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GPS issues in 0.6r1 #247
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Since I'm about to go flying, was this a vanilla v0.6r1? Or does it have the latest commits? And do you get the invalid NMEA's only when flying? Or at your desk too? (Although I don't know how the Stratux would know the difference.) |
Since you remarked about frozen toes, could the Stratux (or your GPS) have been too cold and out of temp spec? Condensation inside something? |
Hi Mike, It was plain vanilla v0.6r1. I don't think it was the cold but who knows. It was inside and in a warm vehicle prior to the flight so I don't think it was that cold to have caused condensate. The CPU temp was 35C according to the logs. Looking at the log it looks like I've had that a few times before, just not to this degree. It looks like it's on startup and then goes away. On this flight it kept repeating. Have a safe and fun flight! |
Thanks. If I get invalid NMEA messages in flight, will I notice it at the Presentation/Application level? That is, will my ownship jerk or something? (Might be a function of EFB.) Or will I only notice invalid NMEA if I look at the gps log? |
I just noticed I lost my position in Foreflight. I went to the web status page and GPS showed no satellites. |
Silly question but does the GPS module face upward and have absolutely nothing between itself and a wide angle view of the sky save a few thin layers of plastic and plexiglas? For example if the Stratux is in the back seat of a 172 the GPS would absolutely not work. On the glare shield, facing up you get may 200 degree field of view which is probably enough, most of the time. The 3rd party UHF antenna is not a factor, except insofar as it is a placebo in this application for relevant air-to-air 978 traffic and ground tower reception. Might help a tiny bit for picking up FL420 traffic at |
It does face up correctly and has worked well until this update and changing the antenna at the same time. It was initially in the back seat and that's where I have generally had it. But when it wasn't working I had my passenger put it on the front dash and that didn't help. Generally at home I'll pick up gps in the house.
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For posterity's sake, the logs indicate that you're running with:
During the run starting at 1553Z, the GPS was communicating with the Pi, but never got a position fix.
I spot checked a few of the PUBX,03 (satellite information) messages during that log, and you were receiving weak signals from only 1-2 satellites at a time. It was enough to set the clock, but never enough to generate a position fix. I'll echo @224XS ' comment -- how / where was the GPS mounted -- not only within the airplane, but also relative the RPi? Anyway, it looks like you ran for about 50 minutes without a position lock, and then rebooted a couple times. On the second reboot where you were seeing the continuous NMEA messages, the Pi was getting gibberish over the serial port:
That's a fairly good sign of a baud rate mismatch between the GPS and Pi. I've seen similar errors when the GPS is transmitting at 38400, but the GPS is receiving at 9600. A hard power cycle is usually a sure-fire way to resolve; commits post-0.6r1 will also attempt to reinitialize the GPS connection. |
As an aside, my first longer flight with the dmurray antennas today and I noticed the same thing. 😞 |
This is the case I had printed: The GPS chip is mounted in the top lid with the antenna for it facing up. I'll double check my connections. Perhaps one of the connections is On Sat, Feb 13, 2016 at 4:15 PM Daniel Whiting notifications@github.com
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Attached is a Tower Signal Strength plot for log file 0013-uat.log. It shows that you were receiving the signal from a tower located closed to Hillsdale, IL at a moderate signal level. In my experience, typically signal strengths above 50 will provide solid Tower data to the EFB App. This log is only about 14 minutes long and it does shows some drops in signal between 5286 and 5288 minutes and between 5288 and 5290 minutes. This could be normal as your relative position to the tower can affect the signal strength. Also looking at your UAT log I see that you were tracking 51 unique ADS-B Downlink messages from UAT equipped aircraft. I do not know what your antenna configuration was when this log was recorded so I don't have anything to compare against. This is the only UAT log in your zip file that had any data. |
Very cool data. Thanks
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@braddward - v0.7b1 for the GPS improvements mentioned by @AvSquirrel. Also see the settings page for the update function - another UI feature that needs fixing up if you're interested... |
Great. I'll take a look at both. Thanks
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Initial couch flight testing is looking good. GPS is locking on 7 satellites (by a window) and both FlyQ EFB and Foreflight are showing 1090 traffic. Also ran through the update process which also seemed to work well.
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@Axtel4 You said that signal strength over 50 is generally good for tower data. Do you know if those calculations changed in v0.7b3? I got a message from iFly today that I had lost a tower connection. Signal strength was about 400 and below. iFly reported the connection back when the signal strength of 500. Maybe the calculations changed by a factor of 10? (50 = 500?) |
Fixed post-v0.6r1, also some GPS reception issues. Please use the issue format next time to document the hardware, version, and steps to reproduce - that way we don't have to dig. |
Hi all,
I was finally able to fly this morning and despite frozen toes was able to capture some data. The air vents on the Skyhawk seemed to be working too well - much better than the heater.
Unfortunately the GPS stopped working. I rebooted and also had my passenger pull the plug and recycle to no avail.
Of course after I got home its working fine from the desk.
This is also the first flight with the dmurray antennas. I had UAT off and on today (probably more off than on). It seems that with the stock antennas I got better reception.
I've also noticed that the AHRS pitch and roll are now way off on this version. Not sure if that's my chip or that this is still being worked on (previous versions seemed to work).
I noticed lots of invalid NMEA messages in the stratux.log (snippet below)
2016/02/13 17:08:40 - Last GPS fix: 51 minutes ago, GPS solution type: 0 using 0 satellites (0/0 seen/tracked), NACp: 0, est accuracy 0.00 m
2016/02/13 17:08:40 - GPS vertical velocity: 0.00 ft/sec; GPS vertical accuracy: 0 m
2016/02/13 17:08:47 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:48 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:49 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:54 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:54 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:56 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:57 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:08:58 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:09:02 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:09:02 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:09:03 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:09:07 GPS error. Invalid NMEA string: Invalid NMEA message
2016/02/13 17:09:10 stats [started: 52 minutes ago]
2016/02/13 17:09:10 - CPUTemp=32.55 deg C, MemStats.Alloc=5.0 MB, MemStats.Sys=14 MB, totalNetworkMessagesSent=45,890
Log files attached.
logs.zip
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