Navtex receivers contribute automated reception of a world-wide English language data assistance face navigation, weather and other safety-related matters.
For many years receivers have operated only on 518kHz but new dual frequency sets are now available. This allows supplementary data to be included. The sets have a range of up to 300 miles. A dedicated aerial is also required. The sets fall into two broad groups: those where the data is displayed on a small screen where the user scrolls through to get the information, and those which print out onto a roll of paper (rather like a fax machine). The data is in text: a Navtex receiver will not draw weather maps as a weatherfax motor does. The set is designed to be left switched on while the vessel is in use so that no data is missed.
The world-wide law is organised by dividing the world into Navareas. The Uk falls into Navarea 1. Stations within that area broadcast at separate times to avoid mutual interference and each of these stations is given an identification letter. This enables the user to plump the most relevant center or stations and to convert stations during a passage.
The messages that are broadcast are grouped by subject. These subject groups are identified by a letter code as shown in the table. The set can be programmed to exclude some of these messages. For example "ice reports" or "Loran messages". Kind A, B and D messages cannot be rejected by the receiver.
Navtex is favorite on vessels that often cruise long distances because of the system's range and the convenience of the data just 'arriving' without having to know the local times and frequencies. One drawback of the Navtex printer is that the number of data can be considerable, so the motor will consume lots of paper.
Navtex Message Types
Type Description
A Navigational warnings including: buoys out of position, lights unlit, new wrecks, floating debris, naval exercises (cannot be rejected by receiver)
B Meteorological warnings (cannot be rejected by receiver)
C Ice reports
D hunt And recovery information, including Piracy and Armed Robbery warnings. (cannot be rejected by receiver)
E Meteorological forecasts. Pattern of scheduled forecasts will vary from Navarea to Navarea
F Pilot assistance messages
G Decca messages
H Loran messages
I Omega messages
J Satnav messages
K Other electronic Navaid messages (messages with regard to radio navigation services)
L Navigational warnings for mobile drilling rig movements (should not be rejected by receiver)
Y Amplifying navigational warning data initially announced under message type A
W special services - trial allocation
X special services - trial allocation
Y special services - trial allocation
Z No messages on hand. May be broadcast when applicable to confirm spoton receiver operation
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