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Tips and questions relating to the GPS modules from SFE
By tbensky
Hi. I have an EM-401 all wired up and am getting a good serial data stream from it (I see the $GPGCC, etc. strings). The problem is that the GMT is wrong, and latitude, longitude, and altitude are all returned as zero!

Do I need an antenna, or does the EM-401 only work outside?

Thanks for any help.
By tbensky
thanks to all those who read my post. After waiting about a week for a reply (none came), I decided to build a long cable so I could put the em-401 outside and connect it to my desktop inside. Sure enough, the em-401 began spewing out proper lat/long/and altitude numbers. So I answered my own question and this might help others: the em-401 needs to be outside with open sky above it, in order to work!