{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM2","mode":1,"time":"2015-08-28T07:38:51.000Z","ept":0.005}
{"class":"TPV","tag":"GLL","device":"/dev/ttyACM2","mode":0,"time":"2015-08-28T07:38:51.000Z","ept":0.005}
{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM0","mode":3,"time":"2015-08-28T07:38:51.000Z","ept":0.005,"lat":-27.550550287,"lon":153.102791027,"alt":56.883,"epx":2.991,"epy":2.991,"epv}
{"class":"SKY","tag":"GSV","device":"/dev/ttyACM0","xdop":0.79,"ydop":0.75,"vdop":1.88,"tdop":1.01,"hdop":0.99,"gdop":2.35,"pdop":2.12,"satellites":[{"PRN":4,"el":0,"az":0,"ss":33,"used":fal}
{"class":"TPV","tag":"GLL","device":"/dev/ttyACM0","mode":3,"time":"2015-08-28T07:38:51.000Z","ept":0.005,"lat":-27.550550333,"lon":153.102791000,"alt":57.800,"epx":11.922,"epy":11.180,"epv"}
{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM1","mode":1}

{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM2","mode":1,"time":"2015-08-28T07:38:52.000Z","ept":0.005}
{"class":"TPV","tag":"GLL","device":"/dev/ttyACM2","mode":0,"time":"2015-08-28T07:38:52.000Z","ept":0.005}
{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM0","mode":3,"time":"2015-08-28T07:38:52.000Z","ept":0.005,"lat":-27.550550218,"lon":153.102790984,"alt":56.919,"epx":2.963,"epy":2.963,"epv}
{"class":"SKY","tag":"GSV","device":"/dev/ttyACM0","xdop":0.79,"ydop":0.75,"vdop":1.88,"tdop":1.01,"hdop":0.99,"gdop":2.35,"pdop":2.12,"satellites":[{"PRN":4,"el":0,"az":0,"ss":33,"used":fal}
{"class":"TPV","tag":"GLL","device":"/dev/ttyACM0","mode":3,"time":"2015-08-28T07:38:52.000Z","ept":0.005,"lat":-27.550550167,"lon":153.102791000,"alt":57.800,"epx":11.922,"epy":11.180,"epv"}
{"class":"TPV","tag":"0x0106","device":"/dev/ttyACM1","mode":1}

#include <iostream>
#include <stdlib.h>
#include <libgpsmm.h>

using namespace std;

int main(void)
{
    int port;
    gpsmm gps_rec("localhost", DEFAULT_GPSD_PORT);
    port = atoi(DEFAULT_GPSD_PORT);
    printf("port: %dn", port);

    if (gps_rec.stream(WATCH_ENABLE|WATCH_JSON) == NULL) {
        cerr << "No GPSD running.n";
        return 1;
    }

    for (;;) {
        // more info for gps_data_t: https://fossies.org/dox/gpsd-3.15/structgps__data__t.html
        struct gps_data_t* newdata;

        if (!gps_rec.waiting(50000000))
            continue;

        if ((newdata = gps_rec.read()) == NULL) {
            cerr << "Read error.n";
            return 1;
        } else {
            cout
                << "path: "<< newdata->devices.list[0].path
                << "tndevices: "<< newdata->devices.ndevices
                << "tlatitude: "<< newdata->fix.latitude
                << "tlongitude: "<< newdata->fix.longitude
                << endl;
        }
    }
    return 0;
}

root@overo:~# gps_test
port: 2947
path:   ndevices: 0     latitude: nan   longitude: nan
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan

path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan

path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5506      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan

path: /dev/ttyACM0      ndevices: 3     latitude: -27.5506      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5506      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5506      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: -27.5505      longitude: 153.103
path: /dev/ttyACM0      ndevices: 3     latitude: nan   longitude: nan