methods of error detection

Interference in data transmission is any disturbance that can cause errors in the data being sent, such as wire degradation or electrical fields changing the signal.

Data loss is when some data is lost during transmission.

Data gain is when additional data is received beyond what was originally sent.

Data change is when some bits in the transmitted data have been altered or flipped.

Interference in wireless technology can be caused by physical barriers (e.g. buildings, walls), bad weather (e.g. rain, clouds), or other wireless signals.

False. ** Wired technology carries more chance of causing an error** as physical components can be damaged, degrade or receive interference from outside signals.

A format is a way of arranging data so that it can be easily understood by people and computers.

It is important to check for errors in data transmission because computers expect data in certain formats, and if data is not as expected, things can go wrong.

Corruption in data transmission is when data received is not as expected and therefore is difficult or impossible to process.

Two examples of date formats are DD/MM/YY (e.g. 13/04/14) and MM/DD/YYYY (e.g. 12/31/2020).

A parity check is a method to determine whether bits in a transmission have been corrupted.

A parity bit is a bit added to each byte transmitted to ensure the total number of 1's in the byte matches the agreed parity (odd or even).

Odd parity requires an odd number of 1's in the byte (including the parity bit), while even parity requires an even number of 1's.

False. Parity checks only check that an error has occurred, they do not reveal where the error(s) occurred.

A parity block is a block of data with the number of 1's totalled horizontally and vertically to check for errors and locate where they occurred.

A parity byte is a byte sent with the data which contains the parity bits from the vertical parity calculation in a parity block.

A checksum is a custom, user-created algorithm that performs mathematical calculations on data to determine if it has been corrupted.

An echo check works by transmitting the received data back to the sender, who then checks the data to see if any errors occurred during transmission.

The main disadvantage of an echo check is that it isn't reliable as an error could have occurred when the sender transmits the data or when the receiver transmits the data back.

A checksum algorithm determines if an error has occurred by calculating a checksum value before transmission, sending it with the data, recalculating it upon receipt, and comparing the two values. If they match, no error has occurred.

A check digit is a digit added to the end of a block of data to determine if the data has been corrupted.

ISBN (International Standard Book Number) is a unique identifier for books that includes a check digit for error detection.

A standard ISBN number has ten digits.

The check digit in an ISBN number is the final digit.

A barcode is a series of black and white lines that can be scanned to identify an item, often including a check digit for validation.

The purpose of a check digit in a barcode is to validate and authenticate an item.

Check digits are calculated using custom, user-created algorithms that perform mathematical calculations on the data.

The main limitation of check digits is that they can determine if data has been corrupted but do not reveal where the corruption occurred.

ARQ stands for Automatic Repeat reQuest (or Query).

Automatic Repeat reQuest (ARQ) is a protocol that notifies the sender that an error has occurred and that the data received is incorrect.

A negative acknowledgement transmission in ARQ is a message sent by the receiver to indicate that the data is corrupted.

A positive acknowledgement transmission in ARQ is a message sent by the receiver to indicate that the data is correct.

A time-out in ARQ is a certain time period that the sender waits before automatically resending the data if no acknowledgement is received.

True. In ARQ, the process is repeated until all data has been received and acknowledged.

If the receiver doesn't send any acknowledgement in ARQ, the sender waits for a time-out period before automatically resending the data.

ARQ handles corrupted data by having the receiver send a negative acknowledgement, prompting the sender to resend the data.

The main purpose of ARQ is to ensure accurate data transmission by detecting errors and requesting retransmission when necessary.

ARQ differs from other error detection methods by actively requesting retransmission of corrupted data, rather than just detecting errors.