Issue with Voyager EFIS GPS.

[a.baudry]

I think you're having a misunderstanding and mixing up resources, the knowledge base Michigan Avionics took over was the articles hosted on Matt's website (previous USA distributor/support in California). Yes some of the articles were made from posts on the forum but the articles are still available in Michigan Avionics website support section, for free. I don't think they're keeping anything from the users.

Ok, my apologize for my misunderstanding of Adam O’Connor’s initial post.
Alain

[JimJab]

Hi All,

Back to the GSP issue, so I have pulled my panel out again, lucky it only takes 10-15 minutes to have it out and ready to go home.

Once home, I swapped the EFIS's over so the pilot side is the EFIS without the GPS issue in flight. I then opened up and removed the GPS /Comm's Board out of the EFIS that had the issue, so to have a good look at the board's components etc.

With the panel out of the plane and having two Voyager EFIS's. This has given me the perfect opportunity to compare the GPS signal strengths with one EFIS having ground plane antenna and the other EFIS without. I did said in a previous post, my Voyagers GPS signals had always been rock solid with out having antenna ground planes.

So before I started this bench test, I did swapped the antennas and EFIS around to check that each were reading about the same GPS signal strength on each antennas and each EFISs showed the same. I also tested the distance between the antennas to see how this may affected the GPS signals. This all took some time as it's all about averaging the satellite signal strengths as they do change.

So here are some pic of testing the antennas with and without a ground plane, the pic shows the antennas about the same distance apart as when in my plane, there seems to be no noticeable signal issues at this distance apart.


Well there is an old saying, "“You Don't Know, What You Don't Know”.

Having a plastic plane (Jabiru) I think for me it's worth the effort to make up some ground planes, as it looks like you can get an extra 10-17% GPS signal strength improvement. But, if I was pretty busy, I would leave it and just go flying.

So the next step will be to test if the thickness of the a ground plan material will affect the signal strength. As I would like to use a thin tinfoil or PCB copper sheeting on the inside of the Jabiru instrument panel cavity as the ground plane.

Cheers
JimJab

Sat Signal Without Ground Plane

GPSSignalWIthOutGroundPlanV2.jpg (81.73 KiB) Viewed 29994 times

Testing antennas at the same time with a Ground Plane and one without.

GPSAntennaGPTest.jpg (28.01 KiB) Viewed 29994 times

Sat Signal With Ground Plane

GPSSignalWIthGroundPlanV2.jpg (85.93 KiB) Viewed 29994 times

disclosure; you my notice these picture are not taken simultaneously or at the same time of day for each of the GPS screen shot. Unfortunately the matching simultaneous picture were too blurred to use on the forum. But as I did this ground plane testing over a few hours, the two pic I have posted gives a fair representation of the difference between a ground plain signal strength and not.

[JimJab]

Hi All,

Just to follow up further on my GPS issue.

Firstly, I believe my MGL Voyager EFIS's being ten years old are still worthy of being fixed if you can do so or find someone who can do this for you. My EFIS's have 1000 hours of flight time and I would say another 600 hours being powered up whilst on the ground. So you have to expect with the hostile environment of an airplane with the engine vibration this will take its toll over time.

This post is for general background knowledge, please make sure you have the electronic knowledge and skills if you do something like this or find someone who does. Yep, if you let that magic smoke out, it's near impossible to put it back without lots of money, its much easier that you don't let it out.

So I opened up and removed the GPS /USB Board from the EFIS, in my situation I had the USB power upgrade done so I had some de-soldering to do, before I could get the board out. I had a good look and then a good clean and good look again at the board's components etc.

Voyager GPS USB Board.jpg (55.29 KiB) Viewed 29971 times

After having a good look around with a Electronics mag scope, I found what could be causing the "GSP not Available" and "GPS Available" problem. As you will see in the pic, there is a very small crack that does go around the SMA antenna pin and there is a crack on one of the support/ground pins as well. So I re-soldered all the SMA pins to the PCB board.

GPS SMA Antenna Pin Crack.jpg (98.68 KiB) Viewed 29971 times

As I reinstalled the EFIS and instrument panel, I added some copper foil for a ground plane on the inside top of the instrument panel under where my GPS antennas sit on top, the foil is not currently earthed. This seems to work as I have never had any GSP signals before with the plane in the hanger. But now I can get a GPS fix.

Have I fixed the GPS issue of losing the satellites and getting the "GSP not Available" and "GPS Available " warnings? Well, after an hour of 3 short flights, I am yet to hear bitching Betty or see the GPS lose its fix, so a few more hours could tell the story.


Disclosure The copper foil is self-adhesive and I feel it would do the job for my trials, but this copper sheet adhesive could easily fail with the sun heating up the dash and having a copper sheet falling into the back of your electrics and switches could be an easy way to have a major disaster. I am planning to fiberglass this copper sheet into place after a short time with proof of concept.


Cheers
JimJab

[JimJab]

Hi All,

For those following this post,

Maybe I should re-cap,

I swapped the Pilot GPS Antenna to the Co-Pilot EFIS and the Co-Pilot Antenna to the Pilot EFIS, but the GSP problem remained with Pilot EFIS. So I swapped the Co-Pilot EFIS to the Pilots side and the Pilot EFIS to the passenger side.


I did re-soldered the SMA antenna connector on the pilot EFIS.

I also installed some copper sheeting for a ground plane and this seemed to give a better GPS signal strength for both EFIS's and now I can get a GPS position even when in the hangar.

So now with about 2 hours of flight time without any GPS issues from bitching Betty, it started to look promising.

Well Betty hit with vengeance during the last 15 minutes of our flight today, it was actually painful listening to the number of times "GPS not Available", "GPS Available " warnings being given, even with the engine near idle.

So which EFIS is now causing the GSP problem, well it's the Co-pilot EFIS that came from the passengers side where it did not have any problems. The Pilot EFIS that is now on the passenger side is not having any GPS issues on that side.


Looks like the instrument wiring on the pilot side is causing some type of GPS interference as Rainer did say it could be much earlier in this post.

JimJab

[Diamond]

Hello, I have now the same issue... (and my plane is also fiber composite, europa XS)

I suddenly had gps lost alerts on my iefis explorer, and at the same time, I have now noisy sounds in the trig radio, and I wonder if it's the same origin...

what can say to you, it's that I changed 3 things, BEFORE/AFTER :

I replaced the battery
I uploaded the last firmware
I touched the spark plug wires because I had to work on my cylinder heads...

And I forget to mention that I also tried to move the antena wire in the area of the panel, because of my radio noise.

What about you ?

Emmanuel

[Diamond]

quick update,
I solved my issues doing 2 things:
I tightened a terminal power block in the panel, and placed aluminum foil under the GPS antenna

[JimJab]

quick update,
I solved my issues doing 2 things:

Diamond thanks for your post and what solved your issues with the GPS.

My issue could be something like that as well, I have not seen any loose wires, but I have not been looking for that type of thing.

But it does seem more likely to be something like that with EMF, after I have now found the problem stays on the pilot side even after I swap my two EFIS's from one side to the other.

So thanks for the heads up.

Cheers
JimJab

[bradwalton]

At Matt's suggestion, I bought a new gps antenna and it seems to have solved the problem. $14 from ebay. Advertised as 26 db boost if I recall correctly. But just a simple matchbox size active antenna.

[JimJab]

Thanks Brad,

In my situation when I swapped over my GPS antennas between my EFIS's the GPS warning kept happening" just on the pilot side EFIS, But thanks for adding your solution and fix for the same problem.

Currently my business and work has got in my way over the last 5 weeks, but next week I am hoping to check out my aircraft power bus connections and the aircraft power supply with my oscilloscope, but I can't do this in flight with my scope.

Also I am pretty keen to try and isolate the Pilot side EFIS from the aircraft power supply and run it off the backup battery to see if that stop the GPS warning, once it starts doing this in flight.

I did try an AM radio with ear buds under my headset on my last flight to see if there was any major electrostatic out bursts in flight. I did hear some constant electrical noise on the AM radio, but no major discharges to speak about, not like you would hear on an AM radio with a weather storms and lighting about.

I really don't know how much constant electrical noise on the AM radio is not good, but it was constant and low level so you needed to turn the AM radio volume up a fair bit to hear it. Turning on and off different thing like strobes, radio, Txsp, fuel pump made some changes in the sound and frequency, but during this flight my GPS/EFIS never played up or gave any GPS warnings.

So the hunt continues.

Cheers
JimJab

[JimJab]

Hi All,

I have been very busy with work for quite a few months.

But if you are like me when reading a forum thread looking for answers, you hope if an answer has been founded it will be posted, and not found and the forum forgotten about.

So just an up date on the issue of my Voyager EFIS losing it's satellite fixes, recently this issue reappeared during my last flight and the EFIS lost it's satellite fixes until I landed and restarted the plane.

So this gave me the time in the air to try and run the pilot EFIS on it's back up battery and isolated it from the aircraft power supply, to see if the aircraft power supply may be causing this issue.

After running the EFIS on it's backup battery, it still could not get any satellite fixes. I turned off the pilot EFIS in flight and powered it up on it's back-up battery to see if the EFIS could pick up the satellites again. To my surprise EFIS still could not get any satellite fixes.

After several more minutes of flight with no satellite fix, I landed and closed down the aircraft and thought well that has to be the GPS board failed.

I restarted the EFIS, engine and avionics and ran the aircraft per normal and then the pilot EFIS came alive with a 3D satellite fix in no time flat. I ran the engine at different rpm ranges on the ground and the 3D satellite fix remained solid. I took my plane for another fly and the satellite fixes remained solid for the rest of the time.

After further thoughts about my impromptu back-up battery testing in flight, did I prove anything as my Co-pilot EFIS was still running on the aircraft power and thinking further, both my EFIS's share the same RDAC and both EFIS's can operate off each others back-up battery. So did I really isolated the pilot EFIS from the aircraft power supply, I am thinking maybe not totally.

This really has me stumped, as it's only on the pilot side EFIS and the problem always remains on the pilots side, even if I swap my Voyages EFIS's from one side to the other. I have even swapped the GPS antenna cables from one side to the other without changing the antenna's physical position and the problem remains on the pilot side EFIS.

I am starting to think maybe the aircraft power supply and cable routing to the pilot side EFIS maybe causing some type of dirty power spikes, maybe I should try swapping the D-9 power plug from one EFIS to the other and see if the problem follows the power supply swap. This will need some D-9 extension cables to be made up, as it would be to hard to change the instrument panel wiring.

This problem has been so intermittent in flight, it's hard to know if you have found a cause or not.

Ranier, Please any insight or help with all this.

Cheers
JimJab