DX7: What can I keep?

[Cralis]

I was kidding about the crashing...
Not trying to get any trouble here. Would never do that.
(use a hammer instead!)
Naaa.. he's a good guy... was kidding..

[jamiem]

ive gone over to a dx7 for my trex 600 cos of the potential glitches associated with an electric model. will report back next weekend hopefully if its all ok, but i predict it will be perfect

[Nutz]

I posted on here about my friends T6E on 35mHz with around 100ft range, when he put the Spectrum into his Rexxy E the range was unlimited.

[Nutz]

Found it http://www.rcheliaddict.co.uk/showpo...5&postcount=12

[Boggy]

posted elsewhere today by 3dx
"I took a big chance today-put my dx7 in a LARGE clear plastic bag-and apart from getting really wet -had a great time flying both my Raptor and 600E- managed about 2 flights each then called it a day!!- gotta love that spektrum aerial,nice and short- would'nt dare try it with 35mhz stuff........."

what more can you say??

[Philimon]

Hi Craig

Re the DX7 (or any other 2.4Ghz gear) and no glitches, as I understand it:

Glitches are caused by other sources of RF at a similar frequency to the one the RX is working on. In the case of 35Mhz and electric gear, it turns out the the ESC, motor, BEC and metal-to-metal vibration radiates broad-sprectrum RF waves that include 35Mhz frequences. Thats why we get interference with our small electric models and we generally use a combination of moving the RF-noise-emititng components apart from the RX, as well as a noise-tolerant RX (such as DSP or PCM).

The beauty about 2.4Ghz is in two places: First, the broadcast frequency is far removed from the RF frequencies emitted by the traditional sources of noise mentioned above. That means that, even though there are sources of RF noise, the RX cannot 'hear' it. Its similar to a human not being able to hear a dog whistle.

Second, just like TCP/IP, there is a digital control protocol between the RX and the TX. Data is transmitted in packets with header and check-digit information. This allows two things: 1. The header information contains the UUID of the RX for which the data is intended. Therefore the RX is able to ignore all data not expressly sent to it by the TX it was 'bound' to earlier. 2: The header information contains check-digits which allows the RX to ensure the integrity of the data received. This allows it to identify bad or corrupted packets and ignore them. Both points imply that even if there was a source of inteference on the frequency that the RX was using at the time, it would simply be ignored.

Hope that helps.

Regards
Andrew

Disclaimer: I may have some of the technical detail incorrect, as it was some time ago that I did my research, but I think most will agree that my principles are accurate.

[Cralis]

Nice one Andrew. Explaining in computer speak makes it a bit clearer. I've won an item on Ebay, but I get the funny feeling I'm gonna get burnt! I won a DX7 (TX and RX) for US$182... The guys has been mailing me, and all seems fine - but this seems too good to be true (And I believe it often is...). It doesn't come with Servos though, but that's cool for me. I was gonna sell em anyway.

Will keep you posted on Ebay-gate, and see if I have been stung.

[Nutz]

I got stung on Saturday on a couple of TP packs form the States

[Cralis]

Didn't pitch up, or the queen demand so cash from you?

[Cralis]

mmm.. some bad news about 2.4Ghz?

"7) The useful operating range of these sets reduces with the number of sets in use at the same time. (These range limitations are still to be verified and confirmed but with many sets in use simultaneously, it could be as little as 200 metres)"

Taken from South African model site @ http://www.samaa.org.za/new_pages/frequencies.shtml

[richieclarkie]

If your heli is 200 meters away from you, you have more than enough problems without worrying about the range.

How many people are we talking about when we are talking similtaneously? Does it say?

[Cralis]

Agreed, 200m would be on the limit. The site says that they are restricting the numbers to 4 Tx's being used at the same time.

[Boggy]

craig i think this may be talking about the dx6

it also says
A similar three-channel system is already on the market and is being used very successfully in model cars. The latest development is a six-channel, 10 model memory set designed for small model aircraft. The transmitter has all the usual trims and mixers, and except for the short stubby aerial, it looks very much like the standard 35mHz equipment we are used to.

FOR THIS REASON THE IMPORTERS HAVE STATED THAT THESE SYSTEMS ARE ONLY SUITABLE AT THIS STAGE FOR SHOCK FLYERS, PARK FLYERS AND MICRO ELECTRIC HELICOPTERS.

this second bit is a quote from the spectrum web site which also states that the dx7 can be used on models of all sizes, and quotes the range as being beyond visual limits!!
they also suggest that 40 flyers could be using at anytime!!!!

"What happens if the band is full (80 users for surface or 40 users for aircraft) and I turn on my transmitter?
In the unlikely event that all channels are occupied, the next transmitter will scan the band indefinitely until open channels are available. The transmitter will then acquire the channel(s) and begin transmitting. Only then will the system connect"


here's a link for you

http://www.spektrumrc.com/DSM/FAQ.aspx#dx7

[ChrisB]

The DX7 is not bothered about how many units are being used,,and as Richie said 200 metres is binocular territory


Dx7 usage is simple,,fit it,bind it,forget about it and fly it

[Boggy]

bugger ive just spent twenty minutes saying that Chris