1. OCR AS Level F451: 3.1.5 Data transmission
d. Explain the relationship between bit rates and the time sensitivity of the information;
e. Recognize that errors can occur in data transmission, and explain methods of detecting and correcting these errors (parity checks, the use of parity in data blocks to become self-correcting, checksums and echoes);

2. OCR AS Level F451: 3.1.5 Data transmission
d. Explain the relationship between bit rates and the time sensitivity of the information;

3. Bit rates vs time sensitivity
OCR AS Level F451: Data transmission
Bit rates vs time sensitivity
Bit rate – The number of bits transmitted each second or the rate at which data is transferred.
Different bit rates are suitable for different applications. Largely based on how time sensitive the information is.
Video streaming: Requires a high bit rate as there is lots of data and any delay will interrupt the video.
Transferring word documents: Can use a lower bit rate as the files are needed on real time and people can wait a few min for the files to arrive.

4. OCR AS Level F451: 3.1.5 Data transmission
e. Recognize that errors can occur in data transmission, and explain methods of detecting and correcting these errors.
(parity checks, the use of parity in data blocks to become self-correcting, checksums and echoes);

5. Errors in data transmission
OCR AS Level F451: Data transmission
Errors in data transmission
Its very easy for data to become corrupted during transmission. There are three main ways that computers check for errors in data.
Echoing back – The receiver sends the data back to the sender who checks that it matches what was originally sent.
Check sums – Extra digits or numbers are added to the end of a complex sequence. These numbers are calculated based on the numbers in the sequence. When the sequence is received the check number is recalculated and if it doesn't match then the data is re-sent.
Parity check – 1 bit in each byte is reserved as the parity bit. The parity bit is 1 if the number of 1s in the rest of the byte is odd and 0 if the number of 1s is even.