BEACON? Antony M0IFA Beacon Synth

• AD9850 - a sine wave output synthesiser

• Programmable in

• Hertz + centi-Hertz 7080000.00 + 100 = 7080001.00Hz

• Varicode to store symbols

• Can do CW, PSK31, RTTY, AD9850 module WSPR… HELL… New ADS9850 library

#define ADS_XTAL 125000000.0

class ADS9850 {

public: ADS9850();

void begin(int W_CLK, int FQ_UD, int DATA, int RESET); void setFreq(double Hz, double Chz, uint8_t phase); void calibrate(double calHz); void down();

private: int _W_CLK; int _FQ_UD; int _DATA; int _RESET;

double _calFreq;

void update(uint32_t , uint8_t p); void pulse(int _pin);

}; Example #include "ADS9850."

// pins #define W_CLK 8 #define FQ_UD 9 #define DATA 10 #define RESET 11

// create ads object ADS9850 ads; void setup() {

ads.begin(W_CLK, FQ_UD, DATA, RESET); // set up pins

ads.calibrate(124999000.0); // calibrated XTAL freq

ads.setFreq(7100000.0, 146); // on & output 7100001.46 Hz

delay(30000); // 30sec

ads.down(); // off } void loop() {

} VARICODE Let’ look at each symbol system ASCII & Morse 0… • Morse is subset of ASCII (0-127) • ASCII code is a 7bits, in decimal numbers morse is 32 = to 90 = • Some do not have Morse symbol .. # $ % &

…127 Morse varicode

Varicode Examples no. Char ASCII index VC bin morse bits

0 48 16 248 11111000 5 - - - - -

1 49 17 120 01111000 5 . - - - -

…

M 77 45 192 11000000 2 - -

‘’ Index = 77 - 32 (SPACE) = 45 Array counts 0 to 58 ASCII & PSK31

Part of PSK31 symbols All ASCII codes (0 - 127)

PSK31 Uses symbols which all start with ‘1’, & end with ‘1’,

Never has ’00’ in symbol, ’00’ is character space

1 is continuous output, 0 is 180deg phase change

Baud rate 31.5, or pulse timing 32ms

Pulses should be cosine shaped - to reduce ‘clicks’ PSK31 varicode

Varicode Examples no. Char ASCII index VC bin bits

A 65 65 125 1111101 7

B 66 66 235 11101011 8

…

Y 89 89 379 101111011 9

PSK31 has all 0-127 ASCII, Index = ASCII code Baudot code RTTY bits bits RTTY uses the 5bit BAUDOT code = 32 characters, so Letters Shift and Figures Shift

add 1 START bit ‘0’ add 2 STOP bits ‘11’

Signals

D = 0 1 0 0 1 0 1 1 RTTY varicode 1st 33 (0-32) are FIGS, then (33-58) LTRS

FIGS

LTRS

A in Baudot = 00011 b4-b0 Varicode is stored b0-b4 24 decimal = 11000 binary RTTY coding bits bits Message is in ASCII code 32 to 90 (SP to Z)

Index into RTTY varicode = ch - 32 (0 - 58) if Index < 33 then send FIGS, else send LTRS

look up Baudot varicode byte b7-b0

Varicode stores Baudot backward = 000b0 - b4

e.g. D 01001 (b4-b0) is 000b0-b4 = 00010010

shift left << 2 to give 01001000 add 3, or b00000011

to give TX byte 01001011 = start bit 0, ‘D’ and two stop bits 11

send b7 to b0 as “D” in signal Coding

This bit is for nerds Morse Code 1 2

3

4 PSK31 Code

1 2 3

4 RTTY Code 1

2

3

Switch LTRS or FIGS 4 Varicode table

5 rttyTxByte

// send at fHzVcode, fChzVcode, vCode 000nnnnn void rttyTxByte(long fHzVcode, long fChzVcode, char vCode) { int bits, val;

// build the byte to send vCode = (vCode << 2) + 3; // shift two left, add B00000011, makes 0nnnnn11

for (bits = 7; bits >= 0; bits--) { // MSB first, b7 -> b0, sends Baudot b0 -> b4 val = bitRead(symb, bits); // Read bit ads.setFreq(fHzvCode + (170 * val), fChzvCode, 0); // Let's transmit (bit 1 is 170Hz shifted up) delay(22); // Gives the baud rate, 22ms per bit } delay(110); // intersumbol pause } Send Send on freq or freq+170Hz b7 - b0 Demo TX -> RX PC & AD9850 SDR & MacBook