UK Spektrum DX-7 ground range - field test

[simon_t]

I'm tempted to put an AR6100 in my Mini Ellipse. It can't be flown too far away due to it's size, but there is some carbon in it. The receivers are frustrating as although the body is small, the whiskers make the actual shape difficult to place in small cross-section gliders. Lack of glider mixing in the DX-7 doesn't help either, although not a problem for the mini ellipse

Simon

[853sp]

Smoothhound and Simon T, where did the reluctance due to carbon fiber come from ? I have the AR7000 fitted in an TRex 600e CF and have experienced no issues at all.

Regards,

Andy

[simon_t]

A trex with carbon at 100-200 yards no problem.

A glider with carbon surrounding the Rx at 0.5 mile + may be a problem. In the US they are selling high end composite gliders marked as '2.4GHz friendly' if the fuz is kevlar or glass rather than carbon, as there has been issues (and they have longer range with their higher power Tx)

Simon

[853sp]

Gee, there is a whole new world out there. Thank you. I have to admit my background from years ago before I got back into modelling was rc armoured fighting vehicles and skimmers. Sail planes and aeroplanes are dark arts as far as I know.

Regards,

Andy

[pchristy]

The problem with carbon fibre doesn't come from the frames. It comes from enclosing the receiver in a carbon fibre box (the fuselage or canopy). This is the equivalent of putting it in a metal box - the signal gets screened.

On 35 MHz, you can let the serial dangle outside the box and avoid screening - not so on 2.4 GHz.

The 6100 receiver is a single receiver - rather than the dual used in the 7000 - which makes it more prone to screening effects.

Its fine at close range, and seems to be fine at extended range, provided there are no large areas of CF nearby which could screen the signal.

--
Pete

[Philimon]

Worried about the AR6100 in a small-space fuzz? Get yourself a AR6200! Dual RX's, the same size as the AR6100 and much more likely to get into those tight spaces. I've got one in a Prodij, a 1.5m all-glass slope speed ship. It replaced a JR 610 micro receiver which is very small. No problems, so far, range is great, too.

For those of you that know the Prodij, you'll know that radio installation is as tight as a bus full of nuns on the way to a rubber band convention.

[moyesboy]

If you used the 9 channel you could put the main rx inside, and then have two external rxs (which are tiny) stuck on the outside somewhere, such as recessed into the wing, antennas at 90 degrees to eachother. That MAY give the same performance as the rx with one sat receiver in the open air. you can get extension leadss for the sat receivers.

[Smoothound]

I've got a 6200, I'm sure I looked into getting it inside the fuse somehow but gave up. I'll have another go later

[ChrisB]

This was all covered in the talk by Paul Beard at 3D Masters this year. The short version is that multiple spektrum sets makes bugger all difference to anything as they transmit on different frequencies and that FAAST has absolutely no effect on spektrum or vice versa. It's all a bunch of rumour mongering by people who think they know what they are talking about but unfortunately don't really.......I'm kind of fed up hearing about it really as it just sets off all the 35mhz 'heroes'....you know the ones, they always say anything new will never work.

Thats the polite way of putting it,,my version is

They are talking BULLSHIT

DX7`s been around for over a year,DX6 even longer,Dx3 longer still and correct me if i am wrong but i aint seen or heard of many problems,,change the bloody record ....

[Smoothound]

Sorry Chris I missed that can you say it a bit louder in laymans terms

[Sesame]

Thats the polite way of putting it,,my version is

They are talking BULLSHIT

DX7`s been around for over a year,DX6 even longer,Dx3 longer still and correct me if i am wrong but i aint seen or heard of many problems,,change the bloody record ....

yeah get off that fence and tell us what you really think

[Ashley Davis]

I'm pretty sure he said he agrees and is worried and has sold all his 2.4ghz stuff ???

[moyesboy]

Never had any problems on 27 AM. I'm digging out my M series and Micron homebuilt.

[Ade_Law]

They are talking BULLSHIT

not meaning to single you out here chris its just a suitable quote to start my post :-)

im not anti 2.4 when my old 9x2 gets long in the toorth I will upgrade. Im just passing on info i have gained from people knowledgeable on 2.4 gig. sure its not spectrum its general 2.4 info this applies to wireless, cameras as well as the 2.4gig we use.

my friend works in the industry and has contacts of the manufacturers of the 2.4gig chipsets and when they were told about specktrum and fasst they had serious concerns with pactet loss which would affect range and latency when a larger number of transmitters are within range of eachother.

claiming its BS is unfounded in my opinion you dont know any more than I do and without real evidence using our equipment i doubt we will ever really know.

im hoping that this weekend we can get >5 tx's at the field and do a proper test at the limit of range on the ground and see if we can replicate the effects that i have mentioned.

Ade

[Angelos]

why would that effect the range, the sets broadcast on a broad spektrum using pattern matching, so 10 tx or 40 it wouldn't make any difference.

With Spread Spectrum transmissions multiple systems use the same band because the transmitter and receiver side share the same sequencing code and this makes it possible for the receiver to extract the correct signal. However, the more transmissions you have the worst the Signal to Noise ratio and thus it gets harder to reliably retrieve your own data.

A good analogy would be 20 people sitting around a table and having several conversations. Because of the way the human brain works each of them can follow whichever conversation he wants. However, as you start to get more conversations the background noise increases and it gets harder to hear the conversation you want.

-Angelos