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C.2 NRM – NAVTEX receiver mask
This command is used to manipulate the configuration masks that control which messages are
stored, printed and sent to the INS port of the NAVTEX receiver.
$ - - N R M , x , x , h h h h h h h h , h h h h h h h h * h h < C R > < L F >
message type mask
4
transmitter coverage area mask
3
frequency table index
2
, 1 to 9
function code
1
, 0 to 9
NOTE 1
The function code is used to further identify the purpose of the sentence. The meaning of the function code is as follows:
0 – request messages for the given mask
1 – set/report the storage mask
2 – set/report the printer mask
3 – set/report the INS mask
4 to 9 – reserved for future use
NOTE 2
The frequency indicator identifies the frequency that the NAVTEX message was received on:
1 = 490 kHz
2 = 518 kHz
3 = 4209,5 kHz
4 through 9 are reserved for future use
NOTE 3
The transmitter coverage area mask is defined as a 32 bit hex field where the least significant bit represents transmitter
coverage area ‘A’, the next bit is ‘B’ and so on up to bit 25 which is ‘Z’. Bits 31 through 26 are reserved for future use and are set to zero.
To select a transmitter coverage area, its corresponding bit should be set to one. To deselect a transmitter coverage area its
corresponding bit should be set to zero.
NOTE 4
The message type mask is defined as a 32 bit hex field where the least significant bit represents message type ‘A’, the next bit
is ‘B’ and so on up to bit 25 which is ‘Z’. Bits 31 through 26 are reserved for future use and are set to zero. To select a message type its
corresponding bit should be set to one. To deselect a message type its corresponding bit should be set to zero.
When another device (for example an INS) wishes to set one or more of the bit masks it sends one or more NRM sentences to the
NAVTEX receiver. When another device wishes to determine the current values of the bit masks it sends a query sentence to the
NAVTEX receiver as follows:
$--CRQ,NRM*hh<CR><LF>
On receiving this query, the NAVTEX receiver will respond with one NRM sentences for each mask type and frequency combination that
it supports. For example, a NAVTEX receiver which supports separate storage, printer and INS masks for each of three receiver
requencies will
return a total of nine NRM sentences in response to the above query.
Example usage:
$INNRM,2,1,00001E1F,00000023*57
This example specifies that message identifiers ‘A’, ‘B’ and ‘F’, received from transmitter areas ‘A’ to ‘E’ and ‘J’ to ‘M’ on 490 kHz should
be sent to the printer port when they are received. Note that this command sets the printer mask for future use; there is no immediate
output generated as a result of receiving this command.
Example usage:
$INNRM,0,2,00001E1F,0FFFFFFF*21
This example requests that all currently stored messages of all message types, received from transmitter areas ‘A’ to ‘E’ and ‘J’ to ‘M’ on
518 kHz should be immediately returned to the requesting device as a series of NRX sentences. Note that this command does not
update any of the stored masks.
