JR to relinquish DSM2

[John Privett]

Pete - you might not know the answer to this,  no problem if you don't!

 

The 2.4GHz band is 80MHz wide (actually slightly more, but we'll call it 80!) You said earlier that FHSS (like Futaba's FASST?) utilizes 100kHz-wide channels. 

 

Now it's been repeated many times that FASST hops between 80 different channels.  So, is that really true, or is it just what people think is happening?  As there are 800 possible non-overlapping 100kHz-wide channels in the 2.4GHz band why do they not use all 800?

 

[buster prop]

I've learned a lot about the differences between DSM2 and FHSS and FASST. It seems to me that if the EU want to outlaw DSM2 could it be because Graupner and Multiplex use FHSS? Removing their main competitor (Spektrum) would be to their advantage. Maybe as a Spektrum user I'm being paranoid. 

[Myron Beaumont]

Funny that Quantum Physics has been used as an analogy ! a few posts back ..What confuses me was the reference to Heathrow ?

[Peter Christy]

Tony: When you start getting into digital spread spectrum, nothing is quite what it appears! Remember, the whole system was originally designed to provide a secure - and possibly undetectable - communications channel for spooks, which makes specifying it for other uses a tad difficult!

 

John M: Please read the earlier posts. There is no way that you are going to become illegal. Nor will your operating a DSM system cause a disaster! Relax! DSM systems operate on a non-interference basis, and even if the world stopped spinning, and the EU DID change the regulations, they would not be retrospective. You would still be able to use your gear.

 

John P: A channel on 2.4 GHz is defined as a 1 MHz chunk. So there are 80 1 MHz wide, non-overlapping channels available. The fact that FHSS only uses 100 KHz  instead of 1 MHz is irrelevant. The chips that are mass produced work in 1 MHz wide steps, even if you don't use all the available bandwidth (and are, in fact, restricted from doing so if you use FHSS)! And yes, FHSS does use all 80 channels, switching between them very quickly. In theory, you could have 800 100 KHz wide channels, but then you would have to tool up to produce special chips for that purpose. This would be very expensive, and probably fall foul of the regulations!

 

Buster: The EU isn't concerned - in this instance - with protectionism. All the "European" 2.4 GHz systems appear to be designed and built in China anyway! (The Graupner system originates in the US, and IIRC Hitec now own Multiplex....!)

 

Myron: I could have said Gatwick, but their arrivals lounge probably isn't as busy as Heathrow....!

 

 

--

Pete

 

No matter how much you push the envelope, it'll still be stationery

 

Edited By Peter Christy on 02/09/2010 20:25:25

[John Manning]

Pete,

Thank you for the re-assurance. The technicalities of radio and electronics are mind blowing enough. Then regulators start throwing their pennyworth in! Some of usare bound to get confused. I am glad that some body like you can explain it to lesser mortals like me. Many thanks

John M

[Martin Harris - Moderator]

Just back from flying this afternoon and a bit of socialising afterwards - what a lot of posts there have been!

 

David (Ashby) - would this thread make the basis of a useful article for the magazine?  I've learnt a lot from Pete's postings and I'm sure the greater modelling community could benefit from his clear explanations.

[David Ashby - Moderator]

Hi Mart

Posted by Martin Harris on 02/09/2010 22:57:57:

Just back from flying this afternoon and a bit of socialising afterwards - what a lot of posts there have been!

 

David (Ashby) - would this thread make the basis of a useful article for the magazine?  I've learnt a lot from Pete's postings and I'm sure the greater modelling community could benefit from his clear explanations.

 Yes indeed Martin, I'll have a chat with Graham assuming Peter's willing.

[Erfolg]

An article certainly would be both useful and interesting, to those with very limited knowledge of telecommunication principles and terminology. That is me.

 

I still feel strongly, that in this instance it is Spektrum and its agents who have not managed its stakeholder, the customer, helpfully, by silence. Some reassuring communication via trade magazines, could have placed issues into perspective. I guess it is the fear that poorly managed communicatitions could make matters worse. Still that  should be the PR departments bread and butter

 

Rumours are a fact of life, ignoring them does not necessarily mean they just go away, particularly if there is some underlying issues, however routine. This one seems to have rumbled on for a long time, but as elusive as trying to grasp smoke. This thread seems to put some substance to the nature of the rumour. The issues do not seem to deal breaking, although an issue.

 

There has been a call for us to support/recognise? the work of the BMFA, in this area. I am sure we all would, if they only communicated to us members a lot better, regarding what they do for us, in all areas. I get the feel of the Civil service, and the concept, of "the need to know", which was, or is routinely interpreted this does not include  the public, replace this with BMFA members. Often on the basis, that disclosure of discussions curtails the room for manoeuvre, compromising the management of members expectations. I really hope this is not the mind set of the BMFA, but just an oversight.  

 

Along with Biggles I have no wish for the present Spektrum system to be found unacceptable, particularly as their equipment has had the magic EU sticker for some time. I strongly believe in competition, both in improving customer services and costs. Although until recently I have had reservations on being looked into a single supplier, Spektrum has always seemed to be more open in this respect.

 

I am probably alone with not blaming the EU for any aspect of interpretation of the Directive. As the EU normally sets out the requirements/concepts and the national government puts these into national legislation. One recent example is the differing interpretation  of the EU directive on domestic wiring. In Scotland a competent person being the requirement, where as in England, the requirement for persons holding the requisite certificate, a lot of documentation and inspection requirements.

 

 

[Steve W-O]

Posted by Erfolg on 04/09/2010 13:49:58: In Scotland a competent person being the requirement, where as in England, the requirement for persons holding the requisite certificate, a lot of documentation and inspection requirements.

 

 

   Is it?

 

Or is that the institute who says so?

[Martin Harris - Moderator]

As far as I'm aware it was that nice Mr Prescott's Office of the Deputy Prime Minister who decreed that any new work in a kitchen or bathroom of an Englishman's (or Welshman's) castle could only be completed by the holder of various certifications.

 

...and introduced new wiring colours at the same time to make it obvious that work had taken place.

Edited By Martin Harris on 04/09/2010 14:37:07

[Erfolg]

I do not wish to divert the thread with any deviation, I understood that the defence by the then government (honest it was not me Mr., I was told to do it) to the change was that it was in response to a EU directive, and that  10 people a year died as a result of electrical faults (although apparently no attempt was made to link the deaths to DIY work) which resulted in the 2005 amendment of the IEE regulations,  that is at least what my newspaper wrote.

 

I guess of topic comparisons should be avoided.

 

I would not be surprised that the JR actions are no more than a strategic move. As has been suggested by licencing agreements, world wide marketing considerations, and the wish not to be hostage to other parties and the opportunities to sell their own technology.

 

I have and had considered Spektrum due to the attractive pricing relative to functionality. JR being just to expensive (although probably excellent). Perhaps the technological changes could encourage others to see JR as technologically safer, offering greater value for money?

 

I have Futaba, the basic 6EX. When the unique identifier rumor started, I initially dismissed them, then became concerned enough to look at the Spektrum, before I was overly committed to the 2.4 Futaba. The promtish communique and action by Ripmax was enough to reassure me to continue with Futaba.

[Peter Christy]

To be fair to HH, I think you have to cut them a little slack here.

Given how strongly some of the rumours have been reported as fact, would they have been believed if they had said anything? It leaves them open to the old Mandy Rice-Davies charge that "they would say that, wouldn't they?"

(For those of you too young to remember, google the Profumo affair!)

Sometimes responding to rumours simply fuels the fire!

 

--
Pete

"No matter how much you push the envelope, it'll still be stationery."

[Bri.]

Long live 35 megs.