Category Archives: Amateur TV SIG

Posts from the ATV Experimenters Night

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.

Saying Adieu to DATV Studio

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Last Wednesday evening a small group of members gathered at the REAST club rooms to disassemble the DATV studio, in preparation for the rear shed being redeveloped by Tasmanian Maritime Radio (TMR) to move their operations hub into.

Amateur Television has played a large part of REAST, with the first broadcasts occurring from VK7OTC in 2005, in a makeshift studio, before moving to it’s own studio in 2010. Broadcasts started out as analogue before moving to DVB-S then DVB-T transmissions.

Digital Amateur Television broadcasts are planned to make a return in 2017 with the studio relocating into space currently used by TMR after they move to the redeveloped rear building. It will be an exciting time with the opportunity to rebuild the studio.

REAST club rooms will continue to open on Wednesday evening with other activities including satellite communications, software defined radio and homebrewing, along with all the regular show-and-tell and discussions you know and love!