Software commands for S53MV DME
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4-digit LCD + four pushbuttons: green,white,black,yellow

Display-digit functions:

Indicating DME channel or VOR frequency (1XX.XX MHz): menus 0,1,2,3,4 or
indicating measured distance: menu 5.

Single digit blinking: parameter setting.
Central decimal point off: indicating DME channel.
Central decimal point on: indicating (paired) VOR frequency.
All three decimal points on: internal error (temporarily PLL unlock
at power-on or at channel/frequency switching).

Pushbutton functions:

Green pushbutton (left): move cursor left (menu-1).
White pushbutton (left/center): increment parameter.
Black pushbutton (right/center): decrement parameter.
Yellow pushbutton (right): move cursor right (menu+1).
Simultaneous depression of green+yellow pushbuttons: write channel or
frequency into current memory number, audio on/off into EEPROM.

Menu functions:

Menu 0: standby (after power-on).
White pushbutton: select next channel/frequency in EEPROM.
Black pushbutton: select previous channel/frequency in EEPROM.
Memory number 0,1,2,3,4,5,6,7,8,9,A,b,C,d or E is shown while green,
white or black pushbuttons are held depressed.

Menus 1,2,3,4: setting the channel/frequency, the blinking digit
can actually be changed. Digit select with green/yellow pushbuttons.
Digit increment/decrement with white/black pushbuttons. First digit
increment/decrement overflow also causes switching from DME
channel display to paired VOR frequency and back. Valid channel
numbers range from 001X,001Y to 126X,126Y. Valid VOR/ILS frequencies
range from (1)08.00 to (1)17.95, the hundred MHz not actually shown.

Menu 5:	DME transmitting interrogations in two different modes:
search or track. White pushbutton: audio on. Black pushbutton: mute.

Search mode: DME transmitting many interrogations waiting for valid
measurements. Display blank except for first segment moving up and down.

Track mode: DME transmitting fewer interrogations while valid repiles
are being received. Display shows measured distance as hundreds, tens,
units, decimal point and tenths of nautical miles up to 150nmi.