Spread Spectrum
 

This was sent to be by a friend. Note the product is labeled "Not yet available". Also note that I have not verified the page is legit, and that this radio is for park flyers. If all is true, a new era starts now, or at least very soon.

http://www.horizonhobby.com/Shop/ByC...ProdID=SPM2460

RE: Spread Spectrum
 

I'm willing to bet that within 3 years futaba (and others) will have a spread spectrum module out for module radios... at least I can be hopeful! (any inside word bax?)

RE: Spread Spectrum
 

Amazing. Simply amazing. Done completely without any AMA support. Watch the AMA fabricate rules to keep them from being used at contests and AMA only flying sites. No more save the frequencies campaigns!!!! Loosers!!!

RE: Spread Spectrum
 

I suggest that this thread be moved to the Radio forum, so that hopefully there will be fewer political coments such as the one above by SoCal GliderGuider, and the discussion can focus on technical aspects of this development.

Here is a link to more technical information on this radio system:

http://www.spektrumrc.com/DSM/Better/DX6-glance.html

RE: Spread Spectrum
 

Ok, I went to the Horizon Hobby site, and it does show up there. So, it must be for real.

Why would it be labeled as a park flyer radio? Is the range limited in some way?

After they use this as a beta test, maybe it will find it's way into 10X replacement...like a 12X!!!

RE: Spread Spectrum
 

Spread Spectrum technology has a few problems with the model orientation relative to the transmitter. Part of the reason that it has been available for RC cars but not airplanes. JR has approached this with dual airborne receivers and two antenna so one receiver is able to maintain contact. Park fliers are the perfect aircraft to develop the technology because of their light weight.

80 channels at 2.4 GHz with automatic selection. Kewl. Thank you Heddy Lamar!!!!!!!!!

RE: Spread Spectrum
 

Ah, I get it. Thanks for the explanation.

RE: Spread Spectrum
 

This is a political forum.

The manufacturers abitrary limit in range and aircraft type is an attempt to limit liability. The actual range is dependent on the power applied. These systems have yet to be fully powered.

There will be two aspects of these SS six channel systems; one the technical and one how the AMA responds. As far as the technical is concerned it's obvious that the AMA has been sitting on it's collective behind. As to the political side; time will tell if/when the AMA bans these systems "until the technology becomes reliable".

Then the hobby has gone off in a direction that the AMA can not control; park fliers.

RE: Spread Spectrum
 

Excerpts from VP Dr. Sandy Frank on the D8 List:

Tony Stillman AMA D5 VP and owner of Radio South has/is flying this
system...

It has been shown at a trade show in CALIF. this week...........

It is to be seen at the JR Indoor EXPO in Columbus,OH in 2 weeks...

and IF AT ALL possible I hope to see it at the SouthWestern Aeromodeling
Conference
in Ft. Worth NOV. 11/12,2005

( IF at all possible there will be one for show and tell at SWAC !!!!)

RE: Spread Spectrum
 

This thread should be left where it is. The news will hit all aspects of the hobby fast enough.

As to SoCalGliderGuider, his protest in his tag line says it all "It's not hot air!". There are plenty of us that would disagree.

RE: Spread Spectrum
 

highplains,
just got bact to this site and found your post about your rc car.
do you still have it, and are you interested in selling it?
i have a number of 1960-1970's rc cars but am always looking for interesting
old cars.
i have gotten into electric planes recently. very frustrating no hand, eye, brain coordination.
contact me at
[email protected]
hasbeen

RE: Spread Spectrum
 

At least I post more in the other forms. Does the AMA pay you for being one of their shills?

RE: Spread Spectrum
 

My understanding, from another post elsewhere, some telephones operate on 2.4 GHz.
Would this be a problem?

RE: Spread Spectrum
 

Post more in other forums? I doubt it.

Does AMA pay me? Asked and answered a number of times in this forum. Do you have a problem using the features of RCU? It might be good practice for you to find the answer. Might also keep you busy for a couple of months, judging from your posts in this forum, and the mental dexterity they show.

RE: Spread Spectrum
 

I note that someone posted that they felt that Spektrum developed this system without AMA support. In a way that is correct as AMA certainly did not help them develop the system. However, AMA has been dealing with the overall spread spectrum issues for more than three years now. AMA published an introductory article in Model Aviation in the July 2005 issue. More than three years ago AMA interfaced with the FCC to determine the legality of this type of system being utilized for radio control of model aircraft. This information was relayed to the manufacturers. AMA has tested most spread spectrum systems now available and will continue to do so to learn from them as this, new to RC, technology continues to be introduced. My own columns in Model Aviation have talked about spread spectrum several times. AMA continues to work with the manufacturers and this technology.

If you have any specific questions please e-mail me directly as I do not respond to posts in forums.

Sincerely,

Steve Kaluf
AMA Technical Director
Frequency Committee Coordinator

RE: Spread Spectrum
 

Well Steve, you just did. ;)

And BTW, thanks. It's good to get it from an authoritative source once in a while.

Abel

RE: Spread Spectrum
 

2.4 Ghz is an international ISM frequency band, besides phones it is also the frequency your microwave oven works on. Part of the reason it works in cooking food also limits it's usefulness for most communication. The RF energy is absorbed by water molecules. I think that part of the requirements is fairly limited RF output power, so the range would be limited compared to our normal 72 MHz sets. Since the RF energy is spread out ( and there are actually several methods that do this) it is able to operate in an environment that is filled with other radio systems also operating on the same band of frequencies. So if another system or even 15 or 20 were all on the air at the same time, the only effect should be a slight degrading of the RF link. I would expect that it would take a lot before you would notice any glitches, and you could fly though most interference.

Since it is on 2.4 GHz, the antenna are also very very short, both on the transmitter and receivers. It looks remarkable for the price.

I recently found where I stored away the Ra/Car which is from about 1968-69 era. It has a two speed transmission with the Indy car body work. It has a K&B .19 and is in great shape except for axle coupler which was an expendable part (and still available). I have no idea of it's value, except it is rare rare rare.

RE: Spread Spectrum
 

Microwave ? Will that thing cook my beans and frank ? Yikes ! Its getting hot in here.

RE: Spread Spectrum
 

according to the info on the horizon site this system uses two different frequencies- when it powers up it looks for two frequencies in its range that have the least interference/signal, and it locks into these two frequencies. it does not hop frequencies after this. so i think this will be more reliable as it would be too slow if it was constantly looking for new frequencies. but then maybe someone else will find a way around this so it can hop more quickly and not miss the servo signals.

it will be a big improvement when they get it so its proven technology. but i'm glad they did it in a park flyer radio- smaller airplanes with less chance of injury if they crash, regardless of the reason.

i wonder why they went to 2.4 ghz? it may be that the circuits are already proven out for the telephones etc that run here so it was cheaper to develop this design. or maybe it was easier to get the frequency approval here.


Ed

RE: Spread Spectrum
 

Very likely chip sets from phones could be used, thus very low cost. No frequency approval needed since it is an ISM frequency.

I also found more info on their site, it is a direct sequence spread spectrum system. This means that a pseudo-random digital code sequence (1's and 0's) is mixed into the data stream and modulated at the RF frequency. This takes the RF energy and smears it into a very broadband signal that has low energy at any discreate point in the frequency spectrum. In other words, if you were looking at it with a spectrum analyser, it would look about like background noise.

(As opposed to the narrowband RC systems we have been using since 1991 where the RF energy, signal and sidebands are restricted to a narrow bandwidth centered on the operating frequency.)

The receiver is also using the same pseudo-random code to extract the RF energy from the very broad band of specturm to recover the control signal. Only systems that have match codes operate together, and other signal sources are just back ground noise and thus ignored.

RE: Spread Spectrum
 

I think it is only a maater of time before you see these in your average aircraft.

meaning, you can purchase these now, they come with micro/mini servos. whats the difference if you cange the servos and use this new JR SS radio in a 60 or 90 size plane.
hmmm.

mark

RE: Spread Spectrum
 

Hey Mark-

If you had some of these now, you could be using your flying field.;)

So, how goes the war?

Abel

RE: Spread Spectrum
 

The size and torque of the servos is depended on the driver circuitry in the receiver. As the receiver is only 7 grams I would speculate that the provided servos (plus two for a count of six) would represent 80% of the expected load. Make that five as a throttle controller does not draw what a servo does. Then this IS something that the radio forum would be better to expound on.

My point is SS is far safer than the AM/FM the AMA stuck the modeling community with. Why there wasn't serious resources spent years ago by the AMA on SS shows their interests lie else where.

RE: Spread Spectrum
 

The Problem is that the range is limited.
When you first turn it on the transmitter checks to see what frequency's are clear to use. That should work OK if you fly close to the transmitter but if you fly too high or far away then the receiver in the plane may start to pick up signals that the transmitter is unaware of and that could be a problem.

Thats the impression I got from reading about it.

RE: Spread Spectrum
 

There is no "driver circuitry in the receiver" in any of the Futaba, FMA, JR, Hitec, Berg or GWS receivers I use. They all provide logic level signals to the servos, which contain the driver circuitry. The Rx could care less if it is sending signals to a park flyer's pico servos or a 40%er's 'truck winch' servos.

Your other point doesn't rate comment.

Abel