Signal impairments

This course introduces the impairments that limit electronic communications. This course can be studied on its own or as part of the "PTT Level 3 Award in Principles of Telecommunications" study programme.

By the end of this course you will be able to:

• explain the cause and effects of noise and loss on information transfer using analogue signals.
• state the formula for expressing loss in decibel units and explain the advantages of using decibel units when comparing power levels.
• give a definition for, and describe the significance of, signal to noise ratio.
• describe the causes, effects and measurement of crosstalk.
• explain the causes and effects of various types of distortion including harmonic distortion and delay distortion.
• list the causes of delay in a network and describe how excessive delay can degrade telephony services and those involved in the transfer of data.
• describe the causes of digital errors including noise, jitter and dispersion.
• define the term Bit Error Ratio (BER) and describe how BER is expressed.
• explain that some types of encoded information are more affected by errors than others.
• explain that a digital signal can tolerate a large reduction in signal to noise ratio before its bit error rate increases.
• explain the concept and significance of noise margin.

This online course includes assessments, the results of which are summarised in a certificate published at course completion.