Garmin GNC 255 Installation Manual - page 89
190-01182-02
GTR 225/GNC 255 TSO Installation Manual
Rev. B
Page B-9
B.2.4.1.5 Select Squelch Override
This input is used to turn the manual squelch on and off.
Message format:
“C” ..........................Message class. This is a GTR/GNC COM message.
“03”.........................Message ident.
n ..............................Squelch test: (ASCII) 0 = automatic; 1 = manual override (displays “SQ”).
Example message:
$PGRMC030
Set the squelch to normal operation.
B.2.4.1.6 Set COM Channel Spacing
This input is used to adjust the configured channel spacing for COM frequencies.
Message format:
“C” ..........................Message class. This is a GTR/GNC COM message.
“13”.........................Message ident.
ss .............................New spacing: (ASCII) 83 = 8.33 KHz spacing; 25 = 25 KHz spacing.
Example message:
$PGRMC183
Set channel spacing to 25 KHz.
B.2.4.1.7 Set Active NAV Frequency
This message is used to set the active NAV frequency.
Message format:
“V” ..........................Message class. This is a GNC NAV message.
“27”.........................Message identifier.
mk ...........................Active VOR/LOC frequency:
m = desired frequency in MHz in hexadecimal, where m = desired frequency -
30h, with desired frequency in range of 108 to 117MHz.
k = desired frequency in KHz, where k = (desired frequency / 25KHz) + 30h,
with desired frequency in range of 000 to 950KHz in 50KHz steps, or the
even numbers from 30h to 56h.
“0”...........................Reserved, data in this field will be ignored.