The major functions of a NAVTEX receiver incorporate the following standard operator controls:

  • Power ON/OFF – this connects the receiver to its power supply so until it is switched on the receiver is useless;
  • Dimmer – all receivers require some form of illumination for the display and controls if they are to be operated in different light levels, that are day/night. This is obtained by the “DIM” control;
  • Selecting the receiving broadcast frequency (only on single frequency receivers) - 518 kHz or 490 kHz frequency could be set.
  • Selecting CRS identifiers - all receivers are programmable to enable the user to ensure that only messages from selected CRS are displayed/printed. Each CRS identifier from A to Z could be set in any of three modes:

- RECEIVE mode - messages are displayed/printed (accepted),
- IGNORE mode - messages are not displayed/printed (rejected),
- AUTO mode - RECEIVE or IGNORE mode is automatically selected depending on vessel's position, but external navigational data like GPS is required.

Most receivers use upper case letters to indicate CRS identifiers in RECEIVE mode and lower case letters to indicate them in IGNORE mode.

  • Selecting message types - all receivers are programmable to enable the user to ensure that only selected message types are displayed/printed. Almost each message type from A to Z could be set in any of two modes:

- RECEIVE mode - message types are displayed/printed (accepted),
- IGNORE mode - message types are not displayed/printed (rejected).

Message types A, B and D cannot be rejected (IMO recommendations indicate that message category L should not be rejected).

Most receivers use upper case letters to indicate message types in RECEIVE mode and lower case letters to indicate them in IGNORE mode. All message types are usually set in RECEIVE mode by default.

  • Receive alarm setting - The audible alarm is generated when messages of type D are received.
  • Error rate setting - The maximum error rate (the threshold level) of messages that are displayed/printed can be selected. If the message exceeds the threshold level the message is not displayed/printed. The threshold level is usually set around 30%.

NAVTEX receivers are usually receiving all message types from all CRS by default. This situation is shown in the following interactive animation.

A vessel is indicated sailing within the Portpatrick NAVTEX CRS zone and towards the Malin Head NAVTEX CRS zone. NAVTEX CRS identifiers can be selected for reception on 518 kHz or 490 kHz as required. Initially all are accepted, that is, capital letters. Click on each of them to accept/reject as required. In the black field are listed basic information about received NAVTEX messages in scheduled transmission time regarding the set up of NAVTEX CRS identifiers and the CRS transmission range.

Because a vessel in the above interactive animation is sailing from Portpatrick CRS zone to Malin Head CRS zone it is suitable for that vessel to accept only messages with CRS identifiers O and Q on 518 kHz and optionally also messages with CRS identifier C on 490 kHz. Messages from all other CRS could be rejected because they have no relevance to the voyage.

Reccommendations on use of the NAVTEX receiver

  • In case that received messages are printed by the receiver, sufficient rolls of paper should be carried on board and enough paper should be always in the receiver.
  • Receiver should be turned on at least four hours before sailing. This ensures that at least one message is received on scheduled transmission time. Receiver could be turned on permanently also if the vessel is sailing often. This avoids the chance of losing vital information that could affect the vessel during its voyage.
  • The Equipment Operating Manual should be available close to the equipment, paying particular attention to the fact that the receiver may be programmed differently from other manufacturers and models.
  • A plasticized copy of the NAVAREAs in which the vessel is likely to sail, showing at least the NAVTEX CRS, their coverage ranges, their respective transmission time schedules and their CRS identifiers should be available next to the receiver. All that my be found in ALRS Volume 5.
  • The receiver should be programmed to accept only those messages identified with the CRS identifier of the NAVTEX CRS which covers the area in which the vessel is currently sailing and the one covering the area into which it is about to sail. This will avoid the receiver printing information which has no relevance to the voyage and will avoid unnecessary waste of paper.
  • The receiver should be programmed to accept only those message types the crew wish to receive. It is recommended that most message types are accepted, but those for navaid equipments, for example Loran, with which the vessel is not fitted may be excluded. Message types A, B, D and L must be included, as they are mandatory.
  • Extra care should be taken not to confuse the programming of CRS identifiers with those types of messages because in both cases just letters from A to Z are displayed. It is very easy for an operator to believe that he/she is programming CRS identifiers when in fact they are programming message types.
  • On single frequency receivers 518 kHz frequency should be always selected. Receiver could be switched to 490 kHz frequency just for few minutes to receive a message on scheduled transmission time.
  • If the NAVTEX message is received incomplete/garbled, the relevant NAVTEX CRS should be informed, giving the time of reception (UTC) and vessel's position. This will help to improve the system.
  • Any safety critical incident observed during the voyage must be passed immediately to the nearest or most convenient CRS in order that other vessels can be informed via the NAVTEX system (if the CRS considers it necessary for all vessels in it’s operational area to receive information about such an incident).