Ground station occasionally reporting wonky iridium GPS

[markshancock]

Our Iridium Payload is setting on a picnic table outside and definitely not moving.
We are also watching on the website eclipse.rci.montana.edu/ and haven't seen it move either.

But every once in awhile the ground station points in a different direction (and sometimes toward the sky).
I checked the Incoming GPS Data Window once and noticed the elevation had jumped from 190 to 270.
When I looked on the website, the altitude was still showing 190.

How do I debug this?

Is there a way to see a log history on the website.  
The website indicates that if I click the balloon I would get the history.  
When I clock, it just shows the one location (probably because it never moved).
Is there a way to get a log (in text) from the website so I can confirm that this wasn't an GPS error at the GPS on Iridium Payload.

Does the Tracker app maintain a debug (like log4python) so I can see whether this was a real database fetch or not?
If so, how do I access it?

[Austin MnSGC]

The GPS on the Iridium is not perfectly accurate, it will jitter around. If it is close to the ground station, sometimes it can report a GPS location very very close to the ground station GPS location, where a small difference in altitude could cause it change its pointing dramatically. I'm not sure if this is your problem, but in general make sure that your payload is a good distance away from the tracker.

There are some log files created that will report what locations were input for the balloon at a given time and the method by which that location was input. There is also a log of the locations that the ground station was pointing. You can look through these to see what your ground station was aiming at for a given time. They're in a folder called Logs

[David MSGC]

If you want the data reported by Iridium go to the tracking website and click on your balloon, below the map there will be a table of the all the data for that day UTC time. If you need Iridium data from another day go to the archive tab and find your IMEI number and the date you want the data from.
Note: when clicking on the balloon on the landing page it opens the same page as clicking on the archive for the current day.

I suggest having the Iridium in front of the antenna by at least 50 feet when testing, this will prevent the antenna from spinning more than 180 degrees and will be more consistent in elevation. It does matter too what the gps on the antenna is reading, if its elevation bounces around it will try to tilt accordingly.

[markshancock]

Thanks. I had decided the altitude changed must have been ground effects.
Being able to see the Historic data is a help in diagnosing
I also found from the code that I can use eclipse.rci.montana.edu/php/antennaTracker.php?imei=300234064905630 to fetch immediate data.

[David MSGC]

From the landing page of the tracking website click on your balloon to get a page with just your balloon's data. If you scroll down to the bottom of the map there will be a table that shows all of your data and will update as incoming data is received. It is good practice to watch this incoming data to help understand what the system is doing or help troubleshoot anything.

[David MSGC]

Jun 17, 2017 16:40:28 GMT -7 markshancock said:

Thanks. I had decided the altitude changed must have been ground effects.
Being able to see the Historic data is a help in diagnosing
I also found from the code that I can use eclipse.rci.montana.edu/php/antennaTracker.php?imei=300234064905630 to fetch immediate data.

There is variation built into any GPS module and the change in altitude or location is to be expected and is normal, it is not ground effects.

To watch your incoming Iridium data go to the tracking website and click on your balloon and it will open a page with just your balloons data. If you scroll down below the map it will have a table with all the Iridium data received and will update as new data arrives.