Go Back  RCU Forums > Radios, Batteries, Clubhouse and more > RC Radios, Transmitters, Receivers, Servos, gyros
Reload this Page >

Are RC events getting too large to be safe? Is anyone studying band saturation?

Notices
RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

Are RC events getting too large to be safe? Is anyone studying band saturation?

Old 08-08-2013, 07:10 AM
  #1  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default Are RC events getting too large to be safe? Is anyone studying band saturation?

I would like to ask for your thoughts on this topic.

This has to do with 2.4 GHz band saturation. In the beginning there was concerned as to whether we could have 40 2.4 GHz radios on at one time. Then we saw tests with 60 and I think I saw one all the way to 100. Are we now complacent?

This year at the International Radio Control Heli Assoc. there were 1100 registered pilots at the AMA site. As I understand it there was no frequency/band control. Should we be concerned? Should we consider capping these events over concern for RF band saturation? I don’t know.

A unique opportunity existed this year at the AMA home site during the IRCHA festival. There could have been hundreds of radios on at one time. Did AMA or one of the manufacturers monitor the 2.4 band? I would be interested to know. When we get this big we may, again, have to go back to some kind of frequency control, or more appropriately, RF band control.

With RC events getting larger and larger, and with no frequency control, do we have a potential safety issue around band saturation? If there were no problems, if someone actually monitored the air and all was good, I would like to see a report. If it did saturate, if there was evidence of RF saturation that could lead to safety problems, did we see problems? Safety should be everyone's top priority.

It might be that the band starts to saturate at 200 or ??? radios. Who would have thought that these events would get this big. I think we need to ask this question and to document the findings. Let us share that with the community, and especially the organizers of these big events, before some $50,000 6 engine jet or some giant scale heli with whirling blades goes out of control into a crowd and takes out some people and property. If there is a guideline to be developed, let the radio manufacturers, working with AMA, develop that guideline.

This is not a witch hunt or an alarmist post. This is not a brand concern as I think all the major brands, and most of the off brands, are pretty good. I am a concerned citizen of the RF community who might like to attend one of these big events. Is it safe? I would like to know if anyone is looking at this for large events.

If we have any RF wizards here, I would like to get your opinions on the question.

Last edited by aeajr; 08-08-2013 at 07:21 AM.
Old 08-08-2013, 08:09 AM
  #2  
Dave Harmon
 
Join Date: Jul 2002
Location: Sperry, OK
Posts: 689
Likes: 0
Received 2 Likes on 2 Posts
Default

If there was 200 radios on the field I'll bet they were not on all at the same time.....there is not enough room in the sky around the field for 200 models to be flown at the same time.
I don't think there is anything to be concerned about considering that sky saturation is about 5 models at one time.
Old 08-08-2013, 08:31 AM
  #3  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Originally Posted by Dave Harmon
If there was 200 radios on the field I'll bet they were not on all at the same time.....there is not enough room in the sky around the field for 200 models to be flown at the same time.
I don't think there is anything to be concerned about considering that sky saturation is about 5 models at one time.
5 models at a time? At our glider club we have 12 models up during contests and that is only limited by the number of timers available. We have no limit to how may can be in the sky at once.

Add to that pilots in the pits doing testing and trimming. That is with a total of 40 pilots at the contest. Now multiply that by 25 and make it Helis that need very little sky to fly.

I understand there were 18 pilot stations at the flight line.

And what about the pilots in the pits who have their radios on, testing, trimming, etc.

And, at a heli event, you will likely have people flying in the parking lot and away from the main flight line. You can fly several micro helis under your Easy-up tent at one time.

With 1100 pilots registered, potentially 1100 radios, even if only 20% were on at any given time that would be over 200.

But this is all debate. The real question is, can the band handle that? And did anyone monitor it?

There has to be a practical limit to what the band can support. Do we know what it is? Or do we wait till something really bad happens?

Last edited by aeajr; 08-08-2013 at 08:35 AM.
Old 08-08-2013, 09:24 AM
  #4  
Dave Harmon
 
Join Date: Jul 2002
Location: Sperry, OK
Posts: 689
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by aeajr
5 models at a time? At our glider club we have 12 models up during contests and that is only limited by the number of timers available. We have no limit to how may can be in the sky at once.

Add to that pilots in the pits doing testing and trimming. That is with a total of 40 pilots at the contest. Now multiply that by 25 and make it Helis that need very little sky to fly.

I understand there were 18 pilot stations at the flight line.

And what about the pilots in the pits who have their radios on, testing, trimming, etc.

And, at a heli event, you will likely have people flying in the parking lot and away from the main flight line. You can fly several micro helis under your Easy-up tent at one time.

With 1100 pilots registered, potentially 1100 radios, even if only 20% were on at any given time that would be over 200.

But this is all debate. The real question is, can the band handle that? And did anyone monitor it?

There has to be a practical limit to what the band can support. Do we know what it is? Or do we wait till something really bad happens?
Wait at the field until something happens.....then come back here and tell everyone about it.
Old 08-08-2013, 10:50 AM
  #5  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

I understand your reactive approach to things. Wait till things go bad, then blame someone for it.

I prefer to anticipate problems and avoid them so bad things don't happen.

Just two different approaches to life.
Old 08-08-2013, 01:16 PM
  #6  
JPMacG
My Feedback: (2)
 
Join Date: Jan 2002
Location: Ivyland, PA
Posts: 2,299
Received 1 Like on 1 Post
Default

If I remember my communications theory classes from 35 years ago correctly, the effect of having many radios operating simultaneously in a code division multiplexed system will be a reduction in the signal-to-noise ratio for each user. So we should expect to see a reduction in range as the number of users increases.

Spread spectrum / CDM is no panecea. You can't cheat mother nature. Ultimately mother nature wins.

Last edited by JPMacG; 08-08-2013 at 01:20 PM.
Old 08-08-2013, 07:50 PM
  #7  
Dave Harmon
 
Join Date: Jul 2002
Location: Sperry, OK
Posts: 689
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by aeajr
I understand your reactive approach to things.
No, you don't.....I just answered a stupid question.....with an equally stupid answer.
Old 08-08-2013, 09:18 PM
  #8  
mongo
My Feedback: (15)
 
mongo's Avatar
 
Join Date: Dec 2001
Location: Midland, TX
Posts: 3,498
Received 80 Likes on 70 Posts
Default

in past years, there have been posts following IRCHA about spectrum guys having problems with getting the rx light that tells em that it and the tx have found channels to lock onto. haven't heard about this year, but i suspect that the move to a hopping system may have cured that problem.
Old 08-08-2013, 09:52 PM
  #9  
ira d
 
Join Date: May 2003
Location: Maricopa County AZ
Posts: 3,249
Received 5 Likes on 5 Posts
Default

I would say at the vast marjority of events it is very unlikely to have 100 radios on at one time. Also I dont think there have been any problems that proved to be caused by saturation,
I do think however it would not be a bad idea for the AMA to request that all radios manufactors test and certify their radios as to how many can operate at one time.

IMO with all the different transmission protocols used by the different manufactors it would be diffcult to tell how many radios that can operate togather when different brands are used.

Last edited by ira d; 08-08-2013 at 09:54 PM.
Old 08-09-2013, 04:59 AM
  #10  
BarracudaHockey
My Feedback: (11)
 
BarracudaHockey's Avatar
 
Join Date: Jul 2003
Location: Jacksonville, FL
Posts: 26,958
Received 343 Likes on 274 Posts
Default

That's exactly it. At IRCHA or Nall, a manufacturer test that says 50 FAAST systems can run at once is nice but not a real world test. Fortunately we are only talking about a small number of events that it's a worry.
Old 08-09-2013, 06:54 AM
  #11  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Originally Posted by ira d
I would say at the vast marjority of events it is very unlikely to have 100 radios on at one time. Also I dont think there have been any problems that proved to be caused by saturation,
I do think however it would not be a bad idea for the AMA to request that all radios manufactors test and certify their radios as to how many can operate at one time.

IMO with all the different transmission protocols used by the different manufactors it would be diffcult to tell how many radios that can operate togather when different brands are used.
I am not an RF engineer and have already been told I am asking stupid questions. However I have always believed that the only stupid questions are the ones that don't get asked, so I will continue the discussion.

I guess there are two questions here. One is related to how well individual protocols within 2.4 can handle a busy site. That is a very important question but not the one I am focused on. I think Bruce Johnson at RCReviews does a really good job of reporting on that.

My focus is on whether the band can become so saturated that none of the protocols can be reliable. At some point the radio and receiver have to have a clear enough link to pass data.

It has been suggested, and it makes sense to me, that lock out when using a hopping protocol, is unlikely. However reduction in range is likely, and delays or sluggishness in response as the system hops from slot to slot trying to get through could be an issue.

For a glider working a thermal at 2000 feet up and 2000 feet out range would be an issue but latency might be less of a concern. But intermittent loss of connection due to range reduction could cause a pilot to lose confidence and come back to the field earlier than normal.

But for those latency sensitive situations like 3D heli and airplane flying, pattern, pylon or other high speed formats, increasing latency due to RF band congestion could become a concern.

Or, are our radio systems so good that we don't have to worry about how large the events get since we will never lock out, never have a range issue and and never have enough latency to be concerned.

Last edited by aeajr; 08-09-2013 at 06:59 AM.
Old 08-09-2013, 07:25 PM
  #12  
radfordc
My Feedback: (14)
 
radfordc's Avatar
 
Join Date: Apr 2005
Location: Lansing, KS
Posts: 1,598
Received 1 Like on 1 Post
Default

Originally Posted by aeajr
This year at the International Radio Control Heli Assoc. there were 1100 registered pilots at the AMA site. As I understand it there was no frequency/band control. Should we be concerned? Should we consider capping these events over concern for RF band saturation? I don’t know.

A unique opportunity existed this year at the AMA home site during the IRCHA festival. There could have been hundreds of radios on at one time. Did AMA or one of the manufacturers monitor the 2.4 band? I would be interested to know. When we get this big we may, again, have to go back to some kind of frequency control, or more appropriately, RF band control.
I appreciate your concern...but shouldn't you ask this question to the AMA or one of the major manufacturers? Or do we expect them to monitor this thread?
Old 08-09-2013, 07:35 PM
  #13  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Originally Posted by radfordc
I appreciate your concern...but shouldn't you ask this question to the AMA or one of the major manufacturers? Or do we expect them to monitor this thread?
As stated in the first post, I would like to ask for your thoughts on this topic.

I have asked AMA, and, yes there is a chance the manufacturers will see and comment in this thread.
Old 08-09-2013, 09:59 PM
  #14  
1320Fastback
Senior Member
 
1320Fastback's Avatar
 
Join Date: May 2008
Location: Northern Occupied Mexico, CA
Posts: 998
Likes: 0
Received 0 Likes on 0 Posts
Default

Believe they flew 100 Parkzone Trojans at a event a few years ago on dsm2 so it is possible that no problems will occur other than the normal lack of preflight or miss installation of radio components.
Old 08-10-2013, 11:38 AM
  #15  
AndyKunz
 
Join Date: Jun 2005
Location: White Heath, IL
Posts: 3,153
Likes: 0
Received 33 Likes on 32 Posts
Default

Originally Posted by aeajr
As stated in the first post, I would like to ask for your thoughts on this topic.

I have asked AMA, and, yes there is a chance the manufacturers will see and comment in this thread.
Why also in this thread? I already commented in the same thread where you posted in in another forum.

Andy
Old 08-10-2013, 04:05 PM
  #16  
TFF
 
Join Date: Oct 2006
Location: Memphis, TN
Posts: 4,183
Likes: 0
Received 1 Like on 1 Post
Default

I would think airspace is more of a problem than being shot down. I know they have done 60 plane hovers at PRO BRO Meets each plane taking a 25 sf space. 5 planes per 150 yards of field is my limit. That is regular type flying. Add hovering pilots and it depends on who it is. If they are in my face I land too. The only contests I go to are scale and at best there is 4 flying at once; that and dwindling participation has no prob with too much going on. Joe Nall should have a limit for airspace reasons. Having 10 planes, 10 helicopters, 10 others all at once is a lot to try and watch at one time.
Old 08-11-2013, 05:34 PM
  #17  
valleyk
 
Join Date: Feb 2010
Location: littleton, CO
Posts: 223
Likes: 0
Received 1 Like on 1 Post
Default

now that people can buy off the shelf 2-4 ghzjammers nothing safe.
Old 08-12-2013, 03:04 PM
  #18  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Originally Posted by AndyKunz
Why also in this thread? I already commented in the same thread where you posted in in another forum.

Andy
Not sure of your point Andy.

Was Spektrum monitoring the RF band? What can you tell us about what you saw?

Why on multiple forums? Because not everyone follows multiple forums, like you and I, so I would like to hear from the people on RCU.

Problem with that?
Old 08-12-2013, 05:52 PM
  #19  
AndyKunz
 
Join Date: Jun 2005
Location: White Heath, IL
Posts: 3,153
Likes: 0
Received 33 Likes on 32 Posts
Default

Yes we have. That's why we made DSMX.

That's all we can say.

Andy
Old 08-12-2013, 07:49 PM
  #20  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Your input is always appreciated Andy. Thanks.
Old 08-16-2013, 06:47 AM
  #21  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

Sharing what I have learned from people who seem to know what they are talking about.


Total lock out - not likely with hopping protocols. When some of the 2.4 systems were on one or two channels and Spektrum was on DSM2, there were lock out reports that might have been related to a busy RF band, but it is hard to be sure of the cause without someone doing RF correlation to time in the air for the model. Apparently DSM2 was great when we had 200 pilot events and half were on 72 MHz but, as Spektrum said, as the events got bigger, they saw the need for DSMX. Now Spektrum hops too.

What about Increased latency? - This seems to be the most likely problem. I remember seeing reports of this when the first hopping protocols came out. As the band got busy the response time went up. I have seen this demonstrated on the RCReviews videos. And I seem to recall seeing reports of this at past big events. But it is hard to pin down the cause without someone doing a correlation between the model in the air and the state of the RF band.

Decreased range - General opinion is that this is also very likely in a busy environment. However this is not something you would notice at a heli event or most airplane events. If your system has a 1 mile (5,280 feet) working range and you are less than 1000 feet from your model you are unlikely to notice a range reduction. This would be of primary concern to glider pilots who fly high and far. So far, none of the glider events have gotten anywhere near big enough to likely cause band saturation.

Now, if you were to host a glider event while the IRCHA event was going on you could see a problem. But that is not likely to happen.


So the consensus is that latency creep is the most likely thing we would see. Unless someone is watching the RF band and doing time correlation of band state to model in the air time, there would be no way to peg the issue to band saturation. Would it be enough to cause a crash or a mishap? Could a latency jump from 10 ms to 100 ms be enough to case a problem on a 3D heli flight or a high speed pass of a jet? Again, hard to say with no one monitoring the situation.

So that is what I have learned so far, but would be very open to other thoughts or opinions.

In my opinion, large event organizers should consider setting up some kind of band monitor/recorder to see what is going on. The low cost versions may not have the absolute precision desired but they might be good enough to see if further study would be merited. There are probably less than 10 events in the USA that are large enough to merit this, but it might still be worthwhile.
Old 08-16-2013, 07:06 AM
  #22  
AndyKunz
 
Join Date: Jun 2005
Location: White Heath, IL
Posts: 3,153
Likes: 0
Received 33 Likes on 32 Posts
Default

Honestly, I think you're trying to create a mountain where there isn't even an anthill.

Andy
Old 08-16-2013, 07:25 AM
  #23  
aeajr
Thread Starter
My Feedback: (2)
 
aeajr's Avatar
 
Join Date: Jan 2003
Location: Long Island, NY
Posts: 8,573
Likes: 0
Received 11 Likes on 11 Posts
Default

So you say Andy, and I respect your opinion. But no one has published anything on this so I am seeking information in an information vacuum.

I have gotten some good feedback and feel I understand the possibilities much better now than I did before, and that was my objective.

Will someone run with this? I don't know.

On a personal note, since I don't typically attend the IRCHA event or events of this size I have no real personal concern or vested interest. Primarily I fly gliders. I was just wondering.

However I did take this into account when I was going to 2.4. I had started to move to Spektrum DSM2 using a Spektrum module in my Futaba 9C radios. But as the events got larger and 72 MHz was being fazed out of the big events, I became concerned. Then Spektrum announced DSMX and explained why. Made total sense to me.

If I could have gotten a DSMX module for my Futaba radios I would have continued with Spektrum DSMX. But I could not get a DSMX module for my Futaba 9C radio, so I switched over to Futaba FASST before I went to the NATs last year. Never a problem. And I am sure DSMX would have worked just as well. I continue to use the Spektrum DSM2 module for Bnfs and never a problem.

But this is not about brands, and it is not about me, it is about "what if". And "what if" is always a valid thing to ask.
Old 08-16-2013, 07:34 AM
  #24  
AndyKunz
 
Join Date: Jun 2005
Location: White Heath, IL
Posts: 3,153
Likes: 0
Received 33 Likes on 32 Posts
Default

Well, you can continue to speculate, but it isn't going to make anybody publish their data. Data is expensive and helps us beat the competition. Why should anybody share that?

It isn't about brands, I agree - all the big-name brands work; we have to, or we would end up dying.

Andy
Old 08-16-2013, 04:10 PM
  #25  
rmh
Senior Member
 
rmh's Avatar
 
Join Date: Dec 2001
Location: , UT
Posts: 12,630
Likes: 0
Received 3 Likes on 3 Posts
Default more info

AJAR - your query brought in some readers but as previously noted, technical feedback-which is really meaningful- could be a long time coming.

The nature of 2.4 use pretty well eliminates any practical concern of problems -- caused by multiple use of equipment approved for and used corrrectly in accord with manufacturers recommendations.

What IS significant , is the increasing misunderstanding of the present equipment.
Why?
it is being use in increasing numbers by those with no understanding of it .
This is a normal outcome of more and more equipment developed for exactly this market.
It is also noteworthy that even with this increased used of 2.4, the use of modified equipment which may cause problems -- remains very small.
I have been at this a long time and active for years in RC contests and the building models , developed for them.
The proportion of technically oriented fliers to non technically oriented , continues to shift to the Plug and Play crowd..
An in depth study of how the 2.4 spectrum deals with apparently saturated situations , would be lost on the majority of readers .
Would it serve any real purpose?
From a purely practical standpoint -coming up with a meaningful density number is not likely.
Acceptance of the study is even more unlikely.
I continue to see -first hand - opinions concerning "problems" (sometimes no problem actually exists) which are technically impossible .
But keep on asking - maybe I am wrong ---------

Last edited by rmh; 08-16-2013 at 08:07 PM. Reason: more info

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.