Radio in the Digital Age Steven F. Goldberg, W3SFG

Part 1: Internet Operating Aids Part 2: Survey of Digital Operating Modes Part 3: Internet Resources and Databases Part 4: Software Applications 15 October 2012Radio in the Digital Age2 Radio in the Digital Age Series Outline

Radio in the Digital Age Part 2: Digital Operating Modes Steven F. Goldberg, W3SFG 15 October 2012 Radio in the Digital Age315 October 2012

Where I Started 15 October 2012Radio in the Digital Age4

Computer encode / decode No Morse Code to learn Weak signal detection Low bandwidth Error correction Data transfer Mic shy / poor conversationalist Why Digital Modes? 15 October 2012Radio in the Digital Age5

Live Keyboard to Keyboard QSO Scripts / Macros – “Recorded” text (e.g. equipment, location) – Custom greetings (with integrated data) – Contest exchanges Data – APRS – – DX Spots Content 15 October 2012Radio in the Digital Age6

Amplitude Shift Keying (ASK): represents digital data as variations in the amplitude of a carrier wave (e.g. CW) Frequency Shift Keying (FSK): digital information is transmitted through discrete frequency changes of a carrier wave – Binary FSK (BFSK): paired frequencies (0 = “space” and 1 = “mark”) – Multiple FSK (MFSK): uses an "alphabet" of M tones – Audio FSK (AFSK): frequency shifted by transmitted audio tone Phase Shift Keying (PSK): conveys data by changing, or modulating, the phase of a reference signal (the carrier wave) – Binary PSK (BPSK): uses two phases which are separated by 180° – Quadrature PSK (QPSK): uses 4 phases, encoding 2 bits per symbol Orthogonal Frequency Division Multiplexed (OFDM): 64 parallel signals Modulation Types 15 October 2012Radio in the Digital Age7

Digital Mode Characteristics 15 October 2012Radio in the Digital Age8 TypeMode Symbol Rate (Baud)WPM Width (Hz) Error Correct Duty Cycle ITU DesignationCoding ASKCW No44%200H0A1AMorse ASKCW No44%50H0A1AMorse ASKFELD-HELL No22%350HA1BNone FSKRTTY No100%270HF1BBaudot FSKRTTY No100%370HF1BBaudot MFSKContestia Yes100%250HF1BASCII-128 MFSKDominoEX Yes/No100%262HF1BASCII-256 MFSKJT65 MFSKMFSK Yes100%316HF1BASCII-256 MFSKOlivia Yes100%250HF1BASCII-128 MFSKTHOR Yes100%262HF1BASCII-256 MFSKTHROB222072No80%72H0F1B44 Chars OFDMMT Yes80%500HJ2DENASCII-128 PSKBPSK No80%63H0G1BASCII-256 PSKBPSK No80%125HG1BASCII-256 PSKQPSK No80%63H0G1BASCII-256 PSKQPSK No80%125HG1BASCII-256

Radio Teletype (RTTY) 15 October 2012Radio in the Digital Age9 Established FSK mode / Keyboard to Keyboard 5 bit Baudot-Murray code represents all letters and numbers + some punctuation (“00100” = space, “00001” = E, “01010” = R); shift between numbers / letters 45 baud (most common mode) corresponds to a typing speed of 60 WPM 50 baud / 75 baud also in use No error correction; QRM/QRN/QSB degrade Many modern HF rigs have RTTY capability / some decode signal AFSK emulation with sound card interface Popular contesting mode (e.g. CQ-WW-RTTY, ARRL RTTY Roundup)

Facsimile image transmission Feld Hell most common for HF, uses ASK (on/off keying) to create images Text characters are "painted" on the screen, as apposed to being decoded and printed Activity centered on special FH events, scheduled QSOs FELD HELL / HELLSCHREIBER 15 October 2012Radio in the Digital Age10

Multi-frequency shift keyed (mode with low symbol rate A single carrier of constant amplitude is stepped between frequencies Full-time forward error correction(sends all data twice) Requires precise frequency alignment Designed for long-path DX Relatively wide bandwidth (316 Hz) allows faster baud rates (typing is about 42 WPM) and greater immunity to multi path phase shift Numerous variants (symbol rate, modulation) MFSK8 15 October 2012Radio in the Digital Age11

MT63 is an Orthogonal Frequency Division Multiplexed (OFDM) mode consisting of 64 parallel carriers each carrying part of the transmitted signal. Highly redundant forward error correction Very robust – compensates for QRM/QRN/QSBto its legendary Relatively wide bandwidth Requires more computer processing power for signal generation / decoding MT63 15 October 2012Radio in the Digital Age12

Binary phase shift keying ASCII-256 user interface is used Narrow bandwidth: less than CW, up to 80 PSK31 signals in bandwidth of 1 SSB signal Weak signal / QRP mode Assuming 500 Hz CW filter, may achieve similar S/N at receiver with 1/15 th power Multiple simultaneous software decode PSK Reporter provides propagation information Extremely popular for keyboard to keyboard QSOs Numerous contesting opportunities (B)PSK October 2012Radio in the Digital Age13

JT65 15 October 2012Radio in the Digital Age14 Developed by K1JT, as part of WSJT for EME and troposcatter QSOs Capable of decoding signals below the noise floor Structured transmissions begin #:01.0 / end #:47.8 – precise clock synchronization required Each frame conveys 72 bits of information additional bits of forward error correction, using MFSK (65 tones) Weak signal mode – 30 watts is considered high power! Typical QSO: – CQ K1JT FN20 – K1JT W6DTW CM97 – W6DTW K1JT -18 – K1JT W6DTW R-16 – W6DTW K1JT RRR – K1JT W6DTW 73 – W6DTW K1JT 73

JT65 QSO 15 October 2012Radio in the Digital Age15

Digital Frequencies 15 October 2012Radio in the Digital Age16 BandDigitalPSKJT65 10 Meters – Meters – Meters – Meters – Meters – Meters – Meters – – Meters – –

Modern transceiver (with rig control [CAT/CI-V]) Sound card interface – Tigertronics – West Mountain Radio – MFJ Enterprises – Buxcom Computer – Windows / Mac OS / Linux / Android / iOS – Some transceivers have encode / decode capability Getting on the Air 15 October 2012Radio in the Digital Age17

Software (many are freeware) – Ham Radio Deluxe / DM780 – WinWarbler – Digipan – MixWMultiPSK – FLDigi – Hamscope – WSJT – Winklink – JT65-HF – MMTTY Getting on the Air 15 October 2012Radio in the Digital Age18

CW/Digital Go Kit 15 October 2012Radio in the Digital Age19

WSPR V4 Chat APRS Pactor / Amtor SSTV Other Modes 15 October 2012Radio in the Digital Age20

– Digital Modes – Sight and Sound (descriptions of various modes)i– – WB8NUT Digital Modes Information Page – Amateur Radio Transmitting Society of Louisville, Kentucky – Digital Modes – The Sights and Sounds of Digital Modes – PSK31 information – Wireless Society of Southern Maine – Digital Modes – WinLINK information INTERNET RESOURCES 15 October 2012Radio in the Digital Age21

15 October 2012Radio in the Digital Age22