Soundcard Digital Modes

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Soundcard Digital Modes

• Tyler Griffiths
• N7UWX

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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 .
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Computer/Radio Interfacing
Line or Speaker Output
Interface
Line or Mike Input
COM Port
COM Port
Transmit Audio
Receive Audio
Push-to-talk (PTT)
Computer ControlCI-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.
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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)
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Sound Card Digital Modes

• Connecting your Radio to your Computer
• T/R Connection

CW PSK31 RTTY PACKET APRS FSK411 JT44 EME
http//www.sv2agw.com/downloads/
PTT is controlled via the RTS and/or DTR outputs
of the computers RS-232 serial port.
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Sound Card Digital Modes

• Connecting your Radio to your Computer
• T/R Connection

CW PSK31 RTTY PACKET APRS FSK411 JT44 EME
http//www.sv2agw.com/downloads/
PTT is controlled via the RTS and/or DTR outputs
of the computers RS-232 serial port.
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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 Frequency VHF Band Frequency
160 M 1807 KHz 6 M 50.290 MHz
80 M 3580 KHz 2 M 144.144 MHz
40 M 7070 KHz 1.25 222.070 MHz
30 M 10140 KHz 70 cm 432.200 MHz
20 M 14070 KHz 33 cm 909.000 MHz
17M 18100 KHz
15M 21080 KHz
12M 28120 KHz Most PSK 31 is USB 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

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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 doppler,
  fading and multi-path

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HamScope Software
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DigiPan Software
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(No Transcript)
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fldigi Software
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Winmor (Winlink 2000)
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APRS Software
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Digital ModesWaterfalls
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. Thats 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
  memorythey 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

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JT44 EME Use

• JT44s 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

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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 SoundcardInterface
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

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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.c
  om/
• Winlink 2000 http//www.winlink.org
• Signal link USB http//www.tigertronics.com/sl
  usbmain.htm
• West Mt. Radio http//www.westmountainradio.com
  /rigblaster.php
• microHAM
• http//www.microham.com/contents/en-us/d158_U3.htm
  l
• Rascal http//www.packetradio.com
• Rig Expert
• http//www.arraysolutions.com/Products/rig_expert_
  standard.htm
• AGW Packet Engine http//www.sv2agw.com/downlo
  ads/
• KB3KAO Sound card TNC http//www.kb3kai.com/sou
  nd-card-tnc
• Sound Card Packet http//www.soundcardpacket.o
  rg/
• Web Radios http//www.websdr.org/