USB GPS receivers are becoming cheap enough to stick on a raspberry pi and screw with just for fun. So that's what this code is about.

more specifically, for ham radio antenna reasons, i'm interested in a reasonably accurate measure of my elevation. so for a start i'm going to collect those statistics, plot the long term averages, and see if they tell me anything.

this code uses the gpsd tools, and python client libraries, and started from an example here:
	http://ozzmaker.com/using-python-with-a-gps-receiver-on-a-raspberry-pi/

at the moment, this code collects 1024 points of elevation data with a not terrible vdop, and computes a running average over it. once a minute this running average is written out to disk and graphed. once a day those running averages are averaged into two bar graphs, one with and one w.o. average expected vertical precision.

the following should get one off to a good start depends wise:
	apt-get install python-gps gpsd-clients python-numpy python-matplotlib gnuplot

this code can be found in the following places:
	https://github.com/mcthoren/gps_tinkering	<--code
	https://wx6.slackology.net/gps_el.html		<--page
	https://wx6.slackology.net/			<--code, page, plots, data

a description of the fields returned by gpsd can be found here:
	https://gpsd.gitlab.io/gpsd/gpsd_json.html

# i've added the following entries to my crontab to further lazify my life:
#minute	hour	mday	month	wday	command
59	23	*	*	*	/import/home/ghz/projects/gps/gen_day_avg
01	00	1	*	*	/import/home/ghz/projects/gps/gen_month_avg
02	00	*	*	*	/import/home/ghz/projects/gps/plot_month_avg