David Gladwin

Why shut it down? Just delete the garbage that some guys introduced. Gordon asked a very pertinent question, we tried to answer that question based on actual experience. I think we achieved something positive and 2.4 IS a very relevant topic to many of us and extensions leads is a highly relevant aspect of Spektrum operation.

Rather like the "BVM gets out" (why not just delete that ENTIRE thread, its pointless) some guys just have to take RCU into a descending spiral, whatever the topic, mods. should, I feel, simply delete their irrelevant posts and allow us to contunue the technical discussion and an interchange of knowledge which helps us to understand our equipment better and get more out of this hobby.

Regards, David Gladwin.

Gordon W

Thanks David. I too don't want this thread shut down because I have another item to discuss regarding the long Rx remote leads, and I for one can just ignore the irrelevancies, which seem to have been minimal anyway in comparison with a lot of threads.

Presumably the 2.4GHz signal is demodulated in the remote Rx's, so what travels down the twisted leads is most likely a pulse train. A similar pulse train must also travel along servo leads. Therefore although the 2.4GHz end of things is immune to any of the interferences we might have suffered/guarded against on 27 and 35MHz, the long remote Rx leads will still be able to pick up stray radiation from the servo leads and other sources. So at the very least all these leads will need a decent separation from any servo leads, specifically the aileron and tail servo leads, and also from any other potential interference generators.

Which means that the same installation principles will apply on 2.4GHz as on the old frequencies.

This came to mind as I designed the fin-mounted installation for my Foxcomp Hawk, and am now working out the wing tip installation of the other remote. I wish I'd known I was going 2.4 before completing the majority of the model! Getting even these miniscule remotes inside the fin and wingtip became a bit of a head-scratcher.

Basically, the tail servo leads go down one side of the fuz and the fin-mounted remote lead goes down the other. In the wing, the remote lead will have to follow the rear spar and the servo leads the front spar. At the root, the remote lead will cross the servo lead at right-angles.

Gotta go for now, but thanks again for all the constructive comments and advice.

Gordon

David Gladwin

Thanks Gordon. I can't comment on the technicalities, I'm not qualified. BUT I have today competed the installation of a 9100 rx in my BobCat XL, range checks at 150 feet revealed zero fades.

For those interested I installed a remote in the leading edge of each outboard wing panel, one aerial longitudanally, one laterally.
Another remote was installed adjacent to the "receiver", aerial longitudanal and the fourth in the canopy , aerial vertical. No soft switch just coupled up the twin Duralites, via regulators,to the two power inputs as with the previous JR receiver.

So far so good, but I have yet to fly it. That said, a similar installation using 9000 receivers in my other Bobcat and L39 are working to perfection ie zero frame losses. !

Regards, David.

GrayUK

Gordon
You are correct in your assumptions.
No matter what technology is used, a good install is still a requirement!
Long extension leads carrying data do need to be kept away from other cables, especially other data cables; this helps avoid ‘crosstalk’ between the two.
Any long cable can act as an aerial so it is wise to consider this as well.
As I said in the earlier post, I am a FASST flyer myself so I do not have these concerns, but listening to David and others, it would seem that ‘long’ extensions are not really necessary. As such, using the KISS principle I would leave them out, range check and then ‘go fly’
[8D] Paul

cactusflyer

My Feedback: (4)

Well stated Paul.

Tailwinds,

John

Gordon W

Well I've decided to meet everyone half-way

The remote in the fin with antenna angled at 45deg stays there and it'll be interesting to monitor its performance vs the rest of the system via the data logger.

The main Rx goes flat on the floor of the nose with one aerial longitudinal and the other transverse, whilst the other remote will velcro on the cockpit wall on the standard extension with its antenna vertical. As I'd already blocked off all access to the wing tips with the aileron servo mounts, it was just too hard to try to mount the remote in there, especially as guys are having complete success with simpler installations.

Thinking a bit more about the data stream travelling along the leads it struck me that if it was FM as opposed to on/off pulse, then it'd be pretty well immune from outside interference. Just a thought. I don't suppose anyone knows the nature of the data stream? (This sort of thing interests me, regrettably )

Gordon

olnico

David,

The 9100 if properly setup can go up to 300 feet with max 1 fade during advanced range test.
It is much better than the 9000 on that matter.

Too bad Spektrum screwed up initially with this soft switch random short cut because it is a beautiful product otherwise.

rhklenke

My Feedback: (24)

Gordon,

That's not really the case. If the data was transmitted via FM, it still would be susceptible to noise that is within the frequency range of the modulated carrier. Plus, you'd have the added expense of the modem chips on either end. The data transmission *might* be via an RS-232 link (which can go up to fairly high data rates), but if it was, then there would not be the 36" restriction on cable lengths. I'd guess its simply a string of PCM pulses at the level of the input voltage of the processor IC's.

For long data transmission in a system like this, LVDS (low-voltage differential signaling) is the best way to go. Its used in military and spacecraft systems for this type of application. The low-voltage part gives you low noise transmission to other systems and the differential signaling part gives you high noise immunity from other systems. It too would add expense to the system although IC's to implement it are not outrageously expensive.

Bob