2.4 radios.how good are they?

Just found this by accident,it's quite an interesting read.
It's probably the best scientific test of the 2.4 systems I've read so far.
http://www.spektrumrc.com/Content/Images/Products/calOrrSPMarticle.pdf
Enjoy.Danny.

If "Futaba" made lager it would probably be the best in the World not nacessarily the cheapest

It's really interesting that that Spektrum article doesn't make any mention whatsoever of broadband noise/signals on the 2.4GHz band. That's about the only real threat (admittedly rather small) to 2.4GHZ transmissions in model flying terms, and Spektrum don't mention it......

Andy

Andy Sayle wrote: -----broadband noise/signals on the 2.4GHz band. That's about the only real threat (admittedly rather small) to 2.4GHZ transmissions in model flying terms, and Spektrum don't mention it......

Andy

It does beg a few questions

Does anyone know:-
What other users are there of 2.4 G systems please? How powerful are these compared to Spectrum, Futaba etc?

Broadband
My router and PC's use 2.4G. Also mobile phones. There's a BT Hotspot nearby.
How could/do all/any of these affect my 2.4G model radio equipment?

Andy:-
Why do you think the threat is "admittedly rather small"?

And finally

Could 35Meg still turn out to be a just as robust and reliable system?

Which radio systems are used in the big models? eg IMAC? Large Scale?

IMAC is almost exclusively 2.4 now, I think at the Nats there was one flyer on 35Mhz, It's just so much more convenient and safe particularly at large events where the fear of a shootdown with very expensive models is a thing of the past and it removes the need for rigid T/X control "compounds" etc There is no way back IMHO Faast forward to the future

PDQ wrote:
What other users are there of 2.4 G systems please? How powerful are these compared to Spectrum, Futaba etc?

Hundreds, if not thousands! The 2.4GHz band that RC model applications have been permitted to use is part of the ISM (Instrument/industrial, Scientific and Medical) allocation. It means there are not just your usual wi-fi routers hotspots and the like using it, but also things like bluetooth applications, and lots of industrial applications for telemetry, communications, all sorts. The best bit is that the not so widely known users of this band are often permitted to use transmission powers way in excess of the 100mW power that users like us are permitted to use.

PDQ wrote:
My router and PC's use 2.4G. Also mobile phones. There's a BT Hotspot nearby.
How could/do all/any of these affect my 2.4G model radio equipment?

In short, the sources you mention won't. All users of the 2.4Band that Model flyers are permitted to use have to follow STRICT access guidelines before transmitting. This is deisgned to prevent one user splattering all over teh bandwidth available, and has to stick to predefined channels. They also have to use specific encoding techniques (spread spectrum) to virtually eliminate the chance of interference. The worse that can happen, is that in a crowded environment where everything operates by the rules, is that the response time drops as "packets" or "frames" of information are dropped. It's really difficult to explain how and why, unless I have my whiteboard and markers to draw diagrams!

PDQ wrote:
Why do you think the threat is "admittedly rather small"?

The threat is admittedly very small because in theory there should be no broadband transmissions covering the entire 2.4GHz band. All users of the band are supposed to adhere to the access rules laid out by OFCOM, This basically limits the number of channels a transmitter can transmit on, and the time when they transmit too (that is a gross over simplicifcation btw...) Of course there is always someone (i.e a manufacturer) who doesn't play by the book though, and this is the "admittedly small risk". A classic example is the cheap 2.4GHz video transmitters you can pick up for pennies off of Ebay. These tend to splatter over about 1/4 of the available 2.4GHz band. Fine if you switch on your Spektrum set after the video tx, but not fine the other way around. The frequency hopping sets (Futaba, MPX, Jeti) will not suffer from this issue (in theory )

PDQ wrote:
Could 35Meg still turn out to be a just as robust and reliable system?

It doesn't come close. 2.4GHz transmission is completely resistant to interference from things like electric motors, metal to metal noise, unconfined sparks etc etc. It is also completely removes the chance of somebody else switching on the same channel as you (shootdowns). It is about as good as you can get, and will be for the foreseeable future too (and that applies to all manufacturers!) Anything that removes the chance of user error = a more robust system.

Need to do some work now, essay over for now

Andy

Cheap video wireless link cameras are bad news for 2.4g radio controlled models?
Quote Andy
....the cheap 2.4GHz video transmitters you can pick up for pennies off of Ebay. These tend to splatter over about 1/4 of the available 2.4GHz band. Fine if you switch on your Spektrum set after the video tx, but not fine the other way around......

We don't seem to have had problems from them so far.
Dave S and Zaidy have managed OK. They would have flagged it up if it was otherwise.

Any comment Dave & Zaidy?

The cameras that Dave and Zaidy use (Rich B has one too, and I had one a while back too) are FlyCamone units, and are NOT video transmitters. They are just cameras with onboard storage cards.

The sort of video transmitters I am talking about are commonly used in First Person Viewing setups as they provide the real time video downlink to the "viewer".

Notice I also said "Admittedly rather small". I've been a VERY happy spektrum user for the last two years now, without a single issue at all. I'm only moving away from it (to Jeti) so that i can play with telemetry

Andy

Thanks Andy :-)

'Tis true Dave. 35MHz may work perfectly well, but 2.4GHz works even better

No worries Zaidy

See you guys later, if I can get out of work, it seems Captain screwup has been visiting St Asaph today

Andy

Quote "35MHz may work perfectly well, but 2.4GHz works even better" Even Suspektrum

Thanks to you all for your info re 2.4G systems
I now see the light
Pity the mags couldn't be as clear
PQ

No worries

It's a shame you can't all see the little whiteboard in my office, I would have you all understanding how spread Spectrum transmissions work, so you can pick out the real benefits from the marketing guff that is laid down upon us by the mags/manufacturers

Andy