.: General Features :.

Vox Maris simulates by software the Navtex receiver.

Its operation is very simple and allows fast and efficient emergency communications, emergency or routine with other vessels. The operation and the graphical display of the equipment are simulated emulating the real equipment available in the market, achieving an unique realism by software allowing the user to operate in the same way that it would on the real equipment. Even the simulator is ready to operate with touch-screen, thereby increasing the realism achieved.

Among the most important simulated functions includes:

• Send and Schedule Navtex messages from Instructor, before and during simulation
• Receiving messages on paper (direct printing capability of received messages)
• Receiving messages on screen
• Setup of NAVTEX stations
• Setup of prority messages
• Self - Test
• Equipment status

NAVTEX System is an international service of telegraphy of direct impression for the diffusion to the ships of nautical warnings, meteorological bulletins and urgent information of marine security relative to coastal waters up to 400 miles of the coast.

Also it transmits weather forecasts of routine and all the storm warnings. NAVTEX System uses a single frequency anywhere in the world (518 kHz).

The mutual interference is avoided limiting the power of the transmitter only to reach the limits of the assigned zone and distributing the frequency time of use. NAVTEX System is integrated within the Global Maritime Distress and Safety System (GMDSS).

All the ships of gross capacity equal or superior to 300 tons will have to take on board a receiver that can receive the transmissions of international NAVTEX service in zones where these services are lent. The NAVTEX acquired obligatory character for these ships and all the ships of passage by virtue of the GMDSS, the 1 of August of 1993.

It is one of the 9 functional requirements that prescribed by SOLAS for the application of the GMDSS, where is established that the units must have capacity to receive marine information of security (MSI).

For that reason this new system was settled down using telex transmitters that were present in some places from the globe from 1971, such as the coasts of the U.S.A. and Norte of Europe.

The origin of its application we exactly found it in 1971 after an ominous event for the navigation, happened in the North Sea when a called ship Brandenburg collides against a helmet to resentment and it sinks. Incredibly 48hs. later another ship collides in the same place against both and it almost sinks also, without having received sufficient information. It motivated that international organisms were interested in the subject and began to study the diffusion of MSI by another organized route but. And thus the Navtex arises. The Word "NAVTEX" is in fact one acronym that comes from the English expression NAVigational TEleX and constitutes one of the important elements of the new system, since it makes possible the reception of marine information of security to a distance of 400nm in the best of the cases.

The fact that the messages are in written form and can be studied calmly is important, specially when who receives them do not dominate the English language. Another one of its advantages is that the required information can be selected by the equipment operator, so that what it is not needed is not printed. However, the important information that all ships receives always will be printed.

Although the receiving ship can be selective until certain point, and the receiver is not watching, a ship cannot reject nautical and meteorological messages nor the information about search and rescue. However, the NAVTEX fundamentally it is not considered as medium to transmit information aid, since by virtue of the GMDSS this is done using the emergency frequencies and security.

International NAVTEX messages are transmitted in determined hours in English in the frequency of 518 kHz, but in many zones there is interest in transmitting analogous information in a second language (for benefit of local navigation, the fishing, etc.). Also messages with a high level of urgency can be transmitted that affect the security in specific marine zones in 518 kHz and in some zones also messages in the frequencies of 4 MHz are transmitted.

Although the main preoccupation of the OMI is the security of the merchant navigation, the NAVTEX also can be of great value for shallow-draft vessels, such as recreation yachts. The necessary equipment to receive NAVTEX messages is relatively cheap, and it is not necessary to take care of it permanently.

The NAVTEX is one of the receivers in NBDP with permanent listening in the frequency of 518 kHz. For correct operation of the system, it is divided to the surface of the globe in 16 geographic areas denominated "Navareas". For the MSI emission each Navarea can get to have up to 24 stations. Those 24 stations are divided in 4 groups, which means six stations for each group. To each group one hour of time of transmission is assigned to it, so each group can transmit once every four hours. And each station only by 10 minutes of every 4 hours

Since all the stations of the system use the same frequency, and to avoid that the same ones are interfered with to each other, is that the application of the concept of timesharing becomes necessary for the MSI emission For that reason each one of them has assigned one UTC exact hour for the MSI emission

The figure shows different the Navareas in that it is divided to the terrestrial surface. There is a total of 16 of them. The Navtex stations within each Navarea (A-z) have assigned a letter of the alphabet and each station has its own transmission schedules, according to already we have seen.