What SIF mode has a limit of 32 codes?

What SIF mode has a limit of 32 codes?

• A. Mode 1
• B. Mode 2
• C. Mode 3A
• D. Mode 4

Answer: (A)

In this SIF context, how many distinct identification codes a mode can use is determined by how its code field is defined. Mode 1 uses a 5-bit identification field, which yields 2^5, or 32 possible codes. That small, fixed set is exactly why Mode 1 has a limit of 32 codes. The other modes work with different schemes: Mode 3A uses a four-digit octal code, giving a much larger range of civilian ATC identifiers; Mode 4 is a secure, cryptographic mode with codes that change and aren’t bound to a fixed small set; Mode 2 uses its own scheme with a different capacity. So Mode 1 is the one with the 32-code limit.

In this SIF context, how many distinct identification codes a mode can use is determined by how its code field is defined. Mode 1 uses a 5-bit identification field, which yields 2^5, or 32 possible codes. That small, fixed set is exactly why Mode 1 has a limit of 32 codes. The other modes work with different schemes: Mode 3A uses a four-digit octal code, giving a much larger range of civilian ATC identifiers; Mode 4 is a secure, cryptographic mode with codes that change and aren’t bound to a fixed small set; Mode 2 uses its own scheme with a different capacity. So Mode 1 is the one with the 32-code limit.