Radio in the Digital Age

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10 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

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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

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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 Age

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15 October 2012

Where I Started

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Radio in the Digital Age

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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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Radio in the Digital Age

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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)

WPM

Width

(Hz)

Error

Correct

Duty
Cycle

ITU

Designation

Coding

ASK

CW
-
100

50

100

200

No

44%

200H0A1A

Morse

ASK

CW
-
20

10

20

50

No

44%

50H0A1A

Morse

ASK

FELD
-
HELL

123

25

350

No

22%

350HA1B

None

FSK

RTTY
-
45

45

60

270

No

100%

270HF1B

Baudot

FSK

RTTY
-
75

75

100

370

No

100%

370HF1B

Baudot

MFSK

Contestia 8
-
250

31

30

250

Yes

100%

250HF1B

ASCII
-
128

MFSK

DominoEX11

11

80

262

Yes/No

100%

262HF1B

ASCII
-
256

MFSK

JT65















MFSK

MFSK8

8

36

316

Yes

100%

316HF1B

ASCII
-
256

MFSK

Olivia 8
-
250

31

15

250

Yes

100%

250HF1B

ASCII
-
128

MFSK

THOR11

11

40

262

Yes

100%

262HF1B

ASCII
-
256

MFSK

THROB2

2

20

72

No

80%

72H0F1B

44 Chars

OFDM

MT63
-
500

5

50

500

Yes

80%

500HJ2DEN

ASCII
-
128

PSK

BPSK
-
31

31

50

62

No

80%

63H0G1B

ASCII
-
256

PSK

BPSK
-
63

63

100

125

No

80%

125HG1B

ASCII
-
256

PSK

QPSK
-
31

31

50

62

No

80%

63H0G1B

ASCII
-
256

PSK

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 1/15
th

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

18.102

18.106

20 Meters

14.065


14.090

14.070

14.076

30 Meters

10.130



10.145

10.142

10.139

10.147

40

Meters

7.030


7.040

7.060


7.080

7.035

7.039

7.076

80 Meters

3.575


3.585

3.620



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


D
i
gital 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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