Gps (ls20031)

NETMF & Gadgeteer
1

I have an odd issue with my GPS, I haven’t used the chip in a while and just re-added it to my board and it’s sending out NMEA strings, although it isn’t picking up a location.

It comes back with at least 1 satellite because it returns the correct UTC time from the satellite but the GLL etc always return false/invalid for anything else and just can’t get a lock.

I’m dumping the strings direct to a COM port and just TeraTerming in at the moment :confused:

Anyone any ideas?

Here’s a sample of output:


$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,02,18,,,32,15,,,33*77
$GPRMC,153403.147,V,,,,,0.00,0.00,171010,,,N*49
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,153403.347,,,,,0,0,,,M,,M,,*48
$GPGGA,153403.547,,,,,0,0,,,M,,M,,*4E
$GPGLL,,,,,153403.547,V,N*7C
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,02,18,,,32,15,,,33*77
$GPRMC,153403.547,V,,,,,0.00,0.00,171010,,,N*4D
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,153403.747,,,,,0,0,,,M,,M,,*4C
$GPGGA,153404.147,,,,,0,0,,,M,,M,,*4D
$GPGLL,,,,,153404.147,V,N*7F
2

Have you tried taking the GPS outside?

3

How long have you waited for the receiver to lock? It can take what seems like a long time for a lock to occur.

4

Not outside, but by a window, it used to work in the same place. I left it for 15 mins the other night and came back and still nothing :confused:

5

It’s odd because it’s seeing at least 1 satellite according to GSV (and the fact it’s getting time from somewhere).

6

Took it too my back window and it’s now working back where I originally said it wasn’t, do these things need to update fixation data or something?

7

A cold start for GPS can take couple minutes to work

8

Try leaving it there for 20 minutes, just to be safe. That is weird, I have never had a GPS take more than a minute or two to get a cold fix inside.

9

It had been powered down for a very long time, like 2 months or so, perhaps it was that, it seems more reasonable now and working as it should.

10

I have my biking GPS powered down for the entire winter season, and when I bring it up in the spring it jumps back to life almost immediately.

Can you take it outside and let it set for a minute?

11

Hmm odd, it’s fine now anyhow hopefully this was just some non issue :stuck_out_tongue:

12

GPS can be a bit finicky, but usually not consistently so. If it’s a one off thing, don’t worry about it.