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HF Digital 102

Stan Gordon K7JIZ K7HFV. HF Digital 102. You can have fun with simple equipment. Digital vs. Analogue. Digital can be defined in steps - - On or Off; Numbers

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HF Digital 102

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  1. Stan Gordon K7JIZ K7HFV HF Digital 102

  2. You can have fun with simple equipment

  3. Digital vs. Analogue • Digital can be defined in steps - - On or Off; Numbers • Analogue - - Smoothly varying properties; not easily expressed in numbers (e.g., Speech, Sweep 2d hand on a clock)

  4. FCC Rules for HF Digital • Modes must have technical characteristics which are documented publicly for the purpose of facilitating communications. (97.309 (a)(4) • Below 28 Mhz can not exceed 1 kHz in width. (97.305 notes 3 and 4) • Station ID may be done in the mode or with CW. (97.119 (b)(3)) • Can not be encrypted to hide meaning

  5. Getting Started • Need a stable SSB transceiver • Computer with a sound card • Method of controlling transmission (PTT or VOX) • Sound card output attenuation.If you don't you’ll overdrive the rig. • Computer program for the mode or modes to be operated.

  6. Sound Card Interfacing Output Attenuation Rig Computer 470 Ohm Microphone in or Aux Speaker out 8 Ohm Capactor To block DC. Line-in Spkr or Aux out PTT Means

  7. A PTT System Rig Computer PTT on Mic or Aux 47k Ohm NPN Serial Port (9 Pin) 7 or 4 (25 Pin) 4 or 20 Common Ground

  8. Off the Shelf Interface Rigblaster plus II $159 West Mountain Radio

  9. TERMS • AFSK - Audio Frequency Shift Keying • Varicode - different size (bits) for each character space 100, e 1100, E 111011100. • FEC - Forward Error Correcting • Macro - pre written “Standard” messages • Type ahead - simultaneous pre typing of your response as your receive text.

  10. Popular MODES • PSK (31, 63, 125) • RTTY (45) • JT65 (A, B or AFSK 441) • OLIVIA (8/250, 16/500) • HELLSCHRIBER • V4Chat • Others poping up all the time

  11. Some Digital Software • Multi Mode Programs: Fldigi or Ham Radio Deluxe are the”Swiss Army knives of the digital world. Each provides all popular modes. • JT65 Stand alone program (WSJT) • V4 Chat Stand alone program • Other programs are being developed all the time. The internet is a quick way to get programs.

  12. Fldigi screen capture

  13. Ham Radio Deluxe

  14. Sounds of PSK31 PSK31 on HF

  15. PSK 31 • Very popular mode using phase shift keying • Band width 100 Hz or less; Text 50 wpm. • No FEC; Varicode • Good weak signal, but fade and noise will affect reception. Helps to use narrow filters.

  16. Log RX area Tx Here Your text goes here! Macro bar Water fall display QSOs Ham Radio Deluxe Screen Shot

  17. SOUND of RTTY on HF Radio Teletype at 50 WPM

  18. Radio Teletype (RTTY) • Two Tone - 170 Hz shift, Fixed Length Code. • Easy to obtain software • Operation is USB, AFSK • Lots of contest activity and DX • No FEC; affected by noise and fading; fair low signal copy

  19. Screen of TrueTTY Tune area RX text Signal Transmitted text Marco Area Type your text here

  20. JT65A on HF Great weak signal mode so listen closely. Program will “decode” signals you can't even hear..

  21. JT65 • Weak signal program for meteor,EME and HF. (EME is best done during a full moon) • Needs accurate computer time!! • Fixed format messages with little chance to change – not keyboard to keyboard • 170 Hz bandwidth and most operation is 76 Khz from bottom of band • Lots of DX stations on 20, 15 and 10

  22. JT65 Screen Capture One Minute Cycle Time for JT65A &B 30 Second AFSK 441 RX Area Fixed Format Messages

  23. Olivia on HF There are sixteen tones spread over 500Hz – mode called 16/500

  24. Olivia • Excellent keyboard to keyboard mode but some subsets are slow (20 wpm or less) • Bandwidth varies by mode subset: Common 8/250 which is 8 tones and 250hz wide and 16/500 sixteen tones and 500hz wide • Fade resistant and good weak signal work. Very robust reception

  25. Olivia Screen Shot

  26. Hellschriber Sounds Sounds a little like highspeed CW

  27. Hellschriber • A “fuzzy”, analogue, direct viewing (real time), 1929 mode. Looks like facsimile. • Key on for black and key off for white; time differential for parts of characters. • Good resistance to noise and polar fade. DX on 20 meters and up.

  28. V4 Chat • Robust operation even in weak signal conditions – both ARQ and FEC • Support for modest typing speeds (40-60 words/minute). • Automatic capture, tuning and tracking (+/- 100Hz). • See page 62 April 2014 QST for more information

  29. V4 Cat Screen Shot

  30. Other Digital Modesyou may see and hear • MSK 16 or 32. Robust but not popular • Contesta. Simular to Olivia • Throb 2,3,or 4 tones on very narrow band width • Packet (AX.25 protocol) HF is 300 baud; error correcting • Many others being used and more coming on line all the time. • Mother of all digital is CW

  31. Digital Tips • Don’t over drive your audio Input. ALC should just flicker (zero is good!) • Use USB • Must have a “Stable” Rig • Macros and the use of “Type ahead” really makes conversations smooth. • Digital round tables can be done in any mode. • Read the software HELP FILES

  32. Tips Page 2 • Tune with the software, using point and click, not the rig dial. • Frequencies are about 70 kHz from band bottom (14070 kHz to 14090 kHz) so hear and look. • Don’t use your speech processor • Be patient there is not a lot of Hell activity but PSK31 is very active. • Read the software help files!!!

  33. To get more information: • Internet search for Ham Digital Modes – Google, Bling, etc • Download software and technical data and extended help • User groups on Amazon and other social media programs • Utah Amateur Radio Club members and local digital users

  34. Digital Future • Computers becoming more powerful and costs continue to drop. • Most amateurs have computers with sound cards. • Internet is efficient means to distribute new software and updates (download your needs). • Use the same computer system for all modes. • Laptops and tablets work just fine.

  35. TNX and 73 Stan and Gordon Questions?

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