Which of the following connections is made between a computer and a transceiver to use computer software when operating digital modes?

• A. Computer "line-in" to transceiver speaker connector
• B. USB port to antenna connector
• C. Ethernet cable to the power supply
• D. HDMI to audio jack

Answer: (A)

The connection between a computer and a transceiver to facilitate the use of computer software when operating digital modes is typically made through the computer's audio input, referred to as "line-in," connected to the speaker output of the transceiver. This setup allows digital signals generated by the transceiver to be transmitted to the computer for processing by software that enables digital communication modes.

The digital modes often require audio signals to be manipulated, and routing the audio from the transceiver to the computer allows software to decode incoming signals and generate audio for outgoing transmissions. This method is widely utilized in amateur radio for various modes like PSK31, RTTY, and others.

Other connection types listed do not serve this purpose effectively. For instance, connecting a USB port to the antenna connector does not establish an appropriate audio link for digital mode operations. An Ethernet cable linked to the power supply wouldn’t transmit audio signals necessary for digital communication. Moreover, an HDMI cable connected to an audio jack does not facilitate the required audio connection, but rather serves different functionalities like video and audio transmission from devices to displays.