Dealing with NMEA sentences

Projects Programming
1

Hi there
I receive from my A7 gsm gps module sentences like :
$GPGGA,200731.000,,,,,0,00,,,M,,M,,00007F
$GPRMC,200731.000,V,,,,,,,141217,,,N4A
$GPVTG,,T,,M,,N,,K,N*2C

I'm trying to get gps datas (altitude, longitude etc) using TinyGps library or TinyGPS++ but my problem is
I can't make TinyGPS to connect serial port directly as A7 returns sentences starting with "GPSRD" word
I processed the return value from GPS to get the sentences :
$GPGGA,200731.000,,,,,0,00,,,M,,M,,00007F
$GPRMC,200731.000,V,,,,,,,141217,,,N4A
$GPVTG,,T,,M,,N,,K,N*2C

How to make TinyGPS process these sentences to obtain gps dats.
Thanks for any help

2

What do you mean "cannot connect directly"?

If TinyGPS does not recognise a sentence, it will ignore it like it never happened.

3

as A7 returns sentences starting with "GPSRD" word

Please give a complete example of what this "return sentence" looks like.

You don't have to feed TinyGSP every character that comes from the device, just the ones that make up a standard GPS sentence.

4

If the NMEA output shown is actually what the GPS is producing then the GPS does not have a fix, so it cannot provide a Location.

The GPS needs to be outside to get a fix.

5

Thanks for replies
Here is what i got from A7 gps pin.

GPSRD:$GPGGA,103257.000,4746.99335,N,00057.75603,E,1,04,5.4,141.2,M,,M,,000042
$GPRMC,103257.000,A,4746.99335,N,00057.75603,E,0.00,0.00,061217,,,A6E
$GPVTG,0.00,T,,M,0.00,N,0.00,K,A*3D

I processed that string to obtain :
$GPGGA,103257.000,4746.99335,N,00057.75603,E,1,04,5.4,141.2,M,,M,,000042
$GPRMC,103257.000,A,4746.99335,N,00057.75603,E,0.00,0.00,061217,,,A6E
$GPVTG,0.00,T,,M,0.00,N,0.00,K,A*3D

So my GPS has a fix.

I connect gps pin of my A7 module to serial port (in another computer) and i can see a good NMEA sentences like
$GPGGA,103257.000,4746.99335,N,00057.75603,E,1,04,5.4,141.2,M,,M,,000042
$GPRMC,103257.000,A,4746.99335,N,00057.75603,E,0.00,0.00,061217,,,A6E
$GPVTG,0.00,T,,M,0.00,N,0.00,K,A*3D

How can i tell tinygps to listen a pin on my arduino mega to obtain NMEA sentences?
Thanks again

6

Can you show us a link or datasheet for the exact GPS module you have? I suspect that it has RS232 output and not 5V TTL which the Arduino requires.

7

Thanky ou all for your help

I managed to get ight datas from my GPS using tniyGPSPlus.

It works.
If you want a piece of code (A7 module), let me know.