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The Navtex Message
All navtex messages begin with a 4 character code. The first letter is
the station ident letter, the next is the message ident letter followed by a
message reference number. At the end of the message the Target
navtex prints the service that was received followed by an error count.
The counter represents the total number of corrupted bits in the data
stream received. As the navtex performs error correction most of these
errors do not result on corrupted characters, however if high counts are
received from local stations the installation should be examined.
Each user has different preferences for which stations and messages
they want to record (that is, to copy to the display screen and save). The
Target Navtex has facilities for including or rejecting selected station
idents and message types so that only desired messages are recorded.
All messages are displayed in real time. Only messages programmed
in are recorded, whereas those programmed out (rejected) are simply
displayed as they arrive, and are not saved. It is a simple matter to
return to the programming screens during standby and to change the
programming to suit the user's requirements at any time.
A universal convention is to transmit distress or search and rescue
messages with a message type D, which navtex receivers are
required always to display and record. The Target navtex does so,
and to indicate this fact, D cannot be programmed out.
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