ErrorsErrorDetectionandErrorControl.pptVIP

Chapter 6 Errors, Error Detection, and Error Control * Data Communications and Computer Networks: A Business User’s Approach Data Communications and Computer Networks Chapter 6 Introduction Noise is always present. If a communications line experiences too much noise, the signal will be lost or corrupted. Communication systems should check for transmission errors. Once an error is detected, a system may perform some action. Some systems perform no error control, but simply let the data in error be discarded. Data Communications and Computer Networks Chapter 6 Noise and Errors – White Noise Also known as thermal or Gaussian noise Relatively constant and can be reduced. If white noise gets to strong, it can completely disrupt the signal. Data Communications and Computer Networks Chapter 6 Data Communications and Computer Networks Chapter 6 Noise and Errors – Impulse Noise One of the most disruptive forms of noise. Random spikes of power that can destroy one or more bits of information. Difficult to remove from an analog signal because it may be hard to distinguish from the original signal. Impulse noise can damage more bits if the bits are closer together (transmitted at a faster rate). Data Communications and Computer Networks Chapter 6 Data Communications and Computer Networks Chapter 6 Data Communications and Computer Networks Chapter 6 Noise and Errors - Crosstalk Unwanted coupling between two different signal paths. For example, hearing another conversation while talking on the telephone. Relatively constant and can be reduced with proper measures. Data Communications and Computer Networks Chapter 6 Data Communications and Computer Networks Chapter 6 Noise and Errors - Echo The reflective feedback of a transmitted signal as the sig