Soundcard Digital
Modes
Tyler Griffiths
N7UWX
Evolution of Acronyms
Human transmitted digital

CW – Operator determines performance
Machine sent digital

RTTY – Baudot 5-bit code
Machine sent corrected data packets

Packet – APRS – TCP/IP
High noise immunity RTTY replacements

PSK31 – QPSK – MFSK – MT63
Intermittent channel weak-signal modes

HSCW – FSK441 (WSJT)
Extreme weak signal mode

JT44 (WSJT)
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Sound Card Digital Modes
Connecting your Radio to your Computer
You can purchase an interface to connect your transceiver
to your computer, OR you can make your own for a few $.
Computer/Radio Interfacing
Line or Speaker Output
Line or Mike Input
Interface
COM Port
COM
Port
Push-to-talk
(PTT)
Receive
Audio
Transmit
Audio
144.390
Computer
Control
CI-V or CAT
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Sound Card Digital Modes
Connecting your Radio to your Computer
Receive Audio Connection:
Connect an audio cable between the transceiver audio
output and the soundcard LINE IN jack.
Sound Card Digital Modes
Connecting your Radio to your Computer
Transmit Audio Connection:
Connect a shielded audio cable between the transceiver
MIC input and the soundcard LINE OUT jack through a
40 db attenuator. If your transceiver has a LINE input,
no attenuation is required. (eliminate the 2 resistors)
Sound Card Digital Modes
CW
PSK31
Connecting your Radio to your
Computer
T/R Connection:
RTTY
PACKET
APRS
FSK411
http://www.sv2agw.com/downloads
/
JT44
EME
PTT is controlled via the RTS and/or DTR outputs of the
computer’s RS-232 serial port.
Sound Card Digital Modes
CW
PSK31
Connecting your Radio to your
Computer
T/R Connection:
RTTY
PACKET
APRS
FSK411
http://www.sv2agw.com/downloads
/
JT44
EME
PTT is controlled via the RTS and/or DTR outputs of the
computer’s RS-232 serial port.
Soundcard Packet
AGW Packet Engine for 1200 or 9600
Supports Terminal, TCP/IP, DX Cluster,
Digipeater
APRS Software support via APRSPoint, UI
View and WinAPRS
Supports multiple simultaneous
connections
Allows remote use over a network/Internet
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PSK 31
Designed by Peter G3PLX
Based on the RTTY mode of operation useful for live
keyboard to keyboard QSO
Works at 31.25 bauds
Uses varicode character coding providing 50wpm
Give very good copy under low Eb/No numbers and is
thus suitable for QRP
That instead of using FSK or on/off keying uses BPSK or
QPSK with a Viterbi decoder
Uses advanced DSP and narrow band (31 Hz!!)
techniques
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PSK 31 Frequencies
HF Band
160 M
80 M
40 M
30 M
20 M
17M
15M
12M
Tyler Griffiths - N7UWX
Frequency
1807 KHz
3580 KHz
7070 KHz
10140 KHz
14070 KHz
18100 KHz
21080 KHz
28120 KHz
VHF Band
6M
2M
1.25
70 cm
33 cm
Frequency
50.290 MHz
144.144 MHz
222.070 MHz
432.200 MHz
909.000 MHz
Most PSK 31 is USB
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QPSK
Quadernary Phase-Shift Keying








Four phases instead of 2 for PSK
Extra capacity used for error-correction
Improvements of up to 5 fold in error-rate
Not as good for QRP (3dB hit)
Extra transmission delay
More frequency sensitive (within 4Hz)
Must use correct sideband
Start BPSK and switch to QPSK
Tyler Griffiths - N7UWX
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MFSK 16
Multiple frequency-shift keying (MFSK) is a
variation of frequency-shift keying (FSK) that
uses more than two frequencies.
Sixteen tone carriers, ~16Hz apart
42 WPM in 316Hz with FEC
High rejection of pulse and broadband noise due
to narrow bandwidth per tone
Low baud rate for sensitivity and multi-path
rejection - data bit rate higher than symbol baud
rate
Tolerance of ionospheric effects such as
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Tyler doppler,
Griffiths - N7UWX fading and multi-path
HamScope Software
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DigiPan Software
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fldigi Software
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Winmor (Winlink 2000)
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APRS Software
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Digital Modes
Waterfall’s
CW
PSK-31
QSPK
PACKET
RTTY
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Interesting Waterfall!
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FSK 441 - WSJT
Frequency-shift keying (FSK) is a frequency
modulation scheme in which digital information is
transmitted through discrete frequency changes of
a carrier wave.[
100% duty cycle, so no extra energy wasted by On/Off
keying
More user-friendly interface--like RTTY or PSK31 modes
Much better S/N than HSCW at same speed
Each character takes about 2.3ms to send with four
tones. That’s 441 baud.
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JT 44 - WSJT
Uses long term signal averaging to recover a signal that
is up to 30dB below the noise floor!
Humans have “short ears” limited by their sensory
memory—they can only analyze a signal in a small
timeframe
Computers can analyze in relatively large timeframes
Inspired by the PUA43 mode (with dedicated hardware)
Uses 44 tones, one for each character in the PUA43
alphabet (same as FSK441), plus a synchronization
tone. Each character is assigned a unique frequency
Slow transmission speed: 5.38 baud
Highly redundant (FEC)
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JT44 – Terrestrial Use
JT44 works well on troposcatter paths that
are too short for MS enhancement
Several operators have used it on 6m for
borderline TE, and marginal Es openings.
Microwave non-line-of-sight paths
Could be a good way of overcoming
atmospheric absorption above 10GHz
Contest stations can make otherwise
impossible contacts
Tyler Griffiths - N7UWX
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JT44 – EME Use
JT44’s ability to recover extremely weak
signals makes it ideal for EME
Most activity by arranged schedule.
144MHz is the most popular band.
Also operation on 50 MHz, 432MHz, and
1296 MHz so far….
A pair of single-yagi stations should be
able to work each other, with QRO power
Portable EME operation can be a reality
Tyler Griffiths - N7UWX
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What Does It Take?
Windows PC


Windows 98 or higher recommended
Pentium 150MHz or better
SoundBlaster compatible soundcard


Most laptop sound systems work
More expensive cards have less noise and
are more frequency stable/accurate
Interface cabling

RigBlaster or Rascal interfaces not necessary
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Soundcard Interfacing
Most radios have audio in/out PTT on
back via a Data or AUX port
These line level in/outs are best
Mike/speaker levels can be used with
appropriate attenuation
PTT support generally via transistor or
optoisolator switch
PTT can be done with CAT port but
requires radio-specific software
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PTT Switching
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Soundcard Interface
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Soundcard Interface
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Built-in Soundcard
Interface
West Mountain
RIGblaster Advantage
$189.95
Tigertronics
SignaLink USB
$99.99
microHAM
USB Interface III
$155.00
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Remote Control
Radio tuning, antenna rotation,
transmission and reception are all
computer controllable
This software is easily remote controlled
via Terminal Server, Team Viewer or
NetMeeting
Using Skype to talk on the radio
Access can be via LAN or Internet
There are shared radios on the Internet
Tyler Griffiths - N7UWX
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Resources
DigiPan:
http://www.digipan.net/
Fldigi:
http://www.w1hkj.com/Fldigi.html
Ham Radio Deluxe:
http://www.ham-radio-deluxe.com/
Winlink 2000:
http://www.winlink.org
Signal link USB:
http://www.tigertronics.com/slusbmain.htm
West Mt. Radio: http://www.westmountainradio.com/rigblaster.php
microHAM

http://www.microham.com/contents/en-us/d158_U3.html
Rascal:
Rig Expert

http://www.packetradio.com
http://www.arraysolutions.com/Products/rig_expert_standard.htm
AGW Packet Engine:
http://www.sv2agw.com/downloads/
KB3KAO Sound card TNC: http://www.kb3kai.com/sound-card-tnc
Sound Card Packet:
http://www.soundcardpacket.org/
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Tyler Griffiths - N7UWX
Web Radios
http://www.websdr.org/