Introduction to Data Communications
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26c. Frequency Shift

Frequency shift is the difference between the transmitted frequency and the received frequency. This is caused by the lack of synchronization of the carrier oscillators.

26d. Non-Linear Distortion

Non-linear distortion is distortion that changes the waveshape of the signal. If the signal was transmitted as a sinewave and arrived as a squarewave, this would be an example of severe non-linear distortion. Amplitude modulated carriers would suffer drastically if the original wave shape was distorted.

26e. Jitter: Amplitude and Phase

There are 2 types of Jitter:

  1. Amplitude Jitter
  2. Phase Jitter

Amplitude Jitter is the small constantly changing swings in the amplitude of a signal. It is principally caused by power supply noise (60 Hz) and ringing tone (20 Hz) on the signal.

Phase Jitter is the small constantly changing swings in the phase of a signal. It may result in the pulses moving into time slots allocated other data pulses when used with Time Domain Multiplexing.

Telephone company standards call for no more than 10 degrees between 20 and 300 Hz and no more than 15 degrees between 4 and 20 Hz.

Introduction to Data Communications
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