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Author Topic: BU-353 Occasional dot missing in coordinate in NMEA GPGGA sentence  (Read 1447 times)

lostInTheForest

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Hello

I am pretty new to GPS devices. I have a BU-353, and have noticed that it sometimes gives an invalid coordinate in the NMEA GPGGA sentence: the dot character is missing from the longitude or the latitude (as here):

$GPGGA,101040.000,654159,N,02526.5670,E,1,05,3.3,20.7,M,21.6,M,,0000*66

In this case, if the 654159N is converted to 65,693167N (in degrees) the location definitely is not the same, or even close, in which I was when I got the invalid sentence --> can't rely on this kind of sentence. Number of satellites is at good level, however.

Can the BU-353 behavior be explained with some acceptable reason, or should I even replace the device in the store it was bought in? Or just skip a sentence like above.

Rgrds J
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GS_TECH01

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Re: BU-353 Occasional dot missing in coordinate in NMEA GPGGA sentence
« Reply #1 on: October 25, 2012, 12:21:36 pm »

Hello J,

Welcome to the forums! Just a couple of questions:

What is your testing environment? The ideal environment would be outside with a clear access to an open sky, with no tall trees or buildings around.
Is the red light on the device blinking? If so, the device is able to get a good signal. If the red light is just steady on, then, it's still not getting a good GPS fix.

Are you using the GPSInfo (our testing program)? Or, do you have your own application that you're testing the BU-353 with?
If you have not test the device with the GPSInfo, please download the program from here: (http://www.usglobalsat.com/store/downloads/GPSInfo.zip). Open it up and extract it. Bring your computer outside where there is clear access to the sky and no tall buildings or trees.
Click on the GPSInfo program, select the correct com port, and choose the appropriate baud rate. Press 'Start GPS'. You should see some scrolling data below. Also, check if the red light is blinking.

As for your reference, you would get invalid coordinates if the device is not able to get a fix.
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lostInTheForest

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Re: BU-353 Occasional dot missing in coordinate in NMEA GPGGA sentence
« Reply #2 on: October 26, 2012, 07:52:59 am »

Hello

Thank you for the answer. I am familiar with the GPSInfo program. The device isn't delivering invalid sentences constantly, but it is working fine most of the time, so it's a bit difficult to sort out the problem.

The testing was done outside, but I can't remember whether the device light was blinking or not nor the color. Anyway, when the invalid sentences began to flow it took about 10s or more from the device to recover.

So, I think I will just discard the invalid sentences, and wait for the bug to reappear.

Rgrds J
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GS_TECH01

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Re: BU-353 Occasional dot missing in coordinate in NMEA GPGGA sentence
« Reply #3 on: October 26, 2012, 11:23:31 am »

Alright, thanks for the update.

If you encounter this issue, let us know and include if the red is blinking or not, as well as the Status (one of the fields in GPSInfo).

As you have mentioned, please disregard the invalid sentences since they're inaccurate and keep us posted. Thanks.
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