ARRL Technician Practice Exam 2025 - Free Technician License Practice Questions and Study Guide

The sound card in a computer plays a crucial role in digital communications by converting received audio into digital signals, which can then be processed by the computer's software. This conversion is essential for effectively decoding and analyzing the audio information transmitted over radio waves.

In addition to converting received audio into a digital format, the sound card also provides audio output to the microphone input. This means it can facilitate sending audio signals generated by the computer back to the transceiver or other communication devices. The digital communication software can then utilize these signals to modulate the transmission as required.

The other functions suggested by the other options describe actions that are not primarily performed by a sound card. Sound cards do not amplify signals before transmission, modulate audio signals directly, or act as a power supply for transceivers. Instead, they focus on the conversion of audio to digital form and vice versa, making them integral to digital communication setups using computers.