As if we all could not control a car w/o OpenTX?
If you are planning to race you do not need more than 2 channels, no need for mixing and all other stuff. Basically you needt EPA, trim and subtrim, D/R, direct accessible brake limit and if needed a steering and throttle curve. All decent transmitters do provide that. You want to swap buttons? I know Futaba can swap buttons for trim etc.

Well if you don't mind tinkering a bit the MT12 gives you access to cheaper receivers and as good or better latency performance plus more range. The range argument only matters if you are going to FPV I guess.

I don't have an MT12 but I do have an NB4. The NB4 kind of doesn't agree with me. People like them so it's probably just me but when I was running my crawlers with it it was pretty difficult to modulate the throttle gently around center. I ended up switching to my airplane radio (Radiomaster Boxer) and now I have heaps and heaps of modulation around center. I even race my B6.4 with the Boxer and podiumed (3rd) with it in 21.5t buggy class at my local club. Now I'm a stick radio guy.

But if I wasn't I'd get an MT12 since I like EdgeTX and ELRS.

I don't think you are making a wrong choice either way. The NB4 is a known quantity. The MT12 will get you more "Interesting, what radio is that?" comments at the track.

Nobody has provided evidence that the MT12 has better latency than Sanwa/Futaba's top offerings.

Isn't it illegal to use an air radio for surface vehicles? They have different power limits.

Would be useful to see a source for the legality query. I assume you mean so far as CASA ACMA is concerned, not RCRA? EdgeTX lets you adjust transmission power both in absolute terms and also dynamically via a telemetry SNR target.

EDIT seems the authority is ACMA in Australia

I can't post links yet properly;
expresslrs.org/software/dynamic-transmit-power/

Latency wise I was comparing with Flysky not Futaba or Sanwa. I don't think it's as good as those two latency wise but should be as good as Flysky. Flysky and ELRS can both do 400hz servo refresh rate and I know ELRS can do 1000hz on the link. Not sure on Flysky's link update but assuming it's somewhere between 333 and 1000hz it's negligible. There was a video posted a few pages back with some ELRS latency testing. It's my understanding Futaba and Sanwa do faster refresh rates for the servo so probably have better latency. But when you are comparing things sub 10ms I think you can genuinely say you'd have to be superhuman to notice. So my point is that it's on par for sure!

Regarding power you are allowed to transmit up to 1W on the ISM bands with an unlicensed transmitter based on FCC rules: https://afar.net/tutorials/fcc-rules/
Which I think is end of conversation when talking about transmit power, ISM band, and legality in the US. Might be some gotchas in there but for RC toys I don't think it matters for the consumer much.

The radio I'm using can go up to 1W, but I use the dynamic power feature which tl;dr means at a race or any normal third person RC car use it would never go over 25mw which is lower than most 2.4GHz radios anyways. I can't cite a source but it's my understanding the standard output power is 100mw for most systems. You can also put a hard limit on the output power on a per model basis in the ELRS lua script. It ties into model match in EdgeTX and lets you configure the tx module completely differently for all your models and it will automatically apply those different settings when you change models. Like a Race drone you would want ELRS in 1000hz packet mode and an airplane you'd want in 100 or 333hz full range packet modes. Then a carpet buggy you might want in 1000hz mode again but power limited to 100mw or something. And an FPV rover you might let go to 1W and put the packet mode to 50hz for maximum range and link reliability. The lower the packet mode is the lower the received signal needs to be in order for the receiver to maintain a link.

Worldwide there are other rules for the max power and an easy adjustable power will never get a European CE certificate.

Regarding latency I wonder if people really know what they are talking about. There are 3 different types of latency going on with an RC transmitter.

1) yes, the framerate of the servo signal is one of them and an important one because it is an variable latency you can not have getting into a rithm driving a fast track. Why it is variable? Reading the channel information is just a train going round. The latency depends on which moment in the frame you make the change. So the faster the frame, the more constant the latency will become.

2) The speed of the electronics. This is a constant factor of processing the information by the processors but with cheap 3rd party receivers it can be a noticeable factor as I have seen with some Orange receivers.

3) Transmission. Yes, the transmission is fast but not always reliable so frames can be missed. Someone on this forum has made a setup to measure the total latency and when you read the results it can be disturbing to see how big that can be. It can even be the biggest factor of the total latency but it is one of which there is no information to find.

I mentioned earlier that the two switches on the additional module aren't working as Switches, but as a Pot. So you can't use them directly in Mixes and Special functions, unless you create Logical switches based on their value.

That was incorrect, you can set them up as actual switches in the Hardware page. After that they have all the normal 'Switch' functionality.

If you check the ExpressLRS site in firmware options they have different versions of the firmware you flash for different regulatory domains:
https://www.expresslrs.org/quick-sta...mware-options/
Handsets in the EU CE regulatory domain should ship with the EU CE firmware. The EU CE regulatory domain limits power to 100mw and enables LBT. So if you have the right firmware you should be EU CE compliant. And if you live over there but a rebel without a cause you can flash the ISM firmware if you want and unlock more transmit power.

For comparison with MT12.
I have measured the latency of SANWA M11X and M17, and it is disappointing that it exceeds your expectations.

M11X latency : 35ms(ave.)
M17 latency : 22ms(ave.)

h ttp://sybrand.blog.fc2.com/blog-entry-312.html
h ttp://sybrand.blog.fc2.com/blog-entry-355.html

Can you repeat such a test outside the living world? In a living area there are so many 2.4GHz signals around that I think they have a lot of influence on the latency.

Jakesterama
I was catching up on this thread and watched your vids. Great to see ELRS is in fact very fast!

Your comments on the radio adjustability are definitely valid though. Radiomaster is kind of a mid-tier manufacturer at best, they might be using cuttign edge tech like ELRS and EdgeTX but the hardware itself is built to a price point, it's also their first surface radio. So yeah that kind is a case of it is what it is, and it is a little disappointing.

I haven't had a radio with ABS function before but assuming you just mean pulsing the brake, that should be possible with logical switches in EdgeTX.
You can use the TIM function to pulse a logical switch.
Then use the A<X function to detect when the throttle input is in braking range, or just in braking range enough that you want ABS to activate. Say maybe you want it to only come on at 70% brake effort or something like that.
Then use the AND function to tie the above two logical switches together. So when throttle input is below a certain value and the TIM function is in True state, the AND function will be true. Then you can use Special functions to override the throttle channel to the neutral value when that AND function is true. Then boom you have ABS!

Most things in EdgeTX are possible with enough creativity, but it's definitely not as intuitive as just having a pre-programmed functions like other platforms. This kind of shows up in planes too with flap mixing and what not.

Chof Those are some disappointing findings. Be interesting to see some others test that as well to proof it out. But I did look at your blog entries and that all seems valid. Also saw it looks like you have an MT12, be interesting to see how that performs in your tests.

Unfortunately, I cannot prepare an anechoic chamber.

I think that even if I test MT12 (elrs), I will only get the same results as other people's tests.
You probably want to check that, but testing takes a lot of effort. I might do it if I feel like it, but please don't get your hopes up.


By the way, I have previously conducted a latency test using the MPM(JP4in1) and the REDPINE protocol.

Radio : X9Lite (EdgeTX2.6, serial_x4_mod)
TX module : JP4in1SE
Receiver : R84 (REDSKY mod)
Latency : 5.7ms(ave.)

I believe the REDPINE protocol is the fastest in MPM, but it still falls short of elrs. MT12 (4in1) has the advantage of being able to bind with many existing receivers, but if looking for performance, I think MT12 (ELRS) is the only choice.

Trim5 was a little difficult to use, so I made custom parts to improve it.

https://cimg2.ibsrv.net/gimg/www.rct...bc9fb6a467.jpg
https://cimg3.ibsrv.net/gimg/www.rct...4dc1102570.jpg

It's now much easier to use.

How can this information get shared with Radiolink so they know to improve on it next time? Things like a drop wheel capability or taller/rounded switches and a color screen could be good feedback type stuff it would be nice to be able to relay to them.