1090MHz Filter for ADSB 472 Issues?

[Garrett]

I think TurboPilot came across the root of problem.(Period) Dynon can work out the details now. There is nothing wrong with filtering out unneeded frequency's and it is logical that the other ADS-B products on Amazon offer the filter or have it built in.

 

[krw5927]

Since they can't fix the problem, Dynon needs to enable industry standard GDL90 receive capability over RS232 on the Skyviews, so we can use another known working ADSB receiver.

Their wholly-owned subsidiary Advanced Flight Systems already does this.

 

[GalinHdz]

Since they can't fix the problem, Dynon needs to enable industry standard GDL90 receive capability over RS232 on the Skyviews, so we can use another known working ADSB receiver.

Their wholly-owned subsidiary Advanced Flight Systems already does this.

Or "partner" with Seattle Avionics and receive ADS-B IN data via WIFI from the MERLIN receiver.

 

[Dynon]

A few comments: A filter like the one that TurboPilot installed does seem to help with some of the issues that people have experienced, especially around weather reception, but it may not improve the issues around traffic that some of you have reported (although it may for others). Driving this to root cause has been a bit like peeling an onion, where each layer reveals that there's more to peel back. We're hesitant to get into the nitty gritty details, because (1) it's very technical and (2) we're working with external partners on engineering a solution.

There have been multiple times that we thought we were close to "the solution", and then ran into a new issue that forced us to peel back another layer. That said, we're definitely looking into other ways, including some of the suggestions in this thread, as additional mitigations.

 

[turbopilot]

A few comments: A filter like the one that TurboPilot installed does seem to help with some of the issues that people have experienced, especially around weather reception, but it may not improve the issues around traffic that some of you have reported (although it may for others).

I have made a few more flights and an extended period of watching the screen with the aircraft in the hangar.

"Hangar flying" the aircraft there is absolutely no doubt the 472 with the filter is working better than the 472 without the filter. The 472 with the filter has better reception than my old 470 in the same situation for weather and traffic.

I continue to fly the aircraft with the Scout playing through ForeFlight on an iPhone X. Comparing the 472 to the Scout may be a low bar for comparison but it is a benchmark. Since beginning these tests I have not seen a situation where I was getting less performance from the 472 compared to the Scout. The majority of the time the 472 acquires weather and traffic faster than the Scout.

Of interest, there appears to be a bug with the iPhone X running Foreflight and the Scout. Periodically all traffic disappears with the Scout still connected. Killing the ForeFlight app then restarting it restores the traffic immediately.

So bottom line, so far applying the filter has not impacted any functionality and has definitely improved performance in my aircraft.

 

[dlloyd]

With the 470 receiver I have always experienced traffic dropping off and reappearing.  I thought that was just the nature of things until people began similar complaints with the 472 receiver. I asked Dynon a couple times but was told no one had complained about the 470.  A few posts back someone mentioned a cell phone.  I always forget to turn mine off.  Antenna is with 3' of my pocket with the phone. Today I flew a short trip with my phone off.  Any displayed traffic was steady, I never saw any unexpected drop.  Correlation?

 

[jakej]

dlloyd,

From my experience it is most likely related. I know my cell phone affects my autopilot (other brand) & the type of USB charger has an impact too.
Why not ry turning your phone off for a few flights & note the difference in systems performance, if any ?

 

[rleffler]

I'm curious about the cell phone interference. For those experiencing issues, how far away is your phone from your 472 and antenna?

I flew for the first time this weekend with a 472 and experienced similar issues and I had my cell phone on. Both my 472 and antenna are about 8' away from the phone.

 

[turbopilot]

I'm curious about the cell phone interference.  For those experiencing issues, how far away is your phone from your 472 and antenna?

I flew for the first time this weekend with a 472 and experienced similar issues and I had my cell phone on.  Both my 472 and antenna are about 8' away from the phone.

Cell phone interference sounds like a reasonable issue, so I did a little experiment. Dialed an ASOS on my iPhone X and placed the iPhone directly on top of my Stratus 2 which was actively connected to an ADSB station and left it there a few minutes. Result - no impact. Stratus continued to receive weather and local traffic.

 

[swatson999]

I'm curious about the cell phone interference.  For those experiencing issues, how far away is your phone from your 472 and antenna?

I flew for the first time this weekend with a 472 and experienced similar issues and I had my cell phone on.  Both my 472 and antenna are about 8' away from the phone.

Cell phone interference sounds like a reasonable issue, so I did a little experiment. Dialed an ASOS on my iPhone X and placed the iPhone directly on top of my Stratus 2 which was actively connected to an ADSB station and left it there a few minutes. Result - no impact. Stratus continued to receive weather and local traffic.

I'm not sure what that proved about anything other than THAT Stratus and THAT phone. It certainly didn't prove anything about the 472 under discussion here...?

 

[alexe]

Just another data point.....
I’m a ADSB 472 customer that has always flown with their cell phone on in the cockpit. Today, I took a ride with the cell phone turned off to see if it made a difference. It did NOT. I encountered the same frequent dropouts as before.
Alex

 

[turbopilot]

Interesting feature in ForeFlight with the Scout. You can turn on ADSB ground stations for display and monitor signal strength from the station.

Continue to fly with the filter. Traffic target performance much better.

 

[NASA515]

Can you filter the output to get rid of the UAL at FL300?

Bob Bogash

 

[turbopilot]

Can you filter the output to get rid of the UAL at FL300?

Bob Bogash

Yes, under "Settings/Traffic" you can "Hide Distant Traffic"

As I fly the Scout against the 472 I like to watch all the traffic and see how the 472 acquires new traffic just coming into range while painted by the Scout outside the 472 window. So far the Scout and 472 seem to be seeing the same traffic at the edge of the 472 cut off parameters.

 

[dwightsmall]

I have now completed 3 flights totaling about 2 1/2 hours using the band-pass filter. I have the -472 dual band receiver. I am experiencing fewer problems, i.e., dropped traffic, but it still happens. Today my display was showing, "ADSB NO RADAR" but was showing 3 targets with N-numbers. Suddenly the display went to "TIS OK" and all 3 targets simultaneously disappeared. After about 30-45 seconds the Skyview went to "ADSB OK" and all targets immediately re-appeared. Later I was following another airplane known to have 1090 out with a dual band receiver and his target disappeared for a few seconds and that happened two or three times. I was 8 miles behind this airplane and should have been displaying him directly on the 1090 airplane-to-airplane 1090 frequency. That airplane showed my target solidly with no interruptions.

 

[GalinHdz]

I just installed the filter in my airplane and will see how it performs in tomorrows IFR flight to Tampa, FL.

 

[jmurtagh13]

I also ordered the filter, installed it today and did some flying.  In a nut shell it was not as good as the direct connection, I had more drop outs with the Dynon 472 and the filter and they lasted much longer. 

I did the testing at 3500' MSL north of ATL.  I used a Garmin GLD39 and Garmin Pilot as a reference.  My ADSB antenna is located on the belly behind the luggage area.  The transponder is also located on the belly front right corner right behind the firewall.

Even though I have dropouts without the filter, they are few and generally re-display quickly, so not as bad as others have reported.

 

[GalinHdz]

Flew with mine on a 1.5hr flight today and at least to me it seems I had less drop outs than before. But again my Stratux on FltPlanGo display was much more stable with no drop outs. I will do it again next week for comparison.

https://flightaware.com/live/flight/N819PR/history/20180126/1700Z/KSGJ/KMCF

 

[jmurtagh13]

Attached is my diagnostic file David DeLong requested of my flight using the FlightAware Filter. The filter was installed starting at 14:30 EST.

 

[rleffler]

My data from a statistical perspective isn't significant.

Two flights with just the 472 showed erratic behavior and dropouts in a metro area with multiple towers in the vicinity.

Two flights with the filter, erratic behavior gone and no drop outs noticed.

Granted this isn't enough to declare any victory, but it does appear to help. AFS logs from all flights sent to Dynon.