An Introduction to the NAVTEX System
NAVTEX, an acronym for "NAVigational TEleX." It is an internationally recognized, fully automated, medium frequency, direct printing service for delivery of marine weather forecasts, marine safety information, and other urgent information to vessels in both nearshore and offshore waters.
In the United States, you might want to think of it as a combination of NOAA WX radio and the U.S. Coast Guard’s safety broadcasts on VHF channel 22A (now 1022.) In Canada, the CMB Service on VHF channel 21B (2021) or in the UK the Marine Safety Broadcasts on VHF channel 23. Add to this important information about navigation aids, warnings of hazardous weather, search and rescue activities, areas where activities that may be hazardous to navigation are being conducted, as well as information concerning terrorist activities and piracy. All rolled into a single system that displays this information in text format to be read by the user.
NAVTEX is a component of the Worldwide Navigation Warning System (WWNWS) as well as a major element of the Global Maritime Distress Safety System (GMDSS.) The system was conceived and designed to provide a low cost Marine Safety Information broadcast system capable of reception from the sea buoy out to between 250 and 400 NM offshore. Much further than VHF capability.
Quality stand-alone NAVTEX receivers can be found starting at a price less than a top quality VHF marine radio. Other styles of NAVTEX receivers that require the use of a PC can be found at prices starting at a little over $200.00. When you consider that there are no user fess associated with the use of the system, I think it can be argued that they have met their design intent for a low cost safety broadcast system.
Since the NAVTEX system is fully dedicated to marine usage, mariners will appreciate the fact that they will only receive the information that they really need.
NAVTEX being a fully automated system, provides the user with numerous benefits:
- Very little user interaction, in most cases, you simply turn it on.
- Low cost, you simply have to purchase the receiver.
- Readable text formatted messages.
- Can be integrated into your existing electronics package.
- Fully automated – no tuning, no squelch adjustment, no volume control. Basically this thing is idiot proof (a very important consideration in my particular case.)
Mariners who do a lot of cruising should carefully consider adding a NAVTEX receiver to the electronics suite aboard their vessels.
What Does NAVTEX Do?
The NAVTEX system basically broadcasts text messages over MF/HF-SSB radio for automatic reception either by dedicated NAVTEX receivers or operator controlled reception using any radio capable of tuning the required frequencies. When using a non-dedicated NAVTEX receiver, a PC and appropriate software is normally used for decoding the signal along with displaying or printing of the received messages.
There are (2) types of NAVTEX transmissions available to the mariner: The first and most important for the cruising sailor being the "International Broadcast." For those sticking a little closer to home; the "National Broadcast" becomes their primary source of information. The international broadcasts are always in English everywhere in the world, while national broadcasts are generally done in the host nation’s language that the transmitting station is located in.
NAVTEX transmissions are made from stations strategically located so as to provide continuous coverage along any given coastline and typically have a small area of overlapping coverage.
The NAVTEX Receiver
The NAVTEX receiver is basically a pre-tuned MF/HF-SSB receiver incorporating signal processing software to decode the incoming transmissions.
The receiver also has some user programmability that allows certain types of information to be excluded from the broadcast.
These transmissions are then converted to text format that can be read. This removes much of the uncertainty when you are only able to listen to a broadcast and then try to remember what the significant wave heights were that were reported at the beginning of the broadcast.
The frequencies used for NAVTEX broadcasts are internationally agreed upon and do not change. Currently there is one frequency set aside for international broadcasts and two frequencies used for national or special purpose broadcasts.
Best of all, NAVTEX receivers are functional right out of the box. Simply connect the antenna and a source of power and you are ready to go. All you have to do is turn it on! Okay, I may have over simplified this last part a bit, but truly, setup on a NAVTEX receiver is no big deal. It is no more complicated than installing a marine VHF Radio.
For those who are interested in a more detailed explanation of the NAVTEX System Read, NAVTEX – The Finer Details.