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A better RC system is coming - Printable Version

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A better RC system is coming - greggold - 09-10-2022

A major development for RC control links for planes -ELRS- is becoming available with the Frsky Twin. However the new technology can also be used in Radiomaster, Taranis, QX7 and other radios, and its already in use for drones where ELRS has started to displace Crossfire.

Twin uses the leading open source protocols developed over many years for racing FPV to improve latency, telemetry, distance and signal quality.

Twin is a dual band system that Mawz says "using 1 FSK link (traditional 2.4G tech, same basic tech as ACCESS and TANDEM 2.4G and 1 LoRA link (same tech as ELRS, Tracer and Ghost on 2.4G, as well as all current 900MHz systems)".
(Mawz post #8 in https://www.rcgroups.com/forums/showthread.php?4216449-FrSky-Twin-XLite-Radio)
Mawz post #22 says:
" That is really a sea change in the available RF performance for 2.4G systems and a major shot across the bows of the older solutions, especially for those of us flying in more challenging RF environments. And it's not one coming from the high-dollar brands, but rather two of the brands often looked down on as 'Budget' solutions and the hobbyist community itself."

Github provides a fuller explanation:
https://github.com/ExpressLRS/ExpressLRS says:
"ExpressLRS is an open source Radio Link for Radio Control applications. Designed to be the best FPV Racing link, it is based on the fantastic Semtech SX127x/SX1280 LoRa hardware combined with an Espressif or STM32 Processor. Using LoRa modulation as well as reduced packet size it achieves best in class range and latency. It achieves this using a highly optimized over-the-air packet structure, giving simultaneous range and latency advantages. It supports both 900 MHz and 2.4 GHz links, each with their own benefits. 900 MHz supports a maximum of 200 Hz packet rate, with higher penetration. 2.4 GHz supports a blistering fast 500 Hz on EdgeTX. With over 60 different hardware targets and 13 hardware manufacuturers, the choice of hardware is ever growing, with different hardware suited to different requirements."

For a good discussion of ELRS see Bardwell, including flashing ELRS onto a Radiomaster with a Frsky R9 Access module and a Frsky R9 access rx.
https://www.youtube.com/watch?v=-TGYy1psWgU
This module is available on Horusrc for $US55 and is compatible with various access Frsky radios including QX7 and Taranis. 

Bardwell says ELRS is a radio control link firmware that has the highest performance, longest range length, and lowest latency  compared to all the competition.

An ELRS module for Frsky Tandem txs is already available on Horusrc for US$70
https://www.horusrc.com/en/modules/dual-2-4ghz-module.
The only rx that currently works with this module (AFAIK) is the Frsky Vantac ELRS rx for US$ 13, but it is a drone rx with no PWM ports for servos. But other receivers and a Twin tx are in the pipeline. See below for rxs available now. I understand the current Frsky ETHOS firmware may require an update to run Twin.


RE: A better RC system is coming - greggold - 09-10-2022

The online experts I have learned to trust seem to agree that the firmware for airplane radio gear that we all use is obsolete. Maybe this is a factor in the interference problem some of us have experienced. I have decided to give ELRS firmware a try.

I have now paid 51 AUD to BETAFPV for 2 ELRS Micro Receivers - ELRS 2.4G V1.2, that have PWM ports for the servo plugs. This is the only ELRS rx I could find with PWM ports.

and
67 AUD to Fpvfaster for a BetaFPV ELRS Micro TX Module 2.4GHz. These prices include postage.

This module is stated to fit a Taranis X9d tx, which I have.

Assuming I can configure the ELRS, I plan to use the rxs in 2 small 80cm span 3d planes. The rxs only weigh 4 gm. Unfortunately each rx only has 4 PWM channels, but that is enough for these planes. It seems clear that soon many more ELRS txs and rxs will become available.


RE: A better RC system is coming - greggold - 13-10-2022

For a quick easy start in ELRS using a Taranis, see
https://www.youtube.com/watch?v=iir5wT_W28k
Notice: no downloads, no lua scripts, no complexity.

These are the 2 ELRS components used in the video
TX module:
https://www.fpvfaster.com.au/products/betafpv-elrs-micro-tx-module-2-4ghz?_pos=2&_sid=26bc0ae0e&_ss=r&variant=39686499565650

Receiver with 5 PWM ports:
https://betafpv.com/products/elrs-micro-receiver

These components are both available in Aust. drone shops, of which there must be about 100:
eg Fasterfpv; Fasterfpv (in Lidcombe) have sold out of the 500 mw betafpv module, but have the 1000 mw one shown in the vid still in stock for $20 more; the BetaFPV 1W ELRS Micro TX Module 2.4GHz BLACK × 1 costs AUD 85. Both modules are fine for line of sight applications where you may set the module power at 25 to 100 mw.

Drone Parts Garage (in Brisbane) sell the BetaFPV ELRS Micro 2.4GHz Receiver shown in the vid for AUD 20.50

To get a 7ch rx, I am investigating Matek rxs.

A Matek ELRS R24-P PWM Receiver 5ch I ordered will require me to microsolder the PWM sockets onto the pcb board.

I am crap at soldering, so I plan to try a professional service.

(a) https://surecando.com.au/

(b) There is a phone repair place 20m from the entrance to Chatswood railway station. I asked about microsoldering on pcb boards, he said they do it every wednesday when they have a technician come and work at their microsoldering station, which he showed me.

This 7ch PCM Matek rx will also require microsoldering on the pcb board.
"MATEK Mateksys ExpressLRS ELRS 2.4GHz ELRS-R24-V 7CH PWM Outputs Vario Receiver Suitable for RC FPV Gliders Fixed-Wings Drones" AUD 34 at Ali Express