GPS intermittent

[201Mooniac]

3 hours ago, Fly Boomer said:

Took a bit just to find the US.  Then I couldn't find cities or states.

You can type a location into the Find box.  It wasn't particularly obvious as it was all just one color with no geographical lines.

[JohnB]

On 8/12/2023 at 1:41 PM, aviatoreb said:

 

Maybe its my antenna?  I guess I need to go to the avionics shop - in Burlington - but I already know what is going to happen - this is intermittent and it will work for them and they will tell me nothing is wrong.  :-?

You wouldn't happen to be using any portable GPS in your airplane would you? I had the exact same issue with using a Stratus which inhibited and intermittently completely eliminated my signal from my panel mounted GPS system a few years back that I discovered AFTER a few $ trips to the avionics shop where they found nothing wrong. 

[Ragsf15e]

19 hours ago, JohnB said:

You wouldn't happen to be using any portable GPS in your airplane would you? I had the exact same issue with using a Stratus which inhibited and intermittently completely eliminated my signal from my panel mounted GPS system a few years back that I discovered AFTER a few $ trips to the avionics shop where they found nothing wrong. 

I thought someone else mentioned a cigarette Lighter usb power port causing interference too… are you using one of those?

[aviatoreb]

21 hours ago, JohnB said:

You wouldn't happen to be using any portable GPS in your airplane would you? I had the exact same issue with using a Stratus which inhibited and intermittently completely eliminated my signal from my panel mounted GPS system a few years back that I discovered AFTER a few $ trips to the avionics shop where they found nothing wrong. 

OMG - yes I am - but why would it be intermittent?  And why would it start now after years of working fine?

 

[Ragsf15e]

2 hours ago, aviatoreb said:

OMG - yes I am - but why would it be intermittent?  And why would it start now after years of working fine?

 

Could the power supply be going wonky?  I might just try everything without anything in the aux port or portable powered up , including phones for good measure…

[aviatoreb]

1 minute ago, Ragsf15e said:

Could the power supply be going wonky?  I might just try everything without anything in the aux port or portable powered up , including phones for good measure…

I wouldn't rule anything out....

but other than two weeks ago where it was failing in the same locality near home base during 4 flights in one week - it has worked flawlessly since - going to Maine - and now to Annapolis MD..which I am glad for that since it is complicated airspace here.

I did make an appointment to avionics for Wednesday in Burlington - to inspect my GPS and also do my ifr cert so I am going anyway and I will see what they say so thank you for all the ideas.

I am intrigued with your suggestion - power source - and the other one - handheld gps.

But I am guessing it was rogue gps blocking.

[81X]

On 8/20/2023 at 10:33 PM, JohnB said:

You wouldn't happen to be using any portable GPS in your airplane would you? I had the exact same issue with using a Stratus which inhibited and intermittently completely eliminated my signal from my panel mounted GPS system a few years back that I discovered AFTER a few $ trips to the avionics shop where they found nothing wrong. 

when I was on a flight review a couple years ago, my GTN750 was intermittent and gave me LOI a couple of times which was odd.  Turns out the instructor had a SPOT running in his backpack in the back seat which is right under the GPS antenna.  
 

So, don’t rule out interference by things like this and other portables.   

[JohnB]

On 8/21/2023 at 4:45 PM, aviatoreb said:

OMG - yes I am - but why would it be intermittent?  And why would it start now after years of working fine?

 

My issue was exactly my Stratus reducing then sometimes completely eliminating the satellite reception bars on my GNS 430. Happened to me first on a on a long flight when my GPS read "no gps signal, dead reckoning" and did not come back. Spent a few trips and over a few thousand at avionics shops with no repair of this intermittent problem. I decided to turn off my stratus and it never happened again. I called garmin and Sportys and they said that was not possible for a stratus to interfere with an onboard system. I tested it and got a great video of when I plugged in my stratus antenna, my 430 bars satellite reception dropped dramatically, some to 0. When I disconnected the stratus antenna, the bars came back up to normal. 

 

I posted a video here a long time ago, which I sent to Sporty's and Garmin, and they then realized this could happen. Ill try to see if I can find the video and re post it here,

[JohnB]

Ok I was able to find the video of a Stratus II unit with Stratus antenna dramatically and nearly completely eliminating the satellite signal received by my on board GNS 430W unit. Before I posted this, both Garmin and Sporty's said this type of interference was NOT possible, which is unequivocally incorrect as the attached video shows.

Unable to attach video, once I figure out how I did it last time, ill repost. 

 

 

[aviatoreb]

4 hours ago, JohnB said:

Ok I was able to find the video of a Stratus II unit with Stratus antenna dramatically and nearly completely eliminating the satellite signal received by my on board GNS 430W unit. Before I posted this, both Garmin and Sporty's said this type of interference was NOT possible, which is unequivocally incorrect as the attached video shows.

Unable to attach video, once I figure out how I did it last time, ill repost. 

 

 

I would very much like to see that.

WOW. That's not what you want.

What was the outcome what did you do about it?

[JohnB]

2 hours ago, aviatoreb said:

I would very much like to see that.

WOW. That's not what you want.

What was the outcome what did you do about it?

Sure happy to share video. Does anyone on the board here know how I can post a video here? Otherwise may just have to send it to you via email if you’re interested. 
 

After I sent the video , Sportys sent me a replacement stratus antenna and the interference went away. Theory was faulty shielding on the original stratus antenna.

[Fly Boomer]

15 minutes ago, JohnB said:

Does anyone on the board here know how I can post a video here?

Some push videos up to YouTube, and then post a link.

[JohnB]

That worked! Thanks @Fly Boomer . @aviatoreb  Here is the video of Stratus II with its antenna inhibiting GPS satellite signal to Garmin GNS 430W panel mounted unit.

 

Stratus II inhibiting GPS satellite signal to GNS 430W

[aviatoreb]

6 hours ago, JohnB said:

That worked! Thanks @Fly Boomer . @aviatoreb  Here is the video of Stratus II with its antenna inhibiting GPS satellite signal to Garmin GNS 430W panel mounted unit.

 

Stratus II inhibiting GPS satellite signal to GNS 430W

WOW - super interesting!

The avionics shop I talked to did mention to ask if I had dropped my cell phone - they said that shielding could become ajar.  To be sure to try and test with the phone off - all the way off not just in airplane mode - this wasn't my problem.  

Actually I had made an appointment to get it looked at this Wednesday and to do IFR cert at the same time -' since I had done pretty much almost 20 hours since any issue which was all in one location and all in one week I didn't bother to have them look at the gps.   I decided it was a jamming issue.  As they said - could even be a rogue trucker with a gps jammer trying to Catcha nap.

[amillet]

On 8/18/2023 at 1:17 PM, PT20J said:

Here's an interesting site that has historical maps showing areas where ADS-B out from aircraft reported degraded GPS navigation accuracy.

www.gpsjam.org.

How do you tell where on earth it depicts?
When I open it there are no land masses showing 

[PT20J]

30 minutes ago, amillet said:

How do you tell where on earth it depicts?
When I open it there are no land masses showing 

Hmmm. I get a globe that I can rotate and zoom in on. The GPS status overlay is green, yellow, red and transparent so I can see the political boundaries and city names as I zoom in,

[amillet]

I opened it on my PC and could see the political boundaries, on the iPad just a big white globe with the color coding
 

[EricJ]

11 hours ago, JohnB said:

That worked! Thanks @Fly Boomer . @aviatoreb  Here is the video of Stratus II with its antenna inhibiting GPS satellite signal to Garmin GNS 430W panel mounted unit.

 

Stratus II inhibiting GPS satellite signal to GNS 430W

Is the antenna you're plugging the Stratus into near the 430's GPS antenna?    One thing that can cause this is if the Stratus has a wonky receiver that is leaking a lot of oscillator energy out the receive antenna.   If both GPS receivers (the Stratus and the 430) use similar receiver architectures the oscillators can interfere with each other, or if it is a direct conversion system (more common these days) the oscillator can interfere directly with the GPS signals received by the 430.

So it could be either a leaky oscillator (which used to be pretty common, less so these days), or just failing shielding that's letting energy out in a similar fashion.

Either way, glad you got it sorted out.

 

[Fly Boomer]

12 hours ago, JohnB said:

That worked! Thanks @Fly Boomer . @aviatoreb  Here is the video of Stratus II with its antenna inhibiting GPS satellite signal to Garmin GNS 430W panel mounted unit.

 

Stratus II inhibiting GPS satellite signal to GNS 430W

Great video and great sleuthing.  Simple once you figure it out, but the process of figuring it out can be a bear.

[JohnB]

On 8/26/2023 at 8:26 AM, EricJ said:

Is the antenna you're plugging the Stratus into near the 430's GPS antenna?    One thing that can cause this is if the Stratus has a wonky receiver that is leaking a lot of oscillator energy out the receive antenna.   If both GPS receivers (the Stratus and the 430) use similar receiver architectures the oscillators can interfere with each other, or if it is a direct conversion system (more common these days) the oscillator can interfere directly with the GPS signals received by the 430.

So it could be either a leaky oscillator (which used to be pretty common, less so these days), or just failing shielding that's letting energy out in a similar fashion.

Either way, glad you got it sorted out.

 

Gps antenna is in the middle of my airplane, the stratus antenna was in the back of the airplane so it wasn’t positioning, but it was thought to be faulty shielding on the stratus antenna which caused the interference, as they sent me a new antenna and no interference.