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AEAJR
10-27-2005, 12:22 PM
Spread Spectrum - Perhaps the perfect solution for parkflyer pilots :rolleyes:

In the old days, when glow planes were king and you had to spend a long time building your plane, you almost had to have the help of a a club and the use of a club field. Finally, after investing all this time and money, you really WANTED the help of an instructor to help you preserve and protect your time and money investment. The club instructor system was, and still is a very good system. But new technology has brought new options, and change.

Enter the small electrics, often called parkflyers. RTFs, ARFs, and foamies mean you can get into the air quickly. The small, quiet nature of these planes means that they can be flown in more places without drawing attention. People are flying them in parks, school yards and some of the slow flyers can even be flown in front yards and in school gyms. And, because they are inexpensive and easy to buy and fly, people are teaching themselves to fly. If you crash the plane, some will just bounce, and many of the others are easy to fix with good parts availability. For relatively little time and money expense, you can replace the whole plane. What could be bad about this?


THE PROBLEM - Channel Conflict on 72 and 27 MHz :confused:

One of the concerns of the RC flying community is that people flying off the club fields are not being taught about frequency control within the 72 MHz RC airplane hobby band. The feeling is that these off field flyers are begining to represent a danger to the safety of planes and people on and off the club fields. If you are flying your RC plane at some school yard you could interfer with those on the the club fields or with other parkflyer pilots elsewhere. You could be causing crashes and not even know it. Or you could be subject to loss of control of your plane and not know why.

The issue is channel conflict. If you are flying on the same channel as another flyer, one or both of you will crash. With the range of today's equipment, you might be a mile away from the other flyer and still effect each other. The AMA recommends that club fields be at least 3 miles apart for this reason.

In the past channel conflict has been handled by frequency control procedures on club fields. But, with the dawn of the low cost parkflyers, many new pilots are not members of clubs and are flying ourside of the frequency control procedures of the clubs.

Pilots using 27 mhz may feel they are not at issue here as their radios typically have shorter ranges and don't impact 72 mhz club radios. However some of the 27 mhz planes are being flown on club fields. In addition, 27 MHz is not dedicated to airplanes. Someone running an RC car on the other side of the park could easily turn your plane into an out of control missle or, at least, turn it into a pile of junk. This could happen and the two of you might not even be within sight of each other. So 27 MHz carries its own problems. What to do?

THE SOLUTION - Spread Spectrum 2.4 GHz :p

Enter a new offering, Spread Spectrum 2.4 GHz radio systems for parkflyers. This technology was introduced to the RC car community a while ago and has been growing in popularity. This new system is extremely well suited to the parkflyer community and does not interfer with the 72 MHz radio that are traditionally used by the club flyers. It also does not conflict with 27 MHz planes, cars or boats. In fact, by design 2.4 GHz devices of all kinds are made to work around each other without conflict. No channel control is required as it is designed right into the specifications of the radio. It is totally automatic!

So, what does this mean to the parkflyer pilot looking for his first RC radio system? It means a new 6 channel computer radio choice that may be the best of all worlds in a radio system. And, it is competitive in price and features with the entry level 5 and 6 channel 72 MHz computer radios while avoiding the whole channel conflict issue. You avoid conflict with the airplane clubs and with other pilots, rc cars and rc boats in the area. Sounds good!

Horizion Hobby has begun distribution of a 2.4 GHz Spread Spectrum system from SPEKTRUM. SPEKTRUM has been selling these systms for RC cars for a while. When you compare it to entry level computer radios like the Futaba 6EXAS, the Hitec Flash 5SX or the Airtronics VG 6000, it is quite competitive in price and features. And since the radio is targeted at the parkflyer community, it is packaged with 4 micro servos and a micro receiver that are very appropriate for these planes.

If you are considering an entry level 6 channel computer radio to fly your planes, add this one to the list of radios you consider.

DX6 DSM 6CH Park Flyer System $199
6 channel micro receiver and 4 -S75 micro Servos
http://www.horizonho6 Channel Park Flyer System (http://www.horizonho6 Channel Park Flyer System)
http://www.spektrumrc.com/DSM/Better/DX6-glance.html

Digital DSM™ Spread Spectrum Modulation
• 10-model memory
• Dual rates on aileron and elevator
• Exponential rates on aileron and elevator
• Dual and exponential rates can be combined on one switch
• Trainer system compatible with Spektrum™ and JR® radio systems.
• Adjustable stick length
• Throttle trim only affects idle position
• Two-speed scrolling
• Throttle-smart fail-safe system
• Digital trims for precise adjustment

Airplane Specific Features
• Aileron to rudder mixing
• Elevator-to-flap mixing
• Flap-to-elevator mixing
• Flaperon mixing
• Delta wing mixing ( elevons)
• Aileron differential
• V-tail mixing
• Three programmable mixes

Helicopter Specific Features
• Two 3-point throttle curves
• Three 3-point pitch curves
• Flight mode switch can combine throttle curves, pitch curves, dual and expo rates,
and gyro sensitivity
• Throttle hold
• Revolution mixing up and down
• One programmable mix
• Supports 120° CCPM mixing
• Independent digital trim setting for each flight mode

Unbalanced prop
10-27-2005, 02:04 PM
Looks good ED..........may have to change my gift list to Santa!!:D

Doug

debhicks
10-27-2005, 04:09 PM
I see it as more opportunity to fly. The concept is been in the works for quite some time. It should be safer as far as frequency control is concerned. So perhaps our 40% practicing for their next competition will not have to worry about a rouge parkflyer in their yard on the other side of the tree's shooting them down. Now, how long it will take to convert is the next question. It would be nice if the RTR park flyers would come out with these radio systems instead of on 72 Mhz and that would ween park flying into the 2.4ghz.

It's a thought. That will make a park flyer a little more expensive in the RTR rhelm but perhaps the added expense for the peace of mind is worth it. IMHO.

I am quite excited to see the electric and technology progress in the R/C field. Before you know it they are going to figure out how to fly full scale jumbo jets on electric power and our electric powered vehicles will get better. I like the George Jetson and the Star Trek method of preparing the public for things to come. I believe that electric and technology is here to stay. We had progress along with it or get left behind. :)

On thing to thing about and if it hasn't been brought up yet is the new system they want to implement here in the states to transmit internet through the power lines. There is a real good chance this may cause problems on 72 mhz for those who do fly close to the power lines. If you have a receiver and transmitter locked into each other and nothing will come in and interfer with it then that may be a good thing.

It's something to think about. Keep in mind they are only recommending these new radio's systems for park flying, assuming park flying means flying within our field boundries :) instead of in the next county.

Nitro Blast
10-27-2005, 04:20 PM
Channel selecting is a great feature, but when you can get that radio to scan your frequency and NOT transmit when someone else is on that channel (like my POLK does) then I'd consider it.

debhicks
10-27-2005, 04:23 PM
Channel selecting is a great feature, but when you can get that radio to scan your frequency and NOT transmit when someone else is on that channel (like my POLK does) then I'd consider it.

Your DX6 selects the channels for you.
When you fire it up, your DX6 automatically searches for, selects and locks onto two clear channels. That's all there is to it. And because international regulations for the band are very strict, your radio will neither sustain interference from — nor cause interference to — any other 2.4GHz device worldwide. And that applies, of course, to its simultaneous operation in close proximity to other 2.4GHz RC radios as well.

Perhaps that is what this paragraph means?

Here is some more data;
The FCC also mandated that transmitters using Spread Spectrum must have the ability to check for, and find an open frequency on the 2.4 band (there are 80 channels, spread in 1MHz spacing.) before transmitting any signal.

So when you turn on your DX6 transmitter, it scans the 2.4GHz band and picks two frequencies which show the least activity. That's right, there two frequencies used with the DX6 system. (see explanation of DuaLink technology.)

Since all devices on the 2.4GHz band are required to avoid other users (or else they wouldn't receive FCC type acceptance) there is no chance that another type of device using 2.4GHz can cause an issue with your radio. It just can't happen. They all work by the same rules.

And some more;
And the DSM system is compatible with all servos, speed controls and gyros you currently own.
Even the range testing is easier. All you have to do is depress the button on the rear of the transmitter (thus reducing the transmitter's output) and check to make sure you have operation 30 paces away. That's it.
The DX6 comes ready-to-use. It comes fully "bound" - that is to say, the receiver recognizes the transmitter, and only that transmitter (see the GUID portion above). When you need to change the Failsafe position (binding the receiver to the transmitter stores the FailSafe position) then you'll need to re-bind.

We will have these as soon as they are available. We are on the wagon and will promote it strongly to parkflyers. Since we do have some IMAC pilots in our area that practice on a regular basis it will ease my mind somewhat. Got to look out for everyone you know. And it's affordable. That is important.

Our scanner module in the Multiplex does it. It doesn't emit a signal until you tell it to but it will search out a free channel or the one you want to see if it is free. It won't turn on if it's not. Thats cool but it was additional and extra money.

rcers
10-27-2005, 04:34 PM
This is certainly a step in the right direction. I can't wait till we have some folks with one playing in hand....

I personally can't wait!

Mike

rcers
10-27-2005, 05:00 PM
The issue is channel conflict. If you are flying on the same channel as another flyer, one or both of you will crash. With the range of today's equipment, you might be a mile away from the other flyer and still effect each other. The AMA recommends that club fields be at least 3 miles apart for this reason.

I think the AMA really likes this....

http://www.modelaircraft.org/spreadspec.asp

Mike

debhicks
10-27-2005, 05:39 PM
I have a new Uniden 2.4ghz phone system. You have to direct link the hand units to the base for the base to even know they are there. They "register with each other" Otherwise it will sit there like a dumb phone until you go through the sequence.

I believe that the binding process for the transmitter and receiver is the same. It is unique to each unit. Then once the two are married when you turn them on they go through and look for an available (2) channel and lock in. They basically have scanner capabilitiy within the frequency spectrum and will not lock onto a channel (2) that is not free. The tranmistters and receivers can't talk to each other until they are bound. So the risk is, in the manufacture words "not there", of shooting down someone else. If by chance your equipment can't find a free channel it will simply not grab it. I hope I explained that right. :) It is how I understand it from reading the literature. We just got our packets in for our reading pleasure. A prelude to the real thing. Big up close pictures and all:)

The AMA has been talking this up for a few years. At the Joe Nall Meet last year when the AMA had a membership meeting Dave Brown eluded that the system was close and hoped it would be available within the next two years.

They are supporting this 100%. Probably something else they had to go ask for through the FCC so it could all be. And be it is. :) I'm pretty excited about it.

bsoder
10-27-2005, 06:21 PM
I think the idea is great - I'm not sure I like the feature set of their controller. I definitely want five-point curves for helis... and more than six channels would be nice. I think it's a great step in the right direction, and I'll probably buy the NEXT one they come out with. :)

AEAJR
10-27-2005, 08:35 PM
Channel selecting is a great feature, but when you can get that radio to scan your frequency and NOT transmit when someone else is on that channel (like my POLK does) then I'd consider it.

I guess you will be placing an order soon as that is how it works. It can only transmit on open frequencies, exactly the way all spread spectrum devices work.

EddyKilowatt
10-27-2005, 08:46 PM
Thanks for post, Ed... this is a great heads-up for all those (like me) who are looking to move up the radio learning curve in the future.

I'm glad to see that radios are getting more smarts; with the ever-growing pressure on spectrum space, they need it.

It's nifty that the radios have channel-negotiation algorithms. Hopefully they also have fall-back-and-regroup algorithms, in case they get blasted off the channel mid-flight, by a source that's not playing by the rules (e.g. a leaky microwave oven, computer hacker souping-up his WiFi link, etc)?

It's been a long time since I learned the theory on spread-spectrum, but I don't think it's going to be the panacea for channel congestion that the FCC hopes it will be. Spread-spectrum avoids immediate and severe interference problems, and saves the FCC a bunch of bookkeeping, but long term as the number of users grows, the RF noise floor inevitably has to grow too... TANSTAAFL! Thus my happiness that the radios are getting the smarts to do adaptive things based on the RF environment that they are operating in. I suspect that the smarts contribute as much to the improved capabilities as the spread-spectrum modulation techniques do.

Ed

AEAJR
10-27-2005, 11:31 PM
I agree that it is about time our radio systems saw a big jump in technology.

What I hope will happen is that Hitec, Futaba, JR, Airtronics release 2.4GHz modules for their radios that have channel modules. This would allow guys like me with a Futaba 9C to 2.4 GHZ while maintaining all of our advanced programming features.

If I read the press and FAQ pages properly, SPECKTRUM is doing that in the car space. That is what I hope will happen, in addtions to great new systems like this one.

AEAJR
01-14-2006, 05:19 PM
DX6 Range
(revised 1/14/06)

The range on this radio is not stated by Spektrum or Horizon Hobby. So I
contacted both to try and get something more specific as to its rated range,
or the dimensions of the planes that they felt were appropriate. I like
specifications I can understand, and "Park Flyer" is not a well defined
specification. Park flyer is a marketing term used by plane makers to suggest
that a given plane can be flown in a park rather than requiring a dedicated
AMA club field. So, how big is a park?

Neither would provide a range rating or any guidance on the size of the plane.
Personally I think the, "we all kinda sorta know what a parkflyer is, like,
you know!" answer is not a precise definition, and no way to define
the safe use of a product.

In this thread we have an unofficial report of a discussion with a Spektrum
engineer. Unofficially he seemed to feel that a parkflyer was something under
2 pounds and around the speed of a Zagi, or slower. So that gives us a little
better feel from one of the designers. Zagi's typically have wing spans of
around 48 inches, though some are larger.
http://www.rcgroups.com/forums/showthread.php?t=464825#post4883555 (http://www.rcgroups.com/forums/showthread.php?t=464825#post4883555)

I also did some market research to see what the market defines as a "park
flyer". I did searches from January 6-10 of 2006. Based on searches done on
Horizon Hobby's web site, Tower Hobbies and Hobby Lobby, using the term park
flyer and parkflyer, planes up to 72 inches and 84 ounces come up.

Based on these results, plus the unofficial engineer's coments, I am going to
suggest we use a working definition of park flyers as having wing spans up to
about 54" and 40 ounces as a practical market definition. The bulk of the
market seems to be in the 16"-48" wing span range and 8-32 ounces. Planes
like the Multiplex Easy Star or the Aerobird Xtreme would be examples of the
upper end of this parkflyer wing span range.

Field reports on the DX6 are coming into this and other forums. It seems that
the 3000
foot range stated for the car radio holds true for the DX6 airplane radio as
well. Again, referencing the engineer discussion post for added guidance, I
am going to revise my interpretation of useable range down to under 2000 feet
as a practical limit. That would be about 6 football fields in distance, just
to give another reference in distance.

Comparing that to the "park flyer" guidance provided by Spektrum and Horizon
Hobby, that would be a bit less than the radios provided with 27 MHz HobbyZone
and Parkzone park flyers. These are also Horizon Hobby brands. It is also a
little less than the 72 MHz 3 channel Futaba, Hitec and Hobbico AM radios that
have been packaged with many RTF parkflyers. The Hitec Focus 3 AM, for
example, has a published range of 2500+ feet, as stated on the Hitec web
site. This radio was packaged with the Sky Scooter and was private labeled as
Hobbico and packaged with my Spirit Select 2M RTF sailplane.

However, if we can use under 2000 feet as a practical outer range, that should
be adequate for this class of plane, especially in consideration of how most
people fly them. Just remember that this is 500 feet less than the radio that
comes with many of the RTF planes. If you are accustomed to
flying planes of this size out at the edge of visual range, you have less
range with this radio. As with any radio, good sense has to be applied. I
guestimate that planes over about 45 inches in wing span could be flown beyond
the range of this radio, so keep that in mind when you are flying. But it
should be enough for normal use.

Page 2 of the DX6 manual also says it is appropriate for unpowered planes in
the "park flyer" size range. Therefore it would probably be good for hand and
discus launched gliders like the flings or the Mountain Models DL50. I would
also think slope gliders would work, again using the 48" Zagi wing as an
example, if kept under 2000 feet away.

That provides a pretty big universe of planes to fly using this radio. Sounds
like a winner to me!

You can see the reports I reference in the links below.

Product Reviews

http://www.rcuniverse.com/magazine/article_display.cfm?article_id=623 (http://www.rcuniverse.com/magazine/article_display.cfm?article_id=623)
http://www.rcgroups.com/links/index.php?id=4936 (http://www.rcgroups.com/links/index.php?id=4936)

Practical field tests - see post 16-25, 31-33, 66, 82, 96-101, 118, 142, 171,
178, 180, 240, 262, 298, 305
http://www.rcgroups.com/forums/showthread.php?t=452817&page=2&pp=15 (http://www.rcgroups.com/forums/showthread.php?t=452817&page=2&pp=15)

Notes from a lecture by a DX6 engineer
http://www.rcgroups.com/forums/showthread.php?t=464825#post4883555 (http://www.rcgroups.com/forums/showthread.php?t=464825#post4883555)

thomdoe
01-14-2006, 08:09 PM
I took my new radio out this last weekend. Everybody was waiting for me to hit them. At the end of the day we all went home, It is a great radio.