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I'm using a Mediatek MT3333 GPS receiver (baudrate: 115200 bpS), but all I'm getting is this:

b'$GNGGA,132002.448,,,,,0,0,,,M,,M,,*5C\r\n'
b'$GPGSA,A,1,,,,,,,,,,,,,,,*1E\r\n'
b'$GLGSA,A,1,,,,,,,,,,,,,,,*02\r\n'
b'$GPGSV,1,1,00*79\r\n'
b'$GLGSV,1,1,00*65\r\n'
b'$GNRMC,132002.448,V,,,,,0.00,0.00,100417,,,N*5A\r\n'
b'$GNVTG,0.00,T,,M,0.00,N,0.00,K,N*2C\r\n'

After some research I found that my receiver doesn't have a fix, any idea how to solve this?

Manfred Radlwimmer
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ahmed9207
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  • What's the brand and model of the GPS antenna you are using? – thewaywewere Apr 13 '17 at 17:13
  • You've taken it outdoors with a clear view of the southern sky, right? Sometimes you have to send a command to enable the receiver on these. – Brad Apr 14 '17 at 01:12
  • @thewaywewere the GPS receive module has an internal antenna it has a built in low noise amplifier so i guess there is no need for an external antenna. – ahmed9207 Apr 14 '17 at 15:48
  • @Brad i haven't tried it outside however i left near the window runing all night and i got it to work but just for a few hours now i'm getting the same results as before – ahmed9207 Apr 14 '17 at 15:51
  • Can you EDIT your post to include some photo images of your GPS and its placement near the window? Also see my answer posted. – thewaywewere Apr 14 '17 at 16:59

1 Answers1

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It looks that the received signal strength is low so that your GPS receiver mode doesn't get a GPS FIX. It would be better to place the device outdoor to verify if there is a stable reception.

From the GPS sentences showed above, your Mediatek MT3333 GPS receiver output modified NMEA 0183 Sentence. All the standard sentence should started with $GP as the suffix and with format of $GPaaa, where aaa is alphabetic.

For instance,

  • b'$GNRMC,132002.448,V,,,,,0.00,0.00,100417,,,N*5A\r\n' should be read as
  • $GPRMC,132002.448,V,,,,,0.00,0.00,100417,,,N*5A if conforms to NMEA. This sentence tells that at 2017-04-10 12:30:02 (GMT) got no GPS fix with speed at 0 knot and course at 0 degree.

If the output of your GPS receiver conforms NMEA, you can use some free software, such as VisualGPS, to evaluation the GPS signal quality.

If possible, suggest to change the GPS antenna to external one, an active GPS antenna with 2-stage amplifier at around 28dBm gain, to improve the GPS signal reception in order to get a stable fix.

From the datasheet of Mediatek MT3333, it did mention below for improving GPS signal reception:

An external antenna and high gain external LNA connected to the internal LNA in low-gain mode, which offers high linearity. In this configuration, external LNA gain ranging from 15 to 20 dB is recommended. The maximum total external RF front end gain including active antenna and external LNA can be 43dB.

Hope this help.

thewaywewere
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