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HomeAircraftHelicopterMain Discussion › Charmouth and 2.4 GHz
03-08-2008 08:34 PM  10 years agoPost 61
Andy from Sandy

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Bedfordshire, UK

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If you read all the bumph on flying in this country then you will know that officially any crash is supposed to be supported by an incident report. At that time all of the evidence has to be collected before anything is removed from the scene. At that time that would probably include noting all the radio equipment being used. Also if the club and the members of that club are responsible then all equipment will be legal and checked to be so. I see your point though as the person could falsify their tx but that would then make them irresponsible and will find it extremely difficult to join another club.

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03-08-2008 09:38 PM  10 years agoPost 62
Bond007

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Leicestershire UK

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YUG..
I reckon it would have to be tested for type approval, exactly the same testing that the DSX9 is undergoing, at this present moment. Would be cheaper to buy a new UK radio I should imagine. I'm sure Pete will clarify this.

Picture the scene of a heli hitting a person, and causing injury. Pilot of said heli is found to be using a non UK verified radio set. Insurance would be invalid for starters.

I wonder what charges the police would bring against the pilot.

Along with a civil prosecution by the injured party.

Now imagine the above where someone was killed

I'm not saying it couldn't happen to someone using a UK approved radio, but the legal consequences would be far worse for the person knowingly using a non UK approved radio.

If that same person were found to have 'tampered' or 'modified' the approval markings, I can't begin to imagine the consequences.

I've been into RC (on and off) for quite a few years. I've found the RC heli flyers are a lot more aware of the dangers involved, and of their personal responsibilities to put safety first and foremost.

I wish a lot of the plank flying community had the same attitudes.

Dazzaster

Guess I owe you a coffee at Charmouth then

Sean

Blitz Avro, Align Trex600, Blade MCX

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03-08-2008 10:38 PM  10 years agoPost 63
9387ASH

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UK

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One section of the CE certification is EMC testing. This is not necessarily related to the RF output level. I have seen a case of a system failing EMC tests yet passing all other tests. This was because a spurious signal exceeded the EU limits at a particular frequency. This was identified as coming from a particular crystal and as such, ALL subsequent systems destined for the EU had to have a particular spec crystal. All other systems (because they didn't use the same limits) were fitted with the standard crystal. This causes a slight increase in the cost.

This particular spurii was slap bang in the ATC approach frequencies for the EU. Hence the initial failure.

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03-08-2008 11:39 PM  10 years agoPost 64
bagobitz

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saddleworth,lancs,UK

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The subject of insurance-compliance is quite interesting. I tend to think that if an accident was NOT ATRIBUTABLE to a non-EC certified part, then the non-certification becomes irelavant.

In my former motor-trade career,I had several odd discussions with Insurance Company accident assessment engineers.

Car with bald tyres...unroadworthy.....insurance paid because another car hit him and the tyres were not cause or effect of the accident.

ball-joint collapsed, car swerved into a wall....paid out because the car had a valid MOT (Annual Government roadworthiness certificate ) therefore , as far as the owner was concerned,his car should have been OK.

In Yug's case, I'd assume that an independent electronic test-laboratories'report covering the parameters required for EC compliance,would make it legal....A lawyer would have a hard time proving that a compliant set was a danger because a sticker and a bit of paper were absent.

Again, this has been upheld in the motor-trade,where components are bought direct from the original supplier and not the car"maker" (aka Vehicle assembler)...provided the component is correct spec. a claim for warranty repairs cannot be refused because a franchisor has not done servicing or sourced "genuine" spares (I once threatened to advise a filter manufacturer that a VA was slandering their product,which exceeded the VA's spec....they backed down!)

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03-09-2008 12:37 PM  10 years agoPost 65
pchristy

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Devon, England

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Just a quick reply here....

Firstly, the insurers of an event such as Charmouth require that organisers take all reasonable steps to ensure safety.

By checking Txs for compliance, and placing reasonable restrictions on sets with known problems, the organisers can be said to have taken all reasonable steps.

That means that if someone deliberately falsifies the markings on their Tx, the *organisers* cannot be held liable.

The pilot who falsified the documentation is however liable for whatever damages he has caused, and the insurers would be well within their rights to refuse to pay out. Whether they would or not, we simply don't know, and I don't want to be the one to find out!

The reduced power levels of EU compliant 2.4 GHz is approximately 3dB down on the US levels. That's 3 dB out of a total path budget of over 130 dB. It is a trivial amount, and will have little or no impact on the technical performance of the system. The permitted EU output is EXACTLY THE SAME as we presently use on 35 MHz, where antenna efficiencies are FAR less, and the overall path budget is also far less. I don't recall anyone complaining that the output on 35 MHz was inadequate, so I have no idea why anyone thinks it will be inadequate on 2.4 GHz.

To use an analogy: in the UK, a typical family car has an engine capacity of 1500-2000cc. In the US, a typical car has an engine capacity of 5000cc. So why isn't everyone over here buying 5 litre cars?

--
Pete

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03-09-2008 05:51 PM  10 years agoPost 66
Dr.Ben

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Richmond, VA, USA

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To use an analogy: in the UK, a typical family car has an engine capacity of 1500-2000cc. In the US, a typical car has an engine capacity of 5000cc. So why isn't everyone over here buying 5 litre cars?
Perhaps in large part because your petrol is approximately 2.5 times as expensive as ours. But we digress..........

Ben

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03-09-2008 08:07 PM  10 years agoPost 67
TOSH

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UK.Peterborough

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So why isn't everyone over here buying 5 litre cars?
l did and yes, it was a lot safer than a Metro.

Flybars. Who needs `em.

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03-09-2008 08:45 PM  10 years agoPost 68
bagobitz

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saddleworth,lancs,UK

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Well, that has provoked a bit of interesting debate.

I agree the reduction of 3 Db is fairly small and likely to have no PRACTICAL effect...which reinforces the theory that some jobsworth threw his weight about "because he could"...and for no practical or sensible reason,to put the European modeller to a financial disadvantage ,being deprived of a standard, off the shelf product....Having said that, I'm amazed they actually adopted a frequency already in production.

Anyone remember the illegal AM CB radios everyone was using in the 60's?....the Gov't. couldn't put the genie back in the bottle,so were forced to allocate spare FM wavebands.(actually, IIRC, they stole the RC bands and allocated us to 35Mhz.

I suspect the true reason for the American cars being so large, is because their country is, too. London-Edinburgh is considered a "long" journey by most UK residents....In USA terms, that's "just down the road"...hence their love of big,lazy cruisers with ride more important than handling...though that's changing.

Anyway, I'm sticking with 35 Mhz until the Gov't steals the band back and flogs it to the highest bidder.

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03-09-2008 10:27 PM  10 years agoPost 69
Andy from Sandy

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Bedfordshire, UK

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Isn't dBs logrithmic so a difference of 3dB represents a factor of 2?

So if you reduce the power by 3dB doesn't that half the power?

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03-09-2008 11:45 PM  10 years agoPost 70
bagobitz

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saddleworth,lancs,UK

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Yes! Andy Not sure if 3Db represents 50%,or not (perhaps Yug will answer this one!)

Also, of course, the very short wavelength of 2.4 makes it much more "line of sight" compared to the "old-fashioned" stuff which should be less prone to blocking if the model temporarily disappears behind a physical obstruction....but it's all academic, anyway, because the radio will still communicate effectively ,well after the model's flown too far away to be visible!

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03-10-2008 12:38 AM  10 years agoPost 71
Yug

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UK. Herts

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Yup, a 3dB power increase represents an increase of twice the power where 3dB=10*log(2/1). However, I'm not sure what measurement conditions prevail for testing because the radiated power largely depends on the beamwidth of the antenna and there is a whole lot of mumbo jumbo when trying to quantify this when considering terms such as the gain of the antenna (dBi) with respect to an imaginary isotropic antenna, ie, one that radiates spherically or equally in all directions. We know from experiance with our DX7s that the range is dramatically reduced if the antenna is pointing directly at the receiver. This implies the antenna has a fairly narrow beamwidth, so there is plenty of scope for 'playing the numbers'.
However, I see no reason why one couldn't simply use a different antenna on the 'illegal' systems to bring them in line with UK requirements. ie, by making the antenna such that the radiated pattern has a wider beamwidth, then we are simply reducing the apparent gain in the vector of greatest radiation. This I see as being very doable given the apparently narrow bandwidth of our X9303/DX7 antennas.
This would also benefit in providing better uniformity of range checking at different attitudes.

Vegetable rights and Peace

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03-10-2008 05:42 PM  10 years agoPost 72
9387ASH

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UK

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Actually here in the UK 35 MHz belongs to the MOD and in time of National Crisis will take it back. It's only on a long term loan.

One of my test frequencies on a 50 Watt Transmitter just happened to be 35 MHz.

If you start adjusting the "beam width", then you would then have to start reducing the output power to take into consideration the gain of the antenna.

A Yagi antenna ( like the TV aerials ) have a high gain but a very narrow "beam width", we have the "ideal antenna" already on 2.4 GHz, ie the dipole. If you look at the polar diagram of a typical dipole you will see that its similar to a figure 8 where the transmitter is in the centre.

Link is to a polar diagram of the dipole....

and the antenna is located....

A high gain Yagi antenna gives the following typical polar diagram...

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03-10-2008 08:37 PM  10 years agoPost 73
Yug

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I've not taken one apart but is the DX7 antenna a simple dipole ?

Vegetable rights and Peace

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03-10-2008 10:10 PM  10 years agoPost 74
9387ASH

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UK

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It should be, there are various ways of doing it but would imagine (cannot verify until I get my first knackered antenna come in) it to be a simple dipole.

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03-11-2008 01:51 AM  10 years agoPost 75
Yug

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UK. Herts

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So if we were to shorten the 2 1/4 wavelength conductors to make it less efficient such that the radiated power was in keeping with 100mW devices plus get it certified, then this is OK and legal ?

Vegetable rights and Peace

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03-11-2008 12:22 PM  10 years agoPost 76
dazzaster

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right next door to hell

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would this talk of playing with the ariel sort out the problem that the aha think the futaba faast system has?

A.K.A 509

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03-11-2008 12:58 PM  10 years agoPost 77
Andy from Sandy

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Bedfordshire, UK

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Yug, If you change the design of the transmitter, change the aerial or some other change to the rf module then the set needs to go for type approval testing. It is not just the output power.

An example of this is if you get a third party rubber duck aerial for a JR PCM 9X. That company would of had to send the set and aerial for testing to get the CE stamp of approval.

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03-11-2008 01:27 PM  10 years agoPost 78
9387ASH

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UK

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And at about 6 - 8K a pop, its not cheap getting it certified !

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03-11-2008 01:53 PM  10 years agoPost 79
pchristy

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Devon, England

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Dazzaster: The Futaba problem is nothing to do with the power output, and would not be affected by changing the aerial. It is to do with the ID codes which should be encoded into the firmware. Unfortunately the firmware doean't seem to be as "firm" as it should be.....!!

Interestingly, I've read somewhere that all the Futaba outfits are 100mW, whether intended for EU use or USA. Is anyone Stateside able to confirm this?

--
Pete

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03-11-2008 02:31 PM  10 years agoPost 80
dazzaster

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right next door to hell

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i relise that, i still cant see what the problem is with the faast system as the bmfa havent told clubs to ban them or have to use them one at a time, the only thing the bmfa have said is if a member of your club hasnt had a tx tested then it should be tested against other tx before anyone flies. but as long as all tx have been tested there isnt a problem, if however you do turn on your tx after it has been teted and the servos on your heli fail to moce (the rx isnt receiving ) then turn everything off and return it to your dealer/ripmax which im sure is what anyone would do as it would then definetly mean its faulty but as of yet i have not seen any proof of anyone reseting there module to zero guild useing the switching on and off method.

A.K.A 509

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HomeAircraftHelicopterMain Discussion › Charmouth and 2.4 GHz
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