https://en.wikipedia.org/wiki/Modem
A modem (modulator-demodulator) is a network hardware device that modulates one or more carrier wave signals to encode digital information for transmission and demodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used with any means of transmitting analog signals, from light emitting diodes to radio. A common type of modem is one that turns the digital data of a computer into modulated electrical signal for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data.
Modems are generally classified by the maximum amount of data they can send in a given unit of time, usually expressed in bits per second (symbol bit/s, sometimes abbreviated "bps"), or bytes per second (symbol B/s). Modems can also be classified by their symbol rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V.21 standard used audio frequency shift keying with two possible frequencies, corresponding to two distinct symbols (or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the original ITU V.22 standard, which could transmit and receive four distinct symbols (two bits per symbol), transmitted 1,200 bits by sending 600 symbols per second (600 baud) using phase shift keying.
Links
https://en.wikipedia.org/wiki/Category:Modems
Subcategories
R
` Radio modulation modes (3 C, 48 P)
Pages
` Modem
`0–9
` 1-Meg Modem
`A
` Acoustic coupler
Alcatel One Touch X020
Answer tone
Apple Modem
AT command
`B
` Bell 101 modem
Bell 103 modem
Bell 202 modem
BT Voyager
`C
` Cable modem
Carrier frequency
Com21
Command and Data modes (modem)
CompuCom SpeedModem
`D
` DC-BUS
Digital subscriber line
DSL modem
`E
` Echo (computing)
`F
` Fax modem
Freebox
`G
` Global Village (telecommunications)
Guard tone
`H
` Hayes command set
Hayes Microcomputer Products
Huawei E220
`I
` Internet outdial
ITU V.23
`L
` Link Access Procedure for Modems
List of ITU-T V-series recommendations
`M
` Microcom
Microcom Networking Protocol
Microsoft Point-to-Point Compression
Modem script
`N
` Nano Ganesh
Narrowband modem
NO CARRIER
Novation CAT
Null modem
`P
` Packetized Ensemble Protocol
PC card modem
PCMCIA modem
Pennywhistle modem
PlayCable
PocketMail
Point-to-Point Protocol
`Q
` Quake Global
`R
` Remote Access Service
`S
` Satellaview
SCSI Multimedia Commands
Softmodem
SupraFAXModem 14400
`T
Technicolor Modems
` Telebit
Time Independent Escape Sequence
Timex Sinclair 2050
`V
` V.92
Vodafone Mobile Connect USB Modem
Voice modem command set
Volksmodem
`W
` Wideband modem
Mobile broadband modem
Qualcomm Gobi
`Y
` Yamar Electronics Ltd
`Z
` Zenith Cable Modem
ZMODEM
Pages in Other Languages
PhD Project Engagement
PhD Project Engagement
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