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[N7IVV]

I currently own (and really enjoy) Delorme's Street Atlas 2003 w/USB EarthMate. I'd like to do APRS with it while I'm mobile. Surely there is a way to capture the position information from the laptop while it's running Street Atlas and feed that into a TNC (probably through the proper software for the TNC)??

Any ideas would be greatly appreciated!

Brad

[KI6LO]

Hardware wise it isn't easily done using a USB interfaced GPS. The NMEA-0183 serial string needs to be fed to the TNC BEFORE going thru the serial to USB convertor into the USB port. If you could tap into the GPS TX data line and feed that into the TNC as a 2 wire (TX data and ground) then that should work. Use a 10K resistor between the TX data line and the TNC serial input.  Keep in mind that the TNC will require 2 things for this to work:

1) It must be configured to accept the GPS data format strings

2) it must the configured to allow 2 serial inputs at the same time (or only GPS data alone)

Otherwise you will probably need some software to be able to recv the GPS NMEA strings into the PC and then spit out the required format position string to the TNC to update it.

If you were to use something like APRS+SA (Street Atlas 5 or higher) the APRS software would take care of reading the GPS position data and packaging the proper commands to the TNC to xmit your location.

Good Luck,

Gene KI6LO

[KA0MR]

Look in Yahoo for APRS+SA and you will find everything you need to knwo.
Bob KA0MR

[KG4UDX]

NO, APRS+SA most certainly DOES NOT work with the 2003 Street Atlas (or any version of Street Atlas with a year for the version).  I'm not certain about using a USB GPS for some other APRS program, but I'm not certain why it wouldn't work.