introduction to digital modes

Introduction to Digital ModesCreede Lambard WA7KPK

INTRODUCTION TO DIGITAL MODES

Creede Lambard, WA7KPKMercury Northwest

November 2012


What is a digital mode?


What is a digital mode?

● Any amateur radio mode that can or must be received, presented, encoded and transmitted by the use of a computer or other dedicated digital device.


The first digital mode



● Morse code!



● Morse code● CW



● Morse code● CW● Frequency-Shift Keying (FSK)


Radioteletype (RTTY)



● Developed when AM was king



● Developed when AM was king● War surplus Teletype machines



● Developed when AM was king● War surplus Teletype machines● Uses FSK on both sidebands


Radioteletype (RTTY)● Developed when AM was king● War surplus Teletype machines● Uses FSK on both sidebands● Uses Baudot encoding (5 bits)


Packet Radio


Packet Radio

● Sort of an “internet via amateur radio”


Packet Radio

● Sort of an “internet via amateur radio”● First became feasible in 1980 when the

FCC allowed transmission of ASCII via ham radio


Packet Radio



● Primarily uses dedicated equipment for communication (TNC)


Packet Radio



● Primarily uses dedicated equipment for communication (TNC)

● Does error correcting


Personal Computers & Sound Cards



● RTTY modem software developed for PC



● RTTY modem software developed for PC● PC software emulating a TNC is available



● RTTY modem software developed for PC● PC software emulating a TNC is available● Research on creating narrow-bandwidth

PC-based modes




PC-based modes● FCC allows ASCII transmission




PC-based modes● FCC allows ASCII transmission● FCC allows other encodings provided they

are published into the public domain


PSK-31


PSK-31

● Created by Peter Martinez (G3PLX) in 1998


PSK-31


● Stands for “phase shift keying”


PSK-31


● Stands for “phase shift keying”● Bandwidth: 31 hz


PSK-31


● Stands for “phase shift keying”● Bandwidth: 31 hz● 80-90 QSOs in the width of a typical SSB

signal


PSK-31


PSK-31


● Stands for “phase shift keying”● Bandwidth: 31 hz● 80-90 QSOs in the width of a typical SSB

signal● Does not do error correcting


Other Digital Modes


Other Digital Modes

● Drinking from the firehose!


Other Digital Modes

● Olivia MFSK


Other Digital Modes

● Olivia MFSK● Developed by Pavel Jalocha (SP9VRC), 2003● Named after his daughter


Other Digital Modes

● Olivia MFSK


Other Digital Modes

● Olivia MFSK● Developed by Pavel Jalocha (SP9VRC), 2003● Named after his daughter● FEC enabled


Other Digital Modes

● Olivia MFSK● Developed by Pavel Jalocha (SP9VRC), 2003● Named after his daughter● FEC enabled● Can be decoded even when below the noise

floor


Other Digital Modes

● MT63


Other Digital Modes

● MT63● Also developed by Jalocha● Similar in some ways to Olivia


Other Digital Modes

● MT63● Also developed by Jalocha● Similar in some ways to Olivia● Used for emergency communications due to

robust FEC


Other Digital Modes

● Several other modes● DominoEX● Thor● Throb● Hellschreiber


JT65


JT65

● “Music Box” mode


JT65

● Developed by Joe Taylor, K1JT


JT65

● Developed by Joe Taylor, K1JT● Also chair of astrophysics department at

Princeton


JT65


Princeton● Also Nobel Prize laureate in physics


JT65


Princeton● Also Nobel Prize laureate in physics

● Based in meteor scatter and EME


JT65● Developed by Joe Taylor, K1JT

● Also chair of astrophysics department at Princeton● Also Nobel Prize laureate in physics

● Based in meteor scatter and EME● Not a keyboard-to-keyboard mode● Based on the minimal information necessary

to conduct a QSO


JT65


A typical JT65 QSO


A typical JT65 QSO

● CQ WA7KPK CN87● (each transmission is one minute long)● (CQ was sent on an even minute)


A typical JT65 QSO

● CQ WA7KPK CN87● WA7KPK JH1KYA PM95

● (reply was sent on an odd minute)


A typical JT65 QSO

● CQ WA7KPK CN87● WA7KPK JH1KYA PM95● JH1KYA WA7KPK -15


A typical JT65 QSO

● CQ WA7KPK CN87● WA7KPK JH1KYA PM95● JH1KYA WA7KPK -15● WA7KPK JH1KYA R-10


A typical JT65 QSO

● CQ WA7KPK CN87● WA7KPK JH1KYA PM95● JH1KYA WA7KPK -15● WA7KPK JH1KYA R-10● JH1KYA WA7KPK RRR


A typical JT65 QSO

● CQ WA7KPK CN87● WA7KPK JH1KYA PM95● JH1KYA WA7KPK -15● WA7KPK JH1KYA R-10● JH1KYA WA7KPK RRR● WA7KPK JH1KYA 73


A typical JT65 QSO● CQ WA7KPK CN87● WA7KPK JH1KYA PM95● JH1KYA WA7KPK -15● WA7KPK JH1KYA R-10● JH1KYA WA7KPK RRR● WA7KPK JH1KYA 73● 30W DPL TU 73


Hardware requirements



● Transceiver (of course)



● Transceiver (of course)● Computer (the faster the better, especially

for higher-latency modes like JT65 or Olivia)





● Sound card or dedicated USB device (e.g. Signalink or Rigblaster)





● Sound card or dedicated USB device (e.g. Signalink or Rigblaster)

● Cables to connect radio to computer


Software


Software

● Ham Radio Deluxe● Very comprehensive (read: steep learning

curve)● Includes most digital modes● Current version (5.0) is donationware; next

version (6.0) will be $60● Numerous other bells and whistles● Windows only


Software

● Fldigi● Reasonably fast● Keyboard-to-keyboard modes only (no JT65)● Developer is very responsive● Associated utilities: flrig (rig control), flmsg, etc.● Windows/Linux/Mac


Software

● JT65-HF● JT65 and similar modes only (no keyboard-to-

keyboard)● IMO much superior to the original JT65

software for HF use● Developer in poor health● Windows only; Linux version does not work on

recent distributions


Software

● Others


Software

● Your favorite browser● Useful for propagation maps, callsign lookups,

help with your program, etc.● Logging program (your preference)


My digital software setup


Comments/questions?


This deck will be available at

http://www.lambard.net/radio/digitalmodes.ppt


Thank you!!

73 ES GUD DXDE WA7KPK!!

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