GPS problems- can't get a fix...

so after a bit of rewiring and poking around, I've gotten the Globalsat 406a ( to talk to the Mega 2650 through an Adafruit shield

It'll read properly parsed empty phrases from the module indoors, and if I take it outside, it gets a bit more data.

But the problem is, it can see 12 satellites, but can't get a fix. Tried it at work, tried it at home, same results. I let it chug along for at least 5 minutes, no luck. Sees 12, no fix. Moving it, sometimes it even loses the $GPGSV phrase. If it was a radio, I'd change the antenna, but this one's part of the module.

Using the Adafruit code modified to read through the hardware serial port 1, I get:

    Time: 6:45:18
    Date: 6/9/12
    Lat: 0* 0' 0.0"
    Long: 0* 0' 0.0"

but even a simple serial1 to serial0 repeater gives the same results.

I'm GPS- clueless. Is there something obvious I could be missing?



On some GPS modules it can take a long time to download the ephemeris details for each satellite. Try leaving the module running with a clear view of the sky for a while... Possibly hours.

If that fails you might need to force a cold start to clear whatever the module thanks it knows about orbits.

Thanks, John- I’ll give that a shot.


I was just curious if things ever panned out for getting a quicker fix with your GPS. I’ve started working with a Maestro A2035-H ( and it is acting similarly. After about 7 minutes it figures out the right time and date (starts off with a date from 2010). It finally gets a fix after about 30 minutes. Until then it just shows that it can find 12 satellites!