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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › New plug-in 2.4GHz modules!
09-08-2006 11:10 AM  14 years ago
w.pasman

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Netherlands

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Gordie
f you put an offbrand module in a radio and it crashes into a crowd, who would be liable, the flyer, the radio manufacturer, or the module/receiver maker?
I think with this stuff the flyer is on his own and he will have to proof quite impossible things if he wants to blame the manufacturer(s). Of course Futaba can not be responsible if you use a module from another brand. And the module manufacturer even states that there *IS* a chance of being on the same channel as someone else, offloading crash responsibility even before anything has happened. Furthermore they can always say that there was a line-of-sight conflict.
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09-08-2006 11:23 AM  14 years ago
ChristianM

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Oslo, Norway

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Line of sight not a big deal
A lot of people are getting all worked up about this line of sight statement. This just means that the range will be reduced to some degree when there is an obstruction between the transmitter and receiver. This is true for all radio transmissions including your current radio and your cell phone. That is also why you have a shorter range for ground applications compared to aerial application since the ground attenuates the signal. Your cell phone does not drop out just because you are in your house unless the signal is weak to begin with (the walls will attenuate the signal). So you are not going to lose control over your model if you fly behind a tree unless it is over mile away or something like that. I think even Curtis would struggle with that one

Christian
Burn fuel, be happy
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09-08-2006 11:25 AM  14 years ago
w.pasman

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Don't know if 2.4 GHz is reserved for any use here.
You can check it on freq info system

If I get it right, anyone can transmit on this frequency as he likes. Also if I'm not mistaken the 'wifi' (build into computers pdas etc) for this frequency can be programmed to pick any frequency you like in software. So anyone with a computer with a transmitter can fool around on this frequency, ignoring all those nice "spread spectrum" protocols etc.
If I'm right anyone with a wifi-enabled computer/pda can shoot you down on the 2.4GHz pretty easy.
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09-08-2006 11:38 AM  14 years ago
ChristianM

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w.pasman

The 2.4 GHz is open for use of SS devices and I believe this to be true world wide. The WiFi units are already using this band. The beauty of SS is that it will reject interference that does not have the correct "code". I suggest that you read the article that helo_cris posted a link to. Here is the link and an excerpt from that article.
Resistance to Interference, and Anti-jamming Effects
This characteristic is the real beauty of SS. Intentional or unntentional interference and jamming signals are rejected because they do not contain the SS key. Only the desired signal, which has the key, will be seen at the receiver when the despreading operation is exercised.

You can practically ignore the interference (narrowband or wideband) if it does not include the key used in the despreading operation. That rejection also applies to other SS signals not having the right key, which allows different SS communications to be active simultaneously in the same band (such as CDMA). Note that SS is a wideband technology, but the reverse is not true. Wideband techniques need not involve SS technology.
Christian
Burn fuel, be happy
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09-08-2006 11:41 AM  14 years ago
Bad Karma

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UK

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If I'm right anyone with a wifi-enabled computer/pda can shoot you down on the 2.4GHz pretty easy.
Nope, thats what the frequency hopping is for, if some device turns on on your channel then it will scan for a free channel, send an instruction to the reciever to start listening to that channel and then the transmitter will start transmitting on that new channel, all in the space of a few microseconds.
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09-08-2006 12:07 PM  14 years ago
Eco8gator

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Palm Beach, FL

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Hello

Ive read that line of site is a concern with this system...

Well consider your router. It works thought walls/floors, youve lost LOS but it still works....

Ive also had lots of experience with 2.4 Ghz video systems that work though walls(ground station in lab and walk out side with the camera/transmitter system)...

Last Ive worked on autopilot systems that are on 900Mhz that again work though walls(different frequency but still SS)...

What Im saying is for the most part, if this system works as advertised, your most likely not going to have LOS problems as the cause of a "glitch/lockout." You have to have on hell of a barrier between you and the model or be extreamly far out.

BTW, its good to see someone is finally making modules with many channels.

Carlo
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09-08-2006 03:02 PM  14 years ago
helo_chris

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goodlettsville, tn

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Yes, probably they will say line of sight was the problem in every case where the communication fails and you crash ...
Once these start to filter out Im sure we will hear all sorts of funny things about cause of crashes. Its hysterical to listen to some people at the field talk about the spektrum radios like they are just plain evil. Want to know how much of an issue line of sight is, next time you are on your cell phone look around for a tower. I know here most of the time due to buildings, trees, or terrain I almost never actually see a cell tower directly and I have very few problems with reception, mostly inside and in the car.

And I for one will be one of the first people on this one. I have been waiting for some thing like this.
"There is a fine line between cutting edge and bleeding edge.."
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09-08-2006 04:34 PM  14 years ago
hcopter

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Pittsburg KS

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Line of site and other 2.4 devices
Here is a paste from Jim Drew of Xtreme Power Systems in a thread over on RCG:

-----------------------------
"A lot of people have been asking about interference from other 2.4GHz devices, like the Spektrum radio and 802.11 devices. ALL of the testing in-house has been done with the Tx sitting next to a Spektrum Tx turned on, and a high powered wireless router with a 14dbi external antenna. With this configuration, we can transmit/receive with no packet loss through our building (metal/wood construction) and through the next building (located 100 yards away) and down the street about 1/2 mile. This way overkill for what we need in R/C, where range of 2,500 is about maximum.

Most of the original testing was done using an electric powered foamie profile plane. The receiver is light enough for these planes (Hobby Lobby profile in this case). There are no issues with the antenna "sticking out" because it only sticks out less than 1" from the top of the receiver. The receiver can fit in all of the HET ducted fan jets.

Carbon is not a problem as far as blocking the signal, however, it has to be squashing the signal to a degree. How much, we are not able to determine at this time. You can fully incase the receiver in carbon fiber and it still responds properly, but we have not done any range testing this way. We will at some point" in the near future."
---------------------------------
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09-09-2006 05:33 AM  14 years ago
kookboy

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Vancouver, BC

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Spectrum doesn't count, since it's a parkflyer only system
Read up on some information before you make that statement.

I have been providing UAV video service to a few ski-heli companies and resorts by flying my 6ft glider unmanned and flying via 2.4 video cam and taking images via Nikon digicam all outside of 'parkflyer' only boundaries and outside of 'line of sight' boundaries for the last 7 months. The furthest my contract went to was our standing point just shy of a 14 mile distance over and behind a glacier.

No my friend.

The DX6 is NOT only a 'parkflyer' and 'line of sight' system.

This merely introduces a new contender into the ring which has been long sought since JR/Spektrum release the DX6.

I'm glad there's another breaking out of the old mold and look forward to testing it capabilities and limits.
... But honey it was only $$$
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09-09-2006 01:28 PM  14 years ago
rob10000

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Western Massachusettes

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I'm quite aware that the performance of the DX6 is very good. Better, in fact than Spektrum leads folks to believe. However, the fact remains that the manufactures markets it as
"Park Flyer System". period.

LINK
Why park flyers only?
This unit was specifically developed for sport park flyers. It has plenty of range for park flyers. Just as we have a different product for airplanes than cars, we'll have a different product for sport flying aircraft that fly at a much farther average range than a park flyer. We wanted to keep this unit small, light and affordable - all attributes we felt park flyers need. Sport flyers have different needs - and we will have products for them, all in good time.
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09-09-2006 02:05 PM  14 years ago
BOOGIE

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LAFAYETTE LA

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so is this thing going to work for nitro models??
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09-09-2006 02:18 PM  14 years ago
Bad Karma

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UK

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It should do, the only issue may be gassers.
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09-09-2006 02:27 PM  14 years ago
JKos

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Redondo Beach, CA

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> It should do, the only issue may be gassers.

Why in the world would gassers be a problem? The CEO of the company said, "This system was designed for us guys that have $10,000 or more invested in a plane and don't want to lose it..." I would think that while that statement implies 99.999% of the R/C market doesn't need this system, it also implies large scale gassers and turbines.

- John
RR rules!
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09-09-2006 04:05 PM  14 years ago
hcopter

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Pittsburg KS

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Kookboy,

"The furthest my contract went to was our standing point just shy of a 14 mile distance over and behind a glacier. "

Are you saying that you are using the Spektrum DX6 to fly a glider 14 miles away? Or are you using a more powerful, specialized 2.4 system?

Mike
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09-09-2006 04:25 PM  14 years ago
caseyjholmes

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Portland, Oregon

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where do I sign, I'll take one system right now
I have a 9Z that is itching to be converted to 2.4ghz
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09-09-2006 04:38 PM  14 years ago
BOOGIE

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LAFAYETTE LA

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Does anyone know if I will work with Spektrum Receivers?
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09-09-2006 05:20 PM  14 years ago
sharam

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Northern California - Fly at Morgan Hill Field

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By definition, it shouldn't!
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09-09-2006 05:28 PM  14 years ago
RappyTappy

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Encinitas, CA

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Yea, the spektrum rx's are specialized for spektrum radios, you'll probably have to use this new companies module and rx together. I have a brushless zagi on spektrum and have zero problems with range.I am so looking forward to getting 2.4 on my 9303, bring it on! Still buyin' and flyin' then crashing and cryin'
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09-10-2006 12:35 AM  14 years ago
Bad Karma

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UK

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> It should do, the only issue may be gassers.

Why in the world would gassers be a problem? The CEO of the company said, "This system was designed for us guys that have $10,000 or more invested in a plane and don't want to lose it..." I would think that while that statement implies 99.999% of the R/C market doesn't need this system, it also implies large scale gassers and turbines.

- John
The word "may", in this context means possibly, I didnt say will, I said may.....

The reason it MAY be an issue is the same reason gassers are currently problems for radio equipment, its because of all the EMI from the sparking, it doesnt imply anything, assuming it does is pointless.

It doesnt matter what signal processing is done, if there is a big enough wattage over enough of the band it can swamp it, dont buy into this BS of "jam proof" there is no such thing.
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09-10-2006 01:54 AM  14 years ago
helo_chris

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goodlettsville, tn

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Resistance to Interference, and Anti-jamming Effects
This characteristic is the real beauty of SS. Intentional or un-intentional interference and jamming signals are rejected because they do not contain the SS key. Only the desired signal, which has the key, will be seen at the receiver when the despreading operation is exercised.

Figure 5.

You can practically ignore the interference (narrowband or wideband) if it does not include the key used in the despreading operation. That rejection also applies to other SS signals not having the right key, which allows different SS communications to be active simultaneously in the same band (such as CDMA). Note that SS is a wideband technology, but the reverse is not true. Wideband techniques need not involve SS technology.
The only way you could jam this signal would be to flood it with so many signals that the processor in the Rx couldnt keep up. That would be extremely unlikely and something that you would have to be intentionally doing.

As far as the Spektrum system, I think it has more to do with liability. Especially since Horizon didnt develop it. It was developed as a module replacement system and the took and marketed it they wat they have. Dont know why, like I said, would think it would be liability but I really dont know.
"There is a fine line between cutting edge and bleeding edge.."
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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › New plug-in 2.4GHz modules!
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