FPV Interference on 2.4Ghz

The latest information and advice on installing and using 2.4 Ghz systems in over 20 Kg model aircraft
Steve Mansell
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Joined: March 1st, 2012, 11:59 pm
Location: Farnborough, Kent

Re: FPV Interference on 2.4Ghz

Postby Steve Mansell » May 13th, 2013, 2:44 pm

"Now 35Mhz is banned, I wonder how long it is before non-frequency hopping transmitters are banned?"

I wasn't aware 35mgz was banned. I am aware that some agreements with certain parties that allow flying on their land prohibit the use of 35mgz, but they are local agreements.

Funny no one mentioned this ban last Saturday when I bought a new dual conversion crystal for my Giant Jabberwock.

As a builder and flyer, but not an electronic or radio expert, I am about to purchase a 2.4 gig module and 2 receivers for my Futaba 9c so I can move over to 2.4 to take advantage of the increased reliability and convenience it offers. Whether it's "frequency hopping " or not, I don't really care, as it is all Greek to me! I just want it to work as advertised.

Techies sometimes forget that most people are users of systems, and don't need or want to know how they work. (no offence meant to the Technical wizards out there!)


Bob Thompson1894
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Joined: December 6th, 2008, 1:08 pm
Location: Notts

Re: FPV Interference on 2.4Ghz

Postby Bob Thompson1894 » May 13th, 2013, 3:20 pm

What was meant was no 35 at LMA and other shows. 35 is still fine for club flying.

Sam Boylett
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Joined: April 18th, 2011, 8:51 pm

Re: FPV Interference on 2.4Ghz

Postby Sam Boylett » May 13th, 2013, 4:35 pm

Who cares how long I took to report it? It's trivial. I certainly don't expect to come under a passive aggressive attack by 3 separate people when there is a much greater issue at hand.

I'll leave you to sort it yourselves, all my models are moving to DSMX or frsky.


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Chris Bradbury
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Re: FPV Interference on 2.4Ghz

Postby Chris Bradbury » May 13th, 2013, 6:16 pm

Hi guys, just been reading through this thread and there's a mass of very wrong information over the legalities of FPV flying here, so felt the need to chip in, just to make sure that people don't base decisions on the wrong information. To clarify my position, I fly regularlar FPV flights at my club, with zero interference to my club mates, fully insured, legally and safe etc.

Before I start however, I would like to state I'm with you all on the need to crack down on those doing things illegally, so please don't mistake me for someone defending the idiots that can ruin the hobby for all of us, they annoy me too.

So some corrections to information on here to make sure we're clear.

Currently 2.4ghz and 5.8ghz is legal in the uk for FPV, but the maximum output is not 100mw, its only 10mw on 2.4 and 25mw on 5.8. There are other frequencies available abroad that do sneak in to the UK, such as 900mhz, 1.2ghz and 1.3ghz, which aren't legal for UK use. There is currently enquiries been made by various FPV associations with OFCOM about the option to use selected 1.3ghz frequencies, but this is way off if possible at all. With good aerials on the receiver etc, a range of around 400m is possible legally, but more than that goes beyond line of site anyway.

BMFA insurance:
BMFA insurance covers you as per any normal RC flight for FPV, provided the flight is carried out as per standard ANO regulations and CAP658. You should only need additional insurance if you are doing things for commercial purposes etc, at which point there is far more involved than just insurance. It's my understanding at this time, that the BMFA is yet to receive a single claim as the result of FPV flying. If you are flying safely over a field you should be fine, fly over your neighbours in your housing estate and do so at your own risk. The ANO are the same whether you fly FPV or not.

Current rules of FPV flight:
As with any RC flight, line of site MUST be maintained, which is not possible when looking at a screen or wearing goggles, hence a co-pilot/spotter is required. When the BMFA first looked at FPV flying the buddy-box requirement was imposed, however this has now been relaxed under a General Excemption certificate, (the most recent being April 2013), where you can now fly fixed wing up to a maximum flying weight of 1.8kg and 2.5kg for rotorcraft without the buddy-box, however you will still need a competent pilot as a line of site spotter by your side. Above these weights, the buddy box is required again. The maximum heights is also limited to 400ft irrelevant of weight. There are other restrictions, such as distance flown from other modellers except for landing and so on, but these are mostly what I would class as common sense for the most part.

5.8ghz is my personal choice for FPV as I won't interfere with other modellers, but 2.4ghz can and will. The main issue is the 2.4ghz video feed is wide and swamps multiple channels. That said if its on first, the modern Tx's will notice this when switched on and swap channels to avoid this. A current one to watch is the newest GoPro 3 camera, as this is fitted with 2.4ghz for downloading to iPads, so if you know someone with one of these, get them to switch the 2.4ghz setting off. So if someone is flying FPV on 2.4ghz at your site, they must always switch video on first and when all other models are not flying.

At the end of the day, no matter what we do as sensible modellers, there will be people who do their own thing. For example, how many of us have gone slope soaring and been the only one insured? I too am frustrated by people doing things illegally, but even if it was all outlawed it won't stop them. No frequency is as safe as we think, for example I've seen 35mhz pilots shot down by someone switching on from a neighbouring field. 2.4ghz does benefit from systems such as model match, built in fail safes and channel hopping.

My opinion is if you know someone is flying somewhere regularly and illegally, report them.
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Bob Thompson1894
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Re: FPV Interference on 2.4Ghz

Postby Bob Thompson1894 » May 13th, 2013, 9:17 pm

Sam Boylett wrote:Who cares how long I took to report it? It's trivial. I certainly don't expect to come under a passive aggressive attack by 3 separate people when there is a much greater issue at hand.

I'll leave you to sort it yourselves, all my models are moving to DSMX or frsky.


Trivial? With models 'dropping left, right and centre'? (your words) no one is attacking you, but some clarification is needed when making accusations that interference was happening at an LMA show and no one was bothered!

Andy Boylett
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Joined: October 18th, 2010, 8:09 am

Re: FPV Interference on 2.4Ghz

Postby Andy Boylett » May 13th, 2013, 10:15 pm

Bob Thompson1894 wrote:
Sam Boylett wrote:At last years Elvington, DSM2 models were dropping left right and centre. We thought it was to do with the large aerial at the airfield occasionally transmitting at high amplitude and knocking out our signals if we were unlucky. It hit me twice and hit others using DSM2. Any model on DSMX or other frequency hopping 2.4 were fine.
I am at a loss what to think here. Models were 'dropping left, right and centre' and yet nobody brought this to the attention of the LMA in any way? The flight line crew did not query or investigate these 'crashes'? Are you avin a laff? :?:

I spoke to just about everyone on the flightline about this. Dave Johnson even congratulated Sam in getting his plane down in one piece after it started throwing 'wobblies' in the air. I spoke with him about it later as well. I think the issue was that everyone assumes that problems with planes are either pilot errors or equipment faults. When I told people about the interference issue with DSM2, noone was interested!! Sam flew his plane again after we converted it to DSMX and I told this to the flightline staff who were concerned to make sure the plane was OK after its previous erratic flight.

As someone else has said, most people are not interested in how stuff works, they just want to use it. I guess that is why it takes some time for issues like this to really become well known.

So, just to be very clear. The ssue is about NONE frequency hopping that DSM2 uses. It was only models using DSM2 that had issues at Elvington. We had 3 planes that were affected, on seperate transmitters as well!

Sam brought it up again here because he noticed that no one has been talking about it in the LMA, whereas at his local club there is nothing but talk about this issue. Anyway, I will go back to building my house again now, backl next year again hopefully. :D ....and maybe one show this year if I am allowed time off from completing the house :( .

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Rob Buckley
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Re: FPV Interference on 2.4Ghz

Postby Rob Buckley » May 14th, 2013, 7:15 am


If you're having inteference issues at a public show, you need to make a formal report, at the time, in writing. Unfortunatly talking to everybody on the flightline puts the issue into the realms of 'hearsay', especially when it is then raised 9 months later.

Do please send me a written report of what happened, as it's only with documented evindence that we can do any form of investigation.

The utube video, while quite pretty, doesn't actually prove anything. Only by plugging a laptop into the receiver to see what it's actually receiving through all the noise would show what effect other 2.4GHz equipment is having.

LMA Secretary - I've got a reasonable idea where you live!

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