GPS not available, but connection seems to be OK

[rhoki]

Hi.
I've been trying to make my GPS (Lowrance M52) work with OpenCPN, but with no success. Here's what I have done so far:
-Successfully connected GPS to my PC via RS232/USB converter, verified by gpsmon.
-Established serial data connection. OpenCPN reads NMEA0183 sentences correctly and accepts them. Most of my attempts I've used GPGGA sentences, but have tried with other too.
-Checked log file. Not much there, just some messages like

21:48:10 CEST: Opening NMEA Datastream Serial:/dev/ttyUSB0
21:48:12 CEST: Changing NMEA Datasource for GPGGA to Serial:/dev/ttyUSB0 (Priority: 2)
21:48:19 CEST: GPS Watchdog Timeout is: 6 sec.
21:48:22 CEST:    ***GPS Watchdog timeout at Lat:33.358   Lon: -79.282

and some about maps, like

21:48:20 CEST: Unable to initialize background world map. No GSHHS datafiles found in /usr/share/opencpn/gshhs/

but I'll deal with those later.
Having done all those things I can't figure out why my GPS connection is still offline, so I'll be grateful for any directions on how to debug this issue.

Some more details:

Version 4.0.0 Build 2015-01-08

which is not necessarily correct, because I've build and installed the OpenCPN package from AUR.

[petter5]

Have you tried using GPSD ?? https://www.archlinux.org/packages/extra/x86_64/gpsd/

( x64 )