1 CS420/520 Axel Krings Page 1 Sequence 5 Chapter 5: Signal Encoding Techniques CS420/520 Axel Krings Page 2 Sequence 5 Encoding Techniques • Digital data, digital signal • Analog data, digital signal • Digital data, analog signal • Analog data, analog signal 2 CS420/520 Axel Krings Page 3 Sequence 5 Digital Data, Digital Signal • Digital signal —Discrete, discontinuous voltage pulses —Each pulse is a signal element —Binary data encoded into signal elements CS420/520 Axel Krings Page 4 Sequence 5 Terms (1) • Unipolar —All signal elements have same sign • Polar —One logic state represented by positive voltage the other by negative voltage • Data rate —Rate of data transmission in bits per second • Duration or length of a bit —Time taken for transmitter to emit the bit 3 CS420/520 Axel Krings Page 5 Sequence 5 Terms (2) • Modulation rate —Rate at which the signal level changes —Measured in baud = signal elements per second • Mark and Space —Binary 1 and Binary 0 respectively CS420/520 Axel Krings Page 6 Sequence 5 Interpreting Signals • Need to know —Timing of bits - when they start and end —Signal levels • Factors affecting successful interpreting of signals —Signal to noise ratio —Data rate —Bandwidth —Synchronization