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Old 03-06-2013, 14:48   #1
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Trouble with NMEA data from Bluetooth gps receiver

Hi all.

This isn't specifically an OpenCPN problem but having investigated this all day, there seems to be a lot of good knowledge here.

I am running Ubuntu 12.04 and have an Emtac mini S3 Bluetooth gps receiver. I have them linked via Bluetooth fine but the data I am seeing when I cat /dev/rfcomm4 is not NMEA data. It looks like raw data or maybe even corrupted.

Any ideas why I am not seeing the output as NMEA data which OpenCPN obviously needs?

Many thanks
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Old 03-06-2013, 15:15   #2
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Re: Trouble with NMEA data from Bluetooth gps receiver

As your gps has a SiRF Star III chipset, my guess is that what you are seeing is the output from Sirf-mode. Either try to reset it to NMEA-mode or try to use gpsd, which works fine with Sirf mode .
Thomas
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Old 03-06-2013, 15:15   #3
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Re: Trouble with NMEA data from Bluetooth gps receiver

Lovinit...
The first thing that comes to mind: man sirfmon - monitor and control a SiRF GPS in binary mode / Commandes / linux

Pavel
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Old 03-06-2013, 16:14   #4
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Re: Trouble with NMEA data from Bluetooth gps receiver

Thanks for the responses.

Using gpsctl I have confirmed that it is in SiRF binary mode. gpsctl has an option to switch to NMEA mode but doesn't work, even using the force option.

Cagney - I read that gpsd should not be running when using OpenCPN so I'm not sure how to make that work.
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Old 03-06-2013, 16:25   #5
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Re: Trouble with NMEA data from Bluetooth gps receiver

Lovinit...
Where do you read it? That text has to be corrected.

Pavel
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Old 03-06-2013, 16:49   #6
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Re: Trouble with NMEA data from Bluetooth gps receiver

Phew, resolved!

I used the windows application SIRFDemo.exe as suggested in the documentation to switch the receiver to NMEA mode. The output is now correct and OpenCPN is reading it correctly.

Quote:
Originally Posted by nohal View Post
Lovinit...
Where do you read it? That text has to be corrected.

Pavel
It was on this thread - OpenCPN Fails to Receive Bluetooth Data Feed

I think I misunderstood slightly and probably should have said "gpsd does not have to be running". I don't have gpsd running currently and don't appear to need it as I have the required NMEA output.

Thanks again to you both for your suggestions, it got me on the right track.
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