一、引言

    国际航行的船驾驶人员要想获得最直接的航行警告的助航仪器必是NAVTEX,该仪器因国际标准中频频率518kHz，也被老一代航海人称518，这种采用英语播放船舶航行安全密切相关的英文海上安全信息（MSI）可以非常直观的获取航行区域内的相关的航行警告，作为驾驶人员会用和读懂NAVTEX内的海上安全信息并第一时间核实处理是否与本船航行安全有关是必学的技能。

二、概述

    2022年6月底，国际海事组织(IMO)在航行、通信和搜救分委员会(NCSR)第9次会议分委会最终确定了《NAVTEX手册》修正案(通函MSC.1/Circ.1403/Rev.1)，经MSC106核准后也于2023年1月1日生效。NAVTEX系统是为海上航行的船舶播发航行警告、气象警告、气象预报和其它紧急信息的广播系统。船舶可利用专用的NAVTEX接收机自动接收和打印上述信息。NAVTEX业务适用于各种吨位和类型的船舶。

三、NAVTEX 系统的中英文主要特性(The principal features of NAVTEX system)

    (1)The service uses a single frequency with transmissionsi from nominated stations within each NAVAREA being arranged on a timesharing basis to eliminate mutual interference.All necessary information is contained in each transmission.

    NAVTEX 系统中在各NAVAREA区域指定的NAVTEX业务发射台采用时分方式在同一个频率上发布海上安全信息，以避免相互干扰。每一次发射包含了所有必要的信息。

    (2)The power of each transmitter is regulated so as to avoid the possibility of interference between transmitters.

    每个NAVTEX发射台的发射功率应受到限制以避免相互间可能的干扰。

  (3)A dedicated NAVTEX receiver has the ability to select messages to be printed, according to

    专用的NAVTEX接收机具有可选择打印电文的功能：

    (a)a technical code(B1B2B3B4), which appears in the preamble of each message; and

    根据每份电文开头的技术编码（B1B2B3B4);

  (b)whether or not the particular message has already been printed.

     根据是否已接收打印过某份电文。

  Certain essential classes of safety information suchi as navigational and meteorological warnings and search and rescue information are non-rejectable to ensure that ships using NAV.TEX always receive the most vital information.

    某些种类的安全信息，如航行警告、气象警告和搜救信息等，是不可拒收的；这样可保证使用NAVTEX业务的船舶能始终接收最重要的安全信息。

  (4) NAVTEX coordinators exercise contro of messages transmitted by each station accord.ing to the information contained in each message and the geographical coverage required. Thus a user may choose to accept messages, as appropriate, either from the single transmitter which serves the sea area around his position or from a number of transmitters.

     根据信息的种类和影响的地理区域，NAVTEX系统协调国可负责管制每个发射台发送的NAVTEX电文。因此，船舶电台可选择其航区附近一个或多个NAVTEX发射台接收海上安全信息。

四、NAVTEX 系统的中英文技术编码(NAVTEX technical code)（B1B2B3B4)

  *B1—represents the transmitter identification character, which is a single unique letter which is allocated to each transmitter.It is used to identify the broadcasts which are to be accepted by the receiver and those which are to be rejected.

  *B1—发射台的识别符B是指配给每个NAVTEX发射台的一个独特字母。船舶电台可预置NAVTEX接收机，以确定接收还是拒收选定发射台的发射。

  *B2—represents the subject indicator tog character ,in which each subject group message is allocated a single indicator character.the character B2 is a subject indicator letter (A-Z) for each oh type of message, and in use:  *B2—每一种类都分配有电文种类标识符B2目前使用的NAVTEX种类标识符B2如下：

A=Navigational warnings A=航行警告

B= Meteorological warnings B=气象警告

C=Ice reports C=冰况报告

D=Search and rescue information D=搜救预报

E=Meteorological forecasts E=气象预报

F＝Pilot service messages F=引航业务电文

G=DECCA messages G=台卡电文

H=LORAN messages H=罗兰电文

I=OMEGA messages I=奥米伽电文

J=SATNAV messages J=卫星导航电文督

K=Other electronic navaid messages K=其它电子助航电文

L=Navigational warnings-additional letter A L=航行警告（对A的补充）

V to Y=Special services V to Y=特别业务

Z=No messages on hand Z=目前无电文发送

  *B3B4—represents a serial number of each message within a subject group,between 01 and 99. This number will not necessarily relate to series numbering in other radionavigational warning systems. On reaching 99, numbering should recommence at 01 but avoid the use of message numbers still in force.The number 00 must only be used for messages of singular  importance,such as an initial distress message.

  *B3B4—在每一个电文种类组中，电文都分配有序列号B3B4，B3B4从01排到99。NAVTEX 系统的电文编号与其它无线电航行警告系统的编号没有任何关系。若电文编号排到99号,应重新从01开始编号，但应避免使用仍然有效的电文的编号。B3B4=00的电文编号必须只用于极为重要的电文中，比如播发初始遇险信息。

五、NAVTEX电文的优先等级（Message priority of NAVTEX)

    These message priorities are used to dictate the timing of the first broadcast of a1 new warning in the NAVTEX service. In descending order of urgency they are:

    在NAVTEX业务中，用三种优先等级电文表明新的警告首播的时限，这些是：

  *VITAL—for immediate broadcast;    VITAL警告—发射台需立即播发的警告；

  *IMPORTANT—for broadcast at the next available period when the frequency (518 kHz) is unused;

    IMPORTANT警告—若在518kHz频率上还没有发射，应播发该警告；

  *ROUTINE—for broadcast at the next scheduled transmission.

    ROUTINE 警告—发射台应在下一发射时间播发该警告。

六、结束语

    港口国对NAVTEX的检查主要是检查值班驾驶员航行时是否保持NAVTEX接收机常开、信息接收是否正常、打印功能是否正常（若有）、若无打印功能，显示器安装在驾驶船舶位置或连接导航系统，能否让驾驶员在第一时间收到重要航行信息并确认处理；是否能清晰地打印出字母A~Z、数字1~9和特殊字符；是否根据航区、季节正确设置；驾驶人员是否会查找NP283或NP285中的NAVTEX章节/ 10)NAVTEX LIST OF COAST STATIONS。所以NAVTEX接收机在海上是船舶航行接收航行安全信息的重要助航仪器，驾驶人员要保证接收机工作状况良好。