Software commands for S53MV VOR/localizer reciver
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4-digit LCD + four pushbuttons: green,blue,red,yellow

Display-digit functions:

Indicating VOR/localizer(ILS) frequency (1XX.XX MHz): menus 0,1,2,3,4 or
indicating signal strength, squelch setting and volume setting: menus 5,6 or
indicating measured VOR radial or ILS localizer CDI menu 7 or
indicating VOR CDI (FORM or TO): menu 8 (in VOR mode only) or
indicating VOR OBS: menu 9 (in VOR mode only).

Single digit blinking: parameter setting.
All three decimal points on: internal error (temporarily PLL unlock
at power-on or at receive/transmit switching).

Pushbutton functions:

Green pushbutton (left): move cursor left (menu-1).
Blue pushbutton (left/center): increment parameter.
Red pushbutton (right/center): decrement parameter.
Yellow pushbutton (right): move cursor right (menu+1).
Simultaneous depression of green+yellow pushbuttons: write frequency into
current memory number, OBS, volume and squelch into EEPROM.

Menu functions:

Menu 0: normal operation (after power-on).
Blue pushbutton: select next frequency in EEPROM.
Red pushbutton: select previous 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, blue
or red pushbuttons are held depressed.

Menus 1,2,3,4: setting the VOR/localizer frequency, the blinking digit
can actually be changed. Digit select with green/yellow pushbuttons.
Digit increment/decrement with blue/red pushbuttons. The one hundred MHz
digit is omitted and is never shown.

Menu 5: setting the squelch level "0-4". "0" squelch inactive, "1" most
sensitive squelch, "4" least sensitive squelch. Also indicating
received-signal strength "0-4" and volume setting.

Menu 6: setting the volume level "0-8". "0" mute, "1" quietest, "8" loudest.
Also indicating received-signal strength "0-4" and squelch setting.

Menu 7: indicating measured VOR radial (on VOR frequency channels) or ILS
localizer CDI (on ILS frequency channels).
Blue pushbutton: force ILS-localizer-CDI display on any frequency.
Red pushbutton: force VOR-radial display on any frequency.

ILS localizer CDI operation:
Alternating left and right decimal points: localizer signal level too low.
Central decimal point and colon only: localizer centerline, signal level ok.
Additional 1-8 bars left: right from centerline (150Hz>90Hz), move left.
Additional 1-8 bars right: left from centerline (90Hz>150Hz), move right.
"HH:" from left: overrange right from centerline (150Hz).
":HH" to right: overrange left from centerline (90Hz).

VOR-radial display:
First three digits blank and degree-sign only: VOR signal level too low.
Three digits and degree-sign: VOR signal level ok, measured radial.

Menu 8: indicating VOR CDI (TO or FORM).
Alternating left and right decimal points: VOR signal level too low.
Colon on: VOR signal level ok, CDI indicating TO.
Central decimal point on: VOR signal level ok, CDI indicating FROM.
Additional 1-8 bars left: 1-8 degrees right from selected radial, move left.
Additional 1-8 bars right: 1-8 degrees left from selected radial, move right.
"HH:" from left: overrange 9 or more degrees right from selected radial.
":HH" to right: overrange 9 or more degrees left from selected radial.
Blue pushbutton: set OBS for currently measured TO radial.
Red pushbutton: set OBS for currently measured FROM radial.

Menu 9: indicating VOR OBS: three digits followed by a blinking "H".
Increment/decrement OBS with blue/red pushbuttons in 1-degree steps.