Navtex Transmitters: Frequently Asked Questions


Sailing the high seas has always had an element of danger to it, but when ships do not have access to differential GPS data, or receive real-time information about inclement weather, obstructions in the sailing route, ice at high altitudes, and other potential dangers, embarking on a long journey in non-local waters can be life threatening. That is why the U.S. Coast Guard and similar organizations in other countries operate Navtex transmission stations, which broadcast critical safety information to mariners. If you need information about Navtex for giving or receiving Navtex transmissions, the answers below will help.

What is Navtex?

It is a system that broadcasts maritime safety information using a narrow-band direct-printing telegraphy. The transmissions are sent from local stations around the globe, with the power of each transmission being regulated to not overlap with transmissions in another broadcasting zone.

What frequencies broadcast Navtex transmissions?

The messages are broadcasted on two frequencies: Navtex 518 kHz (international) and Navtex 490 kHz (national). The international broadcast is in English. The national broadcast is in the local language of the broadcasting source.

What types of transmitters are available?

There are several models of Navtex transmitters. Many Navtex broadcasters consider the SV 1500 system and the SV 3000 system to be the most desirable models. Each is available in a model that contains a dual transmitter system, in which the backup transmitter remains operational during an outage. The models also offer practical benefits such as 750W RF modules that are easy to hot swap, a full function membrane keypad, and an automatic ATU interface.

How do mariners receive information while at sea?

Mariners receive information by having a Navtex receiver on their vessel. The receiver can be programmed to receive only the information that mariners want, and can store and print the information as needed. The receivers also have GPS ports that allow them to connect with differential GPS devices for enhanced information retrieval.

What are the broadcasting requirements for a transmission station?

The International Maritime Organization (IMO) mandates that Navtex broadcasts must have a range of 250 meters, and must provide weather information covering a 250-meter radius. Because the radius is considered “out to sea,” it may actually be as much as 400 meters.

What types of information can the transmissions relay?

The broadcasts relay several types of information, including:

  • Severe changes in sea weather
  • Sailing route obstructions
  • Bad weather in inshore waters
  • Catastrophic geographic events
  • Icebergs and lesser ice collections in high-altitudes

This information helps keep mariners safe while at sea, protects shipping assets, and can expedite travel time.


Navtex transmitters broadcast critical information about sea conditions to mariners who use Navtex receivers, which can sync with other technologies such as differential GPS to provide enhanced information retrieval. In the absence of the broadcasts, mariners have a greater risk of encountering danger from weather conditions, geographic events, and obstructions in the sailing route. For more information about Navtex technologies, contact a provider of high-tech navigation solutions today.

Source by Timothy M. Dalton


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