Paul:

A month or two ago we were experimenting with GPS units.
We both have inexpensive Earthmate dongle-type GPS units that are
distributed with Delorme mapping software. I was not able to get my
Linux computer to communicate with  my particular GPS.  A little online
research indicates that Earthmate GPS units do not all containing the
same chip-sets, and I could not find a readily available Linux driver to
communicate with my particular device.

So I ordered a different GPS dongle, a Canmore, purchased from GPSLot
somewhere out there in CA ($20 +). The initial unit they shipped me was
DOA, so GPSLot sent me a replacement unit.  This one works fine with my
Linux machine.

I just plugged it into my Linux machine running a TCL-based serial-port
communication program and the GPS unit sits there and spits out a stream
of data at 4800 Bps. It repeats the data pattern every second, about 6
lines of data.  One of these lines of data contains almost everything
GPS-related that I need for my experimental aircraft instrument panel.
The format is:

$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A

Where:
     RMC          Recommended Minimum sentence C
     123519       Fix taken at 12:35:19 UTC
     A            Status A=active or V=Void.
     4807.038,N   Latitude 48 deg 07.038' N
     01131.000,E  Longitude 11 deg 31.000' E
     022.4        Speed over the ground in knots
     084.4        Track angle in degrees True
     230394       Date - 23rd of March 1994
     003.1,W      Magnetic Variation
     *6A          The checksum data, always begins with *

I've now ordered a longer dongle-cord for my unit (~$3) so I can get a
better signal thru my office window;
I don't want to go outside in the yard and sit in the snow to play with
my new toy.

I will probably create a display using satellite imagery to make a
pretty map showing current location at all times,
but I will be required to create my own database of maps covering the
general area in which I intend to operate.
It would be fun to instead interface with an iPhone or similar device
for web-based mapping images,
but since we do not have cellphone service where we live and I would
need to set up my R&D department somewhere else.
(It is not always fun living in the armpit of the world).

Otherwise,  I am still experimenting with efficient code to read my
data-acquisition board.

R Berglund


Yes the GPRMC sentences has most of what you need.

Here is a complete moving map program written in QB.


I also have the airport data base that goes with this.

Will run in XP command line.

Perhaps you can find a BASIC in Linux that will run this.

Paul Lamar

Robin, Here is the runway and airport data bases as of about 1998.

Paul Lamar


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