No, Not the Best, But a Great Compromise: Olivia on HF

Discussion in 'Videos and Podcasts' started by NW7US, Dec 12, 2017.

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Have You Had More Than Two Olivia-Mode QSOs?

  1. Nope. Never Had Any.

  2. Nope. Only One or Two, So Far.

  3. Yes; Less Than Ten, Though

  4. Yes; Many

Results are only viewable after voting.
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  1. NW7US

    NW7US Premium Subscriber QRZ Page

    Some HF digital modes were designed for long-distance (DX) propagation (radio wave propagation) via the ionosphere. One such keyboard-to-keyboard digital mode is Olivia.

    Friday evening, 8 December 2017, at 0200 UTC {9-DEC}, Larry, N7ZDR, called an Olivia-mode 80-Meter digital roundtable net. The following video is a snapshot of about nine minutes of on-air net operations as received at my location in Omaha, Nebraska. My antenna is a wire run from an SEA marine autotuner mounted under the three-story-high roof's eaves. I live in a high-RF environment within two miles of eight high-powered broadcast antenna facilities--TV, FM, AM--as well as business and public-service transmitters. All that RF desensitizes my receiver. The noise floor is also affected by industrial-level man-made RF noise.

    No, Olivia is not lightening-fast keyboard-to-keyboard chatting, but it can get the job done. This following video is an example showing some real-world operation in which the very weakest signals did not decode well. However, even with the 80-Meter band (center frequency is 3585 kHz) really difficult to work with, it did well in terms of what was available for the Ham Radio Deluxe DM780 software to decode.



    In 2005, SP9VRC, Pawel Jalocha, released to the world a mode that he developed starting in 2003 to overcome difficult radio signal propagation conditions on the shortwave (high-frequency, or HF) bands. By difficult, we are talking significant phase distortions and low signal-to-noise ratios (SNR) plus multipath propagation effects. The Olivia-modulated radio signals are decoded even when it is ten to fourteen dB below the noise floor. That means that Olivia is decoded when the amplitude of the noise is slightly over three times that of the digital signal!

    Olivia decodes well under other conditions that are a complex mix of atmospheric noise, signal fading (QSB), interference (QRM), polar flutter caused by a radio signal traversing a polar path. Olivia is even capable when the signal is affected by auroral conditions (including the Sporadic-E Auroral Mode, where signals are refracted off of the highly-energized E-region in which the Aurora is active).

    Currently, the only other digital modes that match or exceed Olivia in their sensitivity are some of the modes designed by Joe Taylor as implemented in the WSJT programs, including FT8, JT65A, and JT65-HF--each of which are certainly limited in usage and definitely not able to provide true conversation capabilities. Olivia is useful for emergency communications, unlike JT65A or the newly popular FT8. One other mode is better than Olivia for keyboard-to-keyboard comms under difficult conditions: MT63. Yet, Olivia is a good compromise that delivers a lot.

    Join us -- not just on the HF waterfall, but by joining our email-based group at https://Groups.Io/g/olivia or on Facebook at https://www.facebook.com/groups/olivia.hf

    Thanks for spreading the Olivia love!
     

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