What was the original application of the proprietary digital headend expansion interface (DHEI) protocol?

The original application of the proprietary digital headend expansion interface (DHEI) protocol was primarily to chain multiple General Instrument integrated receiver/transcoders (IRT) together. This design allowed for seamless integration and scaling of broadcasting systems, enabling operators to expand their capabilities by linking multiple devices.

DHEI was specifically tailored to address the need for efficient communication between these transcoders, allowing them to work in unison. This capability was crucial in digital television broadcasting, where multiple devices may need to collaborate to manage the incoming data streams effectively and ensure optimal output quality.

The other choices do not align with the foundational purpose of the DHEI protocol. While connecting various communication devices in a network may be a function of many types of protocols, it does not accurately capture the specific intent of the DHEI. Similarly, compressing video signals for storage or enabling remote access to headend systems are separate functionalities that would not have been the primary focus of the DHEI protocol at its inception. Thus, the answer reflects the core purpose of DHEI within the context of digital broadcast system architecture.