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Automatic antenna switching and diversity reception

Using various antennas and switching with the OH1KK antenna switch extension I am looking for a way
to select antennas automatically.The simplest approach is likely pre-defining band and
antenna combinations and using this as a look-up table for the tuned frequency. The particular Kiwi
owner will have a good idea which combinations work best and could enter such a table for the available antennas
on the admin page.

Another more interesting way might be to measure the actual signal to noise ratio and switch the
available antennas. It appears that the value of the "Auto Scale" (WFmax- WFmin + 40dB) would be
quite useful as SNR indication. For digital modes measured bit error rate might be an additional
switching criteria.

So for starters I would like to put in a request for adding this SNR plotted via the S-meter
extension. On the admin interface page under S-meter graph configuration a selection to show either
the value over the current WF zoomlevel or passband for the selected mode would be useful.

When this value is also available locally at the Kiwi it should be possible to either dynamically
switch to a single antenna based on best SNR or evaluate whether a combination of antennas give
improved results. A limit to maximum allowed (50% bin) noise level is probably also needed to prevent unreasonable selections.

Combining of different antennas this way would give spatial or polarization diversity gain to the
receiver. Obviously with one antenna input to the Kiwi this will work for one of the channels only.

The evaluation of SNR's could be done once or periodically. Even with 8 mechanical relays this would
take less 200 ms provided that is enough time for waterfall snapshots to be taken and processed.
Looking forward to more discussion about this idea.

Best ragrds,
Ben.

Comments

  • Ben, this is a really good idea. You have no doubt seen Marco's recent work using the external Kiwi connection API to process waterfall data: http://sibamanna.duckdns.org/sdr_map.html

    I will add your suggestion to the S_meter extension wish-list.

    Lately I have been working on cleaning up the extension API and writing a document describing how to write an extension. The goal is to make it possible for anyone to contribute, even if they have not had a lot of programming experience.

    There is also the requirement to allow portions of an extension to run in the background (e.g. not started specifically by an interaction with the main user interface). Essentially a generalization of the recent WSPR auto-run feature. This is much more difficult to implement but important for tasks that need to make measurements over a long period of time.
  • Hi John,

    Really looking forward to the possibility of kiwi users to create and share their own extensions. This could be great to test out various ideas and hopefully at the same time reduce your workload..hi
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