AP losing NAV source

[RVN128CE]

Hello.
Finally got some time to look at this more. Set the EFIS & EMS to record data @3 seconds, cleared old data, set Garmin to autopilot mode, sends data every second (gprmc,gprmb,gpbwc,gpbxte,gpapb with*). Went flying, after about 10.min. Nav source lost alarm... Excel chart shows the gps "went nite nite"for at least 3 seconds (1 EFIS scan) shows up when I chart gps grnd spd,valid date,zulu date ect.
The fix, allow a tad more tolerance from the nav source.???

Regards.
Frank

 

[flyingforfun2004]

Hi Guys

I too have seen this a few times then i got wondering (i use a 296 by the way) Is it happening when the GPS is giving a message such as approaching waypoint etc. it may have been a coincidence but I noticed it happen at the same time as airspace warning message.

Regards
Kev

 

[flyingforfun2004]

I had the AP on in track mode today and it lost the signal about 9 times in one hour.


reagrds

Kev

 

[lluciani]

I think it might be related to turbulence. A few days ago I went up high where it was smooth and there were no problems. When I came back down where it was fairly rough lost NAV track every few minutes.

 

[bule]

Although the Dynon docs say to set the 496 serial connection should be set at NMEA9600, it does not work on my recently installed HS34/AP74/D100. However, if you configure the HSI serial connection to 4800 for the 496, it seems to work (does not say "searching for satellite signal" all of the time). After reading some of the previous email on this topic, i need to check the 496 configuration itself on the advanced menu. When i select a destination, the 496 captures and the D100 CDI gives me correct distance info but, always shows course (initially) at 360 degrees. It seems that once i start to taxi, it eventually comes around to the correct course reading.
O also have a 250XL that i tried to connect via the 429 bus and it did not work. I ended up using serial connection 1 for the 250XL and serial 2 for the 496. I had Stein Air build the harness for my configuration and all seems to work as prescribed other than the baud rate issue on the 496. Any insight on "like" experience/fix would be appreciated.

 

[bule]

Baud rate resolved by going in to the 496 set up and selecting "TIS in/NMEA & VHF out". Course still showing 360 initially regardless of (initial) destination selected on GPS. Thank you!

 

[Brantel]

Baud rate resolved by going in to the 496 set up and selecting "TIS in/NMEA & VHF out". Course still showing 360 initially regardless of (initial) destination selected on GPS. Thank you!

Change the advanced setting to normal instead of fast and this issue will go away.....

 

[dynonsupport]

Is it the CDI course or the ground track bug that's initially 360? The former should be correct from the moment it's programmed, while the latter may take some movement to initialize.

 

[bule]

When GPS1 is selected through the HS34, the 250XL (serial 1) provides the proper course, speed (0), and distance to destination selected. However, the "track" indication always reads 360 initially.
When GPS2 is selected through the HS34, the 496 (serial 2) provides proper speed (0) and distance to destination selected only. Course and track BOTH indicate 360 on the D100 HSI display. I tried it several times today with the same result. My next planned cross country trip is to Oshkosh so, I would appreciate any suggestions that you may have.
Thank you.

 

[bule]

All course and track issues resolved by selecting "Aviation in/NMEA & VHF out" on the 496 and selecting "normal" on the Advanced NMEA Output Set Up Menu. Serial 2 selected to NMEA 9600. This forum has been a great help. Many thanks!

 

[RVN128CE]

I Think the "Nav source lost" is the fault of some Garmin GPS's.
after charting tons of my Dynon data all I can find is the GPS sending strings of zeros (0's) that coincide with the AP dropout.
A few days ago I find this on the garmin web site----"Change History
Changes made from version 3.90 to 4.00:
[ch9702]Fixed several errors in NMEA statements introduced in 3.90.
[ch9702]Fixed WAAS information not showing 'D' in satellite bars. Error was introduced in 3.90."
[ch9702]Other minor bug fixes.
So I update. Go for a 1.9 fly. AP worked great. Its a bit premature to call it fixed but my hopes are high.
Are any Folks out there using a "nonG" brand GPS having this problem?

 

[rvator51]

What garmin gps are you using? I am using a garmin 496 handheld using the latest 4.10 firmware, but there is no mention in the release notes of the fixes you mentioned.

I did notice that the firmware for the Garmin 296 and 396 handhelds was no longer in the updates. Dont know if they just moved them to a different area or deleted them from the archives.
Regards,
Tom Velvick

 

[jakej]

Wouldn't surprise me if Garmin is discontinuing the 296/396

Jake J

 

[Brantel]

People using several other brands have reported the AP "Nav" dropout....

The 296/396 have been discontinued per Garmin...