Kai Yang and Gordy each wrote some of the quoted material -- | What I am hearing is if there are over 40 SS system turn-on at | the same time, the 41th one won't be able to send out signal. It | won't shut down other people's plane but just cannot fly your own | plane.
That's the Spektrum DX6 story, and it might extend to the DSM2 stuff too. Other brands and models have different limits/failure modes. XPS gave a chart because they felt it put their system in a better light. And I'm not sure who this `general modeler' is that Gordy is referring to -- pretty much everybody, perhaps outside of Spektrum's marketing department, is aware that there are some sorts of limits. | But, seriously, are you expecting over 40 sailplanes to be in | the air at one time at a typical club field? To be fair, you have to worry about planes on the ground too. Well, really, you're worried about transmitters, not planes. And not all fields are typical ... | ON means transmissions. How is the CD gonna handle 2.4 count and | amounts when their owners feel they are safe to turn on at any | time? Well, once these limits are exceeded (and perhaps even as they're approached) things will start to degrade, but there should not be overt failures, except for Spektrum transmitters unable to find unused channels (which happens while your plane is on the ground, so it's inconvenient, but not a disaster.) Planes should not start crashing just because somebody turned on the 41st transmitter (but with 72 MHz and 50 planes in the air, a plane WILL crash when the 51st transmitter turns on.) Perhaps latency will increase (I'd expect that especially with the Futaba system) and perhaps maximum range might go down, but in general the problems should be mild. The CDs and pilots will learn to adapt, to somehow limit the number of transmitters turned on at any given time to some figure if needed. They could do an impound, pins, whatever. And if somebody ignores this, well, warn or punish them when caught -- but at least it's not likely to cause problems unless many people ignore it. It will certainly be better than the current system, where if one guy accidently turns on when he doesn't have the pin, somebody might crash. | The next one that I didn't see addressed is the 'mixing' part...what | happens when you have Futa, Xtreme, Spectrum, Airtronics, and the | Chinese show up together...regardless of numbers. Yes, should be interesting. And yes, it has been addressed, and is addressed every time there's a large event. Well, at least Futaba/XPS/Spektrum ... dunno about Aitronics or anything from China. And sure, there's room for more testing. | Then there is this one: Ed asked :"Why don't you organize a test " | | Why would I? My hobby is to build and fly sailplanes, my job is to | sell beach cleaners. Where does posting to RCSE fall into this? Hobby or job? You're in a excellent position to organize some sort of impromptu test, and you don't even need to host your own event. You also don't need 500 pilots -- 50 SS TX's and planes would be good, 100 even more interesting. | So far at best 2.4 sort of works, if the install is just right, | if the models materials are cooperative and 'should' work fine | with other 2.4 systems..as long as their aren't too many TX's on | at one time....but no one has come up with control system to | protect against or even determine who will be turning on in the | pits. Of course, *everything* you've just said applies to 72 MHz too. And the 72 MHz impound/pin systems work fine with spread spectrum gear (with minor adjustments to loosen the rules up, and of course, these systems still don't provide protection against troublemakers who turn on in the pits (or parking lot!) and still don't tell who is doing it.) If you like 72 MHz, use it. It's not going away. In fact, you should be telling people how great 2.4 GHz is -- the more people on 2.4 GHz, the fewer people on 72 MHz ... | So what's the skinny....how many of you realized that it is | possible to be shot down with 2.4, If `all of you' = readers of RCSE, probably most of us. It's just harder. | that less than our current 50 TX's can be running at once As soon as Spektrum said `1 MHz channels', `2 channels in use simultaneously' and `80 MHz' band, people were doing the math. | and no one is too sure about how many of a mix of brand | systems are safe? With 72 MHz gear, we're quite aware that 51 simultaneous systems is unsafe -- and you can only reach 50 through *extreme* luck or careful planning. And even if everybody has their own channel, problems are still possible, either with out of tune gear, 2IM or 3IM interference, poor receivers ... it's amazing it works as well as it does. If a number of pilots show up on random 72 MHz channels, it only takes *9* for there to be a better than 50% chance of somebody getting shot down without some sort of frequency control. 2.4 GHz/spread spectrum doesn't have to be *perfect* -- it just has to be a lot better than the current 72 MHz system. And so far, it seems to be. | Was just wondering that's all :-)? Uh-huh. -- Doug McLaren, [EMAIL PROTECTED] I thought I wanted a career, turns out I just wanted paychecks. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
