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Permalink Reply by Christopher Barnes on October 14, 2009 at 4:44pm

Changing the last variable to be UBX_ck_b I can now get a GPS lock indication - hence the line is now:
if((ck_a=UBX_ck_a)&&(ck_b=UBX_ck_b))

I hope this is useful - I'm still very new to this so appologies if this turns out to be rubbish.

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DeveloperPermalink Reply by Jean-Louis Naudin on October 23, 2009 at 10:26am

Hello,

Thanks for this help, I think that this was a bug, so I have corrected in the GPS_UBLOX.pde.

I live in France, and I have still the problem to get the GPS lock (the blue led still flash desesperately quickly).

I have tested this with the UBLOX (with the GPS_PROTOCOL set to 2 ) and also with the EM406 (with the GPS_PROTOCOL set to 1 ) and the result is the same, no GPS lock...

I have some questions :
Does the WAAS must be used for people living in europe ?
Does it is possible to use EGNOS ?

Have you some advices to get a good GPS lock ?

Thanks for your help and your answer...

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Permalink Reply by Christopher Barnes on October 23, 2009 at 11:45am

Have you ever had a GPS lock from your GPS module (presumably it is a uBlox 5)?

For a first fix try to have a good view of the sky and just be patient.

There is a utility "u-center" available from uBlox web site which you can run on a PC which I would recommend for setting up the GPS module to your preferred settings. You need to find a way to connect the GPS tx/rx to the PC either via the Ardupilot PCB or by connecting the FTDI cable and the GPS cable somehow. Normally the GPS tx and PC tx are both connected to the ATmega rx. If you keep the ATmega in reset then you can ignore it and just swap the tx and rx wires of either the PC (FTDI) or the GPS module.

EGNOS was switched from test to operational mode very recently, so yes in Europe I would enable EGNOS (but avoid having the US WAAS enabled, I've found that if your GPS catches sight of a WAAS satellite it can sometimes cause issues as it is not intended for use over here).

As I don't know what level of experience or knowledge you have of GPS or the electronics sorry if this is all obvious or if it doesn't make any sense - just ask for clarification.

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DeveloperPermalink Reply by Jean-Louis Naudin on October 23, 2009 at 12:13pm

Hello Christopher,

Thanks for your answer, I just found the solution to my problem few minutes ago... ;-)

The solution was :
- The WAAS is disabled,
- the GPS cable must be connected directly to the main CPU board and NOT to the shield gps connector,

With this, the GPS lock after only few minutes ( less than two minutes ), so I am happy ...

I don't know why the GPS doesn't work when it is connected to to shield board. FYI, I am using the newest version of the shield ( the blue one ).

I have a small question, how I can watch the serial print output for deugging on my PC ? Where I connect the serial port and what is the serial print baud rate used ?

So, may be I shall be able to test the Ardupilot this WE on my Easyglider ;-)

Stay tuned...

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DeveloperPermalink Reply by Jean-Louis Naudin on October 23, 2009 at 12:22pm

Sorry forget my small questions above...

I have found the answer myself :
- I use the FTDI cable and use COM5 set at 57600 bauds with the Arduino 0017...

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DeveloperPermalink Reply by Mark Colwell on October 23, 2009 at 7:03pm

uBlox 5 has locked with this code for me.. but I am having lock problems with ArduIMU, I am getting lat, lon, & alt data though just no blue LED...

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DeveloperPermalink Reply by Jean-Louis Naudin on October 24, 2009 at 1:53am

I just enable again the WAAS flag and my uBlox GPS lock quickly without problem in France with :

- the correction of the bug pointed by Christopher Barnes in the source "GPS_UBLOX.pde",
- AND the uBlox connected on the main Atmega 328 board and NOT connected to the Shield v2...

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Permalink Reply by Earl on October 24, 2009 at 7:32pm

OK, I have now confirmed it! The Ardupilot software is massaging the reported lat and long put out to the ground station.
This is what comes out the XBee to the ground station LAT:34.618116 Lon:106.320600
The ublox serial port is reporting lat = 34.511842 and long = -106.1970116

I have confirmed this information by reading the ublox serial port while reading the XBee port on another serial port at the same time.

No wonder the google map in the ground station is showing my plane in the wrong place by about 10 miles.
ANYONE else have this problem or am I doing SOMETHING wrong ???

SW 231

I aslo changed the ublox line of code and it locks much better but the ground station data and the ublox are still reporting different lat and long by about 10 miles.

Earl

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