Methods Of Error Detection
Overview
When data travels down a cable or through the air, it can be damaged on the way. Electrical interference can flip a 1 to a 0, lose a bit entirely, or add one that should not be there. A single flipped bit can ruin a bank transfer or a downloaded file, so computers need ways to notice that something has gone wrong.
In this lesson you will meet the main error detection methods on the syllabus: the parity check, the checksum, the echo check, the check digit and the automatic repeat query. You will learn how each one works, what kind of error it catches, and how a system can ask for the data to be sent again when an error is found.
Objectives
- 1 Understand the need to check for errors after data transmission and how these errors can occur
- 2 Describe the processes involved in each of the following error detection methods for detecting errors in data after transmission: parity check (odd and even), checksum and echo check
- 3 Describe how a check digit is used to detect errors in data entry and identify examples of when a check digit is used, including international standard book numbers (ISBN) and bar codes
- 4 Describe how an automatic repeat query (ARQ) can be used to establish that data is received without error
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Methods Of Error Detection. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- An extra bit added to a byte to make the number of 1s odd or even is called a: A. check digit B. parity bit C. checksum D. stop bit Answer: B
- Which method detects errors during data entry rather than transmission? A. echo check B. parity check C. check digit D. checksum Answer: C
- In a positive acknowledgement ARQ, the sender re-sends a packet when: A. a positive acknowledgement arrives B. no acknowledgement arrives before the timeout C. the checksum matches D. the parity is even Answer: B
- A weakness of a single parity check is that it may not detect: A. a single changed bit B. two changed bits in the same byte C. an odd number of 1s D. an even number of 1s Answer: B
- Where is a check digit commonly used? A. RAM addressing B. an ISBN on a book C. a logical shift D. virtual memory Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Recommended Books
Practice Mock Questions
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