Serious accident

GaryMC1 wrote:

I've cut my hands on those too - plastic props still hurt.
And sliced bit off my fingers building them.

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I am one of Casey's good friends. He is making a good recovery at Metr
in Cleveland. Although the last two weeks have been hell, they ar really taking good care of him. We wheeled him outside yesterday fo the first time in two weeks. He is in rehabilitation of the leg and i expected to go home this week. He thanks God every day that he i alive, and does not want anybody to have to go through what he has gon through.
Casey and I talked about the ramifications of this accident on th modeling community. I told him of my concern of the governin organizations taking advantage of this to arbitrarily increase rule and regulations on the modelers. He said that he would make sure tha this accident does not lead to random and unnecessary rules bein applied to us. In other words, based on our discussions, he woul probably agree with most of the statements in this post. He accepts th fact that was unfortunately in the wrong place at the worng time.
Casey is pushing for the following recommendations to modelers (an governing organizations) in wake of the accident:
1. metal geared servos on larger aircraft. 2. PCM receivers on large aircraft with them programmed to kill engin at loss of signal. 3. in the case of non-PCM large aircraft, a secondary system to kil engine in the event of a signal failure. But he is reccomending tha all alrge aircraft have a PCM receiver with engine cutoff programmed.
Casey has made it crystal clear that he does not want to see an impac on the community in the form of rules and regulations beyond this. H has made this clear to Tom Hayden by phone, who has also talked t Dave Brown.
When you are around airplanes, you have to accept some risk. Th airplane that hit Casey was flying on its own and made three left turn before hitting Casey at full power, completely ignoring the operator' commands. It's one in a ten million chance of being hit. Post-acciden checks revealed no problems with the any of the systems.
There is risk in everything. If you don't want the risk, then live in cave, and prevent yourself from growing as a person and experiencin things that make you happy. More rules and regulations are no necessarily going to help, but really just hinder us. We have to fin smart ways, not easy ways, to solve problems. And we have to weigh th benefits of doing something over the risk of doing it.
There is risk in everything. We ran into a guy in the spina rehabilitation section on Casey's hospital floor. He was reading a boo one night in bed, dozed off, fell out of bed, hit is head lightly o the nightstand, twisted his nick slightly, heard a pop, and now he i paralized from the waist down and his hands (but not arms)
-- teryn ----------------------------------------------------------------------- teryn1's Profile: http://www.rcgroups.com/forums/member.php?action=getinfo&userid893 View this thread: http://www.rcgroups.com/forums/showthread.php?threadid &949
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I am very sorry that some one has been hurt, but please when looking to implement change in RC flying rules, look beyond the past. IMO, PCM is redundant old technology from which a number of avoidable crashes have been witnessed and does nothing in the event of switch or power failure. PCM is slow to pull in and out of failsafe, especially passing over live electric fences when on take off or landing approaches. OK for use in smaller models, Helicopters etc to use up old equipment held in stock. For the new models and when buying new equipment, the new Hitec, Multiplex and some other digital servos can be individually programmed, each with own built in failsafe or use a dual conversion receiver, or especially the new IPD or PLL based receivers, with a programmable failsafe unit, in need, to each old fashioned non programmable servo as supplied by Futaba or JR servo. e.g. http://sky-technology.net/product_html/product_detail.asp?product_number=3&set_number=1 Some brands will have IPD and/or PLL synthesised TX Modules and receivers on all the popular frequencies before the end of this year. Crystal based technology has to much room for drift and error - how often do club members actually have their TX and crystals checked for accuracy or drift after being turned on for a few minutes? Larges strides have been made in electronic technology since the advent of the cell phone. Why not question why the fliers of large expensive models do not look forward out side the square and test the new equipment = most expensive or old name brand does not necessarily mean it is still the best equipment today as one may observe reading latest safety tests of motor vehicles. regards Alan T. Alan's Hobby, Model & RC Web Links http://homepages.ihug.co.nz/~atong

http://www.rcgroups.com/forums/member.php?action=getinfo&userid8931
http://www.rcgroups.com/forums/showthread.php?threadid &9496
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I agree with you Alan but am more surprised that so many people seem to fly "old-fashioned" PPM FM systems with no kind of failsafe at all.
I've been trying to get across to people that there's absolutely no reason on earth why anyone should spend good money on a 20th century receiver when 21st-century technology is now readily available at what is often a lower price.
Receivers from the likes of FMA, Berg and others now offers computer-based smart decoding that provides an very useful margin of protection against interference or even idiots who turn their transmitters on in the pits without checking that the channel is free.
That companies like Hitec continue to sell "dumb" PPM receivers to an unsuspecting public is little short of outrageous!
A Hitec 555 costs around US$53 plus $8 for a crystal. The smaller, lighter, and far more interference resistant Berg or FMA receiver costs just $50 *with* a crystal and provides far more protection against being shot down.
With modern models weighing more and flying faster than their predecessors, and with the RF spectrum becoming increasingly crowded, I seriously wonder whether the sale of new dumb PPM receivers ought not to be outlawed.
No doubt many people will say "but I fly with a Hitec (or other dumb receiver) and have never had any problems with glitches or interference) -- but trust me, it's only a matter of time before someone in the pits shoots you down or some random burst of noise hits your model just a you're lining up on final approach or takeoff.
If it was just the increased risk of losing a model that was associated with these old-fashioned receivers then I'd say we should let people take whatever risks they want -- but, as recent events have shown, it's also about the safety of the public and other modellers.
Maybe all those flying dumb PPM receivers ought to think long and hard about how they'd feel if they were in the position of someone whose model had just seriously injured or even killed someone in a situation that could have been prevented by the use of a $50 receiver with built-in interference rejection and/or failsafe facility.
Few modellers are prepared to fly without public liability insurance -- but let's not forget that updating your receiver to one that can reject interference and provide a failsafe capability is also an extremely valuable piece of insurance against needing to make a claim on your liability policy.
An insurance polcy pay-out won't bring back a life. -- Yes it's true, I really am crazy! Look what I'm doing now http://www.interestingprojects.com/jetspeed /
you can contact me via http://aardvark.co.nz/contact /
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| I've been trying to get across to people that there's absolutely no | reason on earth why anyone should spend good money on a 20th century | receiver when 21st-century technology is now readily available at what | is often a lower price.
Of course, what you say is 21st century technology actually came out of the 20th century, but I digress ...
| That companies like Hitec continue to sell "dumb" PPM receivers to an | unsuspecting public is little short of outrageous! | | A Hitec 555 costs around US$53 plus $8 for a crystal. The smaller, | lighter, and far more interference resistant Berg or FMA receiver | costs just $50 *with* a crystal and provides far more protection | against being shot down.
I certainly like my FMA M5s (about half of my planes have them now), and I like the price, and I do like their glitch rejection, but I'm not acting under the deluded impression that they provide `far more protection against being shot down'.
They will handle temporary glitches much better, basically ignoring them. Longer glitches, and they'll just say put rather than having the servo bounce all over the place. But they don't provide that much protection against being shot down. If somebody else turns on their transmitter near you, and their signal is stronger than yours at the plane, your plane is going to crash -- I don't care how smart your receiver is.
Even those receivers that claim to respond only to YOUR transmitter (which smells of snake oil to begin with) and not going to save your plane in that instance.
| With modern models weighing more and flying faster than their | predecessors, and with the RF spectrum becoming increasingly crowded, | I seriously wonder whether the sale of new dumb PPM receivers ought | not to be outlawed.
Just what we need ... more laws.
Did you know they still sell AM receivers too? And things like the Hitec Feather are even worse than the receivers you're referring to.
| No doubt many people will say "but I fly with a Hitec (or other dumb | receiver) and have never had any problems with glitches or | interference) -- but trust me, it's only a matter of time before | someone in the pits shoots you down or some random burst of noise hits | your model just a you're lining up on final approach or takeoff.
... not that your FMA or Berg or even PCM receiver is going to save you from this reliably. It might help if the noise lasts a very short time, but only then.
| Few modellers are prepared to fly without public liability insurance
I wouldn't say that. Certainly, many park fliers are flown by people with no liability insurance.
| -- but let's not forget that updating your receiver to one that can | reject interference and provide a failsafe capability is also an | extremely valuable piece of insurance against needing to make a claim | on your liability policy.
And none of the PPM receivers that you've mentioned have failsafes at all. At best, if they can't pick up a signal anymore, they just stay where they were. Which is good, but not ideal.
What we really need is spread spectrum radio equipment. That won't make all the interference issues go away at once, but it will certainly remove the largest problem immediately -- that of another modeler turning on his transmitter on the same frequency as yours. But there's political (not technical) issues that need to be overcome, and I've gone into them before so I won't do so again now.
--
Doug McLaren, snipped-for-privacy@frenzy.com
We came. We saw. We kicked its ass." -- Bill Murray, _Ghostbusters_
  Click to see the full signature.
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You make some excellent points, Doug. I've always said that most planes can fly through INTERMITTENT interference. CONTINUOUS interference (someone switches on your channel) will shoot down ANYTHING, unless there's another RX in the plane, another pilot standing by with another TX, and the ability to switch to another channel IMMEDIATELY.
Failsafes either go to a preset position, or return everything to neutral. Either one can save your plane or crash it into a house.
|Even those receivers that claim to respond |only to YOUR transmitter How do they do that, Mr. Wizard? :)
I sorta resent the claim that Hitec (and others, I assume) are inferior. Yup, I'm one of the ones who has flown Hitec and FMA RXs for many years without a single problem. I also fly Futaba with no complaints. Either the RX meets the FCC criteria, or it doesn't. If it does, it's probably good enough for 99.9% of the flying sites around the country.
As I've said, some accidents are probably NOT preventable.
| I seriously wonder whether the sale of new dumb PPM receivers ought | not to be outlawed. Let me know when this happens, I'll run out and buy a passle of'em! I agree with you, Doug...more laws? That's EXACTLY what we need!!!
Electronics are neither dumb or smart. They do what they're told to. What's dumb is someone switching on your channel without checking the board.
Dr.1 Driver "There's a Hun in the sun!"
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maybe the same way they can control two model trains on the same track.
Dr1Driver wrote:

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That's cool! How? Dr.1 Driver "There's a Hun in the sun!"
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Its called Digital Command Control or DCC (short). DCC only requires two wires too hook up to the rails and you can slave two of them together to automaticly control reversing loops (some more wires). How it work is that it sends signals threw the rails to a DCC decoder equipped locomotive. My system can control up to 15 decoder equipped trains individually at the same time on the same rails and one convetional. It has hand held controler with 4 throttles and 4 groups A,B,C,D. The first thing you must do is to program the trains on a track hooked up to the DCC system isolated from the rest of the track You can address each loco a throttle. Example: On group A my red throttle controls a conventional loco (no progamming needed), green address 1 (DCC loco ), blue address = address 2 (DCC loco ), black = address 3 ( DCC loco). Now you can go on to group B....address forr DCC equipped locos 4 to 7 ( red throttle will now control a DCC loco in this group and C and D aswell )...Group C......8 to11, and group D 12 to 15. You can also program accceleration, deceleration, and mid power curves to simuilate protypical operation for each loco. Example would be if your train is hauling a heavy load and you want to stop it....you can simulate a slow brakeing effort by adjusting deceleration curve so that the train will slow down come to a crawl and stop when the throttle is shut down instead of it stopping suddenly. You can progam them for MU lash ups, lighting, and almost anything to simulate protypical operation. I only have 4 trains equipped with DCC decoders........runnin 15 of them would realy have me jumping around. The other way (old way ) of operating multiple trains would be to block a section.....isolate a section of track with a throttle and switches ( alot of wiring ) on it and operate that train only....switching, yard work, ect.. Then when another train comes along you need to get that one out or both will operate on the symestaniously on that trak. NMRA has rules governing DCC so that different brand systems and different brand decoders will work on 99.9% of layouts with DCC. Sorry if I could not explain about the "innards" of the DCC unit.... am no electrical wizard....but I think the signals works just like R/C radios........dont know......not sure.....wild guess.
Mike
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"Even those receivers that claim to respond only to YOUR transmitter (which smells of snake oil to begin with) and not going to save your plane in that instance."
I have been field and bench testing IPD & PLL RX for almost 12 months. As the old morse operators could be individually identified by their "key" or "signature" so to is the master TX recognised by some of the new breed of RX. I have had three different brands of TX operating similar RX on the same frequency - the main problem yet to be overcome is if a second transmitter of the same brand and model, on the same frequency, is turned on then the signature is usually to close and the RX will respond to the most powerful signal. With PPM receivers in current usage, problems arise when some users insist on using a micro receiver, designed more for light weight glider/park models with small servos, in a .90+ powered model with multi or heavy drain digital servos instead of the best for the job, especially when weight or size is not an issue, ( IMHO the HFD-08RD Supreme) which can handle the loads imposed on the board, or use another manufacturers crystal in place of the same brand as the RX. Also for consideration, is how often should TX and RX be retuned and issued a warrant of fitness to ensure that minor bangs and repeated hard landings have not sent both out of tune, in opposite directions. Many old units/crystals test well outside ideal parameters. regards Alan T. Alan's Hobby, Model & RC Web Links http://homepages.ihug.co.nz/~atong

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On Tue, 31 Aug 2004 13:17:55 GMT, snipped-for-privacy@frenzy.com (Doug McLaren) wrote:

Well there I disagree :-)
One of the reasons I switched to receivers wiith processor-based decoders was due to very nearly being shot-down by a burst of noise while I was on final approach with a model.
I was using a Hitec 555 receiver and with the plane at about 15 feet from the deck and about 50 yards out, the throttle went to full and the elevator went full down. Fortunately it pulled out *just* before it would have hit the deck.
Turns out that our field has a "dead spot" where your transmitter signal is canceled out by a reflection from a long row of steel hangars. I discovered that every time I flew through that dead spot I got exactly the same throttle-up, pitch down effect.
When I swapped out the 555 and put in an FMA M5 I could sail through that small dead spot without noticing the momentary loss of signal.
So, depending on your proximity to the ground (and perhaps a group of spectators or fellow modellers) the ability for a receiver to ignore a burst of interference can indeed offer "far more protection against being shot down". When that protection comes at *no* extra cost, I see no reason not to take advantage of it -- do you?

I've recently done some quite comprehensive testing of several RC receivers (dumb and smart) and the difference between a dumb decoder and a smart one is far more than you might expect.
As the level of RF noise (interference) is raised, the dumb receivers respond by starting to jitter wildly until the control inputs are dwarfed or totally eclipsed.
By comparison, the receivers with smart decoders respond to noise by simply driving the servos more slowly. If you request full up elevator you will get it -- but it may take several times as long as normal for the servos to move to that position.
This means that while the smart receiver is still affected by the noise, the results are far less likely to cause a crash and will provide a degree of control far beyond the point where the dumb receiver has sent its servos into an apoplectic fit.

However, the difference is that if you're usign a dumb receiver, your plane will probably gyrate wildly and plunge from the skies (probably with the engine still running at considerably more than an idle) in double-quick time -- far less time than it might take to advise others of your problem.
With the a smart receiver such as the Berg DSPIII, you'll either get some legacy of control (with the very slow servo movements I described earlier) or it will go into failsafe mode which, at the very least, will result in the throttle being cut. This has the potential to allow you to advise others of your problem in time for the idiot in the pits to turn off his transmitter.

But they *will* give you a much better chance of survival. And let's not forget you're *not* paying a premium for this improved chance of survival so why not take advantage of it?

So you're against improving public safety then if it means more laws?

Hell yes, but would *you* use a Hitec Feather in a 1/4 or 1/3 scale model???
There may be a place for "dumb" receivers, but that's certainly *not* in anything much bigger than 1/2A -sized models (IMHO).

I've already described the way these receivers *can* provide a valuable extra margin of safety.

Yeah, but a park-flier and a 1/4 or 1/3 scale (or even a .40-powered) model are entirely different beasts.

Wrong. Although the FMA M5 and Berg DSPII are "last-position-hold" receivers, the Berg DSP II has programmable failsafe.

Is the idiot in the pits *really* the biggest problem?
Sure, it does happen, but there seem to be a lot more people who get hit by interference from an "unknown" source.
As you concede, spread spectrum (SS) isn't a universal panacea either -- as anyone who's encountered conflicts between their cordless phone and WiFi home network will confirm.

That's true -- but in the meantime, if you can think of a good reason why someone should buy an old-fashioned "dumb" PPM receiver when there are better (and sometimes cheaper) options available, I'd love to hear it.
-- Yes it's true, I really am crazy! Look what I'm doing now http://www.interestingprojects.com/jetspeed /
you can contact me via http://aardvark.co.nz/contact /
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(Doug McLaren)

If there is a dead spot at your field, are all of the other fliers experiencing your problem? 15 feet high, full throttle, full down elevator and you still pulled it out. Pretty amazing! The only glitch I have ever had in all my years of flying is the one between my brain and fingers. I think true radio glitches are rare. A much bigger concern should be shoddily built planes, poor wiring, poor pilots, etc. I think you will find many more crashes and accidents are a result of these than as you say "dumb" receivers.
John VB
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I agree 100%.
We had a guy at our field who, whenever his plane went wacko, started screaming "I was hit!" Finally, one day he was flying an original Sweet Stik. Low and slow, down the center of the runway. Slower now, nose higher to hold altitude. Slower, nose higher... Suddenly: nose straight up, wing flip, half spin. SMACK! "I was hit, I was hit!" No, you moron, can you say "stall'?
I've been in R/C over 20 years, and have only experienced provable interference twice. One time from high voltage power lines, and one time from another radio on my channel. The first time, my "out of date" PPM radio flew through it, and the other time, my plane was on the ground, in the pits. Dr.1 Driver "There's a Hun in the sun!"
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Couldn't agree more. We are flying with old technology radio equipment. We need to go to newer technology. Spread sprectrum, frequency hopping, intellegent receivers, signatured transmitters and receivers, addressable models confirmation. This is all no big deal, no technology challenge. The AMA needs to take a leadership position, work with the radio manafucturers and FCC and transition to a new non-shared frequency, with a standard data protocol so that regardless of wether it's futaba, JR, Hitec..... they all interoperate and understand each other. Gee's wifi computers and periperials can interoperate, broadband computer modems interoperate. Yes the radios would be more expensive, especially in the beginning, but if I've got a lot of money wrapped up in an airframe, I'm sure willing to spend the money to make the radio part of the system bulletproof.
We consistently preach gloom and doom , BLP will ruin us, radio operated cranes, terrorists will use rc models. WRONG APPROACH. Times change, if we don't change we will eventually loose out. Write the AMA, request them to take the lead into newer, better, safer radio systems!!!!
Wouldn't it be nice, not to have a frequency board, that when your flying and somebody turns their radio on, their transmitter doesn't transmit till it knows whats available to transmit on! That your transmitter and your receiver know that you have the right model selected! That they can cohabitate safely with sporadic interference! Thousands of addresses (channels in old technology) Folks this technology has been around for decades!!!!!!!!!!!!!!!!!
Phil
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wrote:

There is a better "receiver" then the ones you mentioned that everyone owns, its free, you live with it...cant live without it!! Its called a brain and with that "receiver" it = common sense which preflight check, knowing how to set your plane up, and flying safely. No Hitec, Futaba, Berg, or FMA will do that for you whether they are "dumb" or "smart". Anyway Bruce, do any of those receivers (dumb or smart ) come with a " 100 % guarantee...............................or we will replace your plane at no cost to you" statement??
Mike
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Amen, Mike. Preach on, bro!
Dr.1 Driver "There's a Hun in the sun!"
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A preflight check won't protect your plane, your safety, when another transmitter on the same frequency gets turned on while in flight either by accident, malciously or by interference. A BRAIN is when you take advantage of better technology that can solve real problems. With the everything should stay as is mindset, we would still be flying reed radios.
We ARE flying with old technology radio equipment. We would benifit by going to newer technology. Spread sprectrum, frequency hopping, intellegent receivers, signatured transmitters and receivers, addressable models confirmation. This is all no big deal, no technology challenge. The AMA needs to take a leadership position, work with the radio manafucturers and FCC and transition to a new non-shared frequency, with a standard data protocol so that regardless of wether it's futaba, JR, Hitec..... they all interoperate and understand each other. Gee's wifi computers and periperials can interoperate, broadband computer modems interoperate. Yes the radios would be more expensive, especially in the beginning, but if I've got a lot of money wrapped up in an turbine, a pattern plane, a TOC quality giant scale, I'm sure willing to spend the money to make the radio part of the system much more reliable.
Soltuion is simple, one new frequency band, up high where nobody wants to reside because of distance issues. Leave the 75mhz stuff alone and for those who are flying a sport plane, are happy with current equipment.
Wouldn't it be nice, not to have a frequency board, that when your flying and somebody turns their radio on, their transmitter doesn't transmit till it knows whats available to transmit on! That your transmitter and your receiver know that you have the right model selected! That they can cohabitate safely with sporadic interference! Thousands of addresses (channels in old technology) Folks this technology has been around for decades, parts of it are in our radios now. Synthesized transmitters and receivers are part of the solution, digital receivers are part of the solution, computer radios are part of the solution, those elements are in our radios today.
Phil
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BIG SNIP

No technology will eliminate that short between the ears!
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True. NOTHING will!
In your posts, you cite many types of "new technology" that will eliminate the danger from interference, intermittent or continuous. Will you post web sites or other information (showing factual proof) so the rest of us can bask in your advanced knowledge? Dr.1 Driver "There's a Hun in the sun!"
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First URL : http://www.auav.net/spread_spectrum_radio.htm
Others at the end.
Couple of points take for what they are worth: I am a EE designer and was working testing military frequency hopping radios decades ago. I'm not trying to "bask you with my advanced knowledge" just trying to help my fellow modellers understand that we are settling for "spark gap" technology when there are many aids in our plight.
Second let me do some explanations and relate it to things that you see take advantage of these technology today.
Our existing radios transmit a rf signal 100% of the time when you turn them on, that is why you can not have two transmitters on the same frequency. The information that is modulated on those rf signals contain information that does not require them to transmit 100% of the time, it was just a simple and cheap way to do it 40 years ago. Todays electronics are very fast, it is a simple task to esentially turn the on/off switch thousands of times per second. This is part of the fundamental requirement for frequency hopping and networking. In today's world, your cell phones and computer wireless networks utilize this technique to send/share information. For example, a current RC transmitter may send servo update information 50 times a second. Start thinking of that transmitter not being on constantly but the electronics inside your transmitter turning on and off 50 times each second. Now as designed, our radios take a little over .02 seconds to send 8 channels of servo position information for a Futaba/Jr/Hitec PPM system. In reality that can be done much faster and for the purposes of explanation I'll use .0001 seconds just for round numbers. Doing the math, 50 times in one second times .0001 seconds takes .005 seconds. So 50 transmitter bursts of information only takes up .5% of that frequency, 99.5% is available to do other things, like 199 other simulatainious transmitters running interference free. They way 200 transmitters would cohabitate on the same frequency is the also have a built in receiver. They listen before they transmit so to speak. Now think of each second as having 200 time slots repeating 50 times a second. slot 1 thru 200, then repeat 50 times each second. slot 1 is time 0 to .0001, slot 2 is .0001 to .0002, ... flyer a is in the air flying, flyer b turns on his transmitter. flyer b's transmitter listens first before ever uttering a single transmission. It "hears" transmitter a's transmissions and understands that it (transmiter a) has taken time slot 1 time intervals, so it knows it can't use that slot, so it picks time slot 2. In this example 200 flyers would never interfere even though they are on the same frequency. And you don't have to worry somebody is goin to shoot you down while flying. Incorporating this kind of technique thus has eliminated that potential, but if there is other radio ineterference on the same frequency, your still in trouble. In comes: Frequency hopping. i.e. the transmitter can change frequencies thousands of times a second. i.e. slot one is on channel 51, slot 2 is on channel 32. So your transmitter isn't just one one frequency its on many during each one second interval. Vwala, you have become significantly more immune to interference or being hit. You combine the two and you have thousands of "channels". Again this technique is used in your broadband cable modems for your computers, wifi and cell phones. All this time slot and frequency hopping is first determined by a protocol. i.e. a specification and a predetermined sequence that all the transmitters and receivers understand and expect. That makes Futaba, Hitec and JR et all all play together for interoperatabliity. That protocol defines the algorithm or sequence of how the time slots are determined and frequencies are hopped around. i.e. slot 1 is channel 51, slot 1 second frame (time period 201) is channel 37... In the computer world those protocols is 802.x or cell phones it cdma technology. In the computer world every 802.x device has a unique number or address. It's called a MAC address. The address is what establishes "connections" for devices talking to each other so the data is organized. Think of a multi model computer radio, the transmitter is address AV45, you own two receivers XC34 and VS99. In your setup you define airplane 1 as address XC34 and airplane 2 as VS99. Those two receivers are also setup to only listen to transmitter AV45. So you turn on your transmitter and it comes up setup with the last time you used it as flying the airplane with VS99 receiver. In reality you brought the airplane that has XC34 in it with completely different servo settings. You power up you plane, and it does nothing, because your transmitter is sending info to for address VS99.
At this point we have significantly reduced being hit by an accidental transmitter turn on of the same frequency, we've made it less suspectable to noise hits, and we have eliminated selecting the wrong model on our transmitters. Yet there is more that can be done. If you have not been "hit" by radio interference, you probably know somebody who has. AM and PPM are suspectable to that because they can intrepret noise as valid servo position information. In comes data validation. Computers use many types and combinations of error checking, you probably heard the term checksum. Essentially a cecksum is a numeric addition of all the data that was sent in one frame or packet.... In our case as the transmitter is sending those 8 channels of data in slot 1 it adds all the position information of each channel and sends that number like its channel 9. The receiver does the same, it adds all the 8 channels of data and compares it to the checksum the transmitter sent as channel 9. If they match, the receiver updates the servos with the information, it they don't it doesn't update the servo's and it start to gather information to make a decision. In the next slot of time on a different frequency the receiver does the same checksum test. If it's good it updates the servo's at the flyer doesn't have a clue he got hit, if it doesn't the receiver starts down a decision path. That decision path would be programmable, i.e. if you get 20 consecutive frames of non checksum confirmed data, you throttle down to idle, if you get 100 you set the surfaces to a failsafe psition you determine when you set the receiver up initially. So we have just made the noise issue even less impacting, in fact it maybe able to cohabitiate with random noise without knowledge.
This is just some high level explanations of how rf networks work and the computer technology we should be seeing in our radios. Do I propose getting rid of the existing radios, no. Put the new technology on a different band, let the sport flyer or beginner use the $150 radio or the jet guy if he wants. But give hime the option of better technology so if he has a $10000 turbine he can take advantage of making it as safe as the technology allows.
url's http://www.wavewireless.com/classroom/whitepapers/FHSSvDSSS.pdf http://www.encyclopedia4u.com/f/frequency-hopping-spread-spectrum.html http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci525695,00.html http://www.webopedia.com/TERM/M/MAC_address.html
My fingers are worn out. :-)
Phil
Dr1Driver wrote:

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