Testing the Orange DSM2 receiver when shielded

[Tim Mackey]

I've just finished some tests of the new 6 channel "Orange" brand receiver for signal reception, and the use of  satellite receiver.

There are other tests and peoples experiences over HERE as well, but that thread covered other types also, so was not Spektrum specific.

The interesting thing ( apart from the amazing reception shown even when encased in steel and lead ) was that I didnt actually find that attaching a satellite rx unit ( a genuine spekky one ) helped with signal diversity - yet when I used an AR7000 and the same satellite, the range improved. The AR7000 is of course though a full range receiver.This does still leave questions, and more testing is needed to conclude -and as the weather improves I will do some more outside testing. The only real purpose of this test was to see if a genuine spektrum satellite receiver increased signal reception when coupled to the orange version main unit. For me...it didnt.

Video is just over 1 minute long so take a look.

[DAVID CLIFFORD]

Interesting Tim,

I bought two of these from Hobby King for two of my boats to free up the AR500 and AR6100e respectively.

Both bound no problems and range tested with no problems.

Got the boat on the lake first two minutes no problems then suddenly nothing!! could see the Rx through one of the windows and noticed no light on.

Bad connection i thought? then after 30 - 40 seconds came back on.

Checked all connections no bad fittings, no overheating or loose wires.

Changed the battery and went out again. Same thing happened after two - three minutes.

Thank god this was not in a plane or disaster.

Have e-mailed HK but have had no reply up to now.

Anyone had any issues.

D

[Brian Parker]

 

Tim,

Did you re-establish contact with the main receiver before testing the remote receiver in your final test?

[Tim Mackey]

Yes. What I actually did was switch everything off, then plug in the satellite, and re-bound them both back with the tx.

[Pete B]

Hmmm, does that mean that, once the main Rx was sufficiently shielded to 'lose' the signal, the satellite did not continue to act as a 'substitute' receiver? Presumably, as this test was indoors, you weren't able to confirm that?

 

Pete

[Chris Bott - Moderator]

That's interesting Tim. Some good tests there.

Again it seems to demonstrate that all this blanking and reflected signal theory doesn't seem to stack up in practice. 

Do you think there's any chance a signal is getting in along the servo or battery wires?

[Tim Mackey]

Posted by Pete B on 04/12/2010 20:10:10:

Hmmm, does that mean that, once the main Rx was sufficiently shielded to 'lose' the signal, the satellite did not continue to act as a 'substitute' receiver? Presumably, as this test was indoors, you weren't able to confirm that?

 

Pete

 

Well that was my conclusion this time. I will be trying again outdoors at different ranges etc, but for now, I cant see evidence that the satellite was actually active - although the LED illuminated, and flashed when subjected to simulated brown out.

[Tim Mackey]

Posted by Chris Bott on 04/12/2010 20:35:09:

That's interesting Tim. Some good tests there.

Again it seems to demonstrate that all this blanking and reflected signal theory doesn't seem to stack up in practice. 

Do you think there's any chance a signal is getting in along the servo or battery wires?

 

Hmm, that's something I didn't consider Chris. I tend to be a bit blase about such things since I went to 2.4Ghz, believing ( perhaps naively ) that such interference and noise problems were confined to 35Mhz stuff.

I will re-arrange the rig to completely enclose all wiring except for an inch or so feeding the satellite.

[Biggles' Elder Brother - Moderator]

I'm just wondering if the geometery of the shielding is having an effect? What about just shielding the aerial/s in some metal tubing? MIght be simplier as well! You could try some carbon tube as well.

 

BEB

[Tim Mackey]

Dunno.... I can certainly try it  with some small bore carbon tube.

[Brian Parker]

 

 The signal is in all probability penetrating the screening.
 To be fully effective the screen should be grounded. ie connected to the negative 0volt line.

 The power feed cables are always a possible source of ‘noise’ at lower frequencies, but for a 2.4Ghz signal to reach the RF stages through the power cables and at the same time maintaining full integrity is extremely doubtful.

 Intrigued by the results with the remote Spektrum receiver.

 May try some tests to compare results. If OK with you Tim.

Note. The remote will not have quite range of the main receiver.

[Tim Mackey]

Absolutely, please do Brian - the more the better.

I have been pondering the results too, and one question that cropped up in my thoughts, was what exactly differentiates a "standard" full range receiver from a park fly.

I mean, mechanically, electrically etc - what does a full range jobby have that a park fly doesn't ?Surely with the relatively low component count and cost these days, it cant be that much difficult to produce full versus short range ones, which begs the question, why bother with park fly at all?

I guess its sensitivity /amplification of signal detection etc, but a simple non tecchy answer would, I'm sure, be interesting for many .

Edited By Tim Mackey - Administrator on 05/12/2010 10:12:23

[Hamish]

Tim you took the words out of my mouth, what is the difference?   Did a walk test today and still receiving at 75 paces!

[Brian Parker]

  

 

Some unexpected results.

Equipment..        Spektrum AR6200 Receiver.

                                Spektrum Remote Receiver.

                                Orange 6 channel Receiver.

                                Multiplex Tiny-s Servo.

                                4 cell NiMH Battery.

                                Sealed High EMC screening Box

                                Spektrum DX6i Transmitter.

Results..

a)      With Orange receiver + remote + battery all in box with servo outside box with only 2mm cable exposed. (Antenna closer to each other than recommended.)

Transmitter at ‘Range Check’

Range test failed at 9 paces.

b)      With Remote receiver outside the box.

Range test failed at 16 paces.

c)       With AR6200 +remote + battery in box and servo outside

Range test failed at 14 paces.

d)      With remote receiver outside box.

Range test failed at 16 paces.

Range testing (normal). Both receivers (18inches above ground) gave the Orange receiver a slight edge over the AR6200.

Range testing both receivers with the remote receiver connected gave the AR6200 slight edge.

A vertical antenna gave slightly better results than when horizontal. (But remember this was with the receivers close to the ground). Range test failed (as Expected) when the antenna was pointed directly at the receiver.

 

Tim,
Regarding Park Fly receivers. It’s a bit like Performance Cars. You have to do a lot(and spend more) to gain that little extra. With receivers the problem is ‘noise’, selectivity and overloading of  the front end. From what I’ve heard Park Fly2.4Ghz receivers seem to have more than ‘Park Fly’ range.

 

Edited By Brian Parker on 05/12/2010 12:09:34

[Tim Mackey]

That's Interesting Brian - well done, I think you have just saved me the bother of doing further tests.  Now lets try and see where we are

The AR6200 is classed as full range.

The Orange is classed as park fly.

 

A) On their own ( no Sat ) in normal use  the Orange outperformed the AR6200  

 

B) With the satellite connected the AR6200 was slightly better than the Orange.

C) When shielded, the AR6200 + Sat gave over 50% better performance than the Orange.

 

D) Satellite alone works exactly the same on the Orange, as on the AR6200.

 

My initial test was really to establish whether connecting the genuine satellite Rx to the Orange clone master unit actually worked - for me it seemed not to, however in your more controlled and real world scenario it did.

 

I guess the oddest bit is test A) and the most expected is C)

 

I wonder if the results of test B) are down to better compatibility of the AR6200 with the genuine satellite, or the fact that the SAR6200 is classed as full range.

[Brian Parker]

Tim,
Yes, I was surprised at the performance of the Orange Receiver.

A test with an Orange remote (when they come down in price) as opposed to the Spektrum Remote on both main receivers might produce further unexpected results.

More test results
This time with the main receiver only in the screening box.

 The Orange range test was almost the same as its previous test failing at 8-9 paces but the AR6200’s range was reduced to 9 paces.

 The remote RF/antenna on the AR6200 must be increasing the gain of the main receiver/antenna ie. they must be working together (matched?) whilst the Orange receiver is looking at the each antenna separately and using the strongest (switching or locking? more testing needed).
Results of the tests were not fully as expected but confirms that the remote receiver is RF active and will give added security to both main receivers. Also the Spectrum receiver combination performed better overall than the Orange receiver in combination with the Spektrum remote.

 Performance under screened conditions was much better than anticipated throughout the testing.

[Tim Mackey]

I understood that the AR6200 ( in fact all the DSM2 twin receiver setups utilizing "dual link"  ) only ever used whichever of the two received signals that the main unit perceived to be the best. A clever switching device in the main unit doing the work as it were.

[Chris Bott - Moderator]

I agree Tim. As far as I understand it, on any Spekky receivers that also have satellite receiver(s) then that is exactly what you have, two (or more) complete RF receivers. These feed a single decoder in the main unit. The decoder selects whichever receiver is performing best. (In reality it probably sticks to the main unless the main is having problems). Spektrum call this "Multi Link" and the main advantage is "Path Diversity".

If one RF path has a problem then there is another in a different location with a different orientation.

 

At the same time, Spektrum uses two different frequencies. This is "Dual Link". The main and the satellite both receive both of the frequencies and choose the best frequency themselves. Great in the presence of interference on one of the frequencies.It is much better explained here Spekky Website

 

 

 

 

[Brian Parker]

I’m aware of what Spektrum state but my test indicated an increased gain with the remote connected and equally screened.
 How else to explain the difference in range observed when only the main receiver was connected and screened.

[Chris Bott - Moderator]

I see your point Brian.

 

So I just had a quick play with a biscuit tin. This had the Rx, battery and servo inside it.

I'm getting some very non repeatable results. It seems to make more difference where the Rx is inside the tin, than whether it's in the tin or not. So it's not working well as a screen.

 

All outside the tin gives the most range.

All inside gives the least, but changes if I don't put the items back in exactly the same way.

Main inside and Satellite out gives me more than all inside, but nothing like all outside. 

Satellite connected or not doesn't really change the range, but nothing is repeatable enough to really accept any of this as a helpful test.

 

I think outdoors may give me better results? Who knows. 

[Brian Parker]

Chris,

 
My tests were all conducted outdoors and repeated several times (because results were not as expected).

 The only one to vary (and then by only a small amount) was the Orange receiver (screened and without the remote).

 The box is of Die-cast Alloy previously successfully screening a VHF module, not sure of its UHF/micro wave properties and at 6X3X2inches antenna installation just about OK, the antenna wires themselves were not individually supported. Testing was with the box 'earthed' to 0volts and also tried 'un-earthed'.

 I initially expected to have a very weak signal or even no signal at all into the box.

 It seems to me the system very robust and reinforces the view that the majority of failures are due to poor installation or pilot error rather than to system weakness.

 Also the Orange receiver is a good buy.

[Chris Bott - Moderator]

Brian that's obviously far more comprehensive than what I've managed yet. I wonder how much of this is snake oil and speaker cables if you know what I mean?

 

It does seem that this stuff really is pretty robust. We probably shouldn't worry so much. 

I can still see me adding satellites to Orange receivers just as a confidence boost (and possibly a false one).

 

I already have 10 real Spektrum receivers, these will probably always be in my best models and "compatibles" will go in little, less dangerous/less costly models. 

 

I have a DX8 with an AR8000 and telemetry. So I'm wondering if I can do any extra tests with that, looking at signal levels and lost frames etc in real time. Mind you, the telemetry might go out of range at the same time?

 

I'm working away for the next few days so that won't happen immediately. Oh and the Rx is installed in a model too, so that won't help. 

 

 

[Brian Parker]

I'll put an  AR500 receiver in the screening box and compare its 'range test'  to the others tested.

[Brian Parker]

The Spektrum AR500 receiver.

  Comparison with previous Screening tests (and slightly off thread).

 
The test was conducted with the Spektrum AR500 receiver in the screening box as per previous tests.
The receiver passed  full range tests with the transmitter antenna at both horizontal and  vertical  on all but one occasion when it failed at 24 paces (with the transmitter antenna horizontal).
The Long screened antenna was curled and in physical contact with the inside of the box, so the testing was repeated with the antenna padded and away from the sides of the box..it still (as anticipated) passed the range tests.
Conclusion, either this is a very robust receiver or the screening box is useless as a screen.  I suspect the former.

[Tim Mackey]

Quite amazing really - and one cant help wonder if we sometimes get a little paranoid about shielding the things, simply because they may be a little close to an engine etc.

Nice one Brian