HF beacon using Arduino

I recently got a cheap 40MHz signal generator board off of ebay for a few bucks. This board is based on the Analog Devices AD9850, but the ones you find on eBay are probably knock-offs.

Parts List:
Source Code:

I modified some code I found online to use it to be able to send Morse code from the serial port on my computer using putty. Putty is a nice piece of free serial terminal software. The output power is very low (easily measured in microWatts with a small antenna) but after some impedance matching and a amplifier stage you could easily use this for a nice HF beacon project. Here is the code if you want to try it for yourself:

Arduino Code:
//Has the ability to send morse code from the serial port

#define WPM 20
#define pttOut 13
#define pwmOut 5
#define toneFrequency 400  //Hz
#define W_CLK 8       // Pin 8 - connect to AD9850 module word load clock pin (CLK)
#define FQ_UD 9       // Pin 9 - connect to freq update pin (FQ)
#define DATA 10       // Pin 10 - connect to serial data load pin (DATA)
#define RESET 11      // Pin 11 - connect to reset pin (RST)
#define txfrequency 14015000

byte morseLookup[] = {
	//Letters
	B01000001,B10001000,B10001010,B01100100,B00100000,B10000010,
	B01100110,B10000000,B01000000,B10000111,B01100101,B10000100,
	B01000011,B01000010,B01100111,B10000110,B10001101,B01100010,
	B01100000,B00100001,B01100001,B10000001,B01100011,B10001001,
	B10001011,B10001100,
	//Numbers
	B10111111,B10101111,B10100111,B10100011,B10100001,B10100000,
	B10110000,B10111000,B10111100,B10111110,B10111110,
	//Slash
	B10110010
};


void setup(){
	Serial.begin(9600);
	Serial.print("Loading...");
	pinMode(pttOut,OUTPUT);
	pinMode(pwmOut,OUTPUT);
	pinMode(4,OUTPUT);
	digitalWrite(4,LOW);
	pinMode(3,OUTPUT);
	digitalWrite(3,HIGH);
	setupDDS();
	delay(500);
	Serial.println(" complete");
}

void loop(){
	if(Serial.available()){sendSerialMessage();}
	transmitString("Test");
	delay(5000);
}

// transfers a byte, a bit at a time, LSB first to the 9850 via serial DATA line
void tfr_byte(byte data)
{
	for (int i=0; i<8; i++, data>>=1) {
		digitalWrite(DATA, data & 0x01);
		pulseHigh(W_CLK);   //after each bit sent, CLK is pulsed high
	}
}

void sendFrequency(double frequency) {// frequency calc from datasheet page 8 =  * /2^32
	int32_t freq = frequency * 4294967295/125000000;  // note 125 MHz clock on 9850
	for (int b=0; b<4; b++, freq>>=8) {
		tfr_byte(freq & 0xFF);
	}
	tfr_byte(0x000);   // Final control byte, all 0 for 9850 chip
	pulseHigh(FQ_UD);  // Done!  Should see output
}

void pulseHigh(int pin){
	digitalWrite(pin, HIGH);
	digitalWrite(pin, LOW);
}

void setupDDS(){
	pinMode(FQ_UD, OUTPUT);
	pinMode(W_CLK, OUTPUT);
	pinMode(DATA, OUTPUT);
	pinMode(RESET, OUTPUT);
	pulseHigh(RESET);
	pulseHigh(W_CLK);
	pulseHigh(FQ_UD);  // this pulse enables serial mode - Datasheet page 12 figure 10
}

void sendSerialMessage(){//Gets a string from the serial port, and send it out via morse code
	delay(10);
	char message[64];
	int length = 0;
  
	while(Serial.available() && length < 64){ message[length] = Serial.read(); length++; message[length] = '\0'; } transmitString(message); } void transmitString(char* message){ for(int i = 0; message[i] != '\0'; i++){ Serial.print(message[i]); transmitChar(message[i]); } Serial.println(); wordSpace(); } void transmitChar(char character){ int lookupValue; if(character > 64 && character < 91){ //Capital Letter (0-25) lookupValue = character - 65; } else if(character > 96 && character < 123){ //Lower Case Letter (0-25) lookupValue = character - 97; } else if(character > 47 && character < 58){ //Number (26-36) lookupValue = character - 48 + 26; } else if(character == 47){ // slash (37) lookupValue = 37; } else if(character == 32){ // space wordSpace(); return; } else{ return; //Invalid Character } byte length = (morseLookup[lookupValue] & B11100000) >> 5;
	byte pattern = morseLookup[lookupValue] & B00011111;
	byte mask = 1 << length-1;
	for(int i = 0; i < length; i++){ if(mask & morseLookup[lookupValue]){ dash(); } else{ dot(); } mask = mask >> 1;
	}
	charSpace();
}

void dot(){
	digitalWrite(pttOut,HIGH);
	sendFrequency(txfrequency);
	tone(pwmOut,toneFrequency);
	delay(1200/WPM);
	digitalWrite(pttOut,LOW);
	sendFrequency(0);
	noTone(pwmOut);
	delay(1200/WPM);
}

void dash(){
	digitalWrite(pttOut,HIGH);
	sendFrequency(txfrequency);
	tone(pwmOut,toneFrequency);
	delay(3 * 1200 / WPM);
	digitalWrite(pttOut,LOW);
	sendFrequency(0);
	noTone(pwmOut);
	delay(1200 / WPM);
}

void charSpace(){
	delay(2 * 1200 / WPM);
}

void wordSpace(){
	delay(7 * 1200/WPM);
}

6 thoughts on “HF beacon using Arduino

  1. Hi , i am an amateur radio from Italy.
    My call nome is IZ1TJM.
    I al interested to tour project of beacon with DDS and Arduino.
    Suorce code of beacon si OK but there isnt code of DDS.
    Si possibile have it with beacon Inside ?
    Thanks
    73 de iz1tjm carlo

  2. Hello mate, I’m PY5KYW Bahl, I live in Quatiguá in Parana – Brazil, I read your post and became interested in the project, I would be able to obtain further information from your project so that I can play for my personal use, but with your permission. Used parts, components and other in order to obtain the perfect functioning of conjuto by the above program Since you already thank you for your attention and time spent reading this message. 73’s to colleague and recommendations to family cordially PY5kyw – Bahl

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