collection by the AD. First, for setting the sampling frequency, the PRSCVL of AD control register (ADCCON) is changed to divide the frequency of PCLK. Then, automatically convert read mode is set and the data transformmtion begins. Next, the query model is used to determine whether the transformation is finished[3]. Finally, after the AD transform, digital signals with 10 bits are output. Data Storage Module. The NandFlash is mainly used for large capacity storage, with high cost performance, large capacity and small volume. The NandFlash of K9F1G08 is used in this system. The largest number of write is one million. The bit wide is 8 and the capacity is 256M. The size of page is (2 K + 64) bytes [4]. The data storage module is designed to read data from the collection module as the storage buffer. Because the NandFlash width is 8 bits and AD digital output is 10 bits, the 10 bits digital data is