APRS position bouncing

I observed an interesting symptom of my APRS installation where it shows position reports all over the place quite a distance away from where we were in reality. It creates a very ugly track on the map. I had seen this before but never thought a whole lot of it until the latest flight:

http://aprs.fi/?call=N4822C&mt=m&z=11&timerange=10800

After thinking about it more, I can directly correlate the bad positions to time periods of moderate turbulence. This flight for example was in very smooth air to the east of Georgetown. However, later, to the west of Georgetown out at Lampassas it was very bumpy. I'm going to go out and see if I can secure the GPS connector better with a glob of RTV or something.

My GPS plug is well secured and I have seen the same thing. Looking at the raw data I saw bad data sent. I am going to check the box in setup called 'only send valid' to see if it helps...

Thanks for the validation. I'm not as certain of the security of my gps plug so I'm interested to hear of your experience so I don't get my hopes up. I am going to set "only send valid" too.

GPS Bounce

May I ask you gentlemen what GPS receiver you are using?

Allen
VHS

I am using a Byonics GPS2...

I'm using Byonics GPS1. I went out and made sure the gps connection would be perfectly solid and re-programmed to add "only send valid", as well as removing wide1-1 from the config. We'll see how it works out in future turbulent flights.

I've seen this too Scott, I use a Garmin Etrex GPS. I'm fairly certain it's not a GPS connection issue. In fact, after landing, I had some packets show up from much earlier in my route which didn't seem to understand that they were supposed to travel at the speed of light (I think they were only doing about 45 knots )! I don't know if they got trapped in an I-Gate somewhere and were released some time later (software glitch?) but it was weird and really hosed up my track.

Noah said:

I've seen this too Scott, I use a Garmin Etrex GPS. I'm fairly certain it's not a GPS connection issue. In fact, after landing, I had some packets show up from much earlier in my route which didn't seem to understand that they were supposed to travel at the speed of light (I think they were only doing about 45 knots )! I don't know if they got trapped in an I-Gate somewhere and were released some time later (software glitch?) but it was weird and really hosed up my track.

Click to expand...

We've discussed this before, but in case you missed the thread, here is a link to the blog authored by the owner of aprs.fi where he explains many of the errors seen in tracking:

http://oh7lzb.blogspot.com/2008/03/on-duplicate-and-delayed-packets.html

I don't think the bogus beacons are due to hardware problems but are the result of iGate and network glitches.

Thanks for the link Sam. Makes sense. Maybe my new reduced path will help too.