GPS data without a FIX

Question

Hello
I couldn´t finish the Part 1 of Homework 3 because my GPS didn't react when plugged on USB with the TTL cable (the FIX led didn't blink). Even though the FIX led blinks with one second rate when the GPS is on the breadboard, using GPIO.
I write some code to get GPS data, just to print it on console, and besides it didn't get a FIX (the led still blinks on the one second rate), I got the data below (a sample of it):
$GPGGA,003345.799,,,,,0,0,,,M,,M,,*4E$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003345.799,V,,,,,0.00,0.00,060180,,,N*44$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003346.799,,,,,0,0,,,M,,M,,*4D$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003346.799,V,,,,,0.00,0.00,060180,,,N*47$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003347.799,,,,,0,0,,,M,,M,,*4C$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003347.799,V,,,,,0.00,0.00,060180,,,N*46$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003348.799,,,,,0,0,,,M,,M,,*43$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPGSV,1,1,00*79$GPRMC,003348.799,V,,,,,0.00,0.00,060180,,,N*49
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003349.799,,,,,0,0,,,M,,M,,*42$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003349.799,V,,,,,0.00,0.00,060180,,,N*48$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003350.799,,,,,0,0,,,M,,M,,*4A$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003350.799,V,,,,,0.00,0.00,060180,,,N*40$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003351.799,,,,,0,0,,,M,,M,,*4B$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003351.799,V,,,,,0.00,0.00,060180,,,N*41$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003352.800,,,,,0,0,,,M,,M,,*47$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,003352.800,V,,,,,0.00,0.00,060180,,,N*4D$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003353.800,,,,,0,0,,,M,,M,,*46$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPGSV,1,1,00*79$GPRMC,003353.800,V,,,,,0.00,0.00,060180,,,N*4C$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003354.800,,,,,0,0,,,M,,M,,*41$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003354.800,V,,,,,0.00,0.00,060180,,,N*4B$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003355.800,,,,,0,0,,,M,,M,,*40$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003355.800,V,,,,,0.00,0.00,060180,,,N*4A$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,003356.800,,,,,0,0,,,M,,M,,*43$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003356.800,V,,,,,0.00,0.00,060180,,,N*49$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003357.800,,,,,0,0,,,M,,M,,*42$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003357.800,V,,,,,0.00,0.00,060180,,,N*48$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003358.800,,,,,0,0,,,M,,M,,*4D$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPGSV,1,1,00*79$GPRMC,003358.800,V,,,,,0.00,0.00,060180,,,N*47$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003359.800,,,,,0,0,,,M,,M,,*4C$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,003359.800,V,,,,,0.00,0.00,060180,,,N*46$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003400.800,,,,,0,0,,,M,,M,,*47$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003400.800,V,,,,,0.00,0.00,060180,,,N*4D$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003401.800,,,,,0,0,,,M,,M,,*46$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003401.800,V,,,,,0.00,0.00,060180,,,N*4C$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003402.800,,,,,0,0,,,M,,M,,*45$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003402.800,V,,,,,0.00,0.00,060180,,,N*4F$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003403.800,,,,,0,0,,,M,,M,,*44
$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPGSV,1,1,00*79$GPRMC,003403.800,V,,,,,0.00,0.00,060180,,,N*4E$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003404.800,,,,,0,0,,,M,,M,,*43$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003404.800,V,,,,,0.00,0.00,060180,,,N*49$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003405.800,,,,,0,0,,,M,,M,,*42$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003405.800,V,,,,,0.00,0.00,060180,,,N*48$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32$GPGGA,003406.800,,,,,0,0,,,M,,M,,*41$GPGSA,A,1,,,,,,,,,,,,,,,*1E$GPRMC,003406.800,V,,,,,0.00,0.00,060180,,,N*4B
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32 (...)
and so on until stop the application...
My questions are
Why I'm receiving GPS data even if it hasn't got a FIX?
The GPS led at least blinked on both cases for every one? (by USB and GPIO)
Thanks!

Answer 1

Hi manasouza,
for a so called 2D fix are the position for at least three satellites needed. The position of known satellites is send within the GSA record.
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
In your provided record it means that currently no satellites are used for the fix.
GSA Satellite status
  A Auto selection of 2D or 3D fix (M = manual)
  1 3D fix - values include: 1 = no fix
                             2 = 2D fix
                             3 = 3D fix
  12x PRNs of satellites used for fix (space for 12)
  , PDOP (dilution of precision)
  , Horizontal dilution of precision (HDOP)
  , Vertical dilution of precision (VDOP)
  *1E the checksum data, always begins with *
See also additional information about GPS and the NMEA protocol
https://en.wikipedia.org/wiki/GPS_signals
http://www.gpsinformation.org/dale/nmea.htm
cheers
Frank