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Radio - JR & Spektrum DSM > 2.4GHz spread spectrum DX6
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

Hmm, here's a thought... And I know JR wouldn't want us to figure this one out... The DX6 has a trainer port which is compatible with "Spektrum ™ and JR® Radio Systems." Well, it is possible to connect just about any radio's trainer port to any other radio's port. Most can be a direct, straight wire connection but a few combinations might need just a bit of interfacing electronics to shift levels and impedances.

JR to JR is obvious. Here is Futaba to JR: http://www.uoguelph.ca/~antoon/gadgets/futjr.html. I'm thinking Airtronics to JR would also be straight wire connection.

Well, here's my thought... Connect a better radio to the the trainer port of the DX6 and permanently pull the trainer switch. Now you can use all the programming features of your good radio but make use of the new RF link technology.

Heheeeeeeheheeeeee... In effect, they've already made a module for all of us.

Failsafe settings would still have to be made on the DX6 itself.

- John

Protos -- Logo 14 -- Logo 10
10-22-2005 04:41 AM
 
 
yapjy
Key Veteran
Location: Singapore

Cool stuff
10-22-2005 05:37 AM
 
 
onemetre
Senior Heliman
Location: Mansfield, Tx - USA

The module already exists. I wonder if you're limited to 3 channels via the module? Can you use the 6 channel receiver with the module to get a 6 channel system working with any of the module based radios?

Rob
10-22-2005 01:04 PM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

Rob,
If you are referring to the 3-channel ground system module, then no, it isn't going to work with the new 6-channel receiver.

- John

Protos -- Logo 14 -- Logo 10
10-22-2005 04:15 PM
 
 
fitenfyr
rrProfessor
Location: Port Orchard, Washington

About time...

Now all they need to do is wrap it in a 9Z module and get it out for 9 or more channels.

This is something the AP world has needed for a LONG time.

I would convert at least my main cameraship over to a JR if they got this out in 9 or more channels.

Jason Stiffey
Fly Fast....Live Slow...
10-23-2005 03:50 AM
HOMEPAGE  
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

I'd convert to anyone who can demonstrate a radio with reliable spread spectrum technology, even if it has the minimum of needed features ( i.e. no programmable mixes, which I actually love...)

Rhett... There's no power like E Power!
10-23-2005 04:18 AM
 
 
drdot
Elite Veteran
Location: So. California, Orange County.

fwiw..

I posted earlier that I saw and tried the system static...No noticeable latency, saw Danny Szabo fly the system in T-Rex...I'm sold, and this can only get better...

John.
10-23-2005 05:21 AM
 
 
alanhsu
Key Veteran
Location: Vancouver, Canada

great, note on the website they'll have a longer range sport flyer system coming soon. I am assuming that'll have more channel too. All in good time man, I've been waiting for this tech. for quite a while now.
10-23-2005 05:58 AM
 
 
nap_tan
Senior Heliman
Location: Santa Clara CA, USA

The question in my mind right now is the practical range of a 2.4 GHz system @ 1 watt. Any EE out there that can answer this question?
10-23-2005 06:53 PM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

nap_tan,
There are too many unknowns right now to answer that question. Such as, I doubt the radio is actually putting out 1 W EIRP. That's just the FCC limit just as 0.75 W EIRP is the limit on our 72 MHz band yet most of our radios put out well under that. What is the sensitivity of the receiver? Etc.

- John

Protos -- Logo 14 -- Logo 10
10-23-2005 09:31 PM
 
 
nap_tan
Senior Heliman
Location: Santa Clara CA, USA

JKos,

I am assuming ideal conditon (in this case, the max limit set by the FCC). As I understand a 72 Mhz system @ 1 watt will have a much longer range than a 2.4 Ghz system with the same power. Is this accurate? I am just wondering if the 2.4 Ghz system (with the limits set by the FCC) wil be implementable in aircraft RC systems. What do you think? I remember mounting a 2.4 Ghz video system for AP and always had some distortion at certain orientations of the heli. I also had some problems with the range of the system.
10-23-2005 10:28 PM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

Well, there are few things we can do to assume a few things which would have to be assumed. When you do a link budget analysis you have to know things like the type of coding used because that can have a large effect on coding gain. The beauty of spread spectrum is that you can actually "pull" signals out from below the noise floor; a point at which more traditional systems are completely useless.

I'll work a few numbers and get back to you.

- John

Protos -- Logo 14 -- Logo 10
10-23-2005 10:58 PM
 
 
nap_tan
Senior Heliman
Location: Santa Clara CA, USA

Thank you Sir!
10-24-2005 12:45 AM
 
 
heliwilly
Senior Heliman
Location: Hull ENGLAND

2.4 Ghz

Has anyone taken a look at the Nomadio 2.4Ghz set-up?

At the moment it is used for cars only, but with the 2.4Ghz telemetry you can receive as well as transmit information, you can receive r.p.m, temp, etc. Nomadio have intimated that they might be bringing out a multi channel version for Heli's/Planks.
Have a look at :-

http://www.nomadio.net/default.asp?ilevel1=2.

Cheers

Bill.
10-24-2005 09:09 AM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

nap_tan,
Well, I worked the numbers and had them double checked by someone else. I had to make numerous assumptions.

Assumptions:
1. 0.5 W EIRP -- FCC regulation is 1 W max EIRP. Since the DuaLink system uses two channels, I assumed half power allocated to each channel.

2. Minimum Eb/No of 5 dB -- Based on BPSK or QPSK modulation

3. Receiver noise figure of 5 dB

4. Bandwidth of spread signal of 1 MHz -- Also the chip rate

5. Data rate of 5 kbps -- Guess, but approximately what current PCM systems are at

6. 0 dBi antenna gain on each end -- Since the relative orientations of the antennas will never be perfect and constantly changing, this seemed like a fair assumption

7. Operating frequency of 2.4 GHz

Given those assumptions, the maximum range comes out to 500 km (310 miles). Yes, 500 km. Obviously, this is not what we will get with any RC system that comes out; but, it does show what is possible.

One suspect assumption is the 0.5 W EIRP. The DX6 is probably well below that. Also, the RF bandwidth could be less than MHz which would reduce the processing gain and thus reduce the range.

- John

Protos -- Logo 14 -- Logo 10
10-25-2005 11:38 PM
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

So given the variables you've stated, it's basically guranteed that this system should have at the minimum a range equal to the that of current radios.

Rhett... There's no power like E Power!
10-26-2005 12:14 AM
 
 
JKos
Elite Veteran
Location: Town of California in the state of Maryland

Rhett,
Yes, done correctly there will be no issue with range. Tomorrow I'll run a few numbers and see just how degraded (lower tx power and worse receiver sensitivity) from the numbers above the system can be and still give us the ~1 mi range we are use to right now.

- John

Protos -- Logo 14 -- Logo 10
10-26-2005 04:53 AM
 
 
nap_tan
Senior Heliman
Location: Santa Clara CA, USA

John,

Thanks for the info. This is begining to seem like the holy grail of Radio Control.
10-26-2005 05:24 AM
 
 
Ron_Osinski
Senior Heliman
Location: Russellton, PA

I have been flying the DX6 recently, since I-Hobby this past week/end in LA, and have been flying the pre-production models of this NEW system for a while now during it's testing. Let me just say IT ROCKS!

I have this system in my 2 T-Rex 450XL's and 2 E-Flite BCP's. One is brushless w/seperates and the other has a "HACKED" 4in1 that I only swapped out the receiver w/ the DX6 receiver to fly with a brushed motor. All 4 models fly extremely well without any problems. No range issues what so ever and never a glitch. The helis feel very smooth in the air. I felt a locked in feeling once I began flying this system in these helis. The performance/control was improved IMO over the FM and SPCM systems I had in these helis prior to fitting the up with the Spektrum receivers.

I also helped Danny S. get his 2 T-Rex's set up this past weekend at the WMHC event during the I-Hobby show in LA. Horizon Hobby donated a complete DX6 system to him with a spare receiver for his 2nd Rex. He was having problems with bad glitches with the equipment he was flying in his Rex's. They hooked him up and he took 2nd place during the event. Spektrum systems do not get hit by bad bearings, ESC hits or anything for that matter. His helis were locked right in once we put the DX6 in it.

I really like the DX6 and will not fly any other type of modulation in my smaller e-helis/e-planks any more. I can't wait till modules for my existing transmitters or complete Spektrum radio systems are available so I can fly larger e-helis and IC helis on this new technology.

___________
Best Regards,

Ron Osinski
aka - GMRO
10-26-2005 05:30 PM
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Radio - JR & Spektrum DSM > 2.4GHz spread spectrum DX6
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