What is the function of the vertical interval signaling (VIS) code sent as part of an SSTV transmission?
The correct answer is B: To identify the SSTV mode being used. What is the function of the vertical interval signaling (VIS) code sent as part of an SSTV transmission is to identify the SSTV mode being used. VIS codes tell the receiver which SSTV mode format is being used. For amateur radio operators, this is important for SSTV operation. Understanding this helps when operating SSTV.
Exam Tip
VIS code function = identify SSTV mode being used. Think 'V'IS = 'V'ideo 'I'dentification 'S'ignal (mode). VIS codes tell the receiver which SSTV mode format is being used. Not color burst lock, not vertical sync, not call sign - just mode identification.
Memory Aid
"VIS code function = identify SSTV mode being used. Think 'V'IS = 'M'ode 'I'dentification. VIS codes tell the receiver which SSTV mode format is being used. Important for SSTV operation."
Real-World Application
Vertical interval signaling (VIS) code in SSTV: It's sent at the beginning of an SSTV transmission to identify which SSTV mode is being used (e.g., Robot, Scottie, Martin, etc.). The receiver uses this code to decode the image correctly. This is the function - to identify the SSTV mode being used.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Locking color burst oscillator isn't the function - VIS codes identify the mode, not lock oscillators. Color burst lock isn't the function.
Option C: Incorrect. Providing vertical synchronization isn't the function - VIS codes identify the mode, not provide sync. Vertical sync isn't the function.
Option D: Incorrect. Identifying call sign of transmitting station isn't the function - VIS codes identify the mode, not the call sign. Call sign identification isn't the function.
题目解析
The correct answer is B: To identify the SSTV mode being used. What is the function of the vertical interval signaling (VIS) code sent as part of an SSTV transmission is to identify the SSTV mode being used. VIS codes tell the receiver which SSTV mode format is being used. For amateur radio operators, this is important for SSTV operation. Understanding this helps when operating SSTV.
考试技巧
VIS code function = identify SSTV mode being used. Think 'V'IS = 'V'ideo 'I'dentification 'S'ignal (mode). VIS codes tell the receiver which SSTV mode format is being used. Not color burst lock, not vertical sync, not call sign - just mode identification.
记忆口诀
VIS code function = identify SSTV mode being used. Think 'V'IS = 'M'ode 'I'dentification. VIS codes tell the receiver which SSTV mode format is being used. Important for SSTV operation.
实际应用示例
Vertical interval signaling (VIS) code in SSTV: It's sent at the beginning of an SSTV transmission to identify which SSTV mode is being used (e.g., Robot, Scottie, Martin, etc.). The receiver uses this code to decode the image correctly. This is the function - to identify the SSTV mode being used.
错误选项分析
Option A: Incorrect. Locking color burst oscillator isn't the function - VIS codes identify the mode, not lock oscillators. Color burst lock isn't the function. Option C: Incorrect. Providing vertical synchronization isn't the function - VIS codes identify the mode, not provide sync. Vertical sync isn't the function. Option D: Incorrect. Identifying call sign of transmitting station isn't the function - VIS codes identify the mode, not the call sign. Call sign identification isn't the function.
知识点
Vertical interval signaling, VIS code, SSTV transmission, Identify SSTV mode
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.