In analog signals, voltage varies continuously. In digital signals, voltage turns off and on repeatedly, pulsing from zero voltage to a specific positive voltage. An analog signal’s voltage appears as a continuous wave when graphed over time.
To understand this concept, think of two tin cans connected by a wire. When you speak into one of the tin cans, you produce analog sound waves that vibrate over the wire until they reach the tin can at the other end. These sound waves are merely approximations of your voice, and they are significantly affected by the quality of the wire.
Digital Signaling Unlike analog signals where there is a smooth curve, digital signals jump directly to the next value. When digital signals can exist in only one of two values, they go directly to the next value, typically changing between 0 and 1. The jump from one value to another is known as a transition .
Data transmission, whether analog or digital, may also be characterized by the direction in which the signals travel over the media.
1. Simplex- In cases where signals may travel in only one direction, the transmission is considered simplex.
2. Half Duplex - In half-duplex transmission signals may travel in both directions over a medium but in only one direction at a time. Half-duplex systems contain only one channel for communication, and that channel must be shared for multiple nodes to exchange information.
When signals are free to travel in both directions over a medium
simultaneously, the transmission is considered full-duplex.
Full-duplex may also be called bidirectional transmission or
Definition: A network switch is a small hardware device that joins multiple computers together within one LAN. Technically, network switches operate at layer two (Data Link Layer) of the OSI model.
Network switches appear nearly identical to network hubs, but a switch generally contains more "intelligence" (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of that packet, and forwarding it appropriately. generally it gives better performance than a hub
A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP’s network. Routers are located at gateways, the places where two or more networks connect. Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.
A cable is one or more wires or optical fibers bound together, typically in a common protective jacket or sheath. The individual wires or fibers inside the jacket may be covered or insulated. Combination cables may contain both electrical wires and optical fibers. Electrical wire is usually copper because of its excellent conductivity, but aluminium is sometimes used because it is lighter or costs less.