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

http://w3sfg.net/resources/

15 October 2012 Radio in the Digital Age 2

Radio in the Digital AgeSeries Outline

Radio in the Digital AgePart 2: Digital Operating Modes

Steven F. Goldberg, W3SFG15 October 2012

Radio in the Digital Age 315 October 2012

Where I Started

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• Computer encode / decode• No Morse Code to learn• Weak signal detection• Low bandwidth• Error correction• Data transfer• Mic shy / poor conversationalist

Why Digital Modes?

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• 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

Content

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• 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

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Digital Mode Characteristics

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Type Mode

Symbol Rate

(Baud) WPMWidth

(Hz)Error

CorrectDuty Cycle

ITUDesignation Coding

ASK CW-100 50 100 200 No 44% 200H0A1A MorseASK CW-20 10 20 50 No 44% 50H0A1A MorseASK FELD-HELL 123 25 350 No 22% 350HA1B NoneFSK RTTY-45 45 60 270 No 100% 270HF1B BaudotFSK RTTY-75 75 100 370 No 100% 370HF1B Baudot

MFSK Contestia 8-250 31 30 250 Yes 100% 250HF1B ASCII-128MFSK DominoEX11 11 80 262 Yes/No 100% 262HF1B ASCII-256MFSK JT65 MFSK MFSK8 8 36 316 Yes 100% 316HF1B ASCII-256MFSK Olivia 8-250 31 15 250 Yes 100% 250HF1B ASCII-128MFSK THOR11 11 40 262 Yes 100% 262HF1B ASCII-256MFSK THROB2 2 20 72 No 80% 72H0F1B 44 CharsOFDM MT63-500 5 50 500 Yes 80% 500HJ2DEN ASCII-128

PSK BPSK-31 31 50 62 No 80% 63H0G1B ASCII-256PSK BPSK-63 63 100 125 No 80% 125HG1B ASCII-256PSK QPSK-31 31 50 62 No 80% 63H0G1B ASCII-256PSK QPSK-63 63 100 125 No 80% 125HG1B ASCII-256

Radio Teletype (RTTY)

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• 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

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• 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

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• 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

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• 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

(B)PSK-31

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JT65

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• 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 K1JT FN20– K1JT W6DTW CM97– W6DTW K1JT -18 – K1JT W6DTW R-16– W6DTW K1JT RRR – K1JT W6DTW 73– W6DTW K1JT 73

JT65 QSO

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Digital Frequencies

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Band Digital PSK JT65

10 Meters 28.110 – 28.125 28.120 28.076

12 Meters 24.920 – 24.930 24.920 24.920

15 Meters 21.060 – 21.090 21.070 21.076

17 Meters 18.100 – 18.110 18.100 18.10218.106

20 Meters 14.065 – 14.090 14.070 14.076

30 Meters 10.130 – 10.145 10.142 10.13910.147

40 Meters 7.030 – 7.0407.060 – 7.080 7.035 7.039

7.076

80 Meters 3.575 – 3.5853.620 – 3.640 3.580 3.576

• 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

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• Software (many are freeware)– Ham Radio Deluxe / DM780– WinWarbler– Digipan– MixWMultiPSK– FLDigi– Hamscope– WSJT– Winklink– JT65-HF– MMTTY

Getting on the Air

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CW/Digital Go Kit

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• WSPR• V4 Chat• APRS• Pactor / Amtor• SSTV

Other Modes

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• 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

INTERNET RESOURCES

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