August 14, 2020, 06:37:55 am

RCMF Donations

Enjoy using RCMF? How about a wee donation to help us keep you in the style to which you've become accustomed?

Welcome to RCMF. Please login or sign up.

August 14, 2020, 06:37:55 am

Login with username, password and session length

Help, it's been a while

Started by BridlingtonFlyer, July 07, 2020, 12:29:31 pm

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

BridlingtonFlyer

Hi all, I'm looking for some help. After a spell away from the hobby, I'm looking to get back into it. I still have some of my old models and a Futaba FF9 TX with a TM-8 FASST module in it. These all seem to be ok and functioning well. I've also just purchased a S800 wing and a Matek F405 WING flight controller with a view to doing some FPV.

What I didn't realise was an RX talks to the Matek over SBUS. This is something I've not touched on before. I'm getting all sorts of conflicting advise from ditching Futaba in favour of an open TX transmitter. To been told OpenTX isn't necessarily legal to fly in the UK. I thought I'd found a suitable FASST & SBUS RX https://inwoodmodels.com/product/futaba-6303sb-receiver/ but then I was told this won't work as my FF9 TM-8 Combo doesn't support SBUS. But then the RX instructions https://www.rc.futaba.co.jp/english/dl_manual/r6303sb_e.pdf specifically mention paring to a TM-8 module.

Super confused. I could do with some help.


Chris Foss Uno Wot - Mini Kangaroo

pooh

Stick to 35MHz, there's almost nobody there - at least that's my plan  :''
Confucious he say "more than one aircraft in the same airspace leads to structural failure"

BridlingtonFlyer

Long time. Joking aside 35 meg had crossed my mind just for FPV range if nothing else.


Chris Foss Uno Wot - Mini Kangaroo

PDR

Quote from: BridlingtonFlyer on July 07, 2020, 12:29:31 pmTo been told OpenTX isn't necessarily legal to fly in the UK.

That's twaddle - suggest you go back to whoever said that and ask them to explain why they think it's illegal. AFAIK the on;y ones that are explicitly illegal would be original DSM and DSM2 transmitters because they don't do LBT ("Listen Before Talk"), but that only applies to new equipment and it's still legal to fly DSM/DSM2 transmitters purchased before the rules changed.

PDR
There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...

BridlingtonFlyer

What's twaddle is my English. That should have read To being told. Any recommendations if I were to ditch Futaba? I'm not sure I need to though if that SBUS RX does work with my FF9/TM-8 setup. Anyone know for sure?


Chris Foss Uno Wot - Mini Kangaroo

PDR

I've recently bought a FrSky Horus X10s Express which now runs OpenTx, and I love it. You'll find my mini-review of it in the radio gear section. But this transmitter (and OpenTx itself) are only suitable for people who WANT complex transmitters with powerful software that you need to learn how to use.

If you've not had a complex transmitter before then OpenTx can be a bit of a steep learning curve. I found it worth the effort, but others view it differently. Also I came from a Multiplex background, from which it was a less-steep curve!

PDR
There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...

dickw

I know nothing about Futaba, but have used the S.Bus output from a non Futaba receiver to link to a flight controller.

I didn't have to do anything at the Tx because S.Bus is purely a link between the Rx and the flight controller, so any Rx with an S.Bus output should work. I just connected the Rx with the flight controller and programmed the flight controller using its own software.

I believe that if you are using S.Bus to control a series of connected "S.Bus servos" over a single cable then you need to programme the individual servos. I believe that can be done from some Futaba Tx, so perhaps that is what people were thinking of.

Dick
Grow old disgracefully

lanicopter

Quote from: BridlingtonFlyer on July 07, 2020, 13:10:46 pmLong time. Joking aside 35 meg had crossed my mind just for FPV range if nothing else.

Eek. Don't say that on here or you'll be facing pitchforks before you can say return-to-home.

35MHz is much more susceptible to interference than the 2.4GHz systems and with the right antennas range is absolutely not an issue. If you're using 5.8GHz video you'll run out of video range long before you have to worry about losing control.
Current fuel status: "Master Caution"

paulinfrance

July 08, 2020, 12:00:50 pm #8 Last Edit: July 09, 2020, 13:13:17 pm by paulinfrance Reason: loose
The best range I got with standard gear was on 41 MHz and for the FPV gear 1.2/1.3ghz, cheap and you don't suddenly loose your feedback so no panic heart attacks,,

2.4 with 5.8 give a better image but loss of range and don't like going behind trees !
Mode 2 THE only way to fly

FrankS

As Dick says SBus is just a communication between the receiver and device, so if the Rx has an Sbus port then it should communicate with the flight controller.

Another option would be a Frsky FASST rx with SBus like this one https://www.t9hobbysport.com/frsky-tfr4sb-fasst-compatible-2.4ghz-4-to-16-channel-receiver

Ville

July 09, 2020, 10:58:16 am #10 Last Edit: July 09, 2020, 11:49:01 am by Ville
Quote from: FrankS on July 09, 2020, 07:59:04 amAs Dick says SBus is just a communication between the receiver and device, so if the Rx has an Sbus port then it should communicate with the flight controller.

Another option would be a Frsky FASST rx with SBus like this one https://www.t9hobbysport.com/frsky-tfr4sb-fasst-compatible-2.4ghz-4-to-16-channel-receiver

...or one oh these, https://www.xtremepowersystems.net/products.php?cat=8
I have used XtremeLink® X10 + Channel Expander V2 with Flysky SBUS and Multiplex SRXL and it works very well.

/Ville :)

ps.
When it comes to Mpx SRXL, it is only with Multiplex receiver RX-9-DR SRXL16 M-Link that you get 16 channels via the SRXL protocol. With the other RX- (X) -DR receivers, including the compact versions, you only get as many channels as the receiver is intended for, eg 7 and 9 channels respectively.
...
I know what I know and I do what I can

FlyinBrian

If you like Futaba and need SBUS and or telemetry (SBUS2) you will need a new Tx and rx. Check out Futaba's website for the latest info on Tx's but the least expensive SBUS and Telemetry capable rx is the 3008 which is an S-FHSS rx. If you are serious about staying with the hobby, bite the bullet and get a T14SG (getting a bit old now likely to be super-ceded soon)  or 16SG which is newer. These support most Futaba protocols and for cheap and cheerful models - foamies etc there are third party eg FrSky rx available for around ┬ú25

Basic Research is what I do - when I don't know what I'm doing!.

FlyinBrian

PDR -
"That's twaddle - suggest you go back to whoever said that and ask them to explain why they think it's illegal. AFAIK the on;y ones that are explicitly illegal would be original DSM and DSM2 transmitters because they don't do LBT ("Listen Before Talk"), but that only applies to new equipment and it's still legal to fly DSM/DSM2 transmitters purchased before the rules changed."

Re: "Listen Before Talk". This is a simplified way of explaining Ethernet operation and the techie term is CSMA/CD
Carrier Sense Multiple Access/ Collision Detection. Our 2.4Ghz kit is based on Ethernet WiFi principles. In simple terms The sending device listens to the carrier which in our case is a radio channel, if no other activity is detected it can transmit. If the channel is busy it has to wait a randomly determined period and trys again. Now you may think this could slow things down pretty quickly and it did in the early implementation of Ethernet when 10 Megabit was the limit on a coax cable about 20mm in dia. Now we operate at Gigabit speeds there is a lot more capacity - plus of course Frequency hopping is going on spreading the communication across up to 80 channels.

Re DSM/DSM2 - (Probably more information than you want to know)

It was companies like Cisco and other large network providers, (developers of the technology) who until, us modellers cottoned onto this technology, had all of the 2.4GHz bandwidth to themselves, they made waves about illegal operation of 2.4gig R/C sets (splitting hairs really) not sticking to the regs hence the early adopters (Spektrum) had to change how they operated.

DSM/DSM2 works by scanning the 2.4 bandwidth and finding two free channels ie - "It Listens" and not until two free channels are found does it transmit and Bind to the rx. So it does actually LBS; however once the two channels are found it sticks with them and does no further listening. Also it uses only one of the channels unless there is a certain number of missed or bad data frames then it tries the other channel - so it does not hop!

I believe there was some question about the FrSKY original protocol (ACCST?) but there was little came of it however FrSKY now use ACCESS.

A good intro to Ethernet and CDMA/CD can be found here -

https://www.ionos.co.uk/digitalguide/server/know-how/csmacd-carrier-sense-multiple-access-collision-detection/

To round things off nicely the technology has reached a stage where it is no longer necessary to LBS, you just send and the equipment in the network either handle it or flag an error and you re-send. AFAIK This is still in test but will be released shortly. $%&
Basic Research is what I do - when I don't know what I'm doing!.

dickw

Quote from: FlyinBrian on July 10, 2020, 07:38:35 am....................
I believe there was some question about the FrSKY original protocol (ACCST?) but there was little came of it however FrSKY now use ACCESS.

................................

"Little came of it" ???
FrSky, like all the other manufacturers, had to modify their RF firmware to comply with the rules. Their decision was to offer different RF module firmwares for the relevant user's location :-

XJT_ACCST_V2.1.0_FCC.frk    Firmware under NonLbt mode which is certificated for FCC rules.
XJT_ACCST_V2.1.0_LBT.frk    Firmware under LBT mode which is certificated for CE rules.

I believe ACCESS may offer the choice of selection from within the Tx rather than having to flash new software.

Dick
Grow old disgracefully

meharibear

Fascinating stuff!  As there are several of you experts out there perhaps one or more of you could confirm (or otherwise) that the other MAJOR reason sale of new DSM2 equipment was banned was it's very high duty cycle allegedly swamping the airwaves?
Inside every old person is a young person wondering what happened.  (Terry Pratchett)

dickw

Quote from: FlyinBrian on July 10, 2020, 07:38:35 am...........................................
A good intro to Ethernet and CDMA/CD can be found here -

https://www.ionos.co.uk/digitalguide/server/know-how/csmacd-carrier-sense-multiple-access-collision-detection/
................................

Yes. interesting. I particularly noted the bit:-

"Besides the extension of Carrier Sense Multiple Access with Collision Detection, media access can also be provided with collision avoidance CSMA/CA. The latter is particularly needed when it comes to wireless connections; CSMA/CD doesn't work well in radio networks for various reasons. "

That sort of suggests collision avoidance (LBT?) is still needed, or have I read it wrong?

Dick
Grow old disgracefully

dickw

Quote from: meharibear on July 10, 2020, 12:34:26 pmFascinating stuff!  As there are several of you experts out there perhaps one or more of you could confirm (or otherwise) that the other MAJOR reason sale of new DSM2 equipment was banned was it's very high duty cycle allegedly swamping the airwaves?

I think "swamping the airwaves" is a bit over the top, but duty cycle is important. A low duty cycle is an alternative approach to LBT as a way of complying with the current rules.

Dick
Grow old disgracefully

Steve J

Quote from: meharibear on July 10, 2020, 12:34:26 pmAs there are several of you experts out there perhaps one or more of you could confirm (or otherwise) that the other MAJOR reason sale of new DSM2 equipment was banned was it's very high duty cycle allegedly swamping the airwaves?
My understanding is that Spektrum has a low duty cycle and therefore doesn't have to LBT.

meharibear

Quote from: Steve J on July 10, 2020, 13:25:08 pmMy understanding is that Spektrum has a low duty cycle and therefore doesn't have to LBT.
Current versions but not DSM2 as I understand it.
Inside every old person is a young person wondering what happened.  (Terry Pratchett)

Steve J

July 10, 2020, 16:55:27 pm #19 Last Edit: July 10, 2020, 16:56:39 pm by Steve J
Quote from: meharibear on July 10, 2020, 16:11:41 pmCurrent versions but not DSM2 as I understand it.

The difference between DSM2 and DSMX is that DSM2 uses two 1 MHz wide channels 40 MHz apart in the 2.4GHz ISM band and alternates between them and DSMX uses 23 channels spread across the band and jumps between them. The former is not EN 300 328 1.8.1 compliant, the latter is. DSMX spreads the signal about over more of the band than DSM2. Neither LBT.