APRS-A is commonly know as APRS, using 144.39 Mhz simplex, created by Bob Brunda and reported commonly on aprs.fi
144.39 Mhz FM wideband simplex is most widely used but other frequencies are used for both front and back hauls.
APRS was created by Bob Bruninga, WB4APR (SK) in the late 1980's
APRS-D uses a digital transport over the PNWDigital network to connect to aprs.fi via our WA7DMR gateway
The Anytone DMR radios support both analog and digital position reporting methods
PNWDigital supports a digital to analog position reporting gateway