The Aegis-Beacon uses PARIS-standard Morse timing for precise, repeatable transmissions. The engine generates both RF carrier keying and audio click streams.

PARIS Standard Timing

Info

The word “PARIS” = exactly 50 units, calibrating WPM precisely.

Timing Constants

CODE

unit_ms = 1200 / WPM

DOT  = 1 unit
DASH = 3 units
intra-character gap = 1 unit
inter-character gap = 3 units
word gap            = 7 units

Example at 13 WPM

Element	Duration
Unit	92 ms
Dot	92 ms
Dash	277 ms
Intra-character gap	92 ms
Inter-character gap	277 ms
Word gap	646 ms

Supported Characters

Letters

CODE

A .-      B -...    C -.-.    D -..     E .       F ..-.
G --.     H ....    I ..      J .---    K -.-     L .-..
M --      N -.      O ---     P .--.    Q --.-    R .-.
S ...     T -       U ..-     V ...-    W .--     X -..-
Y -.--    Z --..

Numbers

CODE

0 -----   1 .----   2 ..---   3 ...--   4 ....-
5 .....   6 -....   7 --...   8 ---..   9 ----.

Special Characters

CODE

/ (slash)  -..-.    . (period)  .-.-.-

Payload Formats

Configuration Options

Config	Morse Message
Base only	`SOS`
Name only	`SOS DE MARIO ROSSI`
GPS only	`SOS PSN N4553 E01230`
Name + GPS	`SOS DE MARIO ROSSI PSN N4553 E01230`

GPS Coordinate Encoding

Truncated DDM (Degrees + Decimal Minutes x 10):

N4553 = 45 53’ N (lat 45.883)
E01230 = 12 30’ E (lon 12.50)

Note

This encoding is intentionally compact to minimize transmission time. Full decimal coordinates are logged to Serial.

Payload Duration Examples (13 WPM)

Payload	Duration
`SOS`	~2.7 s
`SOS DE MARIO ROSSI`	~15 s
`SOS PSN N4553 E01230`	~18 s
`SOS DE MARIO ROSSI PSN N4553 E01230`	~45 s

RF Transmission

CW Keying

The SX1262 is configured for CW (Continuous Wave) mode:

CODE

// Initialize for CW
radio.beginFSK();
radio.setFrequency(freq);
radio.setOutputPower(power);

// Transmit carrier
radio.transmitDirect();

// Key off
radio.standby();

Timing Implementation

CODE

void transmitDot() {
  radio.transmitDirect();
  delay(unitMs);
  radio.standby();
  delay(unitMs);
}

void transmitDash() {
  radio.transmitDirect();
  delay(unitMs * 3);
  radio.standby();
  delay(unitMs);
}

Audio Output

DAC1 Configuration

CODE

// Initialize DAC
dacOutputEnable(DAC_CHANNEL_1);

// Mid-rail parking at silence
dacWrite(DAC_CHANNEL_1, 128);

// Tone generation via LEDC
ledcSetup(0, 40000, 8);
ledcAttachPin(25, 0);

Click Stream

Each dot/dash produces a click through the earphone:

CODE

void audioClick() {
  dacWrite(DAC_CHANNEL_1, 200); // Click on
  delay(5);
  dacWrite(DAC_CHANNEL_1, 128); // Return to mid-rail
}

Tip

Mid-rail parking (dacWrite(128)) eliminates audible DC-click transients in headphones.

Mid-TX Interrupt

SW_MODE aborts transmission immediately between characters. The interrupt flag is checked after every character — maximum latency is one character duration.

CODE

void transmitChar(char c) {
  // Check for abort
  if (abortFlag) return;
  
  // Transmit character pattern
  for (int bit : morseTable[c]) {
    if (bit == 1) transmitDot();
    else transmitDash();
  }
}

WPM Adjustment

Live adjustment via UP/DN buttons:

Button	Action
SW_UP	WPM +1
SW_DN	WPM -1
Hold SW_UP	Auto-repeat +1 every 150ms
Hold SW_DN	Auto-repeat -1 every 150ms

Warning

Higher WPM reduces transmission time but may be harder to decode by less experienced operators. 13 WPM is recommended for emergency use.