Unit 2 Seminar – Coursework Example
Basic Digital Encoding Techniques Basic Digital Encoding Techniques There are various techniques for transforming digital data intodigital signals. These techniques are employed in some telephone systems and LANs (Stallings, 2007). They include Nonreturn to Zero technique, Bipolar-AMI technique, Manchester technique, and Differential Manchester technique.
The Non-return to Zero techniques are of two types namely the Nonreturn to zero-level (NRZ-L) and the Nonreturn to zero inverted (NRZI). The former converts 0s as positive voltages and 1s as zero voltages. NRZI, on the other hand, possess an energy transformation at the start of a 1, with no voltage change at the beginning of 0 (Stallings, 2007). There is one significant aspect that distinguishes NRZ-L from NRZI. In determining whether a bit is a 1 or a 0, the receiver in NRZ-L must check the voltage level of every bit while the receiver in NRZI, on the other hand, must check if there is any change at the start of a bit.
The second encoding technique is Bipolar-AMI Encoding technique. This method is peculiar to the others since it makes use of three voltage levels (Stallings, 2007). If a device conveys a binary 0, it transmits a zero voltage. Similarly, if the instrument communicates a binary 1, it sends either a negative or a positive voltage. The type of voltage sent depends on the last transmitted binary 1 value. The third technique is the Manchester Digital Encoding method. In Differential Manchester code, each bit possesses at least a substantial change. Some bits may have more than one signal changes for every bit. The last technique, 4B/5B technique, transforms 4 bits of data into 5 bit quantities (Stallings, 2007). These 5 bit numbers are peculiar since no 5 bit code contain over two consecutive zeroes. Afterwards, the 5 bit code is conveyed by an NRZI encoded signal.
Stallings, W. (2007). Data and computer communications. Pearson/Prentice Hall.