Moerig

The one from XPS aka Jim Drew?

Moerig

Sounds like the RF protocol has bi-dir coms for telemetry and SBUS II is now also bidirectional so you can add sensors on the same bus as servos. Wonder if that makes current SBUS servo's etc obsolete? Sure hope it's backward compatible..

VF84sluggo

My Feedback: (55)

Yes, I figure I could fly my Baby Boomer there...no way the L-39! At least it's pretty level grass/weeds if you go off the end

mr_matt

My Feedback: (10)

It looks like S Bus is DESIGNED to use multiple receivers. The real question I have is how (and what) do the S Bus receiver communicate with each other, as opposed to how they drive the servos (still important mind you)

If the receivers form some sort of ad hoc network, then they can decide which of them is receiving the best RF signal and they both use that signal (sound familiar?)

Imagine, one RX in the tail driving 8 servos, another RX in the nose driving a different 8 servos. Meanwhile behind the scenes, the 2 receivers are comparing who has the best signal from the TX and sharing it with the other. The signals to the servos are unaffected, they still come from the receiver they are hooked to.

dragnslayer

I'm not sure these problems are about too many transmitters being on, unless you think three is a lot. At a local field while setting the needles on a new aircraft/engine combo (DA-60), cowl off and hatch off, the receiver totally locked out. Fromeco switch with dual power leads and a freshly charged battery. The receiver would only reboot when the power switch was cycled. At the same time my plane was going through this we heard,"I ain't got it". and a Moki 1.80 powered Extra pounded the ground. Both radio systems use frequency hopping protocol, but different manufacturers. Radio tests after the crash of the Extra revealed no problems and battery and switch tests showed no issues. Range tests on both systems would be considered extraordinary. Both systems were sent back for a check out and have been returned with "no problems found" My repair center replaced the receiver as a courtesy, but the other flyer's repair center replaced nothing. I tried a different transmitter in my plane with a different receiver and this combo locked out twice. I tested it again with another plane bound to the same transmitter sitting next to it and that plane did not lock-out, but the problem plane did. It locked out twice, but I have not been able to get it to lock out again. I installed my old 72 meg. system and tests were without problems so it was flown without incident. This seems to indicate that there is something in my plane that my 2.4 system doesn't like. But what about the crashed Extra. No ignition, and it had had over 50 flights without so much as a glitch. My system had problems in two other planes with lock outs that resulted in a crash, but I found what I though were battery/switch problems. Now I'm not so sure. At this same field we have lost maybe 6 or 8 planes with 2.4 in the last 18 months with some type of radio anomaly. Those planes were NOT using frequency hopping, but were on 2.4 The number of flights at our field on 2.4 without incident is by far the majority, but I can not help but wonder if there is more to the story than we know.

toprudder

IMHO, probably the most accurate assessment of the situation. An event like Joe Nall scares me in that respect, in that there is no control over how many people can turn on at one time. There is only so much spectrum and bandwidth.

Each system has a limited number of frequencies that they can transmit on. I believe thatDSM2 has 80 (40 pairs). As best as I can tell, FASST is limited to 36 (less if in "France" mode). There has to be a limit as to how many can be operating at once, before serious degradation in performance occurs.

It would be wise that anyone needing to turn on a transmitter to setup or checka plane do so in reduced power mode (like you would use for range checking). This would limit the possible negative affect on those that are flying. JMHO.

DougV

Hi Matt:

The way I see it and I can be wrong, when you use S.BUS, you program the servos to lets say elevator, so no matter where in the S.BUS chain you connect that servo, it’s going to be an elevator servo.

Doug.

BR289

My Feedback: (106)

I was wondering the same thing!

StevL

The only other I know for sure was Team Robart's P-47 that went into fail safe and hit the trees behind vendors row... I was standing very near where it went in. I've heard a few other stories but did not see it happen.


Steve

DougV

With the Robart's P-47, I read on FG forum that Eric's plug in module came out.

Doug.

Shaun Evans

Hi,

Maybe the guy that keeps opportunistically hyping this Futaba hysteria can chime in with that information. To read his posts, you'd think every other Futaba-guided plane went in at the Nall....

Moerig

SBUS is not that clever, SBUS II may have more features. The Sbus link simply sends out 25 bytes every 14ms at 100kbs. One header byte the rest are 11 bit sequences in order from 1 to 18 plus some flags for failsafe etc. The servo data is not even byte aligned. Servos are set to look at a specific set of 11bit data. No addresses as in a real network. No checksum or CRC.

StevL

Change it up a moment... Who lost a plane on JR/Spektrum (not dumb thumbed) and was it dsm2 or dsmx?


Steve

shovelrigid

My Feedback: (1)

Ok!! I know how much you old dudes hate change. but come on 72MHz over 2.4GHz. come on!!!! I bet your still using dry cell EverReady's to start your Hornet.

I'm flying with an Airtronics SD-10G channel 2.4GHz radio the latency is half that of most other name brand radios and after two years......... not one little burp!!!!!! I can't blame anything on the radio system. NOTHING.   I had a battery problem once......I Should have had redundancy built in but didn't My BAD . Never a radio problem. I don't fly turbine But I do Scale, Giant scale, Gas, and glow 4cycle. 

Don't listen to gossip. Do the research find the truth. 2.4 gigahertz = 2 400 megahertz a lot faster then 72MHz hah?

Freddy!

Carbon fiber next to your 2.4 reciever antennas will cause interference with your reciever in my Futaba manual it says keep antennas away from carbon fiber at least 1/2 " away, also 90 degrees apart. Just my imput.

mr_matt

My Feedback: (10)

this thread must have hit that front page dohickey that lets everyone know there is something interesting going on.

mr_matt

My Feedback: (10)

duplicate

Freddy!

Hows the weather in Cal ,cold here in Tn

Doug Cronkhite

My Feedback: (34)

Windy, Cold, Raining here in SoCal (or at least it was earlier).

g6rcteam

i guess it wasnt that bad an idea all those jet guys have a whole thead about it ha ha and i wasnt even serious

turkey hunter

My Feedback: (10)

shovelrigid, I believe you will find that 2.4 is not faster than 72mhz. 2.4ghz and 72mhz is cycles per second and not speed.
I believe that all signals travel at the speed of light which is 186,000 miles per second.

Shaun Evans

LOL,

Kinda reminds me of Egypt culling all the pigs in response to the Swine Flu situation...

bigbaggy

The response time is faster, more cycles per second to transmit the data. Faster updates ect.

wojtek

My Feedback: (73)

It was not only Futaba FASST planes going in ... didn't a JR equipped Hawk blow up sometime at the event when that lost link (amongst others) ? I think i saw that posted on one of the other threads ???

~V~

toprudder

72 MHz and 2.4 GHz are merely the carrier frequency. It has nothing to do with response time. It is possible for a 72MHz analog PPM system (4ch) to have quicker updates (lower latency) than some2.4GHz systems. The update rate is more a function of the modulation and encoding schemes.