What is the full name described by HSD 400 in Block 6 - HSD 400?

• A. High Speed Data - 400 Satellite Data Unit Radio
• B. High Speed Data - 400 Secure Data Unit Radio
• C. High Speed Data - 400 Standard Data Unit
• D. High Stability Data - 400 Satellite Data Unit

Answer: (A)

Understanding the naming convention used here helps. HSD stands for High Speed Data, so the first part identifies the capability. The number 400 acts as the specific model or variant, and the remaining words describe the equipment type and its use: Satellite Data Unit Radio. Put together, the full name describes a High Speed Data system, model 400, that is a Satellite Data Unit Radio. The other options change key descriptors (Secure, Standard, Stability) that don’t align with how HSD 400 is defined, so they don’t fit the established naming pattern.