RF Monitoring Service Profile Based on AIS Binary Message

Transcription

1 , pp RF Monitoring Service Profile Based on AIS Binary Message Soyoung Hwang Catholic University of Pusan, Busan, South Korea Abstract. AIS messages where the data content is defined by the application are application specific messages. They are the binary messages 6 and 8. The data content does not affect the operation of the AIS. This paper proposes RF monitoring service profile that can monitor the sensitivity of the AIS signal by using AIS binary message. Keywords: AIS (Automatic Identification System), binary message, service profile 1 Introduction The AIS (Automatic Identification System) is an automatic tracking system used on ships and by VTS (Vessel Traffic Services) for identifying and locating vessels by electronically exchanging data with other nearby ships and VTS stations [1]. Application fields of AIS are collision avoidance, vessel traffic services, aids to navigation, search and rescue, accident investigation and binary messages. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport. There are 27 different types of top level messages defined in ITU that can be sent by AIS transceivers [2]. AIS messages where the data content is defined by the application are application specific messages. They are the binary messages 6 and 8 [3,4]. The data content does not affect the operation of the AIS. This paper proposes RF monitoring service profile that can monitor the sensitivity of the AIS signal by using the AIS binary messages. This paper proposes RF monitoring service profile that can monitor the sensitivity of the AIS signal by using AIS binary message. The remainder of this paper is organized as follows. In section 2, AIS messages are discussed. Section 3 proposes RF monitoring service profile using AIS binary messages. Finally, this paper is concluded in section 4. ISSN: ASTL Copyright 2015 SERSC

2 2 AIS Messages The AIS protocol stack is composed of 1~4 layers according to the OSI reference model physical layer, data-link layer, network layer and transport layer. The data frame structure of AIS data-link layer is shown in fig. 1. Fig. 1. AIS Data-link layer frame format The AIS Information is included in the data field of the frame and it is transmitted in a given time slot. Therefore, AIS transceivers exchange information with prespecified data format. There are 27 different types of top level messages defined in ITU that can be sent by AIS transceivers. The functionalities and informational content of AIS have been augmented by defining new ASM. It is also referred to as binary address and broadcast messages and multiple content structures can be defined[5,6]. 3 RF Monitoring Service Profile A variety of electronic equipment and systems are built for the safe navigation of ships. The AIS provides vessel s navigational data such as position, heading, speed and etc. in real time. Recently, maritime service has been developed to provide a variety of services between center for collecting and utilizing AIS messages and vessels which provides AIS messages. This paper proposes RF monitoring service profile using AIS binary message. The vessel which has AIS RF monitoring device measures and monitors the sensitivity of the AIS signal transmitted from other nearby ships, AtoN devices and base stations. It can facilitate maintenance of the AIS devices and can determine the AIS signal strength. The RF monitoring service consists of a vessel which has monitoring device, other ships and AtoN devices, and base stations. Figure 2 shows the service configuration. The RF monitoring equipment of the measuring vessel measures the RF signal strength of the received AIS messages and reports it to the user through the predefined data format. 56 Copyright 2015 SERSC

3 Fig. 2. RF Monitoring service The proposed RF monitoring service is defined by a mandatory service and an optional service. The mandatory service reports the RF signal strength of the messages for the position report from the received AIS messages. The mandatory service scenario is presented in figure 3. Fig. 3. Mandatory service scenario The optional service specifies target vessel, AtoN devices or base station to be monitored, transmits the measurement request messages to the target. It receives the response messages form the target and measures RF signal strength. The request and response messages are defined by AIS binary messages. Figure 4 shows the optional service. Copyright 2015 SERSC 57

4 Fig. 4. Optional service scenario 4 Conclusions As well as the AIS is a powerful tool for collision avoidance and safety of ships in water transport it can be used as a data communication networks between the ships and land. The interest in the use of binary messages that can define the data content by the application has been increasing. This paper proposed RF monitoring service profile that can monitor the sensitivity of the AIS signal by using AIS binary message. References 1. Wikipedia, 2. Technical Characteristics for an Automatic Identification System using time-division multiple access in the VHF maritime mobile band, Recommendation ITU-R M (2010) 3. Guidance on the application of AIS binary message, IMO, SN/Circ.236 (2004) 4. Guidance on the use of AIS Application Specific Messages, IMO SN.1-Circ.289 (2010) 58 Copyright 2015 SERSC

5 5. Porthin, M. Berglund, R. Seitsonen, L.: AIS+ - facilitating on board use of AIS Application- Specific Messages, International Conference on e-navigation, pp (2011) 6. Burns, W., Johnson, G., Gonin, I. Alexander, L.: Testing of AIS Application-Specific Messages to Improve U.S. Coast Guard VTS Operations, International Conference on e- Navigation, pp (2011) Copyright 2015 SERSC 59