Garmin GTR 225 Installation Manual page 91

B.2.4.1.9 Set NAV Audio Mode
This message is used to change the current NAV audio mode. There are two possible settings for this
mode. The first is "IDENT", which will suppress the voice portion of the NAV audio signal and emphasize
the Morse Code station identifier. The second choice is "VOICE", which will emphasize voice signal and
suppress the Morse Code station identifier (unit will display "ID" in the upper-left corner of the NAV
page).
This message is available in both normal and test modes.
Message format:
"V" ..........................Message class. This is a VHF NAV message.
"31".........................Message identifier.
a...............................NAV audio mode. "I" = IDENT, "V" = VOICE
Example message:
Set the current NAV Audio mode to IDENT.
B.2.4.1.10 Set Omni-Bearing Select (OBS) Value.
This message is used to set the OBS value used by the GNC as the selected radial for computing the course
deviation from a VOR. This message will have no effect unless the GNC is configured to use the serial port
as its OBS source ("NONE" or "SERIAL").
Message format:
"V" ..........................Message class. This is a VHF NAV message.
"34".........................Message identifier.
vvv ..........................OBS Value in degrees, ranging from "000" to "359".
Example message:
Set the OBS value to 310 degrees.
B.2.4.1.11 Set NAV Volume Level
This input is used to set the volume level for the NAV mixed audio.
Message format:
"V" ..........................Message class. This is a GNC NAV message.
"43".........................Message ident.
vv ............................Volume level: 00-FFh; two encoded hex characters (30h-3Fh).
Example message:
Set the NAV volume to 1Dh out of FFh ("=" = 3Dh, -30h = Dh).
190-01182-02
Rev. B
$PGRMV31I<chksm><CR><LF>
$PGRMV34310<chksm><CR><LF>
$PGRMV431=<chksm><CR><LF>
GTR 225/GNC 255 TSO Installation Manual
Page B-11