RCModelReviews and Spektrum/Horizon

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Re: RCModelReviews and Spektrum/Horizon

Postby RCModelReviews » Mon Sep 06, 2010 1:46 am

It would surely be a far better strategy (for *everyone* concerned) to either:

1. state that the problem is not a problem and give reasons why

2. acknowledge the problem and fix it, confirming to concerned users that the fix is available and is now included in all new product.

I suspect they can't do option 1 because it *is* a problem and they can't come up with any plausible explanation to convince people that it isn't.

I suspect that option 2 would involve significant expense, since lots of folks might want to have the fixes applied to their existing equipment and that would involve Horizon having to repair a *lot* of radios.

So their *only* possible strategy is to simply try and ignore it.

What does that say about their famed "customer support" when they ignore an issue that may well be at least partly to blame for the significantly increased numbers of "unexplained loss of control" events with DSM2 equipment, especially in noisy environments?

I had really expected more from Horizon -- but my level of surprise at their indifference diminishes with every passing day.
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Re: RCModelReviews and Spektrum/Horizon

Postby Toumal » Wed Sep 08, 2010 1:01 pm

RCModelReviews wrote:1. state that the problem is not a problem


Ah, you mean pulling a Jim Drew on us and going "this never happens on the field", perhaps with a jedi-handwave as added bonus?

RCModelReviews wrote:2. ...the fix is available and is now included in all new product.


"No no, XPS v3 is an entirely NEW product with advanced features, and we made it because we're awesome like that, and totally not because there was any kind of problem with v2. Now shut up and pay for the bugf...upgrade."
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Re: RCModelReviews and Spektrum/Horizon

Postby cuban8 » Wed Sep 08, 2010 10:12 pm

If you're worried about "all the Spektrum problems" take a look here http://www.rcmf.co.uk/4um/index.php/topic,74421.0.html Should make you feel better!

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Re: RCModelReviews and Spektrum/Horizon

Postby Toumal » Fri Sep 10, 2010 7:45 am

cuban8 wrote:If you're worried about "all the Spektrum problems" take a look here http://www.rcmf.co.uk/4um/index.php/topic,74421.0.html Should make you feel better!


Relevance? We're talking about a real, factual issue here, not some "gut feeling" thing. So yes, a couple guys post that they switched to Spektrum. You'll notice that some people in that thread replied that they switched from Spektrum to another brand. Both things have nothing to do with the issue of suboptimal channel selection, DSSS vs. FHSS, or the way Spektrum communicates with people pointing out technical design issues.

So while it may make you "feel better", it doesn't change the fact that your DSM2 system may choose two adjacent channels, making it vulnerable to interference of a single video transmitter someone might power up on your field, or in your vicinity.
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Re: RCModelReviews and Spektrum/Horizon

Postby cuban8 » Sat Sep 11, 2010 11:11 pm

Sorry, but I just don't understand the hysteria surrounding the "Spektrum Problem". Yes I fully understand and accept the findings regarding the system possibly selecting channels that are relatively close, but just because it's been decreed that this might prove fatal if other random outside influences occur at the same time, doesn't mean the system's no good. Yes, Spektrum's S/W designers have potentially left their product open to possible failure if a very unlikely set of circumstances occur. Too many ifs, buts, maybes, and random effects to really cause owners to lose confidence in their equipment IMHO.
How many wide band 2.4 gig transmissions (video transmitters?) would it take to swamp the whole band and render a FH system useless as well? I don't know whether it's 4 or 6 or 8 or however many. Presumeably it could happen, so why don't we start worrying about that?

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Re: RCModelReviews and Spektrum/Horizon

Postby RCModelReviews » Mon Sep 13, 2010 12:44 am

cuban8 wrote:Sorry, but I just don't understand the hysteria surrounding the "Spektrum Problem". Yes I fully understand and accept the findings regarding the system possibly selecting channels that are relatively close, but just because it's been decreed that this might prove fatal if other random outside influences occur at the same time, doesn't mean the system's no good.

You are absolutely correct.

As I've said in my articles on the matter The sky is not falling.

However, it's not an insignificant issue either.

That I was able to completely disrupt the DSM2 link using something as simple as a video-sender and that this was replicated by a colleague using just a 50mW video sender is somewhat worrying. These video senders are sold in large numbers and some people are using them on RC models for FPV purposes which means the scenario where a DSM2 system selects 2 closely-spaced channels and then someone turns on a video sender that also occupies the same part of the band is a small but definite possibility.

What is of concern to me (and clearly other people) is not that this vulnerability exists in the DSM2 system, but that Horizon/Spektrum won't acknowledge it and fix it. All it would take is a tiny change to the code in the DSM2 transmitter -- something that could be done and tested in a day.

The only reason I can think of is that they don't want huge numbers of existing DSM2 users returning their equipment for an update to the new code -- so they'd rather not acknowledge the problem. Perhaps the new stuff is already fixed but they're not going to say anything for fear of that wave of "please update my old gear" requests, and the costs that would involve.

Yes, Spektrum's S/W designers have potentially left their product open to possible failure if a very unlikely set of circumstances occur. Too many ifs, buts, maybes, and random effects to really cause owners to lose confidence in their equipment IMHO.

The thing is that if Spektrum was a cheap Chinese system that cost just a few bucks I'd agree. However, Spektrum is pitched as a "premium" product and a leader in the field of 2.4GHz RC, with a matching price.

Why should people have to pay top-dollar for a bottom-shelf product?

It is the goal of RCModelReviews to help people make *informed* decisions when purchasing new stuff. They need to know that DSM2 is past its best-by date (for a number of reasons) and that it makes no sense to buy an RF system which is outdated and suffers performance penalties when, for the same or even less money, they can buy much more advanced and resilient systems.

One only has to look at a DSM2 installation in a large model to see how far behind the 8-ball Spektrum is now. Spektrum/JR advise you should use at least 3 satellite receivers and a data-logger to ensure reliable operation in such models and to keep an eye out for potential issues. By comparison, there are a huge number of FASST and other FHSS installations that work perfectly -- with just a single receiver and two antennas. Technology has advanced significantly since Spektrum designed their system but they are steadfastly sticking with old designs and (it would appear) buggy software.

What became very apparent in my tests is that there are now only two brands of 2.4GHz RC systems that select and stick with only two DSSS frequencies. These are DSM2 and the Chinese Assan (one of the first Chinese 2.4 products).

Every other manufacturer has now either gone to constantly-agile (FHSS) technology or opted to use at least three frequencies for redundancy. JR's launch of DMSS is another clear indicator that they don't wish to have their brand associated with the now aging and (in some cases) inadequate DSM2 technology.

How many wide band 2.4 gig transmissions (video transmitters?) would it take to swamp the whole band and render a FH system useless as well?

Well a video sender tends to consume about 1/4-1/5 of the entire band so in theory, as few as 4 video senders operating on different parts of the band would cover it. However, there are peaks and troughs in the video-sender's signal so even then, *some* of the FHSS system's signal would get through. In my testing, it's enough to provide a measure of control that would allow you to get your plane down in one piece. FHSS systems tend to degrade more gradually as you fill up the band with noise. DSSS systems just stop dead.

I don't know whether it's 4 or 6 or 8 or however many. Presumeably it could happen, so why don't we start worrying about that?

It'd only take 4-5 to cover the band -- but a good FHSS signal will still get through adequately to provide a modicum of control. And what's more, the chances of this happening are clearly a lot less than the chances of a single video transmitter being turned on while someone's flying their DSM2 system.

In summary: DSM2 still works for most people but it is now very much a "second tier" system -- so, why would anyone buy a second-tier system for a top-tier price when there are a raft of better options available that provide more insurance against being shot down by interference or suffering a receiver brownout?

The sky isn't falling -- but it's getting awfully cloudy in the Spektrum camp.
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Re: RCModelReviews and Spektrum/Horizon

Postby skyguy04 » Mon Sep 13, 2010 2:21 am

Nice post Bruce!
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Re: RCModelReviews and Spektrum/Horizon

Postby minibell » Mon Sep 13, 2010 3:57 am

With the boom in sales of FPV equipment and as these people fly from anywhere, its is going to be a very real problem sooner rather then later.

Bruce, what other 2.4gHz equipment could be a problem on our band as well?
Given that many park flyers fly close to houses with household items in general, Or near industral areas operating equipment.
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Re: RCModelReviews and Spektrum/Horizon

Postby RCModelReviews » Mon Sep 13, 2010 4:51 am

In a "park" environment the majority of devices you'll have to do battle with will be cordless phones, microwave ovens and home WiFi networks.

A leaky microwave oven can leak a *lot* of energy into the 2.4GHz band and that could be an issue but fortunately most microwaves are carefully designed to avoid any chances of leakage.

Some folks do use 2.4GHz video senders to extend the signal from their cable or satellite decoder into the bedroom -- so that's something to consider, and in some areas there are a lot of those cheap 2.4GHz video systems used as security cameras so that people can see who's at the front door or gate while sitting in their easy-chair watching TV.

Fortunately, none of the above items will totally obliterate the band so as long as your RC system has enough 'spread' and delivers sufficient headroom to cope with the combined total of all these "noise" sources, you should be fine.
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Re: RCModelReviews and Spektrum/Horizon

Postby minibell » Mon Sep 13, 2010 8:30 am

Thanks Bruce.

Just out of interest, does our 2.4ghz systems cause other people grief in any way?[those not associated with flying]
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