I recently created a map from APRS archives of a recent trip by some friends over about eight weeks through central and north west Australia and back by the southern coast.
Above is a graphic of the created map, but the ‘real’ map is not simply an image, but it is a kml file for Google Earth which you can view / zoom / scroll, for example in Google Maps by clicking on the map above.
This article explains how to create the kml file from APRS archives.
Step1: fetch the archived posits from findu.com.
findu.com offers a valuable service that contains an archive of posits for about six months, a great service that is deserving of financial support.
To fetch the last 48 hours for YOURCALL, use http://www.findu.com/cgi-bin/posit.cgi?call=YOURCALL&start=48&comma=1&time=1.
The screen display looks like plain text, but it is HTML so use your browser to save as plain text, for example:
- in Firefox, choose File / Save page as and choose Save as type text to save the file; or
- select the entire page in the browser, Copy and Paste it into a plain ascii editor and save it as a text file.
Documentation of the findu posit report parameters is at posit – displays parsed position reports.
Step 2: Convert to kml using GPSBabel
GPSBabel is a great file converter, free, and again deserving of financial support.
Script findu.bat for Windows accepts two optional positional parameters, a file name (without extension, default is finduposit) and colour (in the form AABBGGRR in hex, default is ff0000bf for red).
@echo off rem convert track findu (eg from http://www.findu.com/cgi-bin/posit.cgi?call=VK4ZZ&start=99&comma=1&time=1) to kml rem copy the screen output and paste it into an ascii editor (for html to text conversion). set findu=finduposit if not *%1==* set findu=%1 set colour=ff0000bf if not *%2==* set colour=%2 set GPSBABEL="\Program Files\gpsbabel\gpsbabel" %GPSBABEL% -i xcsv,style=finduposit.sty -f %findu%.txt -x transform,rte=wpt,del -x simplify,error=0.01k -o kml,track=1,points=0,labels=0,line_color=%colour%,line_width=3 -F %findu%.kml
GPSBabel is available for *nix, and a shell script could be written for similar behaviour.
finduposit.bat uses a gpsbabel style file finduposit.sty to describe the format of the input data as follows.
# Author: Owen # Date: 27/10/2015 # DESCRIPTION custom EXTENSION tab # # FILE LAYOUT DEFINITIIONS: # FIELD_DELIMITER COMMA RECORD_DELIMITER NEWLINE # # INDIVIDUAL DATA FIELDS, IN ORDER OF APPEARANCE: IFIELD GMT_TIME,"","%Y%m%d%H%M%S" # Datetime IFIELD LAT_DECIMAL,"","%f" # Latitude IFIELD LON_DECIMAL,"","%f" # Longitude IFIELD PATH_COURSE,"","%f" # Course IFIELD PATH_SPEED_KNOTS,"","%f" # Speed IFIELD ALT_FEET,"","%.0f" #Elevation
APRS has a host of issues that degrade the quality of such mapping, and a solution is to collect a stand alone track log of your trip. A simple inexpensive extension to typical APRS configurations is described at OpenLog for TinyTrak. Comparisons of the stand alone track with APRS are given at OpenLog for TinyTrak – drive test.