Stratus external GPS antenna satellite interference follow-up.

[cnoe]

Back in 2014 @JohnB started an excellent post regarding interference issues caused by a failing (external) GPS antenna on his Stratus ADS-B receiver. Specifically a failing external (active) GPS antenna can suddenly cause your CERTIFIED GPS devices to lose satellite reception. The problem can be intermittent or last for considerable periods of time. Experiencing such a failure while on a direct-to route in IMC can be a real nuisance requiring notification to ATC and conversion to alternate methods of navigation.

This issue has since been explored more fully (on MS, BT, and elsewhere) and the quick fix while enroute is to simply unplug the external antenna which should restore your panel GPS' functionality. This may or may not be a simple thing to do if your unit isn't readily available in the cockpit (under a seat or on a hat-rack). The folks at Appareo (the maker of Stratus units) have now admitted the existence of the issue and it is noted in their User Manual which states... "WARNING: Avoid pinching or bending the external GPS cable, especially near the antenna. This could damage the cable and cause interference between the antenna and other on-board GPS receivers. The cable’s minimum bend radius is 1 inch."

As an avid user of the Stratus units I prefer to place it beneath the pilot seat (out of the sun and out of the way) and I employ both external ADS-B and GPS antennas which provide outstanding reception/coverage. Then I too experienced unexplained simultaneous GPS outages in my certified Garmin navigation equipment (as well as every other GPS receiver in the plane including the iPad and iPhone). At the time I was unaware of the issue described. Thanks to Mr. B and others I was able to discover the issue with some online sleuthing prior to spending large sums of money at the A&P/Avionics shops.

So, when I decided to replace my existing (failing) antenna I wanted to look for an alternate, perhaps more robust antenna and began looking at options. As it turns out there are several antenna manufacturers out there with comparable products. The connector is a standard MCX version and I'd always been unhappy with the routing of the stock Stratus (actually AntennaFactor/LinxTechnologies) antenna which employed a straight-out cable. So after some studying and perusing I came to believe that the Garmin GA-25MCX antenna would be a suitable replacement (at half the cost for you CB'ers), and to make matters even better the connector employs a 90 degree fitting which permits much better cable routing in my case. So I bought one to try and am making this post to confirm that it works just fine so far. I've yet to complete in-flight testing with it but in ground testing I found it to pick up a full compliment of satellites without issue (see photo).

Let me end by stating that I will monitor it for interference issues and if any arise I will report them here, but it is my understanding that the issue only occurs when the antenna is experiencing a failure of some sort, which mine was. I hope this helps somebody, as Mr. B's post helped me.

[JohnB]

8 hours ago, cnoe said:

Back in 2014 @JohnB started an excellent post regarding interference issues caused by a failing (external) GPS antenna on his Stratus ADS-B receiver. Specifically a failing external (active) GPS antenna can suddenly cause your CERTIFIED GPS devices to lose satellite reception. The problem can be intermittent or last for considerable periods of time. Experiencing such a failure while on a direct-to route in IMC can be a real nuisance requiring notification to ATC and conversion to alternate methods of navigation.

This issue has since been explored more fully (on MS, BT, and elsewhere) and the quick fix while enroute is to simply unplug the external antenna which should restore your panel GPS' functionality. This may or may not be a simple thing to do if your unit isn't readily available in the cockpit (under a seat or on a hat-rack). The folks at Appareo (the maker of Stratus units) have now admitted the existence of the issue and it is noted in their User Manual which states... "WARNING: Avoid pinching or bending the external GPS cable, especially near the antenna. This could damage the cable and cause interference between the antenna and other on-board GPS receivers. The cable’s minimum bend radius is 1 inch."

 

That is great that they are finally admitting that the stratus antenna/cable can disable on board gps! Even after I showed them my video, they still discounted it being a significant problem and sent me a new antenna. Interesting, so it sounds like the insulation on the cable to the antenna if its damaged, it can disable your onboard GPS as with mine, the actual antenna was located in my back window. Interesting. Glad you liked my video. Thanks for the followup!

 

[M20S Driver]

My Stratus causes interference with both Com radio and GPS and it is worse with optional ADS-b antenna.  They advised me to keep it away from the radio stack and it worked fine if I put it on the rear seat.  

It is funny that they were skeptical at first and were not receptive to discuss any issues caused by their design.  I am done with their products  

[LANCECASPER]

I wanted to make the switch from Garmin Pilot to Foreflight. I had a Stratus 2S for about a week and was really disappointed in the quality (and this was an improvement over the 2).  I found out that the Garmin GDL39-3D could be used with Foreflight and thankfully hadn't sold mine yet. I sold the Stratus and never looked back. I have a GDL-52 now and really like it.

[JohnB]

I looked at my original post in 2014 and I'm not sure I posted the video of this that I shared with Garmin and Sporty's as I didn't see it. But here it is for anyone who is interested. The replacement antenna they sent did not have this problem. So just a note if you're having bizarre onboard GPS failures and have a stratus GPS antenna, you may want to look at this as a potential cause.

 

[MIm20c]

@cnoe did you use the stratus external antenna or wire it up to an old dme antenna?  I’m trying to find the proper connections to make my own cable. 

[cnoe]

On 10/11/2018 at 2:06 PM, MIm20c said:

@cnoe did you use the stratus external antenna or wire it up to an old dme antenna?  I’m trying to find the proper connections to make my own cable. 

My issue was with the external "GPS" antenna, not the ADS-B antenna. I replaced the Stratus (GPS) antenna with Garmin's GA-25MCX and haven't had any problems since. Sorry I can't give you any help with your project.

 

[Yetti]

That's crazy amount of local oscillator noise that the Stratus is putting out.  I guess they know what happened to MH370 now.    For the GPS on the Stratux  I have a USB Ublox on 3 foot usb extension cable that hangs over the rear seat with the Stratux on the rear hat rack.  No GPS interference.  I could see where a Raspberry PI could generate enough stray RF to mess with a GPS signal, but not so far.

[flying maniac]

how did you make the connection to the raspberry usb port ?