This page calculates the necessary GPS message (C1 message on most Icom radios) to use your Icom radio in GPS mode (not GPS-A mode)
MyCall is the complete callsign entered in your radio including the ID (8th) character.
Note that the symbol code occupies the first four characters of the GPS
message (space padded) and that there is a checksum appended to the text
preceded by an asterisk.
The D-PRS CallSSID can be used to look up your station on any APRS-IS database.