Monthly Archives: August 2024

Special Joint (VK4 & VK7) Presentation Night – Optical Communications with Rex VK7MO

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REAST and BVHFG Joint Presentation Night Recap – 28th August 2024

On Wednesday night, 28th August 2024, the Radio and Electronics Association of Southern Tasmania (REAST) and the Brisbane VHF Group (BVHFG) made history with their first-ever joint presentation night. This special event, featuring contributions from both clubs, brought together amateur radio enthusiasts from across Australia, with a focus on optical communications.

Presentation Highlights:

  • History of Optical Communications: Rex provided an overview of the history of LEDs and lasers in amateur radio, referencing the pioneering work documented on modulatedlight.org.
  • Detector Choices: Discussions on the pros and cons of different detectors, including red, blue, and infrared options.
  • The “Something for Nothing” Law & Line of Sight: Rex explained the physics behind line-of-sight communications and how natural and man-made obstacles affect signal propagation.
  • Building Reflection & Over-the-Horizon: Techniques to extend the range of optical communications beyond the horizon, leveraging building reflections.
  • Stanley to Mt Horror and Beyond: The remarkable 288km optical communication link from Stanley to Mt Horror, followed by Mt Horror to Cape Liptrap. Rex also shared some gripping stories from the Mt Horror bushfire and police encounters.
  • Weak Signal Communications: Demonstrations of signal decodes using Weak Signal Communicator (VK3HZ) software, showcasing the power of weak signal modes in optical comms.
  • Recent Developments: Updates on the latest in optical communication technology, including the FST4 mode, advancements in LEDs, and lens performance improvements.
  • Test Results: A summary of tests conducted from White Hills to VK7ZBX using FST4 mode, comparing equipment performance at wavelengths from 630nm to 730nm.
  • Propagation and Signal-to-Noise Ratio: An exploration of how different cloud types in Tasmania and aerosols affect signal propagation and SNR.
  • Safety Concerns: Public concerns about the use of bright red LEDs and eye safety were addressed, emphasizing the importance of responsible experimentation.

The presentation concluded with a lively Q&A session, with special thanks extended to Rex VK7MO, Richard VK7ZBX and Justin VK7TW for their contributions.

Video of the event is available at the REAST Youtube channel.

For those interested in further reading, historic research papers on optical communications experimentation in VK7 can be found on the REAST website: Optical Transmissions.

REAST @ the Australian Antarctic Festival

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The Australian Antarctic Festival rolls around every two years and in 2024 REAST was asked if it would like to participate with a focus on radio in Antarctica.

https://www.mawsons-huts.org.au/2024-festival-program/

We jumped at the chance and thanks to Kim Briggs VK7KB and Justin Giles-Clark VK7TW we were able to source a chronology of ex-Antarctic radio equipment for the display.

AAF 2024 - REAST Stand

AAF 2024 – REAST Stand

From the 1911-14 Mawson Expedition we had a spark transmitter / receiver thanks to Richard VK7RO and we had the output going out loud on an amplified speaker that caused people to jump when they heard it – the kids thought it sounded like a fart which got people laughing!

We moved to Collins gear from the 1940-50-60 with some great supplementary pictures from the Australian Antarctic Division.

Eddystone and Collins gear covered the 1960-70 and ICOM gear covered the 1970-1980s.

There was the Ionospheric Prediction Service Beacon on display (VK0MA) and an aviation Non Directional Beacon Antenna Tuning Unit both from Mawson Base.

The 1980-90s were covered by a Barrett 950 HF gear and the 2000s to the present day was covered by ANARESAT Satellite Technology pictures.

Mike Hawkins VK7DMH bought along his weather satellite receiving gear and we had weather satellite pictures coming through over the weekend.

There were five Arduino based Morse code decoder available for kids and parents to learn Morse code on and they were definitely the highlight of the weekend.

Morse Code AAF 2024

Morse Code AAF 2024

Those people who came along to the festival were able to learn and play with the very code  that was being used to link Antarctic bases with the rest of the world in the past.

AAF 2024 - Morse Code

AAF 2024 – Morse Code

On the Sunday we also had a HF QRP station setup and live contacts were made with a range of stations including ALARA contest stations.

AAF 2024 - VK7WN Contact

AAF 2024 – VK7WN Contact

A great weekend of promotion and celebration of Antarctica, radio technology throughout the ages and amateur radio.

A huge thank you to Kim Briggs VK7KB, Herman Westerhof VK7HW, Mike Hawkins VK7DMH, Warren Nicholas VK7WN who helped out making this weekend a success.

73, Justin, VK7TW