The undetected long-delayed duplicate posits that are a feature of APRS VHF are a significant corruption of mapping.
Program code has been written to collect posit records direct from APRS-IS and where the record contains a HMS timestamp (as mine do), to apply a timestamp consistent with that timestamp, and then to not write records with duplicate timestamps to the database.
The above map has two journeys, one a loop to the north of home to Mittagong, and another SW to Marulan and back. The Marulan trip extended to 40km from the prominent digi VK2RHR-1, and coverage in the area became poor, evidenced by the poorer APRS mapping in that region.
The map can be browsed interactively at http://owenduffy.net/map/20160204.htm. The red trace is APRS VHF derived using the processing detailed below.
The cyan trace is from stand alone GPS logger above attached to the case of the TinyTrak 3+. The transmitter is 65W output to a quarter wave in the middle of the wagon roof. Continue reading APRS duplicate removal – trial #2