In digital television, what does a coding rate of 3/4 mean?
The correct answer is A: 25% of the data sent is forward error correction data. In digital television, what a coding rate of 3/4 means is that 25% of the data sent is forward error correction data. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. For amateur radio operators, this is important for digital TV operation. Understanding this helps when operating digital TV.
Exam Tip
Coding rate 3/4 = 25% of data is forward error correction. Think 'C'oding 'R'ate '3'/'4' = 'C'orrect data is '3'/'4', 'R'est ('1'/'4') is 'F'EC. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. Not compression, not guard interval, not word size - just FEC percentage.
Memory Aid
"Coding rate 3/4 = 25% of data is forward error correction. Think 'C'oding 'R'ate '3'/'4' = '2'5% 'F'EC. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. Important for digital TV operation."
Real-World Application
A coding rate of 3/4 in digital television: It means that 3/4 of the transmitted data is actual video/audio data, and 1/4 (25%) is forward error correction data. The FEC helps correct errors during transmission. This is what coding rate 3/4 means - 25% of the data is forward error correction.
Key Concepts
Why Other Options Are Wrong
Option B: Incorrect. Data compression reducing data rate by 3/4 isn't what coding rate means - coding rate is about FEC, not compression. Compression isn't coding rate.
Option C: Incorrect. 1/4 of time interval used as guard interval isn't what coding rate means - coding rate is about FEC, not guard intervals. Guard interval isn't coding rate.
Option D: Incorrect. Three four-bit words per pixel isn't what coding rate means - coding rate is about FEC ratio, not word size. Word size isn't coding rate.
题目解析
The correct answer is A: 25% of the data sent is forward error correction data. In digital television, what a coding rate of 3/4 means is that 25% of the data sent is forward error correction data. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. For amateur radio operators, this is important for digital TV operation. Understanding this helps when operating digital TV.
考试技巧
Coding rate 3/4 = 25% of data is forward error correction. Think 'C'oding 'R'ate '3'/'4' = 'C'orrect data is '3'/'4', 'R'est ('1'/'4') is 'F'EC. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. Not compression, not guard interval, not word size - just FEC percentage.
记忆口诀
Coding rate 3/4 = 25% of data is forward error correction. Think 'C'oding 'R'ate '3'/'4' = '2'5% 'F'EC. A 3/4 coding rate means 3/4 is data, 1/4 is FEC, so 25% is FEC. Important for digital TV operation.
实际应用示例
A coding rate of 3/4 in digital television: It means that 3/4 of the transmitted data is actual video/audio data, and 1/4 (25%) is forward error correction data. The FEC helps correct errors during transmission. This is what coding rate 3/4 means - 25% of the data is forward error correction.
错误选项分析
Option B: Incorrect. Data compression reducing data rate by 3/4 isn't what coding rate means - coding rate is about FEC, not compression. Compression isn't coding rate. Option C: Incorrect. 1/4 of time interval used as guard interval isn't what coding rate means - coding rate is about FEC, not guard intervals. Guard interval isn't coding rate. Option D: Incorrect. Three four-bit words per pixel isn't what coding rate means - coding rate is about FEC ratio, not word size. Word size isn't coding rate.
知识点
Digital television, Coding rate, 3/4, Forward error correction
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.