Physical Layer Functions

The physical layer standards deal with three basic functions which described below:

Physical Components

The physical layer takes frames from the data link layer then converts these frames into electrical, electromagnetic; optical signals through different line coding techniques. Transmits these signals through wired/wireless telecommunication links (cables/antennas) to next hop.

Components of this layer are the electronic hardware devices; media, and other connectors such as NIC, cable, and connector that send and carry the signals. Hardware components such as NIC, interfaces and connectors, cable materials, and cable designs are all specified in standards associated with the physical layer.


Encoding is a technique of converting a stream of data bits into a predefined “code”. Codes are groupings of bits used to give a predictable pattern that can be recognized by both the sender and the receiver. In the case of networking, encoding is a pattern of voltage or current used to represent bits; the 0s and 1s.


The physical layer must generate the electrical, optical, or wireless signals that represent the “1” and “0” on the media. The method of representing the bits is signaling. The physical layer standards must define what type of signal represents a “1” and what type of signal represents a “0”. This can be as simple as a change in the level of an electrical signal or an optical pulse. For example, a long pulse might represent a 1 whereas a short pulse represents a 0. Modulation techniques are a common method to send data. Modulation is the process by which the character of one wave modifies another wave.