2.4 Aerial Issue

[Stephen Grigg]

As many of you are aware there is a lot of rubbish spoken about 2.4 especially by the older members of clubs who believe 35mh is all.Had a classic today.We at our club  have a very  experienced member who is unbelievably opinionated  and tends to berate all around .Today he came out  with the following.My collegue had  a tip stall flying his model to slow,he saved it  but called for help.I came out of my chair and went to his side.This member also came over.He stated that Mike had had a radio glitch because I was standing next to Mike and had shielded the aerial from the model,and I should move away.Weve just been allocated a pilot box.Does this mean  only 1 2.4 pilot can fly at any given time alone,on his own in the pilos box,Paaaaaah!!!!!!!!!!!!!!!!!!!!!!!!!!!!Or maybe someone is talking Rubbish

[Martin Harris - Moderator]

In theory, 2.4 is far more sensitive to bodies, human and foreign, being in the way and this was one of our concerns when 2.4 GHz sets appeared at our club. The human body is mostly composed of water and 2.45 GHz is the frequency chosen for microwave ovens as its radio waves excite water molecules terribly making them get all hot and bothered instead of passing easily through them...

 

From the above, you'll see that there might well be valid reasons why it's best not to deliberately put a person between an aerial and a model BUT in functional testing with various strategically placed bodies, we were unable to reproduce any problems whatsoever.

 

As we often buddy learners and have half a dozen or more people on the flight line within a few yards of each other I'm sure we'd have seen problems by now - which I can say with some confidence has not been the case.

Edited By Martin Harris on 31/08/2010 23:53:08

[Bob Cotsford]

surely you are only likely to block the signal if the pilot tries to fly behind the flight line as long as you stand alongside and not in front of him?

And yes, there's plenty of sphericals talked about both 2.4 and 35.

[Bob Cotsford]

duplicate post - this site's getting worse!

Edited By Bob Cotsford on 01/09/2010 00:05:53

[Chris Channon]

Hi all, i wonder if 2.4 is as good as we were lead to believe?

For me ( on Futaba 2.4) i have lost two aeroplanes for no apparent reason, if it were pilot error i would honestly say so, reading the show report in this month's RCM&E there were a lot more crashes than would other be the norm at the LMA.

For me, it takes all the fun away from flying model aeroplanes if i have to worry about the radio link failing. Now i only fly 35 megs, never had a failure.

Regards

Chris

[Stephen Grigg]

That is the point Chris no one has a problem with 35mh.Ive only had 2.4 and did have a number of issues that were always put down to loss of signal,by the experts standing with me.Atc the start of the year I changed to a different make of 2.4 and have not had a problem since.One guy had a problem at our club ,the aerial became entangled in the safety fence,and of course the classic,Ive seen models disappearing because someone has forgotten to put his aerial up!!!.It was the comment  on Tuesday by an expert who accused me of shielding the 2.4 signal from the model when standing 3 feet from another pilot when he had a glitch.At the time,I was sitting in my chair away from the pilot when he had his glitch the turned out to be the way he was flying

[Steve W-O]

I was reading earlier how several people had forgotten to extend the antenna on their 35MHz transmitters. 35MHz (or any of the HF/VHF FM systems) can have two people on the same frequency with obvious results. 35MHz is also more likely to be interrupted by interference (electric fence, noisy car ignitions, welding machines. Although FM minimises these, radio design reducing weight doesn't allow elimination of the problem, receivers with DSP are a big advance though) when the interference is stronger to the receiver than the control signal. (or if in  a park, some retard purposely turning on a transmitter on your frequency)

 

So any system could have disadvantages, personally I think a reasonable 2.4GHz system with two receivers with the antennas at 90 degrees to each other is the safer option for everyday flying.

 

If a radio glitch was definitely caused by you standing next to him, the radio system wasn't up to the job in the first place, as most systems have a range far greater than we can see the model.

[Chris Channon]

Hi, electric fence ? perhaps, welding machine and noisy car ignitions? i think not, perhaps 30 odd years ago but not now.

Blimey we are going back to the days when you bought a battery that supplied so many amps on cranking !!!!! nowadays, if the engine does not start within about 5 seconds then there is a problem !

Actually in over 30 years of flying i have never flown when someone has been Mig, Tig or Arcing.

 

I wonder how many people have gone from 35 megs to 2.4 gig and then back to 35?

 

For me, i will only use 35 from now on, worked well enough for years.

 

Regards

 

Chris

[Steve W-O]

Do you ever listen to any parts of the HF spectrum? The background noise level is higher than what would have been called a strong signal not so many years ago.

 

Ideally things like spark emissions would not get to the output of an FM receiver, as they are amplitude modulated and should not be demodulated, but they do enter the RF circuits, and could for instance de-sense the receiver, one way would be through the ALC circuit, or plain overload in the IF section.

 

There are plenty of cars around with faulty HT leads, the car will still run OK, but it can cause a lot of interference.  Plasma TVs can generate strong signals all over the place.

 

Unfortunately the ideal world in not the everyday world

 

We all have our preferences, sometimes created by bad experiences,  but I think we should be open to the different possibilities.

[Martin Harris - Moderator]

Once again people are saying they've had interference problems with 2.4

 

This was the subject of another thread recently where someone (BEB?) was proposing running a survey to dee if we could establish any patterns or common causes. Have I missed it or wasn't it practical?

 

I have to say that the only problems I've witnessed since the introduction of 2.4 at my club and any others I've been to have been battery related.

Edited By Martin Harris on 01/09/2010 19:48:12

[Ed Darter]

The only issue I have had with 2.4 (not wanting to temp fate) didn't result in the loss of a model, but nearly did. I never got to the bottom of it, but the only thing I can put it down to is a combination of events. My aerial was pointing directly at the model (a definate no no on 2.4GHz) and someone stood directly between myself and the model. This resulted in a lock out.

Before and since then I have had no issues whatsoever.

As said by others, 35 or 2.4 are going to have some kind of issues, but I think 2.4 is inherrently safer in that a lot of the human error side of things is taken away, such as leaving your aerial down or shooting someone else down when you forget to get the peg.

Ed

[Hamish]

Well I can confirm electric fences do effect your flying ability.  Flying a glider in a large field yesterday and overshot and went into an area with some cows.  First I approached the cows to see what there reaction would be and they moved off.  Then I noticed the electric fence.  Recalled a story in the past that the fences were switched off after a short learning curve for the cows.  Boldly touched the fence with no effect so climb under and retrieve model.  On the way back brushed against fence and wham did I get a belt.  I can now confirm these fences actually pulse however I am not sure if it 35 Mhz or 2.4Ghz but will keep within my flying area in future.

[Stephen Grigg]

Thats why I fly 2.4 I have enough to think about as it is so I eliminate as much as I can ,I did as you say originally Ed flew with a straight aerial until Timbo said NO,NO<NO

[Myron Beaumont]

This issue was discussed some time ago and as a consequence I tried a few experiments myself -from a tin box for the Rx to standing behind my camper van .Out of sight in other words . No problems ,but wouldn't guarantee the range of course .

I use Futaba But I think you'll get the same results with the others although I don't really know.

My cheapo RadioLink set is equally as good

[Garry Pollard]

Stephen

Its about time someone sorted your friend out, verbaly. IT cant do your flying any good whtsoever having him in your face all the time. Ours is supposed to be a relaxing hobby to be enjoyed, not having to wonder what the lunatic will say next.  belong to a 120 member club and NO we have not got one of those and if it was tried he would soon be put in his place

  Garry

[Spice Cat]

Re electric fences; if you are in doubt if it is live, get a six inch blade of grass and hold the tip on the fence. Move the blade forward so the fence gets nearer your hand. Live fences will give an increasing tingle as you move forward. This has saved me, and my wedding tackle on a number of occasions.

Garry, unfortunately there are some that have to be the Alpha Male regardless of the group being a rugby team or the local knitting circle! Sad but true.

Edited By Spice Cat on 02/09/2010 21:24:06

[Stephen Grigg]

Sadly Gary I Think half the reason I left  Tuesday  was I got fed up with the ranting,and the rubbish spoken of 2.4 you are right,

Edited By Stephen Grigg on 02/09/2010 22:21:22

[Lee Smalley]

i think we tend to have a rose tinted glasses syndrome with 35meg its allways had its problems and so does 2.4, most of those problems stem from poor install and associated equipment  (batts, switches and escs to name a few)  i have had 3 radio crashes since restarting this hobby and switching to 2.4 gig, 1 was and still is unexplained, 1 was flying too far away with a parkfly reciever (and the txs aerial had fallen over due to cracks in the joint) and the other was BEC failure, so in the grand scheme of things its been almost as reliable as my old JR pcm kit and the fact i dont have to mess around changing frequencies or waiting for someone else to finish flying then you can keep 35 meg!

[Wingman]

The great thing about 35MHz is that it is legally ours and ours alone and this position will be rigorously defended by the Governments Radiocommunications agency in cases of interference or misuse. However that is not the case with 2.4GHz where any change in regulations or lobbying by 'MegaCorp inc' could have us and our 'toys' kicked off of the band without us having anything to say about it.

The problem is that, with the popularity of 2.4GHz increasing, manufacturers will cease manufacture of 35MHz equipment, the 35MHz band will fall into disuse and there will then be no need for 35MHz to be reserved for model flying. We will then be left out in the spectral wilderness possibly faced with the prospect of having to buy new TX's and RX's

each time the radio control of toys is moved to another frequency band. 

[Steve W-O]

Posted by Wingman on 03/09/2010 11:18:22:

The great thing about 35MHz is that it is legally ours and ours alone and this position will be rigorously defended by the Governments Radiocommunications agency in cases of interference or misuse. However that is not the case with 2.4GHz where any change in regulations or lobbying by 'MegaCorp inc' could have us and our 'toys' kicked off of the band without us having anything to say about it.

The problem is that, with the popularity of 2.4GHz increasing, manufacturers will cease manufacture of 35MHz equipment, the 35MHz band will fall into disuse and there will then be no need for 35MHz to be reserved for model flying. We will then be left out in the spectral wilderness possibly faced with the prospect of having to buy new TX's and RX's

each time the radio control of toys is moved to another frequency band. 

 

 

You may find that interference investigations have almost come to a halt, unless you are a large fee paying customer!

 

 

[Lee Smalley]

where do you get this wonderful theory from wingman is it just your opinion or are you speaking from any standpoint of respectability, honestly!! i think you will find that before the 2.4 gig band get Overcrowded or bought by some fictitious mega company they will be moving even higher up the band for for greater bandwidth phones are already on 3gig we are developing this already for our meter comms, so i think your opinions are already slightly out of date  

[Wingman]

Lee - Our position is protected on 35MHz but not on 2.4GHz.

[Stephen Grigg]

So should I switch from 2.4 to 35mh Wingman,oh dear Ive already had one expensive change this year

[Pete B]

Stay where you are, Stephen - there nothing wrong with, or going to happen to 2.4Ghz, that an anti-hysteria pill won't fix!

 

Pete

[Stephen Grigg]

Thanks Pete Im calming down already