What Is Analog Transmission?

Analog transmission, which transmits information in the form of analog signals in a transmission medium.

Analog transmission

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1 Transmission media 1.1 Cable Types 2 Transmission Methods 3 Transmission Modes 4 Data Communication Equipment (DCE) 5 Data Transmission Equipment (DCE) 5 Transmission Services

Analog transmission transmission medium

Transmission media can support the propagation of acoustic, electromagnetic, and light wave signals. These media are usually capable of confining these signals to metal wires or fiber optic cables inside them. Radio transmission is provided by linear microwave and satellite communications. The type of medium, its shielding, and even the number of twisted wires in a copper wire pair determine the possible data transmission rate on this cable.

Transmission lines can be "balanced" or "unbalanced." A balanced cable is usually a twisted pair or twisted pair cable containing two conductors. An unbalanced cable is usually a coaxial cable. In a balanced line, both wires are connected to the generator (sender) and receiver, and they both have the same current, but the current is in the opposite direction. In an unbalanced cable, current flows through the conductor and returns through the ground.

Analog transmission cable type

The following describes the types of cables commonly used in network communication systems.

Straight cable A straight cable consists of a copper wire wrapped with an insulator. These wires can be bundled, or like flat cables, used to connect short-range or low-bit-rate peripherals. The serial cable used to connect the modem or serial printer uses this type of wire. Crosstalk can occur between adjacent wires, but twisting these wires can reduce crosstalk, as described below.

A twisted pair cable is a pair of copper core wires wrapped with an insulator. The two wires are twisted together to form a balanced circuit. This kink avoids interference problems. Twisted pair is commonly used in audio telephone systems and computer networks. High data rates (100Mbps) can be obtained by using advanced cables (category 5) and ensuring the connectivity of all twisted pairs to the connection points. If necessary, use twisted-pair shielded cables.

Coaxial cable A coaxial cable is a solid copper core wire wrapped by an insulator and a grounding combined shielding net with an outer sheath. High data rates can be achieved with coaxial cables, but some of the more recent rated transmission technologies for twisted pair cables can provide the same or close to coaxial data rates. However, the rated transmission distance of coaxial cables is still higher than that of twisted pair cables.

Fiber optic cables Fiber optic cables include a central glass core for light wave propagation. This core has a glass coat that reflects the light from the inner glass core back to this core. A thick plastic jacket surrounds them with special fibers for added strength. If you need to span a large distance, you can use an optical cable with increased strength and a metal core. Fiber optic cables transmit photons through clean glass. There is no signal interference and no signal radiation. Fiber optic cables can also span longer distances than copper cables. See "Fiber Optic Cable".

Open Space Transmission This type of transmission is achieved using infrared and radio waves.

See Microware Communication, Satellite Telecommunication, Wireless LAN Communication, Wireless Mobile Communication.

Analog transmission

Transmission Methods

The use of electronics, radio waves, or light to generate signals is to transmit encoded information. There are two ways to transmit signals on the medium, namely analog signal transmission and digital signal transmission.

An analog signal represents an infinitely continuously changing voltage or wave within a device. This device generates, measures, records, or transmits this signal. For example, a waveform generated by a telephone in a telephone hall is an analog signal.

Digital signals are transmitted by changing the level in the channel between high and low states. Its basic task is to encode information as a transmission signal with binary numbers 1 and 0.

Analog transmission

Analog signals are a way of transmitting energy, such as sound waves propagating through vibrating air. A tone and volume change sound wave can be mapped on the paper.

A telephone is a conversion device that converts analog sound waves into corresponding electrical signals. At the receiving end of the telephone or audio system, the amplitude (volume) and tone of the speaker's vibration signal are received. The pitch reflects the vibration frequency of the torsional wave. Frequency is usually measured in cycles per second (cps) or hertz (Hz). One hertz is one cps. 1 kHz (kilohertz) is 1,000 Hz, 1 MHz (megahertz) is 1,000 kHz, and 1 GHz is 1,000 MHz. Humans can hear in the range of 20Hz to 20,000Hz, and this is also the working range of high-fidelity audio equipment.

Analog waveforms can be very simple or very complex. A sound wave produced by a single piano tuner consists of only a single frequency. A complex waveform-such as a human voice or an organ sound-contains many combinations of different frequencies, as shown in Figure T-16.

Telephone systems use analog switched lines for audio communications. In general, there are some issues that limit the usefulness of data communication over analog lines. Modulation is required to convert digital signals to analog signals, and because the frequency band of audio lines is narrow, the transmission rate is limited. Moreover, analog signals must be amplified step by step over long distances, so the distortion in these signals will also be amplified. Applications that require large amounts of information (such as graphics and speech processing) require greater bandwidth than analog service capabilities.

Digital transmission

Audio, video, data, and other "information" can be encoded into binary values that can be transmitted efficiently, and these values are transmitted in the form of electrical pulses. The voltage in the cable changes between high and low states. Thus, binary 1 is transmitted by generating a positive voltage, and binary 0 is transmitted by generating a negative voltage. Digital services can provide higher reliability than analog services, especially for long-distance situations. If this signal needs to be amplified, the digital signal needs to be simply regenerated. In contrast, the analog signal needs to be amplified step by step over long distances, and it also amplifies various noises in the cable.

Analog-to-digital conversion, or digitization, is the process of converting continuously changing waveforms in the real world into digital signals that can be stored and processed in a computer. This analog-to-digital conversion process (commonly known as pulse code modulation, PCM) involves sampling the signal at regular time intervals and collecting its amplitude and frequency information in binary form. The accuracy of this value depends on the number of bits used to hold it. If an analog wave is sampled at 1,000 times per second, 1,000 discrete digital values can be obtained for storage or transmission. When speech is converted for transmission over digital lines, it is sampled 8,000 times per second, and each sample is converted to an 8-bit binary value. A digitized audio channel requires 64,000 bits per second .

Analog transmission transmission mode

Transmission Modes

Data can be transmitted in a bit-oriented or character-oriented (also known as byte-oriented) manner. In bit-oriented transmission, these bits represent a continuous stream of data (like image data). They have no special meaning to the sender or receiver except for a specific flag bit that indicates the beginning of the frame. In the general character-oriented protocol, 8-bit sequences represent control codes and alphanumeric characters. The character-oriented protocol contains many transmission modes, which are discussed below.

Simplex circuit A unidirectional connection, just like a radio broadcast, in which the receiver cannot answer. In data communication, a simplex circuit is used in a master-slave configuration, where one device controls other devices and does not need to be responded by the controlled device. When human interaction is required at a controlled site, simplex circuits are usually not used.

A half-duplex circuit is a type of duplex transmission, but can only communicate in one direction at a time. The best example is CB: CITIZEN BAND radio communications, where only one operator can speak at a time. When one operator finishes speaking, he or she says "end" so the other operator can speak. Similarly, a half-duplex circuit uses a signaling system to indicate when one device has finished transmitting or receiving, so other devices can access the line. Half-duplex communication can use single, double, and twisted-pair cables.

A full-duplex circuit is a two-way simultaneous communication. In digital networks, two pairs of wires should be used to complete this circuit. An analog circuit connected by a modem requires only one wire pair. The bandwidth of this circuit is divided into two frequencies, which allows data to flow in both directions simultaneously.

When the terminal is connected in half-duplex mode, the characters entered on the terminal will be displayed and transmitted. However, a terminal in full-duplex mode does not display until it returns an "echo" from the receiving system. Problems can occur if the communication system does not use the same mode. For example, if a terminal is in half-duplex mode, it immediately displays the typed characters. If the receiving system or host is in full duplex mode, it also returns a character to the terminal, which causes a character to be typed on the terminal but two displays appear on the screen. If the terminal is in full-duplex mode and the host is in half-duplex mode, the terminal will not display any characters, because its full-duplex mode needs to wait for an echo from the host, but because the host is in half-duplex Mode, it does not send an echo to the terminal.

Data Communication Equipment (DCE)

A large number of data communication equipment are named after DCE in DTE / DCE (see "Data Communication Equipment"). DCE is between the data terminal equipment (DTE) and the transmission circuit or channel. It provides two types of connections for connecting DTE to or from a communication network. In addition, it usually terminates a circuit and provides a clock for this circuit. Some types of transmission equipment are discussed below.

Modem A modem (modulator / demodulator) converts a digital signal into an analog signal and transmits this signal over an audio telephone network. Digital electrical pulses representing binary 0's and 1's are converted into analog waveforms at one end of the transmission and converted back to digital signals by another modem at the other two end. This modem is controlled by the command of the data communication packet. It handles dialing and telephone answering. It also controls the transmission rate. The transmission rate varies from 300bps to 9,600bps. If compression technology is used, the latest standard can reach 28,800bps, and higher speeds are being developed.

Channel service unit (CSU) This device is used to connect digital communication lines (such as T1). Not only is it cheap, it also provides an end to digital signals. The CSU provides different loops on the line, and if other communication equipment connected to it fails, it can maintain the connection on this line. CSU is often combined with DSU.

The data service unit on the data service unit (DSU) is a hardware device used when transmitting digital data over a digital channel. This device converts data from bridges, routers, and multiplexers to bipolar digital signals used on digital lines.

Signal distortion of repeaters and circuit drivers on long-distance lines may make digital signals unrecognizable. To overcome this problem and increase the transmission distance, repeaters can be introduced into the line to read the distorted pulses and reproduce them. In a telephone system, a repeater is required every 1,818 meters (6,000 feet). A serial connection from a computer to a peripheral device requires a line driver approximately every 15 meters (50 feet). Some line drivers can extend this distance limit to 5,000 feet.

Bridge A bridge connects two similar or dissimilar packet-oriented LANs. It works at the data link layer of the Open Systems Interconnection (OSI) reference model. Bridges can forward packets to other LANs or filter packets to reduce Internet traffic.

Router A router interconnects a local area network (LAN) and other LANs to a backbone cable or to a wide area network. A router is like a bridge, but it provides advanced features. It can know the destination of a node and the route to get there, then choose the best route to pass the packet to the destination.

Analog transmission transmission service

Transmission Services

Transmission services are provided by telecommunications companies or other companies that have established MANs. These services are detailed in "Telecommunications Services".

Related entries: Asynchronous Communication; Bandwidth; Cabling cabling; Carrier Services telecommunications services; Data Transfer Rates; Synchronous Communication; Wide Area Networks.