Which of the following must be programmed into a D-STAR digital transceiver before transmitting?
Why D-STAR sends your call sign as digital data in every transmission, so the radio must have MYCALL programmed before it will identify you properly on the air. This is the digital equivalent of station identification, and many repeaters and gateways will reject or ignore a transmission from a radio with no call sign entered. Other D-STAR fields like UR, RPT1 and RPT2 control routing, but the call sign is the one that must be set.
Watch out The codec is not a user choice: D-STAR uses the AMBE voice codec exclusively, so there is nothing to program. Output power is set with a control or menu item like any FM radio and is not part of the digital data stream.
D-STAR stands for Digital Smart Technologies; the smart part is that your call sign rides along in the data.