Final answer:
The DHS common interoperability channels that do not use repeaters are called simplex channels, used for direct communication in emergency scenarios without amplifying equipment.
Step-by-step explanation:
The DHS common interoperability channels that do not require access to a repeater are known as simplex channels. Simplex channels are direct communication channels used for point-to-point communication without the aid of any additional amplifying equipment, like a repeater. In emergencies, first responders and agencies use these channels to communicate directly with each other. The absence of a repeater can be advantageous in certain conditions, especially in a rapidly changing environment where infrastructure might be compromised or non-existent.