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USB Communications
This article provides information about the communications aspects of Universal Serial Bus (USB): Signaling, Protocols, Transactions. USB is an industry-standard used to specify cables, connectors, and protocols that are used for communication between electronic devices. USB ports and cables are used to connect hardware such as printers, scanners, keyboards, mice, flash drives, external hard drives, joysticks, cameras, monitors, and more to computers of all kinds. USB also supports signaling rates from 1.5 Mbit/s (Low speed) to 80 Gbit/s (USB4 2.0) depending on the version of the standard. The article explains how USB devices transmit and receive data using electrical signals over the physical layer, how they identify themselves and negotiate parameters such as speed and power with the host or other devices using standard protocols such as USB Device Framework and USB Power Delivery, and how they exchange data using packets of different types and formats such as token, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Signal
A digital signal is a signal that represents data as a sequence of discrete values; at any given time it can only take on, at most, one of a finite number of values. This contrasts with an analog signal, which represents continuous values; at any given time it represents a real number within a continuous range of values. Simple digital signals represent information in discrete bands of levels. All levels within a band of values represent the same information state. In most digital circuits, the signal can have two possible valid values; this is called a binary signal or logic signal. They are represented by two voltage bands: one near a reference value (typically termed as ''ground'' or zero volts), and the other a value near the supply voltage. These correspond to the two values ''zero'' and ''one'' (or ''false'' and ''true'') of the Boolean domain, so at any given time a binary signal represents one binary digit (bit). Because of this discretization, relatively smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isochronous Signal
In telecommunications, an isochronous signal is a signal in which the time interval separating any two significant instants is equal to the unit interval or a multiple of the unit interval. Variations in the time intervals are constrained within specified limits. "Isochronous" is a characteristic of one signal, while " synchronous" indicates a relationship between two or more signals. See also * Synchronization in telecommunications * Synchronous network * Mesochronous network * Plesiochronous system * Asynchronous system The primary focus of this article is asynchronous control in digital electronic systems. In a synchronous system, operations ( instructions, calculations, logic, etc.) are coordinated by one, or more, centralized clock signals. An asynchro ... References Telecommunications engineering Synchronization {{Telecomm-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Recovery
Clock recovery is a process in serial communication used to extract timing information from a stream of serial data being sent in order to accurately determine payload sequence without separate clock information. It is widely used in data communications; the similar concept used in analog systems like color television is known as carrier recovery. Basic concept In serial communication data is normally transmitted and received as a series of pulses with well-defined timing constraints. In asynchronous serial communication this presents a problem for the receiving side: if their own clock is not precisely synchronized with the transmitter, they may sample the signal at the wrong time and thereby decode the signal incorrectly. Partially, the problem may be addressed with extremely accurate and stable clocks, like atomic clocks, but these are expensive and complex. More common low-cost clock systems, like quartz oscillators, are accurate enough for this task over short periods of ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Coding
In telecommunications, a line code is a pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium. This repertoire of signals is usually called a constrained code in data storage systems. Some signals are more prone to error than others as the physics of the communication channel or storage medium constrains the repertoire of signals that can be used reliably. Common line encodings are unipolar, polar, bipolar, and Manchester code. Transmission and storage After line coding, the signal is put through a physical communication channel, either a transmission medium or data storage medium.Karl Paulsen"Coding for Magnetic Storage Mediums".2007. The most common physical channels are: * the line-coded signal can directly be put on a transmission line, in the form of variations of the voltage or current (often using differential signaling). * the line-coded signal (the '' baseband signal'') u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Speed Negotiation
High may refer to: Science and technology * Height * High (atmospheric), a high-pressure area * High (computability), a quality of a Turing degree, in computability theory * High (tectonics), in geology an area where relative tectonic uplift took or takes place * Substance intoxication, also known by the slang description "being high" * Sugar high, a misconception about the supposed psychological effects of sucrose Music Performers * High (musical group), a 1974–1990 Indian rock group * The High, an English rock band formed in 1989 Albums * ''High'' (The Blue Nile album) or the title song, 2004 * ''High'' (Flotsam and Jetsam album), 1997 * ''High'' (New Model Army album) or the title song, 2007 * ''High'' (Royal Headache album) or the title song, 2015 * ''High'' (Keith Urban album), 2024 * ''High'' (EP), by Jarryd James, or the title song, 2016 Songs * "High" (Alison Wonderland song), 2018 * "High" (The Chainsmokers song), 2022 * "High" (The Cure song), 1992 * " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pull-down Resistor
In electronic logic circuits, a pull-up resistor (PU) or pull-down resistor (PD) is a resistor used to ensure a known state for a signal. More specifically, a pull-up resistor or pull-down resistor ensures that a wire will have a high logic level or low logic level, respectively, in the absence of a driving signal. It is typically used in combination with components such as switches and transistors, which physically interrupt the connection of subsequent components to ground or to VCC. A closed switch creates a direct connection to ground or VCC, but without a PU or PD, when the switch is open, the rest of the circuit would be left floating (i.e. it would have an indeterminate voltage), which is generally undesirable. For a switch that is used to connect a circuit to ground, a pull-up resistor (connected between the circuit and VCC) ensures a well-defined voltage (i.e. VCC) when the switch is open. For a switch that is used to connect a circuit to VCC (e.g. if the switch is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Termination
In electronics, electrical termination is the practice of ending a transmission line with a device that matches the characteristic impedance of the line. Termination prevents signals from Signal reflection, reflecting off the end of the transmission line. Reflections at the ends of unterminated transmission lines cause distortion, which can produce ambiguous digital signal levels and misoperation of digital systems. Reflections in analog signal systems cause such effects as ghosting (television), video ghosting, or Power margin, power loss in radio transmitter transmission lines. Transmission lines Signal termination often requires the installation of a terminator at the beginning and end of a wire or cable to prevent an RF signal from being reflected back from each end, causing Interference (communication), interference, or power loss. The terminator is usually placed at the end of a transmission line or Daisy chain (electrical engineering), daisy chain Bus (computing), bus (s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-duplex
A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow for simultaneous communication in both directions between two connected parties or to provide a reverse path for the monitoring and remote adjustment of equipment in the field. There are two types of duplex communication systems: full-duplex (FDX) and half-duplex (HDX). In a full-duplex system, both parties can communicate with each other simultaneously. An example of a full-duplex device is plain old telephone service; the parties at both ends of a call can speak and be heard by the other party simultaneously. The earphone reproduces the speech of the remote party as the microphone transmits the speech of the local party. There is a two-way communication channel between them, or more strictly speaking, there are two communication channel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Characteristic Impedance
The characteristic impedance or surge impedance (usually written Z0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a wave travelling in one direction along the line in the absence of reflections in the other direction. Equivalently, it can be defined as the input impedance of a transmission line when its length is infinite. Characteristic impedance is determined by the geometry and materials of the transmission line and, for a uniform line, is not dependent on its length. The SI unit of characteristic impedance is the ohm. The characteristic impedance of a lossless transmission line is purely real, with no reactive component (see below). Energy supplied by a source at one end of such a line is transmitted through the line without being dissipated in the line itself. A transmission line of finite length (lossless or lossy) that is terminated at one end with an impedance equal to the characteristic impedance appears to the sourc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twisted Pair
Twisted pair cabling is a type of communications cable in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair, a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves rejection of external electromagnetic interference. It was invented by Alexander Graham Bell. For additional noise immunity, twisted-pair cabling may be shielded. Cable with shielding is known as shielded twisted pair (STP) and without as unshielded twisted pair (UTP). Explanation A twisted pair can be used as a balanced line, which as part of a balanced circuit can greatly reduce the effect of noise currents induced on the line by coupling of electric or magnetic fields. The idea is that the currents induced in each of the two wires are very nearly equal. The twisting ensures that the two wires are on average the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Signaling
Differential signalling is a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conductors can be wires in a twisted-pair or ribbon cable or traces on a printed circuit board. Electrically, the two conductors carry voltage signals which are equal in magnitude, but of opposite polarity. The receiving circuit responds to the difference between the two signals, which results in a signal with a magnitude twice as large. The symmetrical signals of differential signalling may be referred to as ''balanced'', but this term is more appropriately applied to balanced circuits and balanced lines which reject common-mode interference when fed into a differential receiver. Differential signalling does not make a line balanced, nor does noise rejection in balanced circuits require differential signalling. Differential signalli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
