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Digital VHF Weak Signal Modes

Discover the world of VHF propagation modes beyond the norm. Learn about Aurora, Meteor Scatter, Moon Bounce, and more for long-distance communication using WSJT software and specialized equipment.

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Digital VHF Weak Signal Modes

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  1. Digital VHF Weak Signal Modes Gary Sutcliffe, W9XT Ken Boston, W9GA

  2. Esoteric “Space” VHF Propagation Modes Want to make distant contacts beyond “normal range” • Aurora - bounce off northern lights • 6 & 2M, mostly CW, “Donald Duck” on SSB • Meteor scatter – bounce off ionized meteor trails • Mostly 6 & 2M, SSB, WJST • Popular during meteor showers • Moon bounce (EME) – use moon as a reflector • 6M & up, CW, SSB, WJST • 2M most popular band

  3. WSJT – Weak Signal Joe Taylor • Written by K1JT – Joe Taylor • 3 Modes • JT6M – Scatter on 6M • FSK441 – Meteor scatter • JT65 – Moon Bounce • Each mode optimized for that type of operation • JT6M – weak signals from scatter • FSK441 – short bursts, Doppler shift • JT-65 – Very weak signals, slow fading, slow Doppler shift

  4. What do you need? • Stuff you have • VHF Transceiver – must have SSB mode • Antenna • PC • Stuff you need to get • PC/Rig interface (inexpensive – build or buy) • WSJT program – Free download!

  5. Sound Card Interface Unified Microsystems SCI-6 Sound Card Interface Schematic

  6. WSJT Software • Free down load • http://physics.princeton.edu/pulsar/K1JT/wsjt.html • Standardized QSO formats – not a rag chew mode • Step by step defined sequences • 30 or 60 second transmit/receive periods • Requires synchronized PC clocks

  7. WJST User Interface

  8. WSJT QSO Sequence Stations alternate 30 or 60 sec. transmissions: Station 1 Transmission Station 2 Transmission CQ W9XT EN53 W9XT W1XYZ GRID W1XZY W9XT RPT R RPT RRR 73

  9. Meteor Scatter • Meteor burst • Several milliseconds to maybe 30 seconds, short ones much more common • Longer on 6M, short on 2M, very short 222 MHz • Maybe 1 burst per minute visible during a good shower • Maximum range out to about 1200-1400 miles. • Station Requirements • 50-100W good, more is better • Medium sized antenna best • High gain antennas too narrow – don’t know exactly were meteor will appear

  10. FSK441 – Meteor Scatter

  11. Moon Bounce • Signal path • Round trip to moon and back ~2.4 seconds. • 250 dB loss • Station Requirements • 100W single long Yagi minimum – work a few really big stations • 350W, 4 Yagis with elevation – can work equivalent stations • Need to track moon Az-El

  12. JT65 – Moon bounce

  13. W5UN

  14. W9XT “QRP” EME Station • Equipment: • Yaesu FT-847 All mode transceiver • Mirage B2518G 150W 2M amp • Cushcraft 13B2 13 element Yagis (2) • CATV 75Ωhardline • Dell PC running XP • Unified Microsystems SCI-6 PC I/F • Plans for 2012: • Increase to 4 Yagis • KW amp

  15. W9GA EME Station Equipment: 144 system: Kenwood TS-711 2M All mode transceiver Henry 2002 2M 700 W amp 2 X 9 el M2 Yagis, hand aimed (not shown) M2 preamp Laptop PC 50 MHz system: Yaesu FT1000MP mkV w/FTV1000 H.B. KW amp with a pair of 3CX800s 2 X 6M5X vertically pol, with elevation PC with WSJT

  16. 50 MHz EME antenna

  17. QSLs received

  18. Scatter Modes • Lots of propagation modes • F2 – Regular HF propagation mode if high solar levels • Es - Common in spring months • JT6M lets you make contacts when there is not enough signal to make CW & SSB QSOs

  19. JT6M – Scatter modes (6M)

  20. Ping Jockey

  21. WSJT Resources • WSJT Download: www.physics.princeton.edu/pulsar/K1JT/ • N0UK Ping Jockey page: http://www.pingjockey.net/cgi-bin/pingtalk • Unified Microsystems: www.unifiedmicro.com • Inexpensive PC sound card to radio interface kit • ON4KST chat page: www.on4kst.org/chat Slide deck will be put up on www.w9xt.com

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