海上无线电（GMDSS）通信业务CHAPTER

《海上无线电（GMDSS）通信业务CHAPTER》由会员分享，可在线阅读，更多相关《海上无线电（GMDSS）通信业务CHAPTER（46页珍藏版）》请在装配图网上搜索。

1、 CHAPTER 4 NARROW BAND DIRECT PRINTING (NBDP)INTRODUCTIONlNBDP relates to the terrestrial radio telex services in the MF and HF marine radio bands.Telex is also available using satellite communications which is covered by INMARSAT system.lMarine terrestrial radio telex is also referred to as Narrow

2、Band Direct Printing(NBDP)or sometimes Radio Teletype(RTT).lThe procedures specified in this section should be employed for routine communication except in cases of distress,urgency or safety.lFor communication between two stations,the ARQ(Automatic Repetition Request)mode should be used when availa

3、ble.(point to point)lFor transmissions from one coast or ship station to two or more other stations,the FEC(Forward Error Correcting)mode should be used when available.(point to surface)Modes of telex operationlRadio circuits are liable to interference,fading or bursts of static which can mutilate s

4、ections of a telex message.An effective means of error detection and correction is therefore needed.lThere are two main modes of operation namely ARQ and FEC.ARQ(Automated Repetition request)lARQ means Automatic Repetition Request and provides error detection and error correction.lHowever,it require

5、s both communicating stations to have their respective transmitters and receivers active simultaneously.lThis mode is normally restricted in use between two stations e.g.a ship and a coast station or perhaps two ships.ABARQ(Automatic Repetition Request)modeARQ(Automatic Repetition Request)modeABmess

6、ageShip A transmitter Ship B transmitter Ship A receiver Ship B receiver Error detection codeIf no error,ship A will send next message,otherwise the existing message will re-sent.ARQ(Automated Repetition request)ARQ(Automated Repetition request)FECFEC (Forward Error Correction)(Forward Error Correct

7、ion)lFEC means Forward Error Correction and provides error detection only.If any doubtful letters occur in the text,a gap(or sometimes an asterisk)will appear.With FEC the receiving station(s)do not need an active transmitter.lThis mode of operation is therefore ideal for broadcasting information to

8、 numerous stations simultaneously and it is used for sending traffic lists,weather and navigational warnings etc.It is therefore sometimes referred to as the broadcast mode and is the preferred telex mode for distress,urgency and safety messages.FEC FEC(Forward Error Correcting)mode(Forward Error Co

9、rrecting)mode ABmessageShip A transmitter Ship B receiver Ship A sends each message twice only.If two message received by Ship B is identical,ship B will print it.same message sent at second timeFECFEC (Forward Error Correction)(Forward Error Correction)CFEC:collective FECCFEC:collective FECSELFEC (

10、selective FEC,SFEC)SELFEC (selective FEC,SFEC)A derivation of FEC is called A derivation of FEC is called SELFECSELFEC.Again the.Again the recipients transmitter does not have to be active and it recipients transmitter does not have to be active and it is similar to FEC in all respects is similar to

11、 FEC in all respects except that the except that the transmission is addressed to a particular receiving transmission is addressed to a particular receiving stationstation(i.e.by addressing the call to the appropriate (i.e.by addressing the call to the appropriate MMSI).MMSI).It is an ideal mode of

12、transmission for It is an ideal mode of transmission for ships to receive telex messages whilst in ships to receive telex messages whilst in a port where the use of transmitters may a port where the use of transmitters may be restricted or forbidden.be restricted or forbidden.Band between 415 kHz an

13、d 535 kHzlAll ships equipped with telex equipment in this band shall be able to:l(a)send and receive class F1B or J2B emissions on the working frequencies necessary to carry out their service;l receive class F1B emissions on 5l8 kHz if complying with GMDSS.l490 kHzl490 kHz will be used exclusively f

14、or the transmission by coast stations of meteorological and navigational warnings and urgent information to ships by means of telex in local language.Telex FrequenciesTelex Frequenciesl518kHz lIn the MF maritime mobile service 518 kHz is used exclusively for the transmission by coast stations of met

15、eorological and navigational warnings and urgent information to ships by telex(international NAVTEX system).l2174.5 kHzlExclusively reserved for distress and safety traffic using telex in MF band.It should be used for shiptoship onscene communications in FEC mode.lBands between 1605 kHz and 4000 kHz

16、 and 4000 kHz and 27500 kHzlAll ships equipped with telex to work in these bands shall be able to send and receive class F1B or J2B emissions on working frequencies necessary to carry out their service.l4209.5 kHzlIn the HF maritime mobile service 4209.5 kHz is used exclusively for the transmission

17、by coast stations of meteorological and navigational warnings and urgent information to ships by NAVTEX type transmission.l4177.5 kHz;6268 kHz;8376.5 kHz;12520 kHz;16695 kHzlIn the HF maritime mobile bands these frequencies are reserved exclusively for distress and safety using telex.l4210 kHz;6314

18、kHz;8416.5 kHz,12579 kHz;16806.5 kHz;22376kHz;26100.5kHz lIn the HF maritime mobile bands these frequencies are reserved exclusively for the transmission by coast stations of maritime safety information by telex in FEC mode.Identities of NBDP 1)1)Selcall numbersSelcall numbersEach ship station and c

19、oast radio station having radio telex Each ship station and coast radio station having radio telex facilities is assigned a unique facilities is assigned a unique selcallselcall number in addition to number in addition to its international call sign.its international call sign.The first number(s)of

20、the The first number(s)of the selcallselcall indicates the country to indicates the country to which a particular station belongs.which a particular station belongs.Ship Ship selcallselcall numbers have five digits numbers have five digits,e.g.47579.,e.g.47579.Coast station Coast station selcallselc

21、all numbers have four digits numbers have four digits,e.g.3220.,e.g.3220.lChina allocation of selcall numbers is as follows:Ship stations:19700 to 20399Coast stations:2010 to 2039lShips selcall numbers will be found in ITU List of Ship Stations and coast station selcall numbers will be found in Volu

22、me 1 and ITU List of Coast Stations.l2)MMSITelex answerbacksTelex answerbacksTo ensure that an operator To ensure that an operator has been connected to the has been connected to the correct coast radio station,correct coast radio station,ship station,or telex ship station,or telex subscriber ashore

23、,it is subscriber ashore,it is normal to exchange normal to exchange answerbacksanswerbacks at the at the commencement of a telex commencement of a telex link.link.Each telex installation has Each telex installation has a unique answerback to a unique answerback to identify itself and this is identi

24、fy itself and this is programmed into the programmed into the equipment.equipment.ABCall Ship B with its MMSI Answer owns answerbacklWhen,for example,the automatic radio telex facility controlled by Coastal radio station is accessed,the following answerback will be received:“004122100 XSG CN.lWhere:

25、004122100 is Shanghai radios MMSI;XSG indicates the identification of Shanghai radio;and CNindicates the country in this case China.lA ships answerback might be “41217910 BRYC X.Where:41217910 indicates the ships selcall number(MV.LIUHE);BRYC is the ships international call sign;l X indicates that i

26、t is a maritime mobile station.lTelex subscribers ashore have answerbacks which include their telex number followed by a short word or group of letters indicating the name of the company or Organisation and finally the country identifier,e.g.33103 SMTCO CN.l33057 COSCO CNNBDP电传电文格式电传电文格式 若船舶电台配备有NBD

27、P设备，船舶电台可利用国际海上无线电传业务与岸上的电传用户进行电传通信，其电文应满足下列格式：l TO：收报人电传号码与识别(或用户应答码)l ATTN：具体收报人或部门l COPY：分抄部门(如果没有，可略)l FM：发报人名址(对船台：船名呼号MMSI)l DD：报文交发时间、日期(用UTC)l 电传优先等级，日常可略l REF：参照号(如果是针对某个电文的回电，需要时可提供参照号)l 空一行l 电传电文l 空一行l NNNN(电文结束标志)An example of message：TO：(85)33057 COCOS CN ATTN：TECHNICAL DEPT COPY：CREW D

28、EPT FM：MV SHENGHEBOLU412001000 DD：0830UTC 5TH AUG 1999 REF：TLX No220799 ETA PILOTSTN 0330LT8TH PLSADV WHHSHIPYARD FORREPAIR PLSARRNG RADAR(DECCA3610A)SERVICE ONARRVL CE RETIRESHAI PLSARRNG AIRTICKET TOHKG BRGDSMASTER NNNN三、特殊符号的传递和错误字符的处理三、特殊符号的传递和错误字符的处理 因为陆上电传网络上传递的是国际电传2号码1TA N02，在该网上只能传递下列字符：英文字

29、母A-Z，阿拉伯数字0-9，符号+一?：()，=和空格，以及回车、换行、字母转换、数字转换等功能字符。如果其他字符也被编进电文里，对方收到为空格。因此在编电文时必须对一些特别字符进行处理后才能传递。1分数的传递 当一组数字包含有整数和分数时，整数与分数之间应用划线分开，但不能留有空格。如：3 应发送3-1/2。2百分号的传递 10应发送为10-0/0或10 percent。3非标准符号的传递非标准符号的传递 如：如：“应发送应发送”AND，“”应发送应发送“AT”，“$”应发送应发送“DOLLARS，“#”应应发送发送“NR”，“口口”应发送应发送”SQUARE“等。等。4重要字组的重复重要字

30、组的重复 对电文中出现的重要数字或字组，可以重复对电文中出现的重要数字或字组，可以重复一次以示重要。比如：一次以示重要。比如：2500(2500)，或，或2500 REPEAT 2500CANCEL REPEAT CANCEL等。等。5通信过程中错误的处理通信过程中错误的处理 如果在紧急的情况下，以在线的方式发送电如果在紧急的情况下，以在线的方式发送电文，这时如果发生差错，应紧接着发送文，这时如果发生差错，应紧接着发送“XXXXX和一个空格，或三组和一个空格，或三组”EEE“和一个空格，和一个空格，如：如：ETA NAB TOGXXXXX TOWER。6取消电传电文取消电传电文 在发送电传电文

31、的过程中，因故必须取消该电在发送电传电文的过程中，因故必须取消该电文，船舶电台的操作员应在发送电文的屏幕上文，船舶电台的操作员应在发送电文的屏幕上另起一行，并发送另起一行，并发送ANUL ANUL ANUL的字的字样，表明取消该电文。样，表明取消该电文。Telex transmission proceduresTelex transmission procedures(ARQ mode)(ARQ mode)Where the appropriate facilities are provided by the Where the appropriate facilities are provi

32、ded by the coast station,traffic may be exchanged with the telex coast station,traffic may be exchanged with the telex network either:network either:(a)(a)in conversational modein conversational mode where the stations a where the stations a connected directly,either automatically or manually;orconn

33、ected directly,either automatically or manually;or(b)(b)in a store and forward modein a store and forward mode where traffic is stored where traffic is stored at the coast station until the circuit to the called at the coast station until the circuit to the called subscriber can be set up,either aut

34、omatically or under subscriber can be set up,either automatically or under manual control.manual control.Coastal radio stationInternational telex networkSubscriberShip station Procedures for ARQ operation lShip to shore ARQ callinglThe ship station calls the coast station on a predetermined frequenc

35、y using telex equipment and the MMSI of the coast station.The coast station telex equipment detects the call and responds on the appropriate paired frequency either automatically or manually.Preparatory work before transmittingPreparatory work before transmitting1)edit the message1)edit the message2

36、)tune the 2)tune the tran-cievertran-cieverBefore transmitting,a station should take Before transmitting,a station should take precautions to ensure that its emissions will precautions to ensure that its emissions will not not interfere with transmissions already in progressinterfere with transmissi

37、ons already in progress.If interference is likely,the station shall wait for If interference is likely,the station shall wait for an appropriate break in the communications in an appropriate break in the communications in progress.progress.Ship to shore automatic calling 1）ship station call coast st

38、ation：input coast station MMSI，start up calling；2)establish connection,ship and coast exchange answer back automatically；3)coast station send GA+；4)ship station send services instruction，DIRTLXxy+where x is the telex destination code(country code)in accordance y is the land subscribers telex number

39、and+indicates end of sequence;；5)coast station sends MOM；6)ship station sends subscriber answer back and MSG+；7)ship station sends edited file；8)ship station and subscriber exchange answer back；9)ship station sends KKKK，cut off land line link and keep wireless link；10)ship and coast exchange answer

40、back automatically；11)coast station sends some information about communication time and duration etc；12)coast station sends GA+；13)send another file,start from step 4,nothing any more,send BRK+，end communication。Following is an example that ship station(412001000)will send an text to subscriber(3305

41、7)through coast station(004122100)ship：004122100+coast：004122100 SHAIRDO CN ship：412001000 BOLU X coast：GA+ship：DIRTLX08533057+coast：MOM 33057+33057 COSCO CN MSG+ship：TXT NNNN (WRU)coast：33057 COSCO CN ship：412001000 BOLU X ship：KKKK coast：004122100 SHAIRDO CN ship：412001000 BOLU X coast：TIME：08 25

42、99 1230 SHIP：412001000 BOLU X SUBSCR：33057 COSCO CN DURATION：15MIN GA+船：船：BRK+Shore to ship ARQ callinglTwo waysl1.call ships through DSC firstly,and indicate in the message that subsequent communication is ARQ;l2.Ship scans on coast station working frequencies by sending FREQ“to coast station.Ship

43、to ship ARQ calling through DSC call ships,and indicate in the message that subsequent communication is ARQ;2岸到船的ARQ通信 岸到船的NBDP呼叫有两种方法：1)岸台首先通过DSC呼叫船台，并指明后续通信方式为ARQ，以及随后的工作频道或频率。船台应答后，船岸双方各自转到工作频道或频率上进行ARQ通信。2)船台的NBDP终端对经常联系的岸台的电传信道进行扫描值守；或者船台主动将自己的值守安排通过FREQ指令通知岸台。于是岸台可使用NBDP设备在其规定的电传发射频率上以ARQ方式呼叫船

44、台，船台检测到后将在值守的岸台发射频率的对应频率上进行应答，建立通信链路。3船到船的ARQ通信 船到船的ARQ通信，与岸台呼叫船台类似，也是通过DSC进行的。被叫船应答后，双方均转到工作频率上即可以进行ARQ通信。Commands for NBDP communication “+”Commands function BRK+To clear the connection with the coast station DIRTLXxy+Direct dialing telex GA+I am ready.Transmit your command.HELP+Ship station use t

45、his command to get coast station commands and information KKKK Terminate the land telex link.MED+Request medical advice MSG+Request sending message OPR+Call operator for general help TGM+To indicate that the following message is a radiotelegram TLX+Store and forward telex TEST+Request coast station

46、to send a test message for checking the ship station.三、国际电传系统常用代码三、国际电传系统常用代码ABS absent subscriber/office closed 用户不在/办公室停止办公DER out of order 故障FMT format error 格式错误MOM wait/waiting 请等候NC no circuits 没有线路 OCC subscriber is engaged 用户占线WRU who are you 你是谁Operation in FEC modeOperation in FEC modelMes

47、sages in Forward Error Correction(FEC)mode may be sent,by prior arrangement,from a coast station or ship station to one or more ship stations in the following cases:l(a)where a receiving ship station is not able to use its transmitter or is not permitted to do so;l(b)where the message is intended fo

48、r more than one ship;l(c)where unattended reception of the message in the FEC mode is necessary and automatic acknowledgement is not required.FEC CALLING PROCEDURESl1.tune the transmitter to an appropriate frequencyl2.Choose FEC mode and start a calll;If choose SFEC mode,enter called station MMSI.l3

49、.Send edited message;l4.End the communication.四、四、FEC方式下的通信操作程序方式下的通信操作程序 CFEC方式常用于发送遇险、紧急和安全信息及播发通报表。事先应使用DSC进行报警或呼叫，并指明随后通信方式是FEC电传及通信频率。收方收到后将接收机调到指定频率上准备接收。CFEC通信的发送程序如下：1、选择CFEC，选择发射频率，启动呼叫；自动进行定相信号的发送2、调发事先编辑好的电文，或边输入边发送；3、发送完电文拆线。如果用SFEC方式发送，则需输入对方的选呼码。其他程序类似。五、用五、用NBDP传递无线电报的方法传递无线电报的方法 1、船台在与岸台建立联系并收到GA+后；2、输入通信指令TGM+，然后发送无线电报格式的电文。