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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › New plug-in 2.4GHz modules!
09-07-2006 05:07 AM  14 years ago
JKos

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Redondo Beach, CA

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BTW, did anyone catch this in the owners response about a removable antenna...

"This system was designed for us guys that have $10,000 or more invested in a plane and don't want to lose it."

Gee, I guess that means the other 99.9999% of modelers don't need this system.

And, I just can't get over their marketing BS about the 4096 resolution. Sorry folks, the radios we are working with simply don't have that much resolution coming out even in the PPM stream. They act as if plugging this into a radio magically makes it have 4096 resolution.

I'm also curious about the latency of this system. It's obvious the actual transmission of data is very fast, but how long does it take to get the last PPM frame out the door. And, how does it handle the asynchronous nature of its data output versus the frames coming from the radio.

Don't get me wrong folks, this is the way of the future!!! I'm just saying that when JR and Futaba come out with their own systems and Spektrum with their next system, I sure do hope they more tightly integrate the new technology with the processor crunching the numbers. This system cannot do that and will always be dependent on the PPM data from the tx.

> and fairly good A/D conversion stuff in it.

No A/D necessary as it is a digital stream. Just timing between transitions is necessary.

- John
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09-07-2006 05:28 AM  14 years ago
Roamer

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Albuquerque, NM

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Things get tricky when you start talking about an analog signal vs. digital (aka: "steps of resolution". They are two totally different worlds and the rules are very much different. It really all depends on how accurate the time reference is in the radio that is generating the pulse train. And, frankly, 11 bit accuracy is not that spectacular. digital tends to need a LOT of bits to cover data that is basically analog in nature.

Of course, it is probably a LOT more than my fingers can output! As long as it has twice the resolution when it is all said and done as my fingers, I'll never know the difference.

As for waiting for Futaba and JR, well, let's face it: unless someone comes out (like these folks and the Spectrum folks), Futaba and JR are going to sit on the 72Mhz fence until the FCC kicks there butts off! They have NO incentive to change the status quo and invest the money in a new transmittion technology. They are going to stick with what got them were they are.

That is the same with companies everywere and it is why you almost never see true innovation from a large company. They will not risk their position putting out something new and untested (and that might cut into their existing line!). It's only when a small company comes along and releases something special that they HAVE to get off the fence. Untill then, they are quite content growing a rut in their bum!

But, I do agree with JKos in that WHEN the big guys come out with something along these lines, they WILL be able to integrate it much better with the radio than any aftermarket company can.

Of course, that will mean buying a new radio to get that new integrated functionality...
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09-07-2006 05:29 AM  14 years ago
dkshema

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Cedar Rapids, IA

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This is odd. They are claiming 4096 bits of resolution. That translates to using a 12-bit A to D converter. But to get that kind of resolution, they would need to be actually feeding the reference voltage to the transmitter's stick pots, and then digitizing the voltage at the pots. To do THAT, they would need to completely bypass all of the guts already in your transmitter and that's just not going to happen with a module that plugs into the transmitter and essentially gets power, ground, and either a PPM or PCM encoded signal on the modulation pin of the connector.

Since they're not actually digitizing the stick position within the transmitter, that means they have to be sampling the output of the modulator (again, either a PPM signal, or an already encoded PCM data stream). I guess you could do that with a fairly simple microprocessor, some decent gate-able counter-timer circuits, and a bit of software.

At that point, you're kind of dependent upon the accuracy and repeatability of the transmitter's encoder section, and either the stability of your own internal clocks, or a good bit of DSP coding and processing magic to be able to make that claim. Of course, doing the sampling using a clock that is in no way slaved or sync'ed to the transmitter's internal clock (and how stable is THAT over temperature and voltage?) just makes your task a lot harder.

It's a step in the right direction as far as getting a more reliable link between the ground and the air, but at the same time, the "line of sight" thing is a bit scary. Spherical radiation or no, I'm wondering what happens to the received signal when something like the all metal (or carbon fiber, or even plastic) heli gets between the TX antenna, and that little stubby RX antenna. The shadowing problem is one of the bugaboos of this line-of-sight stuff, but is the price you pay as you go up in carrier frequency.

One other comment -- that little stubby antenna on the RX that has to be perpendicular to the printed circuit board...etc...seems to be MIGHTY vulnerable in a crash. I'd think it would be the first thing to be ripped out of the receiver in a crash, essentially trashing the receiver and most likely rendering the circuit board unrepairable.

Dave
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09-07-2006 05:58 AM  14 years ago
JKos

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Redondo Beach, CA

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> At that point, you're kind of dependent upon the accuracy and
> repeatability of the transmitter's encoder section

Bingo! And think about this... All the math leading up to output as either a PCM stream or PPM stream is the same. Now, what do you think is more "stable"... Outputing the results of the math in digital format (PCM) or creating a pulse stream of which the pulse transitions are of upmost importance (PPM)? Hmm, I'm guessing the former.

It will be quite interesting to see where this all goes.

Another "don't get me wrong"... I'm not saying this system can't work quite nicely and feel great. I'm just saying their claims don't quite tell the whole story.

- John

P.S. I sent them an e-mail with a few technical questions as well as a plea to produce an Airtronics module.
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09-07-2006 06:11 AM  14 years ago
Nick Jones

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anderson

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09-07-2006 11:50 AM  14 years ago
Lorents

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Oslo, Norway

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Spherical radiation or no, I'm wondering what happens to the received signal when something like the all metal (or carbon fiber, or even plastic) heli gets between the TX antenna, and that little stubby RX antenna.
This rx can probably not be placed inside a CF frame then? What happens if you have it on top of a CF frame and you fly the helicopter in a dive with skids pointing towards you - no line of sight then right?

I really like the telemetry part of it! Does anybody know if is the sensor interface on the rx (I guess it cant be called a rx any more ) follows any standards or do you have to get sensors made specifically for this system?


What comes around goes around.
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09-07-2006 11:59 AM  14 years ago
GM1

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Tallahassee, Florida US

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Well................
I suspect that the technology can be made to work BUT my question about liability would be about changing from the tx manufacturer's module to a third party module, would they all just pass any liability claims back and forth and end up (legally) blaming the pilot for installing a "non-standard" module . God, I hope I am never in that position. I agree with Paul, everybody would get sued, it's just a question who ends up paying.
If they made not only tx modules, but also txs, the liability issue would be a lot more clear but it doesn't appear that is going to be the case.
Gordie
On a dog sled team, if you're not the lead dog, the view never changes.
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09-07-2006 12:49 PM  14 years ago
matman

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White Oak Texas USA

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I suspect that the technology can be made to work BUT my question about liability would be about changing from the tx manufacturer's module to a third party module, would they all just pass any liability claims back and forth and end up (legally) blaming the pilot for installing a "non-standard" module . God, I hope I am never in that position. I agree with Paul, everybody would get sued, it's just a question who ends up paying.
Ir's funny any time there is any change the first thing anyone thinks of is who is going to get paid, all the way down to law suits and liability. GM1 I am not picking on you. You were just the last to post on this subject of liability. I know you didn't start it you were just commenting on it.
"Respect my Authoritiah!"
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09-07-2006 01:38 PM  14 years ago
pilotError

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Long Island, NY

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Futaba and JR are going to sit on the 72Mhz fence until the FCC kicks there butts off! They have NO incentive to change the status quo and invest the money in a new transmittion technology.
This is simply not true.

Futaba was working on releasing one with the 14mz as previously stated by Geordi (GM1). I certainly think this puts pressure on the Futaba and JR to get with the times, but don't think they haven't field tested their versions of the technology.
Good Judgement comes from Experience. Great Judgement comes from Bad Experience.
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09-07-2006 01:47 PM  14 years ago
Pelos

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Bizkaia (Spain)

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Legal status?
What I'm wondering is what's the legal status of this devices.

In Spain, as far as I know, 35 MHz is the legal frequency reserved for remote control of air models. Don't know if 2.4 GHz is reserved for any use here.

What about it in your countries?
Is there a life outside the sim?
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09-07-2006 02:18 PM  14 years ago
yf22k

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Long Island, NY

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I wonder how this compares to the spektrum. I have a spektrum setup on my 80mph brushless/lipoly rc car. I would't trust it to anything else as I have never had a glitch. I have been waiting for spektrum module and receiver to come for use in my Futaba 9c. If this is just as good or better I'd definitely stick it on my t-rex. well worth the cost for peace of mind.
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09-07-2006 03:42 PM  14 years ago
Chopper

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Stow,Oh- oops, I mean St Louis, nope Stow again,

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There is always one guy out there........

anyway, I am excited for the technology. I am a little sceptical about the claims however. It seems too good to be true.

Hey Gordie. I missed ya at IRCHA.
Paul Soha is a free agent now. Wow.
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09-07-2006 04:17 PM  14 years ago
Roamer

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Albuquerque, NM

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Quote
Futaba and JR are going to sit on the 72Mhz fence until the FCC kicks there butts off! They have NO incentive to change the status quo and invest the money in a new transmittion technology.

This is simply not true.

Futaba was working on releasing one with the 14mz as previously stated by Geordi (GM1). I certainly think this puts pressure on the Futaba and JR to get with the times, but don't think they haven't field tested their versions of the technology.
PilotError,

Futaba "WAS" working on something AFTER Spectrum came out and AFTER YEARS of discussion on why don't they (RC radio manufacturers) get with the times. So saying "This is simply not true." is a pretty bold statement.

How long has the 2.4Ghz band been available? How long have CHEAP freqency agile devices been using this band? Futaba just released a transmitter that cost TWO GRAND and it still is using radio technology that has it's roots in the late 1950s...

I'll stand by my statement.
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09-07-2006 04:21 PM  14 years ago
GM1

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Tallahassee, Florida US

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IRCHA
Hey Paul,
I was planning on doing the team trials, then staying for IRCHA but there were some issues I had to deal with at home that just kept me away. Also Dave had a triple bypass and I would have been traveling alone. I missed being there.
I wanted to see your new model as I hear it is awesome.
All,
I will not be the first on 2.4GHz but I won't be the last either. Both Futaba and JR have worked on SS aircraft radios but from my understanding couldn't get it to be 100% totally bulletproof and therefore could not introduce it as a working system. I'm sure they are still working on it but will not certainly not introduce it until they are totally confident that it is foolproof.
Gordie
On a dog sled team, if you're not the lead dog, the view never changes.
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09-07-2006 05:01 PM  14 years ago
rob10000

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Western Massachusettes

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Roamer is right.
If Futaba had released the 12 or 14MZ on 2.4, I would have bought one.
Now, those owners will have to sit on the sidelines and watch while 9C owners fly on 2.4 with immunity to little Tommy turning on his 72Mhz transmitter and shooting down their aircraft. Maybe Futaba will release a 2.4GHz module, or maybe they'll just have you buy a 14MZ Super, instead. Or maybe they won't even bother. Look how long it took them to release the synth module, while for years people used Hitec modules in their Futaba transmitter!
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09-07-2006 05:20 PM  14 years ago
helo_chris

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goodlettsville, tn

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Yeah, they can put a Win CE device and mp3 player and a $2000 price tag yet they are latched on to 72MHZ technology like a kid with a pacifier. And the technology is actually much older than '50s.

As for the legality, spread spectrum is actually an IEEE standard so it should be the same in all countries that recognize it, and most do. It is the same frequencies that wi-fi and cell phones operate on. It is unlicensed therefore and device that meets regulatory specs for that frequency range can be used.

And I think they will sit on the fence until people stop buying their $1500-2000 radios because you can get the truly latest and greatest technology for less than half that.
"There is a fine line between cutting edge and bleeding edge.."
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09-07-2006 05:51 PM  14 years ago
ChristianM

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Oslo, Norway

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helo_chris

Just to nit-pick, the cell phones do not use the 2.4 GHz frequency. In the US they use 800 and 1900 MHz and in Europe it is 900 and 1800 MHz. You are correct about the Wi-Fi system although you get some some systems on 5.6 GHz also.

This looks like a very promising development.

Edit: I think it is a good thing that it does not share the same frequency as the cell phones since it does reduce the chance of loading up the frequency at fun flys. I know that you can have a lot of radios at the same time but if they have to fight for "room" on the frequency with a large number of cell phones then it could get interesting.

Christian
Burn fuel, be happy
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09-07-2006 05:53 PM  14 years ago
sharam

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Northern California - Fly at Morgan Hill Field

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I am most certainly willing to buy a Flight Pack and give it a go!

I may have missed this but are these available for sale yet?
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09-07-2006 06:25 PM  14 years ago
helo_chris

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goodlettsville, tn

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Christian, not a problem, if I am wrong please correct me. I had seen where some newer cell phones were using the 2.4 band. Although it is possible they could have used 2.4 and spread spectrum to mean the same thing, I have seen more than a few people do that. I will look and see if I can find where it came from. Cordless phones do however use 2.4, could be bad news for all you guys flying electrics in the neighborhood, lol."There is a fine line between cutting edge and bleeding edge.."
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09-07-2006 06:33 PM  14 years ago
helo_chris

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goodlettsville, tn

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And since we are on the subject of spread spectrum, a trivia question.

Who was the first to describe the process of sending radio communications spread across available bandwidth?? I found this out researching spread spectrum, it was pretty surprising, nut very interesting to read about.
"There is a fine line between cutting edge and bleeding edge.."
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