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Old May 27, 2010, 10:23 AM
First to go over 106K feet
Crist Rigotti's Avatar
USA, IA, North Liberty
Joined Mar 2008
2,460 Posts
Quote:
Originally Posted by trappy View Post
pretty cool stuff from a technical perspective and as a short term workaround, but you guys are aware that 2.4GHz is a bad idea on R/C, right? I mean all the ranges I'm seeing here, even including the boosters, are easily achieved with a standard, analog link and a 4m servo wire antenna. The risk of getting shot down on the old TX is a lot smaller than the risk of you guys losing LOS out far and completely losing R/C. Adding a patch antenna on R/C without a automatic tracker is possibly the worst idea since world war 2.

If 2.4 is a requirement (it's probably not, but just saying) you should consider getting quality stuff like XTremeLink or Weatronic. These systems get 6 miles out of the box with legal output power and zero crazy mods. At the price of these systems, you're better off buying a LRS, though.
Trappy,
Thank you for your opinion. Remember, everybody has different requirements, needs, and goals in this hobby. Those won't necessarily align as to what you think is best.
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Old May 27, 2010, 10:31 AM
Videopilot
Derek_S's Avatar
United States, NC, Charlotte
Joined May 2009
2,706 Posts
Quote:
Originally Posted by trappy View Post
pretty cool stuff from a technical perspective and as a short term workaround, but you guys are aware that 2.4GHz is a bad idea on R/C, right? I mean all the ranges I'm seeing here, even including the boosters, are easily achieved with a standard, analog link and a 4m servo wire antenna. The risk of getting shot down on the old TX is a lot smaller than the risk of you guys losing LOS out far and completely losing R/C. Adding a patch antenna on R/C without a automatic tracker is possibly the worst idea since world war 2.
I know your location can change this a lot, but I occasionally get a lot of intereference with my 72mhz Futaba both in relatively ruaral areas and seemingly less so in the city. It is very sensitive to metals (like my desk lamp when I am bench testing) and sometimes even my body's proximity ot the model causes some kind of intereference. I have never had a problem with my Spektum stuff, not even twitching, but this is newer technology, right?

I am speaking purely about regular 3rd person flying, as I have not really gotten running in FPV yet. However, I have wondered if a developer/manufacturer bothered to advance their 72/35/40 mhz technology, could they integrate more robust signal authenticating firmware that improves the signal interpretation? Or maybe this exists in the form of much better (and more expensive) Rx's? I noticed Trappy that you use a relatively expensive Multiplex RX. Does this greatly contribute to your success or only marginally so?

BTW, please note I do not claim to be any expert on RF and thge associated RC systems, so I am just wondering here.
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Old May 27, 2010, 10:39 AM
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trappy's Avatar
Austria
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Derek S: The systems have improved a lot, especially with synthesizer technology which locks to a very narrow frequency (much narrower than crystals, for example). Metal objects do, however, cause interference. I have never experienced them as close range as you have, but I did notice some issues when I was experimenting with aluminum tape (my range reduced to ~2 miles).

Crist: The reason why I warn so heavily about 2.4 on R/C is because of the physical limitations of this frequency band. Fly behind yourself (in FPV there really is no way of knowing) or have your spotter walk between you and the plane, and this could be the last time you've seen your plane in 1 piece. I have a lot of experience with 2.4GHz (on video) and I know the limitations of them. If I were to fly on 2.4 R/C I would lose my plane a couple of times per flight. Sure, not everyone has the same requirements as me, but if you do fly long range why take the risks ... accidentally you may get yourself into a situation that I get myself into on each flight (tree or hill far out between plane and groundstation). One single crash generally costs more than a LRS or a 35/72 system.

So, long story short, unless your requirement in this hobby is to go as far as possible with the gear that causes crashes in FPV almost daily, then I really don't understand why you are doing this. If physics don't convince you, try statistics: Do a search on radio loss here in the FPV forum and make a bar chart on the frequencies that the crash was caused with.
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Old May 27, 2010, 10:55 AM
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Wolt's Avatar
Joined Oct 2008
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I wanted to do the same job, but I saw that the booster did not accept dbi so high, and so I stopped (i have the USA dx7). I did not know that there are attenuators ... now I will make!
is possible to make a switch for change between normal antenna and booster during flight?
thanks!
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Old May 27, 2010, 11:53 AM
FPV Desert Beta Test Center
Mesa, Arizona
Joined Nov 2006
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Quote:
Originally Posted by trappy View Post
So, long story short, unless your requirement in this hobby is to go as far as possible with the gear that causes crashes in FPV almost daily, then I really don't understand why you are doing this. If physics don't convince you, try statistics: Do a search on radio loss here in the FPV forum and make a bar chart on the frequencies that the crash was caused with.

Maybe thatís because, at least here, 2.4 is the most popular radio. That doesn't make it a long range system but for VLOS it is unequaled. There are major RC events in the U.S. that will not even allow 72 anymore. Most all FPV planes using any RC system that have been lost due to the RC link occurred because there was no reliable RTH system installed not because of the specific RC system. You know the one you don't think is necessary. All systems have a range limit in spite of what some would have you believe and if you fly long enough and far enough your going to encounter failsafes. The vast majority of people doing FPV are looking for a bulletproof system for range that equals 900MHz video with a ground patch antenna so that would be a few miles. Some will haul a yagi tracking antenna around to go further but most will not.
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Old May 27, 2010, 12:06 PM
Registered User
Italia, Piemonte, Torino
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Quote:
Originally Posted by Crist Rigotti View Post
Neo, I see you are from Italy. What dbm is your DX7 rated at? My USA DX7 was 21.3dbm. Perhaps yours was lower than 20dbm which is the max rated input to the booster, hence you didn't need the attenuator? There was a little sticker on my transmitter module with that info on it.
Yes i'm from italy.

Is Futaba T7C i don't know the dbm, but i think is 100mW output power, however when I used it I don't have put the attenuator!!
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Old May 27, 2010, 12:07 PM
JettPilot's Avatar
Miami
Joined Apr 2005
9,572 Posts
Back when I was flying on 50 MHZ, there were times that my plane would go into failsafe 100 times in a single flight Having an FMA copilot onboard made this a non event, failsafe did not even worry me. I could always just hold my radio up high and vertical, get control back, and get closer ! I also like return to home, but in my years of FPV flying have never had to use it But I still highly recommend it, in case you loose video totally, or something like that.

Having a plane that goes into a dive, or out of control when it goes into failsafe is totally unacceptable, and your FPV career will be more reparing than flying. An FMA copilot is only 69 dollars, it is a very cheap device that will pay for itself many times over.

Mike
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Old May 27, 2010, 12:12 PM
First to go over 106K feet
Crist Rigotti's Avatar
USA, IA, North Liberty
Joined Mar 2008
2,460 Posts
Quote:
Originally Posted by JettPilot View Post
Back when I was flying on 50 MHZ, there were times that my plane would go into failsafe 100 times in a single flight Having an FMA copilot onboard made this a non event, failsafe did not even worry me. I could always just hold my radio up high and vertical, get control back, and get closer ! I also like return to home, but in my years of FPV flying have never had to use it But I still highly recommend it, in case you loose video totally, or something like that.

Having a plane that goes into a dive, or out of control when it goes into failsafe is totally unacceptable, and your FPV career will be more reparing than flying. An FMA copilot is only 69 dollars, it is a very cheap device that will pay for itself many times over.

Mike
I have to agree. I have a FMA Co-Pilot and have RTH set up using a transmitter switch. I have used it while flying mainly to test it and it is neat to watch the airplane come home then circle overhead at the preassigned altitude.
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Old May 27, 2010, 12:13 PM
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trappy's Avatar
Austria
Joined Feb 2007
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2.4 is popular in regular R/C. we're not flying regular R/C, our requirements are fundamentally different. I haven't seen a SINGLE person flying with TSLRS only for VLOS operations, yet I'm sure thomas has sold more than 500 units world wide for FPV use.

a decent R/C transmission system will give you feedback on signal strength, either through RSSI or gradual degredation of signal quality. it will also not be affected by people or small objects in front of you. I once had a farmer stop with his tractor right in front of my patch while I was 3 miles out to see what I was doing. I immediately lost video signal but R/C was not affected. I was able to keep the plane level based on looking at the noise for the 30 or so seconds it took me to wait for the dude to turn off the engine, me to explain to him the problems he was causing, and for him to drive away from the antenna beam.

Sure, every system has it's limits. You should not even fly at those limits. The limit of my R/C is well beyond 6 miles, the furthest I fly with it is 4 miles.

The vast majority of people doing FPV are looking for a bulletproof system. 2.4GHz Spektrum is CERTAINLY NOT one of them. Not with a booster, not with a patch antenna, not even with both on a tracker. If you want something bullet-proof, get a LRS. If you want something cheap for long range flying, use 72MHz. If you want something that is guaranteed to cause a lockout (and force you to invest into a RTH), get a 2.4GHz R/C system.

I've got over 400 hours of FPV clocked only last 14 months. I've never needed RTH, I've never had a single R/C loss. I encounter video losses (2.4GHz) on every flight. I've flown over towns, over mountains, over glaciers. The minimum distance from "Home" I fly on each flight is 1.5 miles.

At this point I do what I always do in these discussions .... I've made my point, and I'm unsubscribing since this really isn't on topic with the thread parent. If you don't believe what I say, fine ... but don't say you haven't been warned.
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Last edited by trappy; May 27, 2010 at 12:45 PM.
Old May 27, 2010, 01:04 PM
FPV Desert Beta Test Center
Mesa, Arizona
Joined Nov 2006
2,303 Posts
Now that the straw man has been defeated back on topic.
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Old May 27, 2010, 01:35 PM
Videopilot
Derek_S's Avatar
United States, NC, Charlotte
Joined May 2009
2,706 Posts
Quote:
Originally Posted by Crist Rigotti View Post
I have to agree. I have a FMA Co-Pilot and have RTH set up using a transmitter switch. I have used it while flying mainly to test it and it is neat to watch the airplane come home then circle overhead at the preassigned altitude.
I hate to ask but can you or someone when you have time post instructions (similar to your booster ones here) about how to set up a simple RTH/stabilization system? I am curious as I can see how a Copilot will stabilize an airplane, but what equipment will maneuver it back towards home?

Or maybe a link to a previous post/instructions on the topic?
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Old May 27, 2010, 01:40 PM
It's all fun till Crunch!
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InSane Diego
Joined Jan 2002
1,903 Posts
Right,

I still don't undderstand the 4 Meter Servo Wire antenna concept.

For 72 Mhz Receiving, it might be OK, but a tuned 5/8ths wave length would be better, right?

If you use servo wire you could make a dipole or dipole-like antenna, but why?

Sorry to dwell on this, but there's something I don't fundamentaly understand here.

PS, Trappy you are very right and those of us with even a little (like me) understanding of RF know 2.4 GHz is strickly Very Short Range! Period... Nothing you do less than a KiloWatt will make it work long range!

Those of you that want to max out your Spectrums, just get a 2.4 Ghz Dipole antenna from OSDPRO and replace your plain wire ant., oh, and tune your RF deck too. But youy'll only add a few hunderd meters to your range, not miles!

Crunch
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Old May 27, 2010, 01:42 PM
JettPilot's Avatar
Miami
Joined Apr 2005
9,572 Posts
Everything we have said here is very relevant to this thread. When talking long range, RTH and stabilazation are very real concers. With 2.4 GHZ RC control being used for long range, people are most definately going to be getting lots of failsafes !!!

RTH is ususally a part of the OSD, The Dragon OSD + has a very good Return to home system. Used in conjunction with an FMA copilot, is a really good thing to have and will save your plane many times over.

Mike
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Old May 27, 2010, 01:56 PM
FPV Desert Beta Test Center
Mesa, Arizona
Joined Nov 2006
2,303 Posts
I agree. 2.4 isn't a long range system but anything that improves the OEM range is a good thing. I have gotten from 1/4 mile to 1 mile range at the same location with a DX7 which is nothing to write home about. I've flown several differant systems and highly recommend RTH with stabilization for any application. Reading about other peoples experiences with amp's on 2.4 is very interesting. This is the way we learn.
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Old May 27, 2010, 02:17 PM
First to go over 106K feet
Crist Rigotti's Avatar
USA, IA, North Liberty
Joined Mar 2008
2,460 Posts
Quote:
Originally Posted by Derek_S View Post
I hate to ask but can you or someone when you have time post instructions (similar to your booster ones here) about how to set up a simple RTH/stabilization system? I am curious as I can see how a Copilot will stabilize an airplane, but what equipment will maneuver it back towards home?

Or maybe a link to a previous post/instructions on the topic?
The RTH that I use is part of the Eagle Tree OSD PRO,v3Logger and v4 GPS system. There is plenty of information in the thread for the ET OSD. As far as the FMA Co-Pilot, I just followed the instructions. My Sky Surfer with Easy Star wings uses 2 eSky EK2-0704 rate gyros along with the Co-Pilot. I did sneak up on the settings in the ET OSD to enable the RTH to work properly for my set up.

Here is the link on the ET OSD PRO:
http://www.rcgroups.com/forums/showthread.php?t=924018
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