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2.4Ghz Helis?

Old 01-17-2009, 12:17 AM
  #1  
floorunner
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Default 2.4Ghz Helis?

Okay, I've been shopping for my first heli and have been coming across helis that operate on 2.4Ghz. Most are more expensive. So, is that better?

Correct me if I'm wrong, but is 2.4Ghz not the insanely over-crowded, wifi infested frequency? It's being advertised as less prone to jamming. This just seems completely stupid to me. Wireless networks drop every time the microwave oven or 2.4ghz cordeless phone gets used. I don't want my helicopter to drop everytime it crosses a phone, microwave oven, or wireless network!

I can't possibly be the only one that has realized this. Surely the large companies can figure this out. So...I guess they just have a bunch of anti-jamming electronics. Does that work every time though? Also, is the normal frequency(Is there a "normal" frequency...?) very prone to getting jammed? Plus, why would anyone want to manufacture a radio system on 2.4Ghz? The extra electronics are just going to make the cost go up...

So, does anyone have one of these? Anyone care to explain?
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Old 01-17-2009, 12:20 AM
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floorunner
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Oh, and and 35Mhz is I guess the normal frequency.
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Old 01-17-2009, 01:20 AM
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Heli Jim
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The 27 MHZ and 72 MHZ radios are very crowded and you can't fly if someone else is on
the same frequency as you.. Also, they get hit by CB radio and other interferance.

Now....2.4 Ghz is a whole different ball game. The transmitter will pick a frequency that is clear and then hook up with the heli and you can fly without any trouble. Worth extra bucks? You BET!!!!!

Spektrum and Futaba and JR radios are probably the ones that get the most press. Read a lot.....check it all out.
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Old 01-17-2009, 02:19 AM
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As Jim outlined 2.4GHz is pretty solid stuff.

35MHz is not legal in the USA. Primarily you find model aircraft on 72 MHz here.
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Old 01-18-2009, 01:52 AM
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Originally Posted by Heli Jim;
Also, they get hit by CB radio and other interferance.
When you make a statement like this you should either provide all of the correct information or not make the statement.

Yes it is possible that a 27mhz radio or receiver could have problems with CB radio's because CB radios also use the 26 and 27mhz bands. There is no way a CB radio will effect 72mhz radio's unless the radio in question has been in some way modified to transmit on 72mhz, which would be illegal.

http://www.futaba-rc.com/faq/frequency.html

http://www.csgnetwork.com/cbradiofreq.html
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Old 01-18-2009, 10:21 AM
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I understood that 2.4GHz does not suffer from interference because the transmitter constantly "flips" frequency, which the receiver responds to, so even if another 2.4GHz heli is in the area, (a) the likelihood of them being on the same exact frequency is very small, and (b) they will only be on the same frequency for a fraction of a second, so the control is unaffected.
I think this is called "spread spectrum" technology.
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Old 01-18-2009, 06:44 PM
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Originally Posted by Jaguar View Post
I understood that 2.4GHz does not suffer from interference because the transmitter constantly "flips" frequency, which the receiver responds to, so even if another 2.4GHz heli is in the area, (a) the likelihood of them being on the same exact frequency is very small, and (b) they will only be on the same frequency for a fraction of a second, so the control is unaffected.
I think this is called "spread spectrum" technology.

Well not all radios use what is called FHSS I am sure you have seen this if you have checked out Futaba radio's, FHSS is Frequency Hoping Spread Spektrum. Both Spektrum and JR radio's don't use freq hoping. As far as I know and since I am no expert you should look it up but, Spread Spektrum scans all channels before picking one or two open channels. At least thats the way I understand how Spektrum and JR radio's work by selecting 2 open channels but Futaba does use the FHSS so it works slightly different. There have been many articles about these systems, if you can find some they should answer most questions. Or check out the web sites.

http://www.spektrumrc.com/

http://2.4gigahertz.com/
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Old 01-18-2009, 07:00 PM
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MaxAdventure
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There are quite a few threads that have some great contributions with accurate information on RF, talking about the pros and cons of 2.4, 72, 27, ham bands, etc. If you search around the hobby sites and use google, you can hit some great facts.

As for interference, IMHO the biggest contributor is that the RF noise generated by electric motors doesn't reach into the 2.4Ghz band, thus you don't have electrical interference and is great news to us watt flyers. Also, the new technology uses much faster transfer rates with a digital signal that does a significant amount of error correction, so even if you do get interference, the system compensates and the user never notices.

2.4Ghz is at higher risk of shadowing, but it's hardly a concern for the average pilot.

an overview (IMHO):

-FM has great new features that enhance the receiving of the command, compared to AM for controlling R/C
-FM PCM has great new features that enhance the receiving of the command, compared to FM PPM for controlling R/C, as it introduces digital error correction
-2.4 has great new features that enhance the receiving of the command, compared to FM PCM for controlling R/C, as it introduces additional error correction, speed, redundancy, fail safes, and eliminates having to wait for frequencies to open at the field.

see a trend? Newer technology has improvements, so if you're just starting out, the new technology is great. Need to save cash? use 72Mhz technology, it still works great!

(I'd skip AM unless it's a surface vehicle due to the poor signal quality)

my $0.02US

ps, I love the AR6100e and at $40 think it's an awesome amount of RX for the $$

pps, I will NEVER give up my two 72mhz radios I have and use all the time, and I am sooooo glad I invested in my X9303 last year and love the 2.4 advantages

Last edited by MaxAdventure; 01-20-2009 at 11:10 PM. Reason: technical ambiguities
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Old 01-20-2009, 02:32 PM
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floorunner
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Thanks for all the info.
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Old 01-20-2009, 06:56 PM
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Don't forget to factor cost into the mix.

I personally got fed up with paying $70+ for a single 7 channel receiver that would be safe for larger planes. I've decided to go back to using quality 72MHz gear and have had zero glitching or brown out issues.

Also keep this in mind. Some of the 2.4GHz receivers are very voltage sensitive and will lock out, brown out and or reboot making them pretty much useless for a few seconds (on some units up to 10 seconds). Yes that's easy to fix by installing a separate BEC or battery. Never have I had this issue on 72MHz gear.

Just blanketly saying any one kind of band is better than another is just as misleading as other statements made previously in this thread.

I want to make something clear here. I am not bashing 2.4GHz gear. My point is that most of the stuff out there is of good quality (The X9303 I had was magnificent) but the technology is still maturing and there will be issues. We as a group of hobbyists have been flying 72MHz for decades mostly with great success. Just because the new shiny tech has come along does not make 72MHz gear worthless, dangerous or something to run away from.
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Old 01-20-2009, 11:04 PM
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let me replace 'superior', with 'great new features that enhance the receiving of the commands'. - otherwise what I posted was in line with TWmaster, who is a very knowledgeable and excellent source of info.
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