helino

I watched as a fellow modeler was flying his gasser airplane. Straight and level, then nothing. Crash. Radio, DX-7 with 7 flights. Apparent after all parts were collected, radio lost "link". Horizon has it (radio) and is testing now. Horizon advised radio had lost link and is not sure why. Is sending him another radio. I'm sure glad it was not a very nice expensive machine or someone was hurt. I will still use my DX-7 but I am now more concerned. I hope it can be found to be only this one radio out of the thousands.

BRYAN01601

My Feedback: (48)

That's funny I have had the same thing happen to me with my 10x and pcm on it's first flight... Whats your point???

jfetter

Helino,

Can you provide a little more detail as to what happened? I am not doubting your story but occasionally someone runs in and yells "the sky is falling...", starting a long, drawn-out thread with nothing more than a "someone told me..." point of view.

Can you provide any detail as to the mounting of the receiver, the RX battery used, the number of flights that day, anything flaky with the TX ever (blank screen), was the pilot programming something during the crash (I have seen people editing sub trim and travel while flying), what was the range at the time, did he try re-orienting the TX, etc.

Many of us use this web site to keep informed but post like yours with little detail usually results in all of us saying !QUOT!pilot error!QUOT! and ignoring it. I really am interested in this story though because I built a new Fliton Inspire 60 and went DX7 at the same time, after the first day of flying I came home and ordered 4 receivers to convert half my fleet, I am in the middle of listing my JR TX and 8 770/790's for sale so this is of interest to me...

Thank you,

JFetter

Zeeb

My Feedback: (41)

Other than the fact that both the Spectrum and your JR are used to remotely control a model via radio waves, there's very little similarity.

Maybe you might want to read up on how the new system works and why it would be of particular interest that the rx seems to have lost it's "link" to the tx since that is not supposed to happen. Establishing that link is what is known as "binding" and your JR 10x does not do anything close to that.

If this is a case of "dumb thumbs", a power supply problem, or a faulty installation of the components then maybe your point is applicable. But if it was a case of the link between the two failing, that would be the first reported case I've seen and VERY worrisome to those who have the system, or those of us who are considering it...

Danny;
I didn't mean to butt in on your support forum, but as one who is considering this new system I'm extremely interested in the answer to this question.

Wlouigene

My Feedback: (66)

Lost link to the tx is not supposed to happen.

jfetter

I know human nature says if I don't like or have it, it's crap and likewise if I own it, it rocks but let's try and be objective here. I have a DX7 and I love it (so far) but I am genuinely interested if there is something happening to these systems that is both unpredictable (no way to know until it happens) and will result in complete loss. I get that the binding process is "supposed" to be unique and permanent but let's also understand this is something that requires a programmable chip, which can be flawed just like any other electronic component (we have all seen electronics die, this is nothing new).

I for one want to hear what people are seeing in the field, I am not interested in what is "supposed" to happen or telling them they have to be wrong because mine works. Let's leave our own personal bias out of this and simply try and dig down to the facts of the matter. I fly a DX7, I am replacing my entire fleet of receivers, I am the person that NEEDS to know this information. I am happy with the system so far, it has been 100% reliable and flawless (Axi 4130/16 electric setup, 55 Amp draw, receiver mounted semi-casually under the 6600 6S2P LiPo (3" away) under a carbon mounting plate and the remote receiver oriented 90-degrees to the main receiver right next to the Lipo, no special care taken simply velcro'd to the wood fuse) but I am also watching to see that there are no inherent flaws in the design or manufacturing process.

JFetter

[]TEX[]

I doesn't matter what you do, the Tx should NEVER lose com with the Rx...NEVER. These spectrum radios work on the same technology as your cordless house phones. How often does your phone loose com from the base? I don't have enough fingers to count the amount of times my cordless has lost com with the base, even after the so called "bonding".

FM systems don't and won't lose com unless there is a power failure. Even with interference AM and FM radios will not loose communication.

The technology is too new for me to trust a pricey plane on the DX system. I wouldn't fly a cheap park flyer on it.

These systems continuosly scan for new signals, that may be the issue here. This is a very serious issue and I am glad someone spoke up. It will be interesting to see how this plays out with these new systems.

onewasp

[quote]
I doesn't matter what you do, the Tx should NEVER lose com with the Rx...NEVER.
[quote]

Let us know when you reach earth ------ things are a little different here.

jfetter

TEX,

The Spektrum DX7 does not continuously scan for new signals, that is called Frequency Hopping Spread Spectrum (FHSS) but instead employs Direct Sequencing Spread Spectrum (DSSS). The difference is FHSS systems transmit a narrow band signal and rapidly jump from from one frequency to the next, spending only a few milliseconds on each frequency while DSSS systems transmit on a single selected frequency but on a very wide band.

When the DX7 transmitter is turned on, the system scans the 2.4GHz band looking for an open channel (79 channels are available). When an open channel is found, the system locks in and transmits on that channel, this process takes about 2 seconds. In the unlikely event an open channel is unavailable, the transmitter continues to scan without emitting a signal until an open channel becomes available. The transmitter will remain on that selected channel until it's turned off (important point!).

On top of that, each individual TX is factory programmed with its own unique GUID (Globally Unique IDentification code). Once a receiver is programmed to a specific module (called binding) the receiver will only recognize that TX, ignoring signals from any other source. There are over 4 billion possible GUID's making it virtually impossible for a receiver to listen to anything other than its bound transmitter.

While this all sounds good, it can break (like anything else), I only commented to correct the statement that these systems jump frequencies or channels...

JFetter

[]TEX[]

[quote]ORIGINAL: onewasp

[quote]
I doesn't matter what you do, the Tx should NEVER lose com with the Rx...NEVER.
In my 20+ experience, my Tx never lost com with it's Rx. I'm just being realistic...sometimes that is hard to swallow.

[]TEX[]

I totally understand what you are saying and my comment was not meant to bash DX users. I misunderstood some info I read on that so thank you for clarifying the DSSS. It still seems odd to me that people would "expect" a Rx to lose com with it's Tx or find this to be a normal characteristic.

I've never used a DX system, only seens them in action personally. I am not totally sold on them for this reason posted before.

jfetter

TEX,

I understand, I didn't mean to do anything except make sure the correct information was given, glad we can discuss this instead of resort to the flaming that seems to be getting into all the various discussions about this technology.

I became a DX7 user by happenstance really. I was at the LHS pricing out a new Fliton Inspire 60 (and everything except the motor and LiPo necessary to complete it), when we started talking about the flight pack, it became apparent that I'd have to spend $225 to get 4 digital servers and a JR 790 RX. The talk turned to the new DSS radios and spending only an additional $125 to get my flight pack AND a new TX using DSS!

Needless to say I had read enough to know this wasn't a gimmick and I had already been to the AMA site and looked up their position. Given my comfort level with their position, comfort level with the technology and comfort level that JR was manufacturing the TX (it's a 7202 with a different TX and firmware/software), I decided what the heck.

10 flights into my new electric Inspire 60 I have nothing but rave reviews to offer. Fast, reliable, feature packed and all of this with no more frequency worries, is-my-card-in-the-right-slot and worrying some guy with a new X-mas present just got out of his car in the parking lot and fired up his new radio.

But... I am also able to recognize there may be genuine issues, either inherent in the design or by-products of the manufacturing process that will manifest as problems, so I come here and read up and look for patterns. The Internet is a great place for this kind of information sharing, you just have to know your source and try and get details...

Have a Merry X-mas TEX (seriously). I hope Santa brings you more planes, a place to keep them and a Wife that still thinks they cost only 100 bucks or so ;-)

JFetter

[]TEX[]

LOL, that's hilarious because she thinks everything costs less than $100.

Happy Holidays to you as well.

Zippi

My Feedback: (10)

helino,

I am in the process of buying the DX7 and really find it hard to believe that it lost it's signal. The DX7 has a "Safty Net" called Dualink. Dualink is when you turn the TX on it scans for an open signal and locks onto it and it then scans again to find another signal and locks onto it as well. If for some reason it looses the first link it picks up the second one. That's why I say I find it hard to believe it lost it's link.

ncrego

My Feedback: (40)

How is it hard to believe? 2 channels or 400, it doesn't matter how many if there is a power problem, or a problem with a chip in the receiver or transmitter. There's a lot more to reliability than just being locked out of a channel.

Zippi

My Feedback: (10)

ncrego,

helino made this statement "Horizon advised radio had lost link and is not sure why" thats why I say it's hard to believe that it lost it's link. I guess there could be some sort of power loss but I was hitting on the point that Horizon said it lost it's link.

ncrego

My Feedback: (40)

I think you are reading "Lost its link" too narrowly. It could happen for any number of reasons.

BRYAN01601

My Feedback: (48)

My point was simply planes crash on maiden flights or flights with new equipment all the time. As A matter of fact I believe most crashes are during the first 25 or so flights. For someone to come on here and accuse a spektrum system of loosing it's link w/o any other hard facts is a shame. The plane crashed so let's point to the one thing that I think it could be.... Must be that new spectrum technology... becuse everyone knows planes never crash for any other reasons. Let's not jump the gun and start pointing fingers at one cause w/o doing a complete investigation not ruling anything out.

Bob Pastorello

My Feedback: (198)

So far, on this thread, the "other" thread on RCU, and on Flying Giants, there seems to be a commonality that suggests (to me, anyway) of some unknown TX-related issue, perhaps connected to blanking of the screen. If I'm not mistaken, the TX screen goes DARK when power is removed. If this happens while "bound" to an RX, when it powers back up..... what channel will IT be on? And what channel is the RX "listening" on?

I'd bet a bunch that we're seeing TX issues.... now, trying to figure out WHAT, exactly, well.... that is an elf of a different Toy Shop. Maybe Santa will drop solutions down our chimneys...

GOOD Discussion is really refreshing to observe..... I'm trying to think up/design some kind of TX testing protocol to use when mine gets here this week. Any ideas?

[]TEX[]

He does have hard facts, directly from Horizon.

Zippi

My Feedback: (10)

ncrego,

If anyone has taken "Lost its link" too narrowly, then I would say it is Horizon Hobbies. I'm am just replying to what was stated.

Wlouigene

My Feedback: (66)

helino

Regarding the Defect: The aircraft was checked by and observed flying by Fred Johnson, sponsered by JR. Fred owns the full size AT-6 that Horizon modeled. So when Horizon got word of the radio losing it's link to the reciever, the pilot that lost the aircraft recieved a personal call from one of the desighners of the system. He confirmed the radio lost "link" and were conducting tests. My point, nothings bulletproof. Maybe try in a foamie for a while before trusting in something valuble.

Zippi

My Feedback: (10)

helino,

Thanks for the update. Well, now I don't know what to do. I was planning on buying the DX7 in a couple weeks but now I don't know if it's a good idea or not. If there is in deed an issue with the radio I sure don't wont my first big gasser going in. When Horizon replaces the radio that's great that they stand behind their product but what about the cost of the plane?

jfetter

Can we get a little more accurate and in-depth detail on this one? I am not trying to be harsh but if possible, can we get a statement directly from the pilot or Horizon? The phrase "lost its link to the receiver" means nothing for a DSS system, the TX is not bound to the RX but the other way around. The TX turns on, scans for an open channel and locks on, the RX does the same, looking for the GUID of the TX it was bound against (and the matching model number assigned when bound), assuming it finds both, the RX locks on the TX.

So did the RX lose it's binding to the TX, did the RX lose signal and go into fail-safe (setting the control surfaces to the position they were in when bound in the case of the DX7), did the RX fail altogether? A failure can be caused by so many reasons, it seems if Horizon really admitted an issue and went so far as to send a new TX to the pilot, then there would have to be some admission of liability, that's what I want to see please, the statement given when the promise for a new TX was made...

JFetter