[greggold]

Elrs already has solved my radio signal problems for line of sight flying at McCoy field, but the elrs project continues to improve the radio link in order to achieve better long range (ie 20 km) signal quality for fpv. 

I (and I think other club members) do not need to upgrade to gemini. Normal elrs does the job, given the current level of radio interference at McCoy.

But gemini is amazing. You can now purchase a full featured elrs gemini tx by Jumper, or a gemini tx module that fits any tx that can run edgetx/elrs. Gemini rxs are available, indeed last saturday I noticed someone in the club is already using one.

To get a picture of gemini this website may be a good place to start,

https://www.youtube.com/watch?v=7NUzkUWB0Ls

You can buy the jumper gemini tx for AUD $271 from Aliexpress.

For more detail on gemini check the Bardwell review:  https://www.youtube.com/watch?v=PZVUGKmBD24&t=928s

Bardwell uses the betafpv gemini tx module (cost AUD 130 from Fpvfaster) in his tests. https://www.fpvfaster.com.au/collections...tter-black

What is very interesting is the finding in the flight tests that using the module in the switching mode (so the tx signal is sent polarised in 2 planes at right angles, one antenna at a time) caused a notable jump in link quality performance. Having gemini mode working both in the tx and rx is required for maximum benefit, but there was a difference with just tx in switching mode. 

I am very tempted to try this module, as there is fairly little time required to reconfigure everything on my tx and planes if you just use the tx module. 

here is another test of gemini
https://www.youtube.com/watch?v=FoSREiyDQDA

I predict in a year or two we will all be using elrs gemini.

[greggold]

If you fly with elrs at McCoy, you will find that problems of control glitches (/- crashes) do not occur, or at least the crashes are not caused by radio signal issues. So a major upgrade to standard elrs is superfluous, just not needed. Gemini is for fpv models flying at many km distance.  But in my case, the possibility that a $127 upgrade lets you try what is arguably the world's best RC signal was impossible to resist.

I can shift some blame onto Bardwell (a well known RC guru), who described how Betafpv this time (unlike last time) cooperated with the elrs devs over a long period and waited a year before releasing the product - and it shows. Further Bardwell showed how even if you only buy the tx module and do not touch/change your rx in any way, a significant benefit is achieved.

The module - BetaFPV SuperG Nano ELRS 2.4G Module - was purchased from FPVfaster at Lidcombe, and I was very impressed how simple the process was (see photo with the 2 tx antennas set at a right angle). Slip it in the adapter, slip it into the JR module bay, and then for the models you want to fly with the gemini, just set the model to external module from RF internal module (its the first menu item when you press "model" in edgetx). Then press radio/elrs to run the elrs lua. The tx immediately announced it was the betafpv gemini and there were the usual settings for packet rate (chose 100) and telemetry ratio (choose 1:32). Since I do not have any capable gemini rxs, I choose "switch" mode. The module had elrs 3.3. Then I went into tx wifi and added my binding phrase.

Then I was ready to fly, it took only several minutes to set up, and in my first 9 flights today in switch mode (using 3 planes) there were no issues at all. I have a flight log setup that I will use to compare the signal quality before and after the move to switch mode in a number of my models.

What is switch mode? In flight, EVERY SECOND the tx sends around 97 control packets to the rx, and the rx sends around 3 packets to the tx to advise the tx if packets are missed or faulty. On the tx module the 2 antennas (lets call them L and R) are at 90 degrees to each other, and control packets are sent alternately from each. So suppose control packet number 48 in a given second from L antenna is missed due to interference or blocked line of sight to the rx antenna. Control packet 49 comes from R antenna, and it is sent/propagated in a different geometric plane. This means it has a better chance of arriving than if all packets were sent in the same plane.