What is the advantage of including parity bits in ASCII characters?
The correct answer is D: Some types of errors can be detected. The advantage of including parity bits in ASCII characters is that some types of errors can be detected. Parity bits allow the receiver to detect when an odd number of bits have been corrupted.
Parity bits add an extra bit to each character to make the total number of 1-bits either even (even parity) or odd (odd parity). If a single bit error occurs (or any odd number of bit errors), the parity check will fail, indicating an error. However, parity can only detect errors - it cannot correct them. Also, if an even number of bits are corrupted, the parity check will pass incorrectly. Despite these limitations, parity is a simple and effective way to detect many transmission errors.
Exam Tip
Parity bits advantage = Error detection. Remember: Parity bits in ASCII characters allow detection of some types of errors (odd number of bit errors). They detect errors but don't correct them.
Memory Aid
"**P**arity **B**its = **E**rror **D**etection (think 'PB = ED')"
Real-World Application
You're receiving ASCII data with parity. Each character has a parity bit that makes the total number of 1-bits even. If a single bit error occurs during transmission, the parity check fails, and you know the character is corrupted. However, parity can't tell you which bit is wrong, so it can only detect errors, not correct them.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Parity bits don't increase transmission rate. They add overhead (one extra bit per character), which actually slightly reduces the effective data rate.
Option B: Incorrect. Parity bits don't improve signal-to-noise ratio. They're for error detection, not signal quality improvement.
Option C: Incorrect. Parity bits don't provide a larger character set. ASCII with parity still has the same character set - parity is just an extra bit for error detection.
题目解析
The correct answer is D: Some types of errors can be detected. The advantage of including parity bits in ASCII characters is that some types of errors can be detected. Parity bits allow the receiver to detect when an odd number of bits have been corrupted. Parity bits add an extra bit to each character to make the total number of 1-bits either even (even parity) or odd (odd parity). If a single bit error occurs (or any odd number of bit errors), the parity check will fail, indicating an error. However, parity can only detect errors - it cannot correct them. Also, if an even number of bits are corrupted, the parity check will pass incorrectly. Despite these limitations, parity is a simple and effective way to detect many transmission errors.
考试技巧
Parity bits advantage = Error detection. Remember: Parity bits in ASCII characters allow detection of some types of errors (odd number of bit errors). They detect errors but don't correct them.
记忆口诀
**P**arity **B**its = **E**rror **D**etection (think 'PB = ED')
实际应用示例
You're receiving ASCII data with parity. Each character has a parity bit that makes the total number of 1-bits even. If a single bit error occurs during transmission, the parity check fails, and you know the character is corrupted. However, parity can't tell you which bit is wrong, so it can only detect errors, not correct them.
错误选项分析
Option A: Incorrect. Parity bits don't increase transmission rate. They add overhead (one extra bit per character), which actually slightly reduces the effective data rate. Option B: Incorrect. Parity bits don't improve signal-to-noise ratio. They're for error detection, not signal quality improvement. Option C: Incorrect. Parity bits don't provide a larger character set. ASCII with parity still has the same character set - parity is just an extra bit for error detection.
知识点
Parity bits, Error detection, ASCII, Parity checking
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.