YAAC (Yet Another APRS Client) is an application for accessing the Automatic Packet Reporting System (APRS) amateur packet radio network, originally invented by Bob Bruninga, WB4APR. It functions as an end-node and digipeater for APRS datagrams when connected to an AX.25 Terminal-Node Controller (TNC) and radio transceiver. With YAAC, you can:
monitor APRS traffic
display the geographic locations and status of other APRS stations on a map
report your station's status and position to the APRS network
send messages to other APRS stations
receive messages addressed to your station
In receive-only mode, anyone can use YAAC. To transmit information over the APRS network, you must be a licensed amateur radio operator with privileges to transmit digital data in your country of residence.