skyview dirty rf ...testing... resolved.

[schristo]

anyone with their panel wired up who is using skyview please help out with a simple test of the rf noise from the skyview...

first power the minimum panel for tuning a radio with the skyview on...

tune a marginal station (atis inside of a hangar should be a good test) listen to the quality of the transmission, clarity, static, etc.

now turn the skywiew off... how does this effect the radio signal?

is your unit a 10" or 7"?

for me, the skyview swamps marginal signals with a layer of noise and noticeably degrades good signals, very strong signals are not significantly impacted.  i get similar results even if the skyview is removed from the plane and powered with a benchtop source not connected to the aircraft in any way.

an 'advanced flight systems' unit in another rv appears to behave similarly, but the d10 in the same plane was rf silent.

dynon has replaced the screen (no change to projected rf noise) and has directly observed the rf noise at my hangar.

rf noise from my skyview even degrades fm radio reception from a shop dewalt radio from across the room.

i remain hopeful that the observed rf noise is only an issue when ground testing and that it is not a factor when flying... i really like my skyview and am not interested in going another direction but it is quite frustrating that the units appear to consistently generate dirty rf.


yesterday i stopped by dynon to pick up a set of the capacitve filters that they have come up with to address the rf noise from the leads on the skyview system.  after installing them there is no descernable difference in reception from the aircraft radio with skyview on or off.  

it is important to install all three of the filters, one to each of the db9 connectors and the db37... in my testing i initially installed a single filter to the db37 line without much impact to the noise... with all three in place the skyview unit appears to be rf silent.

robert at dynon noted that the usb tail coming from the db37 connector would not work with the filters (i had already removed mine) and that they would be making them available on request to anyone as soon as they have stock.

here is a shot of the filters installed; you have to reverse the connector studs on the filters.

 

[schristo]

Re: help with dirty rf test...

hello world... surely someone has a unit installed to test out... i really love the skyview but the rf noise is like a festering thorn in a otherwise healthy foot.

 

[Jamie]

Re: skyview dirty rf ...testing...

Hi Stephen,
As know one has sent you a reply, I hope I can help.
Here is my panel

I just have a few more wires to run this week, then I can FIRE UP the panel.
I will give you a report next weekend or so.

 

[dpbarnes]

Re: skyview dirty rf ...testing...

I have two Skyview 10" screens in my Lancair ES that is still under construction. When I first fired them up I noticed that my SL40 (only comm with an antenna on it) had noise on it. No matter what frequency. By raising the squelch level quite a bit I got it to silence the noise. I am not at an airport so I really can't get weak signals to see. I do have a hand held and it breaks squelch anytime I get within five feet of the plane. I also have a vertical power vp-200 which has a screen. It also seems to generate some RF noise although not as much. Holding the hand held near either Skyview creates lots of noise.

I am sure anything with a microprocessor in it is going to generate some RF noise. I don't know if Skyview's is to much.

 

[JohnH]

Re: skyview dirty rf ...testing...

Hi I just completed an installation today. I was warned by another installer about the high possibility of RF interference. Sure enough, it is a problem. I have an SL40 in a Kitfox 7 with a new Skyview installation with one 10" display. The SL40 shows an rf signal with the Skyview dead of around 35, Switch the Skyview on and the rf jumps to 56. All I did was set the squelch value to 60 for the radio and it seemed to have solved the problem. I do however hear a hum in the background without the engine running, but in flight I don't think it will be noticeable. If I power off the Skyview by holding down button 1, the rf interference changes to a pulsing signal about every second. This only happens with the Skyview off and the circuit breaker connected. Pulling the SV circuit breaker shows that the pulse is related to the SV.

 

[wkeehner]

Re: skyview dirty rf ...testing...

Hi,

I have just fired up my 10" and it opens the squelch on my SL40. I have done some testing and the interference is comming in the antenna cable (it gose away when I unplug the coax). It swamps weak signals, and increases the noise level on strong signals.
I have also found that there is no interference when the Skyview is running on battery.  The interference is not affected by the screen brightness or when all network cables are unplugged. I thought it might be someting to do with the battery charging cct. however its still a problem with the battery unplugged.

We will need a soloution for this problem...

 

[mmarien]

Re: skyview dirty rf ...testing...

I have the same problem. Turning on the Skyview produces static in both my iCOM 210 mounted in my panel and my iCOM A6 handheld. I get the same affect when I get the iCOM A6 near my computer.

I tried adjusting the squelch but it has no effect. Turning off Skyview does get rid of the static although I don't suppose that is a viable solution.

 

[dynonsupport]

Re: skyview dirty rf ...testing...

Just fyi - this is on our radar and we're looking into it right now. Nothing to report at this point, unfortunately.

 

[schristo]

Re: skyview dirty rf ...testing...

i have ordered some ferrite rings that are specifically built for vhf frequencies from mgl (through acs) to test... they continue to be on backorder but will i report findings when available.

 

[visioninaction]

Re: skyview dirty rf ...testing...

Same here. Brand new Australian Jabiru J230 with 7' Skyview installed has rendered 2 onboard Miroair radios useless as there simple isn't enough squelch adjustment to overcome the rf noise!!

My handheld radio (I thought it may get me out of trouble for a while) is also useless if its within 5 metres of the Skyview (if its turned on).

Lets hope a solution is found very soon.

Cheers

Kelvin

 

[pbennett]

Re: skyview dirty rf ...testing...

Hmmmmm....
My 7" Skyview sits in my RV6 panel with an Apollo GPS/COM and MGL radio. I have no obvious hash problems on the radios. I have a single point ground on the firewall to which every instrument is grounded individually. All cable screens are grounded at one end only. Headphone jacks are isolated from the panel they mount on. All antenna leads are RG400.

I chose Dynon over over MGL because, among other things, MGL haven't got their act together on conducted RF suppression, so they surround their units with ferrites. As far as I am aware, in my installation Skyview doesn't have an interference problem.

I am about to receive a replacement Skyview following a hardware problem. When I get it I'll check to see if I can detect any noise at all from the Skyview.

Peter

 

[dynonsupport]

Re: skyview dirty rf ...testing...

Just a quick update. We performed tests at a fully certified lab that Boeing (we're in the Seattle area) also uses. SkyView meets/exceeds RTCA DO-160F, category H, for aviation COMM, NAV, and GPS bands. Cat H is the hardest to pass, for devices that are in direct view of an antenna. We did our tests with a full SkyView network with long cables, modules, servos, GPS antenna, battery, etc. As some of you have found, the display by itself is "quieter" than a whole network, but the whole network does pass including all accessories and wiring.

Certification requirements do allow some noise output. No electronics are silent, and the standards do have noise limits. This is why you will see squelch level differences when you have a SkyView on vs. off. We're by no means claiming it does not output RF noise at all.

We have also tested a D100, and it also passes by a substantial margin. We have never heard of EMI issues with a D100, so it appears that some customer installations are more sensitive than the FAA requires.

RF interference can be a hard issue to track, and wiring configuration, antenna location, antenna ground-plane, and general dimensions and construction materials of the airplane can make a big difference. Even manufacturers of certified planes struggle with these problems. So we're thinking that some installations are more sensitive than others, which is why not every customer is experiencing issues.

We do a lot of work on EMI, and as proved recently, we do pass the certification requirements for avionics. Even though that is true, we're committed to making SkyView work well for everyone, so we'll continue to work on improvements, including hopefully some hints on wiring practices that may help a lot.

UPDATE: The good news is that we lab-tested and field-tested filters that are simple plug-in devices on the D37 and D9 connections that offer a large amount of noise reduction. It performed in the field as well as it worked in the lab, solving any noise issue, and we should be able to offer it shortly.

 

[mmarien]

Re: skyview dirty rf ...testing...

That is good news. However, it looks like not all systems are affected. It could very well be the method of wiring we used for those that have high levels of noise. Are there any resources that someone could point out that may help us with the wiring if that is the problem.

I have the PS1200, iCOM 210, Garmin GTX 327 and Garmin GPS 495 in my avoinics stack. They have a separate power bus although they are grounded to the same ground bar as the Skyview. The harnesses are all purchased and made by Stein Air, the same people that make the Dynon harnesses. The headphone wires are all grounded shielded and grounded on one end.

That all may be mute as my handheld iCOM A6 has the same noise.

I left all the extra wires on the Dynon harnesses and rolled them up behind the panel for later use. Could this be a source of the problem?

 

[knowlesbg]

Re: skyview dirty rf ...testing...

Interesting reading I had problems with Autopilot errors coming up on a regular basis every time comms where activated. Noise was a problem at times (inconsistant). Problem significantly improved after I replaced old CHT harness that had the unused leads cut short behind panel with new harness that connected all 6 cylinders.

Bruce

 

[mmarien]

Re: skyview dirty rf ...testing...

Thanks for the tip Bruce.

The harness came with leads for four cylinders so I have no extras. I did roll up some excess length and leave it behind the panel.

I may spend the money on a pin remover for the D Sub connectors and remove all the wires that I am not using. It would be easy to put them back if I needed them later.

I'd be interested in hearing from the others that are having trouble.

First, are your harnesses purchased (professionally prepared)?
Second, did you leave all the wires on and open ended?
Third, did you roll up excess wire or cut it to exact length?

Or better yet, anybody that have any of the conditions mentioned above but don't have noise. That would eliminate these methods as causing the problem.

Murray

 

[knowlesbg]

Re: skyview dirty rf ...testing...

My Jabiru j430 was built under the experimental and builder assist rules and in the process I was there more as an observer and helping where I can. I have the D100, D10, AUTOPILOT BOTH AXIS.
The harnesses was Dynon supplied
The unused wires (4) with old harness were cut short and open ended behind panel
also at the same time the EGT cables were cut (6) as I did not have the sensors installed at that time.
In my case with the new harness excess wire was cut to length although I have been told rolling them up for more efficient readings is possible (??)
The improvement with comms was really more by pure chance with the change of Harness. Up until then it was a tedious hair pulling exercise trying to resolve the problem.

bruce

 

[MavSmith]

Re: skyview dirty rf ...testing...

From the testing on my installation - the interference is coming from the EFIS only. Not the EMS/ADAHARS etc(all unplugged). All unused wires have been removed from the EFIS harness. The interference is Radio Frequency and is coming in the antenna and is strong enough to completely swamp otherwise perfectly readable signals. The effect is much worse when running on ships power than when running on the Dynon battery.
I will be doing more testing this weekend including antenna relocation and supply volts variations.

 

[mmarien]

Re: skyview dirty rf ...testing...

Thanks guys.

It looks like that almost eliminates a wiring problem. Lets us know how the antenna relocation works. My antenna is under the pilots seat so it's within a couple of metres of the Skyview.

 

[flybuddy]

Re: skyview dirty rf ...testing...

Look forward to the noise filters. I checked RF and noise readings on my SL40 and the numbers are doubled with the Skyview on. Just completed install and have only one short flight to work out bugs.

 

[dynonsupport]

Re: skyview dirty rf ...testing...

On removing wires from the SkyView harness: So, RF/EMI interference is voodoo magic, so removing/changing the orientation or wires coming out of the harness may help, but we probably wouldn't recommend it as something that we would likely cure the problem. If you're feeling adventurous, we wouldn't discourage you from trying it, but since we do have those filters coming, we'd generically recommend waiting for those to be available.