Lost NAVSRC worse after upgrade to 5.4

[JR]

D180 + Garmin 296
I had lost NAVSRC problem since AP roll servo installed ~100hrs ago, not very often maybe once every hour or so of flight
Recently added pitch servo and upgraded to 5.4 and problem is now much more of a problem. Every 10-15 minutes now
Using NAV mode isnt a reliable option now
When will this problem be addressed?

 

[jakej]

JR

I've also seen this problem, seems to be the 296 that's at fault. Do you have the latest software in it ?

Jake J

 

[JR]

Yes I have upgraded to ver 6.0 in the 296, also turned off all extra output data, tried 4800, 9600, auto etcetc
It seems to be a problem which gets worse the longer you fly
This problem has been a complaint for a long time, and a few software upgrades have been done over this time, when will a fix be presented?

 

[dynonsupport]

We've tried the last few software updates to "cure" this behavior, but have so far been unsuccessful. We don't currently have an active D10/D100 series software release in-progress, but it will be the the top bug we'll be looking to kill when we do one.

 

[JR]

This problem has been there and complained about for 2 YEARS now yet still Dynon claim their AP system is Garmin compatible.

At this stage my AP cannot be used in NAV mode so whats the solution - send the equipment back and buy something else that actually delivers on promise?

 

[dynonsupport]

Hi JR,

So I had to do a little bit more research to fine out the full current state of this particular issue.

So first, that there is an active research project going on to figure out the best way to deal with the dropouts effectively. I'm sorry to report that I don't have a date to give you on a software fix that would be related to this, but do know that we are working on it.

For a bit more background - this has been a challenging problem to solve. At the root, we are pretty sure that some GPSes simply stop sending valid data - sometimes for extended periods. We have "timeouts" to deal with this. In other words, the system will allow momentary lapses of data. But if that goes on for too long, now you don't have a data source to follow anymore. The permanent dropdown to heading mode isn't ideal, and we're looking for a more graceful solution here.

I know this is a frustrating one, but do know that we're continuing to work on solving it.

 

[JR]

Can you identify if it particular units, particular models or say all Garmin units which give the problem?

 

[Brantel]

This problem is not limited to Garmin units. Others have reported the same issue on other brands of GPS's using NMEA.

 

[JR]

If the D180 + AP doesnt work in NAV mode from NMEA, (which it doesnt) it should be indicated to new customers on the website at the least and those who have invested in the equipment have it replaced with equipment which works.
Your efforts are noted but 2 years + is too slow

 

[rich1]

I just installed a roll servo with my EFIS D10A, EMS D10, Garmin 396 and 5.4.3 software. About 10 min. after I activate the AP I get NAV SOURCE LOST. I can reconnect with the GPS by going back and selecting the NAV MODE button and it stays locked on for the rest of the 30 min. flight. This happens every time I use the AP.
  I tried changing the NMEA 4800 to 9600 baud with no change.
I hope Dynon gets this bug fixed. 

 

[dynonsupport]

We are actively working on this problem as we speak.

Because the problem is difficult to reproduce, we would like to get data from anyone who has the problem on a regular basis.

What's necessary is to tap the TX wire from the GPS to the EFIS.
Bring the TX wire to pin 2 on a female D9, and bring signal ground out to pin5.

If you are using the programming port on your system as the GPS input, a Y-harness can be inserted between the GPS and the EFIS.

The D9 can then be connected to a serial port on a laptop and the data recorded.  The laptop you use to upgrade your system will work fine.

A terminal program such as TeraTerm can be used to log the data; be sure to set it to the baud rate you use for your GPS.

Note the time you saw NAVSRC LOST and send us the data log and we'll do the rest.

 

[dynonsupport]

We have an update on this issue, and a solution for you to try out:

To recap, some customers have been experiencing momentary GPS data dropouts from 3rd party GPS devices that can feed a D10/D100 series-based autopilot. When this happens, and the autopilot is following the GPS through either the NAV or TRK modes, the autopilot decides that the GPS has gone away. This, in turn causes the autopilot to revert to heading mode. Some customers experience this routinely, as often as every few minutes.

We've had a hard time characterizing the exact nature of the problem, and getting a smoking gun of the problem happening in action is pretty difficult for affected customers to do. So, while we aren't 100% sure that this attempted fix will work, we're fairly confident in it.

Below is a "beta" version of D10/D100 series firmware that is exactly the same as 5.4.3, except for that it includes an attempt to fix the above undesirable behavior. It has no new features, and it does not fix any other problems. This software is not considered an official release. Though it is considered stable, it has not received the full set of release testing that would normally be performed on a firmware release.

PLEASE tell us if this firmware fixes the dropout issue for you. We'd love to get both positive and negative confirmations from everyone that installs it. A post here or an email to support at dynonavionics dot com are the best ways to let us know how it works for you.

[old file removed]

 

[chasn]

I have also had the loss of NAV problem (D10, AP74, Garmin 695) but it drops out to TRK mode which infers that it is still receiving at least part of the GPS signal. I will try the suggested beta firmware to see if it solves or reduces the problem. Typically at the moment I get dropouts of variable frequency but in the order of 10/hr.

 

[chasn]

I have tried the 5.5 beta firmware and still get the same frequency of NAV dropouts. Typically it is about 10 dropouts/hr. They seem to come in groups of 2 or 3 at a time, typically 30sec to 2 minutes between dropouts followed by 15 to 20 minutes before the next dropout. Each dropout results in TRK rather than HDG and is resettable immediately after dropout having acknowledged the failure. As the dropouts result in TRK rather than HDG, GPS info must be still available to the autopilot.

 

[juhee]

Same experience as described by Nigel above. How can I tell which model servos I have 32 vs 42 vs 52.....If I have a 32 or 42, other than settings and config settings, can I simply plug and play/replace with 52 or will mounting have to be modified due to size or ?????

Please respond Dynon tech support!

 

[dynonsupport]

So the above issue with the NAV mode falling down to HDG mode has nothing to to with the servos. It has to do with the data coming from the GPS.

If you mean your questino in the general sense - in other words - if you're seeing a lot of servo slips, can you simply replace the servos, the answer to that is basically yes. But the motor on the SV52 is longer than the motor on the SV42, whose motor is bigger than the motor on the SV32. So yes, you would also need to make sure that your aircraft can accomodate the increased size.. See the installation documentation for specific dimensions.

There isn't any way to determine which servo you have without looking at it physically.

 

[JR]

Any progress on this?
There are still customers flying with AP system which dont work correctly - having to reset source every 5 min
I see Garmin units are still listed as compatable with your AP system too

 

[mmarien]

I just returned from a 40 hour xcountry trip and was using Skyview AP mostly connected to my GPS495. I had a couple of random mode changes. It's announced via the SV voice warnings. When I checked, the AP had changed from NAV to TRK. I didn't notice any when I was using GPS0 (SV-GPS-250) as the source but then I wasn't really paying attention other than I thought of this thread when it did it a couple more times.

The GPS495 tends to do that. Before AP I noticed once in a while I will get terrain warnings from the GPS495 even though I was more than 1000' AGL. In the hanger the other day I was reading zero satellites on the GPS495 but the SV-GPS-250 was receiving eight. The antennas are side by side.

IMHO the GPS495 is a nice navigation device but not always reliable.

 

[Brantel]

For the long term NAV source lost issue:

Let me be clear. I do not think the issue is with the Garmin GPS's or the Garmin NMEA data stream. I personally think the issue is in Dynon's code.

Reasons I think this:

•No other user of Garmin's NMEA data stream have reported an issue.
•People with other brands of GPS's have reported the same issue.
•I have spend hours and hours logging NMEA data from my Garmin GPS's and have never found an error in the data stream

 

[JR]

Does the issue occur with Skyview and Garmin x96?
If not then replace the faulty units with these.
You would have happy customers instead of the ones now who feel more than a little cheated
In one thread, Dynon support discussed releasing Beta 5.5 as it solves the problems!!!!
Doesnt seem like this is receiving much effort