Futaba 2.4 GHz FASST Service Advisory

On Thu, 24 Jan 2008 09:40:59 -0600, flieslikeabeagl


Bit unfail, my WinCE PDA has performed without any issues, I guess it's the little darlings in the stores trying to break them and either trying to load or just deleting things they should not. Not what you'd do if it was your own.
However I thought it was an odd choice, but it gave Futaba the photo and MP3 ability they use for the display. I dare say they use it in industrial machines too,
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've had exactly "one" problem with Spektrum. I had a Slow Stick lock up and be totally nonresponsive at SEFF last year. The Horizon Hobby team (on site for the event) was very responsive to the problem, checked out my equipment, and determined I had a TX range issue. They took my TX with them, sent me a brand new one. No problems whatsoever in the following 9 months! I had numerous problems with glitches on 72MHz, and I'm not going back.
PCPhill
I'll be manning the raffle at SEFF '08. If anyone from Rec.Models.RC.AIR are there, please stop by and say "Hi"! I'd love to put some faces to the names...
A side note: During the noon demos, Horizon had a midair with a huge Extra 260 and some other 3D plane. They gave the damaged Extra to my daughter (who was assisting the event director) and then sent her replacements for the damaged parts. Needless to say I'm a confirmed Horizon fan!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
... | > Let's not forget that Futaba was one of the first with 2.4 | > GHz gear for R/C cars, which preceded Spektrum by many | > years.
And years before that, Futaba had spread spectrum industrial R/C gear. I don't know why they took so long to get it into modelling R/C usage. Perhaps because they already saw themsevles as a/the industry leader, why try harder? I do not know ...
| True. It's also true that RC cars don't roll, loop, do snap-rolls, etc, | and a glitch is rarely destructive as the model stays on the ground.
You'd be surprised how much damage an out-of-control R/C car can do. Consider an 1/8th scale car running into your shins at 60 mph -- or worse, hitting something and going airborne, flying at your face ...
| I attended a seminar given by Spektrum engineering manager John Adams | back in 2006; during his talk he commented that providing a solid RF | link to a model aircraft was an extremely difficult technical challenge, | for the reasons above - the need for a continuous link without any | dropouts at all, and the continually changing orientation of the model | wrt the transmitter.
Cars have similar issues and needs, but the ranges are a lot lower.
| Also when the Tx frequency hops, the Rx has to do likewise, which | means the two have to sync up again after every hop. And what | happens when something goes wrong and the sync up doesn't happen | immediately as intended?
This sync-up thing is pretty well worked out. People have been doing spread spectrum like this for what, 50 years? They know how to make it work, and it works. Basically, this is just FHSS FUD.
| Most forms of RF link can tolerate the brief dropouts that result from | this sort of thing (FHSS sync gone wrong). Model aircraft cannot. | Apparently this is why Spektrum tried FHSS, found it wanting, and went | to a DSSS solution.
I know they weren't happy with FHSS, but I've never really seen a technical explanation for why. If you have a reference, I'd like to see it.
| > Statistically, Futaba's SS system is much more robust. | > | I take shiny marketing pamphlets with a large grain of salt
You must have had lots of salt when you read Spektrum's original press releases and FAQs then!
| (Not that Spektrum is perfect, for instance it would have been | really nice to have two-way telemetry and eventually force feedback | from the servos actuating the control surfaces on the model. :) )
The car people already have built-in telemetry from Nomadio and have had it for a while. XPS has promised it for planes, and their literature makes it sound like it's available now, but I can't seem to find a place to buy it -- which suggests it's not ready yet.
--
Doug McLaren, snipped-for-privacy@frenzied.us
Man who falls in vat of molten optical glass makes spectacle of self.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It sounds like in this example, a few loops and rolls and spins are still possible with a car! <g>
--
Jim in NC



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Doug McLaren Wrote:

I'll take your word for it. :) I have little personal experience wit RC cars. Doug McLaren Wrote:

A very good point! Doug McLaren Wrote:

I'm not so sure...most 2.4 GHz FHSS RF links we use have the odd shor dropout that simply isn't of much consequence. Anyone who's used cordless phone or a Wi Fi ethernet card has probably experienced thes little glitches. They simply don't matter in the applications mentione above. But even a very short glitch causes loss of pilot confidence whe flying an RC model, and a slightly longer glitch can cause a crash. Doug McLaren Wrote:

From memory, John Adams said that the FHSS systems had more shor dropouts in the RF link, and the problem was never overcome. There wa also reduced range and S/N ratio with FHSS due to the increase processing gain of a DSSS system over an FHSS system. Doug McLaren Wrote:

Sure. When I worked as an engineer I quickly found out how wide the ga is between what the engineers say and what the marketers say!
That was one of the reasons I attended John Adam's talk back in Ja 2006. This guy is an engineer and RC pilot (he brought a passel of hi micro electric helicopters with him to the talk). I think he wa Spektrum Chief Engineer at the time, now he's Engineering Manager o something. Exact title notwithstanding, after his talk and the flood o questions he answered from the very interested audience, I came awa with a quite positive impression of the Spektrum engineering teams work He didn't give us marketing BS - he gave us technical answers t technical questions.
-Flieslikeabeagl
-- flieslikeabeag ----------------------------------------------------------------------- flieslikeabeagl's Profile: http://www.rcgroups.com/forums/member.php?u303 View this thread: http://www.rcgroups.com/forums/showthread.php?t 331
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| Doug McLaren Wrote: | > | > You'd be surprised how much damage an out-of-control R/C car can do. | > Consider an 1/8th scale car running into your shins at 60 mph -- or | > worse, hitting something and going airborne, flying at your face ... | > | I'll take your word for it. :) I have little personal experience with | RC cars.
As do I. But I have seen some crashes that could have really hurt somebody had somebody been in the wrong place ... ...
-- let me re-insert some text that was trimmed --
| > > Also when the Tx frequency hops, the Rx has to do likewise, which | > > means the two have to sync up again after every hop. And what | > > happens when something goes wrong and the sync up doesn't happen | > > immediately as intended?
--- re-introduction complete ---
| > This sync-up thing is pretty well worked out. People have been doing | > spread spectrum like this for what, 50 years? They know how to make | > it work, and it works. Basically, this is just FHSS FUD. | > | I'm not so sure...most 2.4 GHz FHSS RF links we use have the odd short | dropout that simply isn't of much consequence. Anyone who's used a | cordless phone or a Wi Fi ethernet card has probably experienced these | little glitches. They simply don't matter in the applications mentioned | above. But even a very short glitch causes loss of pilot confidence when | flying an RC model, and a slightly longer glitch can cause a crash.
I was talking specifically to the idea of FHSS `losing sync' when it hops. The only time that this will generally happen is if the TX or RX loses power, or gains/loses some time somehow (going through a wormhole or something similar might do it, let's hope your flying field doesn't have many.)
As for WiFi, it doesn't use FHSS at all, so it's a poor example of FHSS glitching. And cordless phones could use either form of spread spectrum -- or perhaps no spread spectrum at all.
As for glitches not causing problems, even a 1% packet loss in a TCP/IP link, over whatever medium, will really mess things up. The system can recover, yes, but throughput will drop by a very large margin. TCP does handle lost packets, yes, but not very well.
Losing 1% of your R/C frames probably wouldn't even be noticeable by most flyers, because once the next valid frame arrived, all would be well again. With PPM, frames usually aren't lost but are instead corrupted, so you might have a visible `glitch' in the controls where the servos do something you didn't tell them to, but with PCM and SS usually invalid frames are quietly dropped and you probably won't even notice.
| From memory, John Adams said that the FHSS systems had more short | dropouts in the RF link, and the problem was never overcome. There was | also reduced range and S/N ratio with FHSS due to the increased | processing gain of a DSSS system over an FHSS system.
In any event, it sounds like Futaba worked out whatever the problem was. They have been doing spread spectrum in their industrial R/C stuff for well over a decade now, so they probably do know what they're doing -- they just moved slowly in getting it packaged for us. This problem with the zero GUID has nothing to do with FHSS vs DSSS -- it's either a manufacturing process glitch, or overlooking a `weakness' in the components they use (and forgetting to add some sort of failsafe to detect that. They could certainly make their firmware throw an error if a 0 GUID is detected or an invalid CRC in the flash memory, had they considered it.)
(And which is more dangerous? An out of control R/C plane, or crane? Could probably go either way ...)
In any event, Futaba's system does sound like it has one big advantage over Spektrum's system -- how it handles _bad_ interference. Suppose somebody brings their 2.4 GHz camera to the field, and it's using the usual six MHz of bandwidth. Suppose that both 1 MHz channels that your Spektrum system are using are within this 6 MHz (and if Spektrum keeps them far apart, suppose that two people bring their 2.4 GHz cameras ...)
Spread spectrum can cut through interference to some degree, but the range will be greatly reduced. Since Spektrum can't hop channels at all, you'll crash once you get out of the greatly reduced range.
In the Futaba case, OK, less than 10% of the band is `ruined' -- but the rest is fine. So maybe you'll lose 10% of your frames -- the plane might seem slightly `jerky' (or maybe you'd need to lose a lot more than 10% for it to be noticeable) but it's still completely flyable. In fact, you could probably lose 95% of your frames and still fly the plane.
Of course, this is all guesses, because I don't have any Futaba spread-spectrum gear and have not tested any of it.
| That was one of the reasons I attended John Adam's talk back in Jan | 2006. This guy is an engineer and RC pilot
To be fair, if you get a job designing R/C equipment, people will take you a lot more seriously if you actually do R/C. Even if he knew nothing about R/C before getting hired, I'll bet his job/boss probably *required* that he pick up the hobby if he wasn't already into it.
(It would be nice to be able to deduct R/C stuff on your taxes!)
| Exact title notwithstanding, after his talk and the flood of | questions he answered from the very interested audience
Being first is neat like that!
| I came away with a quite positive impression of the Spektrum | engineering teams work.
Futaba's team probably would have put on a similar performance, had they been first. They could do it now, but people wouldn't be quite so interested anymore -- now there's several R/C spread spectrum vendors, lots of people are using it, ho-hum.
--
Doug McLaren, snipped-for-privacy@frenzied.us
`If one studies too zealously, one easily loses his pants.' -- Albert Einstein
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
flieslikeabeagl wrote:

I think this is an accurate summary from our doggy friend.
Apart from the fact that the current issues have nothing to do with FASST per se, but more, it seems, due to penny pinching the design around the way the FLASH ram is used to store GUID's..
The argument is raging as to whether its ever safe to store something so fundamental in RAM which can get corrupted. As much as how easy it seems to be to corrupt it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Natural Philosopher Wrote:

Very true, and I didn't mean to suggest otherwise. The point I wa trying to make was that I think there is some reason to believe th entire design process was rushed, from the choice of the fundamental R technology to the implementation of the actual firmware. We don't ye have statistics on any issues with the choice of FHSS, but I wouldn't b surprised of some emerge over the next year or two. We'll just have t wait and see. The Natural Philosopher Wrote:

This didn't even occur to me, but you're absolutely right. A fe passing gamma particles (the sun streams them at us all the time) migh be all it would take...
-Flieslikeabeagl
-- flieslikeabeag ----------------------------------------------------------------------- flieslikeabeagl's Profile: http://www.rcgroups.com/forums/member.php?u303 View this thread: http://www.rcgroups.com/forums/showthread.php?t 331
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Complete and utter speculation. mk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
MJKolodziej wrote:

But experienced and educated and, as I know from elsewhere, disinterested speculation.
However Futaba phrase it, I bet you this model of tranny will be (effectively) replaced inside of 6 months..
"It just got better!!" ;-)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The Natural Philosopher Wrote:

Thank you for the vote of confidence. :) Yes, I do strive fo scientific objectivity as much as possible during these sorts o discussions. Since we humans are subjective by nature complet Spock-like objectivity may be forever beyond us (Malcom Gladwell's boo "Blink" is a fascinating read on the subject), but all we can do is mak our best effort, and I endeavour to do just that.
-Flieslikeabeagl
-- flieslikeabeag ----------------------------------------------------------------------- flieslikeabeagl's Profile: http://www.rcgroups.com/forums/member.php?u303 View this thread: http://www.rcgroups.com/forums/showthread.php?t 331
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
flieslikeabeagl wrote:

I got an interesting response from the LHS..they too claimed it was all part of the 'brand wars' between Spektrum and Futaba.
That is a dangerous conclusion to come to IMHO.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
MJKolodziej Wrote:

Which part? The first paragraph is objective fact, we've even had a least one Futaba rep post here on RCG admitting that Spektrum had caugh them flat-footed and they were racing to catch up. If you're in lawyering mood, those were not his exact words, but as close as I ca remember to the content of his post.
The second paragraph is speculation, yes, however it is based on th evidence I've seen so far. For example, when a company chooses t release a new microcontroller based RC transmitter in the year 2007 an it has only six model memories, it is a dead giveaway that this is a old product using old electronic components that are nearly obsolet technically - they must be from an era when the price of flash memor was so high that the cost of the few hundred bytes needed to store models settings was significant. Another giveaway is Futaba's use of custom RF chip in an era when 2.4 GHz spread-spectrum equipment i ubiquitous and dozens of much cheaper off-the-shelf solutions exist they probably were using what they already had and knew, rather tha taking the time to come up to speed with currently available parts. third giveaway is this enormous blunder with non-unique GUID's - tha smells of a rushed job if anything does.
By the way, if it isn't already obvious, I have nothing against Futab the company - in fact my first microcontroller based transmitter wa made by Futaba; back in 2005 I bought a Futaba 7CAP that served me wel until Spektrum made a better mousetrap.
-Flieslikeabeagl
-- flieslikeabeag ----------------------------------------------------------------------- flieslikeabeagl's Profile: http://www.rcgroups.com/forums/member.php?u303 View this thread: http://www.rcgroups.com/forums/showthread.php?t 331
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
flieslikeabeagl wrote:

I really doubt that the reason the 2.4GHz TX has only 6 model memories - either Futaba didn't have the flash space or else it is an intentional restriction to position the TX to the low end of the market.
> Another giveaway is Futaba's use of a

That's basically a stupid argument. It's 100 fold easier to move to 2.4GHz by using other peoples chips than to have to grapple with the intricacies of a completely new system. I'm prepared to bet that Futaba's comparatively late entry to the 2.4GHz field has some dependence on their decision to go it alone with the consequent huge development effort entailed by that.
> A

They had a manufacturing problem where a process was not applied to part of their poroduction run. I really don't see what that has to do with your speculative "rush to get something on the market" ?

Me neither :-) In fact all the TXs I've owned in the past have been Futaba ones but the lamentable failings of the 9C Super I own mean I am now looking to jump ship when the 2.4GHz market settles. Ironically, Futaba's version of 2.4GHz seems like it may have major advantages over the Spektrum / JR implementation (in respect of x-country glider application) so I may have to go with them after all.
--
Boo

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Boo wrote:

No. That sadly is a blind.
They have a hardware circuit that makes two fundamental errors.
- they store something that is supposed to be unique,and unalterable in FLASH ram, which is very alterable.
- They fail to design around WELL KNOWN problems with FLASH RAM under which power supply voltages outside of known limits cause completely unpredictable behaviour in it. Because of the nature of Flash, you have to erase and rewrite whole sections of it to change a single bit. Lose power at that point, and you end up with a whole section erased, and not re-written.
The hardware workaround is a big fuckoff capacitor and some voltage detection stuff that signals to the circuit that power is failing,and holds enough voltage in the cap to complete a write cycle, and then shuts down cleanly.

Me neither. But in this case they have made a big cockup, and haven;'t yet gotten around to admitting the full extent.
Personally speaking, I think that with the bugs out, the FASST stuff looks a market beater. That doesn't mean I am prepared to excuse the COVER UP on the cockup. Altho the cockup itself, is - well understanable, if not excusable.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Natural, you have it exactly correct.
Non-volatile memory, like Flash and EEPROM, does NOT mean non- corruptible. There are other technologies, some quite old like fusible link memory, hardware program cards/chips/plugs, etc., that are truly permanent memory. However, those methods could add significantly to production cost. The question is: "What price safety and reliability?"
To points brought up by others: As for re-using older transmitter technology and adapting it to the new 2.4GHz RF link instead of designing new circuitry throughout: that is a far more common practice than most people realize. Most new and complex systems build upon older, proven (read as "reliable") technology. The fact that the FASST system only allows three digit naming indicates that Futaba re-used much of its older encoder sub- system. So what? It works. I always thought that the main reason for going to 2.4 was to improve the RF link. Keep in mind that if you go with an XPS system, that is exactly what you're doing.
Finally, I haven't seen it mentioned anywhere, but I hope that Futaba has a handle on exactly what group of radios has the 0000 ID problem. Surely they can nail it down to serial numbers or production dates?
DougSter
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I just bought a 9C. What failings can I expect? mk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
MJKolodziej Wrote:

A fairly sizeable latency for one:
http://www.runryder.com/helicopter/gallery/8588/latency_pcm13.gif
http://www.runryder.com/helicopter/gallery/8588/latency_pcm13_avg.gif
-Flieslikeabeagl
-- flieslikeabeag ----------------------------------------------------------------------- flieslikeabeagl's Profile: http://www.rcgroups.com/forums/member.php?u303 View this thread: http://www.rcgroups.com/forums/showthread.php?t 331
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I didn't see my TX there, are we on the same TX? Fut 9C ? mk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
So far, the problem seems to be limited to the original 6EX transmitters and some 7 channel transmitters.
CR
MJKolodziej wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.