Modem — Network Device
What does a MODEM mean?
A Modem, also referred to as ‘Modulator Demodulator’, may be a device that converts (i.e. modulates) computer’s digital signal into an analogue signal for transmission over an existing telephone line. It also does the reverse process, therein it converts analogue signals from a telephone line into digital signals (demodulates), to enable the pc to process the info.
Modems are essentials wont to allow computers to attach to networks (for example, the internet) over long distances using the prevailing telephone networks.
Dial – up modems operate at transmission speeds of about 60 kilobits per second, which is extremely slow by today’s standards. [60 kilobits = 60000 bits. 1 bit refers to a digit and has the worth of 1 or 0.]
How modems did inherit picture?
Modems were first used with teletype machines to send telegrams and cablegrams. Digital modems were developed from the necessity to transmit large amounts of knowledge for North American defence during the 1950s. The primary commercial modem was introduced in 1962. Dennis C. Hayes invented the private computer modem in 1977, marking the emergence of the web and Internet era. Within the beginning modems were used primarily to speak between data terminals and a number computer. Later the utilization of modems was extended to speak between hosts in networks. This required modems that would transmit data faster, resulting in the introduction of compression techniques to extend data rates and error detection and correction techniques to enhance reliability. However, still faster transmission speeds were required.
From 300 to 56,000 Bits Per Second
At 56 Kbps downstream, the ITU's V.92 was the last standard for dial-up modems. Decades ago, the primary modems transmitted 300 bps, and while 56 Kbps (56,000 bps) might sound sort of a huge leap, it's extremely slow for website retrieval. for instance , a high-speed cable modem can support 100 Mbps (100,000,000 bps).
A modem dials the road and answers the decision. While performing digital-to-analogue and analogue to digital conversion, it also provides error correction and data compression. A modem's automatic feature negotiation adjusts speed downward to synchronize with a slower modem at the other end also on accommodate noisy lines.
Optical modem
Optical network terminal (ONT) or Optical network unit (ONU) may be a Modem that connects to fiber optic network. These are commonly utilized in fiber to the house installations, installed inside or outside a house to convert the optical medium to a copper Ethernet interface, after which a router or gateway is usually installed to perform authentication, routing, NAT, and other typical consumer internet functions, additionally to "triple play" features like telephony and TV service.
The throughput could be maximised using the quadrature AM of Fiber optic systems. 16QAM uses a 16-point constellation to send four bits per symbol, with speeds on the order of 200 or 400 gigabits per second. 64QAM uses a 64-point constellation to send six bits per symbol, with accelerates to 65 terabits per second. Although this technology has been announced, it's going to not yet be commonly used.
There are even more sorts of modem like Null Modem, Short-Haul Modem, Radio, Broadband, Leased Line Modem.
References:
https://en.wikipedia.org/wiki/Modem (Images and Information)
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