NAVTEX

NAVTEX ( " Navigational Text Messages " - formerly known as " Navigational Warnings by Telex " ) is used worldwide in shipping to disseminate safety and weather information ( Maritime Safety Information ) and is part of serving the worldwide Global Maritime Distress Safety System ( GMDSS).

The messages are disseminated with the error-correcting radio teletype method SITOR B on the frequency 518 kHz in English and in some countries also on the frequencies 490 kHz and 4209.5 kHz in the local language. Japanese TV broadcast NAVTEX messages in Japanese on the frequency 424 kHz.

Stations and Navareas

For the transmission of information in the world 16 " Navareas " ( internationally established Seewarngebiete ) is divided. There is provided an extension for another five Navareas, which will cover the Arctic waters. In the Navareas the individual transmitters with letters from A to Z are referred to ( in the northern hemisphere from north to south ). Stations in an area, send one by one to avoid mutual interference. The range is up to 600 nautical miles.

On 29 August 2006, the German Weather Service has officially taken a new NAVTEX stations in Pinneberg in operation. Pinneberg is the only German station and supplies the entire German coast and parts of the North and Baltic Seas.

Set stations

The display of a NAVTEX receiving device, all stations appear as letters A to Z. Each station can be as an individual choice to be voted out and created, for example: " AbcdefGHIijklmnopqrStuvwXYZ " (uppercase = a, lowercase = off).

Setting the message types

All message types are transmitted sequentially. The display shows all message types to appear as letters A to Z. Each notification can be as an individual choice to be voted out and created, such as: " ABCDEFGHIJKLMNOPQRSTUVWXYZ " (uppercase = a, lowercase = off). A, B, D, and L are always output. E weather forecast is also one of the essential data.

Building a NAVTEX message

The structure of the message may differ from the example below in detail. The first and last line are always the same structure in any case.

ZCZC PA09 NETHERLANDS COAST GUARD Navigational warning NO. 9 172128 UTC August PLATFORM L10- G 53 - 29.4N 004- 11.7E UNLIT NNNN

Each NAVTEX message starts with the letters ZCZC. Followed by the message identifier ( PA09 ). The first letter of the message identifier is used to identify the transmitting station. It is in this case NETHERLANDS COAST GUARD (P). In the second letter, the message is coded here navigational warning ( navigational warnings ). The last two digits of the message identification (09 ) are a serial number. The number 00 has a special position. It is reserved for distress messages. NAVTEX messages have a timestamp. He can be seen at the end of the third line ( 172128 UTC August) and means: August 17, 21:28 UTC. The time stamp refers to the date on which the message was created, not the time for broadcasting. After that, the message content follows. The message ends with NNNN.

Weather forecast

ZCZC JE92 error rate = 0.0% 170500 MAY UTC SWEDISH WEATHER SHIPPING WEATHER SUMMARY FROM HIGH IN GREEN COUNTRY RIDGE OF HIGH SOUTH EAST WARDS TO SWEDEN, WEAK AREA OF LOW OVER WEST_EUROPE: LOW NORTHWEST OF LOFOTEN ISLANDS LATER TODAY deepening. GALEWARNINGS NIL FORECAST VALID 24 HOURS SKAGERRAK; KATTEGAT; THE SOUND: AROUND EAST 3-7 M / S SOMEWHAT INCREASING; IN WESTERN PART OF SKAGERRAK DURING DAY AROUND 10 MAINLY GOOD VIS, IN SKAGERRAK AT TIMES SOME RAIN. THE BELTS; WESTERN BALTIC: Belt, Easterly 7-11. GOOD VIS. NNNN Beginning characters, transmitter / type / serial number and error rate At 0500 UTC 17th of May Swedish Seewettervorhersage weather From the high over Greenland high pressure ridge southeast to Sweden, weak low over Western Europe: low north-west of the Lofoten, later in the day in depth. No storm warnings (literally "nothing" ) Forecast valid for 24 hours Skagerrak; Kattegat; Sund: East winds around 3-7 m / s, some increasingly; in the western Part of the Skagerrak during the day to 10 mostly good visibility, Skagerrak, little rain. Belts; Western Baltic: Belt, easterly winds 7-11 (kn, since without m / s), good visibility end character Meteorological expressions

In NAVTEX messages internationally defined terms are used for better understanding. See list Meteorological expressions in German, English, Spanish and French.

Technology

The 26 land stations transmit the NAVTEX messages in F1B - operation (remote write method SITOR B with Forward Error Correction) within the transmission range of the center shaft. Uniformly in English on 490 kHz in the local language, to 518 kHz. For areas where the center shaft is affected by atmospheric disturbances can be avoided on the shortwave frequency 4209.5 kHz. When transferring a 100 baud frequency shift keying ( FSK ) is used with a frequency shift of 170 Hz.

Send NAVTEX stations in a 4 hour cycle in ten minute time windows. By the time offset obtained a plurality of stations can use the same frequency without causing mutual interference. Exception are emergency messages, they will be shipped immediately.

The transmission range of NAVTEX stations typically includes 100-500 nautical miles in the vicinity of the station. With very good receiving antennas but can also be received from much greater distances.

Devices

• Fixed receiver stations

• Black- box receiver

• Portable Navtex receiver

NAVTEX decoder

• Http://www.meteoserver.net/sites/de_in08.htm Bonito MeteoCom international MeteoServer
• Http://www.dxsoft.com/en/products/seatty/ (PC / commercial)
• Http://www.frisnit.com/navtex/ (PC / Mac (Java) / free)
• Http://www.winradio.com/home/ads-navtex.htm (PC / commercial)
• Http://www.blackcatsystems.com/software/multimode.html ( Mac / commercial)
• Http://www.jvcomm.de (PC / Shareware)
• Http://arachnoid.com/JNX/ (PC / Mac (Java) / Free ( GPL)

Examples of the NAVTEX ads

• Http://www.frisnit.com/cgi-bin/navtex/view.cgi

NAVTEX messages via the Internet

Some organizations dine NAVTEX messages in the Internet so that they can be accessed with a browser worldwide; the reliability of the transmitted via the Internet NAVTEX messages is not guaranteed by the operators, so that this information may not be used for safety-related decisions unaudited:

• Meteorological Service Greece ( Hellenic National Meteorological Service HNMS ) (on Maritime Bulletin click )
• JCOMM official of the Inmarsat -C SafetyNET Seewetterdienste website (marine weather information broadcast via Inmarsat -C SafetyNET )
• Worldwide live reception of NAVTEX messages