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Radio in the Digital Age

Radio in the Digital Age

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Radio in the Digital Age

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  1. Radio in the Digital Age Steven F. Goldberg, W3SFG

  2. Radio in the Digital AgeSeries Outline • Part 1: Internet Operating Aids • Part 2: Survey of Digital Operating Modes • Part 3: Internet Resources and Databases • Part 4: Software Applications http://w3sfg.net/resources/ Radio in the Digital Age

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

  4. Where I Started Radio in the Digital Age

  5. Why Digital Modes? • Computer encode / decode • No Morse Code to learn • Weak signal detection • Low bandwidth • Error correction • Data transfer • Mic shy / poor conversationalist Radio in the Digital Age

  6. Content • Live Keyboard to Keyboard QSO • Scripts / Macros • “Recorded” text (e.g. equipment, location) • Custom greetings (with integrated data) • Contest exchanges • Data • APRS • Email • DX Spots Radio in the Digital Age

  7. Modulation Types • 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 Radio in the Digital Age

  8. Digital Mode Characteristics Radio in the Digital Age

  9. Radio Teletype (RTTY) • 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) Radio in the Digital Age

  10. FELD HELL / HELLSCHREIBER • 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 Radio in the Digital Age

  11. MFSK8 • 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) Radio in the Digital Age

  12. MT63 • 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 Radio in the Digital Age

  13. (B)PSK-31 • 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 1/15th power • Multiple simultaneous software decode • PSK Reporter provides propagation information • Extremely popular for keyboard to keyboard QSOs • Numerous contesting opportunities Radio in the Digital Age

  14. JT65 • 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 + 306 additional bits of forward error correction, using MFSK (65 tones) • Weak signal mode – 30 watts is considered high power! • Typical QSO: • CQ K1JTFN20 • K1JTW6DTWCM97 • W6DTWK1JT -18 • K1JTW6DTWR-16 • W6DTWK1JT RRR • K1JTW6DTW73 • W6DTWK1JT73 Radio in the Digital Age

  15. JT65 QSO Radio in the Digital Age

  16. Digital Frequencies Radio in the Digital Age

  17. Getting on the Air • 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 Radio in the Digital Age

  18. Getting on the Air • Software (many are freeware) • Ham Radio Deluxe / DM780 • WinWarbler • Digipan • MixWMultiPSK • FLDigi • Hamscope • WSJT • Winklink • JT65-HF • MMTTY Radio in the Digital Age

  19. CW/Digital Go Kit Radio in the Digital Age

  20. Other Modes • WSPR • V4 Chat • APRS • Pactor / Amtor • SSTV Radio in the Digital Age

  21. INTERNET RESOURCES • http://www.w1hkj.com/FldigiHelp-3.20/Modes/index.htm • Digital Modes – Sight and Sound (descriptions of various modes) • http://wb8nut.com/digital/ • WB8NUT Digital Modes Information Page • http://www.w4cn.org/about-ham-radio/digital-modes • Amateur Radio Transmitting Society of Louisville, Kentucky – Digital Modes • http://wiki.ham-radio-deluxe.com/index.php?title=DigitalSignals • The Sights and Sounds of Digital Modes • http://www.arrl.org/tis/info/HTML/psk31/index.html • PSK31 information • http://www.qsl.net/ws1sm/digital.html • Wireless Society of Southern Maine – Digital Modes • http://winlink.org/ • WinLINK information Radio in the Digital Age

  22. Radio in the Digital Age