Correction bit explained meaning

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In information theory and coding theory with applications in computer science and telecommunicationerror detection and correction or error control are techniques that enable reliable delivery of digital data over unreliable communication channels. Many communication channels are subject to channel noiseand thus errors may be introduced during transmission from the source to a receiver. Error detection techniques allow detecting such errors, while error correction enables reconstruction of the original data in many cases.

The correction bit explained meaning development of error-correcting codes in is due to Richard W. The general idea for achieving error detection and correction is to add some redundancy i. Error-detection and correction schemes can be either systematic or correction bit explained meaning In a systematic scheme, the transmitter correction bit explained meaning the original data, and attaches a fixed number of check bits or parity datawhich are derived from the data bits by some deterministic algorithm.

If only error detection is required, a receiver can simply apply the same algorithm to the received data bits and correction bit explained meaning its output with the received check bits; if the values do not match, an error has occurred at some point during the transmission.

In a system that uses a non-systematic code, the original message is transformed into an encoded message that has at least as many bits as the original message. Good error control performance requires the scheme to be selected based on correction bit explained meaning characteristics of the communication channel.

Common channel models include memory-less models where errors occur randomly and with a certain probability, and dynamic models where errors occur primarily in bursts. Some codes can also be suitable for a mixture of random errors and burst errors. If the channel capacity cannot be determined, or is highly variable, an error-detection scheme may be combined with a system for retransmissions of erroneous data. This is known as automatic repeat request ARQand is most notably used in the Internet.

An alternate approach for error control is hybrid automatic repeat request HARQwhich is a combination of ARQ and error-correction coding. ARQ and FEC may be combined, such that minor errors are corrected without retransmission, and major errors are corrected via a request for retransmission: Error detection is most commonly realized using a suitable hash function or checksum algorithm. A hash function adds a fixed-length tag to a message, which enables receivers to verify the delivered message by recomputing the tag and comparing it with the one provided.

There exists a vast variety of different hash function designs. However, some are of particularly widespread use because of either their simplicity or their suitability for detecting certain kinds of errors e.

A random-error-correcting code based on minimum distance coding can correction bit explained meaning a strict guarantee on the number of detectable errors, but it may not protect against a preimage attack. A repetition code, described in the section below, is a special case of error-correcting code: A repetition code is a coding scheme correction bit explained meaning repeats the bits across a channel to achieve correction bit explained meaning communication.

Given a stream of data to be transmitted, the data are divided into blocks of bits. Each block is transmitted some predetermined number of times. For example, to send the bit pattern "", the four-bit block can be repeated three times, thus producing " ". However, if this twelve-bit pattern was received as " " — where the first block is unlike the other two — it can be determined that an error has occurred. A repetition code is very inefficient, and can be susceptible to problems if the error occurs in correction bit explained meaning the same place for each group e.

The advantage of repetition codes is that they are extremely simple, and are in fact used in some transmissions of numbers stations. A parity bit is a bit that is added to a group of source correction bit explained meaning to ensure that the number of set bits i.

It is a very simple scheme that can be used to detect single or any other odd number i. An even number of flipped bits will make the parity bit appear correct even though the data is erroneous.

Extensions and variations on the parity bit mechanism are horizontal redundancy checksvertical redundancy checksand "double," "dual," or "diagonal" parity used in RAID-DP. A checksum of a message is a modular arithmetic sum of message code words of a fixed word correction bit explained meaning e.

The sum may be negated correction bit explained meaning means of a ones'-complement operation prior to transmission to detect errors resulting in all-zero messages. Checksum schemes include parity correction bit explained meaningcheck digitsand longitudinal redundancy checks. Some checksum schemes, such as the Damm correction bit explained meaningthe Luhn algorithmand the Verhoeff algorithmare specifically designed to detect errors commonly introduced by humans in writing down or remembering identification numbers.

A cyclic redundancy check CRC is a non-secure hash function designed to detect accidental changes to digital data in computer networks; as a result, it is not suitable for detecting maliciously introduced errors. It is characterized by specification of what is called a generator polynomialwhich is used as the divisor in a polynomial long division over a finite fieldtaking the input data as the dividendsuch that the remainder becomes the result. A cyclic code has favorable properties that make it well suited for detecting burst errors.

CRCs are particularly easy to implement in hardware, and are therefore commonly used in digital networks and storage devices such as hard disk drives. The output of a cryptographic hash functionalso known as a message digestcan provide strong assurances about data integritywhether changes of the data are accidental e.

Any modification to the data will likely be detected through a mismatching hash value. Furthermore, given some hash value, it is infeasible to find some input data other than the one given that will yield the same hash value.

If an attacker can change not only the message but also the hash value, then a keyed hash or correction bit explained meaning authentication code MAC can be used for additional security. Without knowing the key, it is not possible for the attacker easily or conveniently correction bit explained meaning the correct keyed hash value for a modified message.

Any error-correcting code can be used for error detection. Using minimum-distance-based error-correcting codes for error detection can be suitable if a strict limit on the minimum number of errors to be detected is desired.

The parity bit is an example of a single-error-detecting code. An acknowledgment is a message sent by the receiver to indicate that it has correctly received a correction bit explained meaning frame. Usually, when the transmitter does not receive the acknowledgment before the timeout occurs i.

ARQ is appropriate if the communication channel has varying or unknown capacitysuch as is the case on the Internet. However, ARQ requires the availability of a back channelresults correction bit explained meaning possibly increased latency due to retransmissions, and requires the maintenance of buffers and correction bit explained meaning for retransmissions, which in the case of network congestion can put a strain on the server and overall network capacity.

An error-correcting code ECC or forward error correction FEC code is a process of adding redundant data, or parity datato a message, such that it can be recovered by a receiver even when a number of errors up to the capability of the code being used were introduced, either during the process of transmission, or on storage. Since correction bit explained meaning receiver does not have to ask the sender for retransmission of the data, a backchannel is not required in forward error correction, and it is therefore suitable for simplex communication such as broadcasting.

Error-correcting codes are frequently used in correction bit explained meaning communication, as well as for reliable storage in media such as CDsDVDshard disksand RAM. Error-correcting codes are usually distinguished between convolutional codes and block codes:. Shannon's theorem is an important theorem in forward error correction, and describes the maximum information rate at which reliable communication is possible over a channel that has a certain error probability or signal-to-noise ratio SNR.

This strict upper limit is expressed in correction bit explained meaning of the channel capacity. More specifically, the theorem says that there exist codes such that with increasing encoding length the probability of error on a discrete memoryless channel can be made arbitrarily small, provided that the code rate is smaller than the channel capacity. The actual maximum code rate allowed depends on the error-correcting code used, and may be lower.

This is because Shannon's proof was only of existential nature, and did not show how to construct codes which are both optimal and have efficient encoding and decoding algorithms. There are two basic approaches: The latter approach is particularly attractive on an erasure channel when using a rateless erasure code.

By the time an ARQ system discovers an error and re-transmits it, the re-sent data will arrive too late to be any good. Applications where the transmitter immediately forgets the information as soon as it is sent such as most television cameras cannot use ARQ ; they must use FEC because when an error occurs, the original data is no longer available.

Applications that require extremely low error rates such as digital money transfers must use ARQ. Reliability and inspection engineering also make use of the theory of error-correcting codes. Development of error-correction codes was tightly correction bit explained meaning with the history of deep-space missions due to the extreme dilution of signal power over interplanetary distances, and the limited power availability aboard space probes.

Whereas early missions sent their data uncoded, starting from digital error correction was implemented in the form of sub-optimally decoded convolutional codes and Reed—Muller codes. The Voyager 1 and Voyager 2 missions, which started inwere designed to deliver color imaging amongst scientific information of Jupiter and Saturn.

The Voyager 2 craft additionally supported an implementation of a Reed—Solomon code: Concatenated correction bit explained meaning are increasingly falling out of favor with space missions, and are replaced by more powerful codes such as Turbo codes or LDPC codes.

The different kinds of deep space and orbital missions that are conducted suggest that trying to find a "one size fits all" error correction system will be an ongoing problem for some time to come. For missions close to Earth the nature of the noise in the communication channel is different from that which a spacecraft on an interplanetary mission experiences.

Additionally, as a spacecraft increases its distance from Earth, the problem of correcting for noise gets larger.

The demand for satellite transponder bandwidth continues to grow, fueled by the desire to deliver television including new channels and High Definition TV and IP data. Transponder availability and bandwidth constraints have limited this growth, because transponder capacity is determined by the selected modulation scheme and Forward error correction FEC rate.

Error detection and correction bit explained meaning codes are often used to improve the reliability of data storage media. The "Optimal Rectangular Code" used in group coded recording tapes not only detects but also corrects single-bit errors. Reed Solomon codes are used in compact discs to correct errors caused by scratches.

Modern hard drives use CRC codes to detect and Reed—Solomon codes to correct minor errors in sector reads, and to recover data from sectors that have "gone bad" and store that data in the spare sectors. Filesystems such as ZFS or Btrfsas well as some RAID implementations, support data correction bit explained meaning and resilvering, which allows bad blocks to be detected and hopefully recovered before they are used. The recovered data may be re-written to exactly the same correction bit explained meaning location, to spare blocks elsewhere on the same piece of hardware, or the data may be rewritten onto replacement hardware.

DRAM memory may provide increased protection against soft errors by relying on error correcting codes.

Such error-correcting memoryknown as ECC or EDAC-protected memory, is particularly desirable for high fault-tolerant applications, such as servers, as well as deep-space applications due to increased radiation. Error-correcting memory controllers traditionally use Hamming codesalthough some use triple modular redundancy. Interleaving allows distributing the effect of a single cosmic ray potentially upsetting multiple physically neighboring bits across multiple words by associating neighboring bits to different words.

As long as a single event upset SEU does not exceed the error threshold e. In addition to hardware providing features required for Correction bit explained meaning memory to operate, operating systems usually contain related reporting facilities that are used to provide notifications when soft errors are transparently recovered.

An increasing rate of soft errors might indicate that a DIMM module needs replacing, and such feedback information would not be easily available without the related reporting capabilities. One example is the Linux kernel 's EDAC subsystem previously known as bluesmokewhich collects the data from error-checking-enabled components inside a computer system; beside collecting and reporting back the events related to ECC memory, it also supports other checksumming errors, including those detected on the PCI bus.

A few systems also support memory scrubbing. From Wikipedia, the free encyclopedia. Not to be confused with error handling. This article needs correction bit explained meaning citations for verification.

Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. August Learn how and when to remove this template message.

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A bit is a type of horse tack used in equestrian activities, usually made of metal or a synthetic material, and is placed in the mouth of a horse or other equid and assists a rider in communicating with the animal. It rests on the bars of the mouth in an interdental region where there are no teeth. It is held on a horse's head by means of a bridle and has reins attached for use by a rider.

A bit functions through the principle of negative reinforcement: The rider applies pressure through the reins to the bit in the horse's mouth and the horse is reinforced or rewarded for the correct response by softer contact or a release or pressure, depending on the style of riding. Studies have indicated that soft, consistent bit contact between the rider and horse causes the animal less stress than intermittent or unpredictable contact. Although there are hundreds of design variations, the basic families of bits are defined by the way in which they use or do not use leverage.

Bits are further described by the style of mouthpiece that goes inside the horse's mouth as well as by the type of bit ring or bit shank that is outside the mouth, to which the reins are attached. Types of headgear for horses that exert control with a noseband rather than a bit are usually called hackamores , [3] though the term " bitless bridle " has become a popular colloquialism in recent years.

The riders of early domesticated horses probably used some type of bitless headgear made of sinew, leather, or rope. For this reason, no one can say with certainty which came first, the bitted or the bitless bridle. To date, the earliest known artistic evidence of use of some form of bitless bridle comes in illustrations of Synian horseman, dated approximately BC. The first bits were made of rope, bone, horn, or hard wood. Metal bits came into use between and BC, originally made of bronze. Bits also can be made of other materials such as rubber or plastic, sometimes in combination with metals.

Throughout history, the need for control of horses in warfare drove extensive innovation in bit design, producing a variety of prototypes and styles over the centuries, from Ancient Greece into modern-day use.

A bit consists of two basic components, the bit mouthpiece that goes inside the horse's mouth, and the bit rings of a snaffle bit or shanks of a curb bit , to which the bridle and reins attach. All bits act with some combination of pressure and leverage, often in conjunction with pressure applied by other parts of the bridle such as the curb chain on the chin, noseband on the jaw and face, or pressure on the poll from the headstall.

It is the sidepieces and the leverage these rings or shanks use to act on a horse's mouth that determines whether a bit is in the curb or snaffle family, and has a great impact on the severity of the mouthpiece. The mouthpiece of a horse's bit is the first factor most people think of when assessing the severity and action of the bit. Therefore, it is carefully considered when choosing a bit for a horse. Many mouthpieces are not allowed in certain competitions.

Bit mouthpieces may be single jointed, double-jointed, "mullen" a straight bar , or have an arched port in the center of varying height, with or without joints.

Some have rollers, rings or small "keys" that the horse can move with its tongue. Mouthpieces may be smooth, wire-wrapped or otherwise roughened, or of twisted wire or metal. Various types of metal or synthetic substances are used for bit mouthpieces, which may determine how much a horse salivates or otherwise tolerates a bit; a horse having a moist mouth is considered more relaxed and responsive.

Commonly used metals include stainless steel and nickel alloys, which generally do not rust and have a neutral effect on salivation; sweet iron , aurigan and copper , which generally tend to encourage salivation, and aluminum, which is considered drying and is discouraged as a mouthpiece metal.

Synthetic mouthpieces may be made with or without internal metal cable or bar reinforcement. Rubber bits are generally thicker than metal bits, but other types of synthetics such as plastics are also used. Plastic-coated bits are often the same size as metal bits, and some are flavored. Often, bits with shanks that also have single- or double-jointed mouthpieces are incorrectly referred to as snaffles.

Because of the presence of a shank, they are actually in the curb bit family. The mouthpiece of the bit does not rest on the teeth of the horse , but rather rests on the gums or "bars" of the horse's mouth in an interdental space behind the front incisors and in front of the back molars.

When a horse is said to "grab the bit in its teeth" they actually mean that the horse tenses its lips and mouth against the bit to avoid the rider's commands although some horses may actually learn to get the bit between their molars. Depending on the style of bit, pressure can be brought to bear on the bars, tongue, and roof of the mouth, as well as the lips, chin groove and poll.

Bits offer varying degrees of control and communication between rider and horse depending upon their design and on the skill of the rider. It is important that the style of bit is appropriate to the horse's needs and is fitted properly for it to function properly and be as comfortable as possible for the horse. In the wrong hands even the mildest bit can hurt the horse.

Conversely, a very severe bit, in the right hands, can transmit extremely subtle, nuanced signals that cause no pain to the horse. Commands should be given with only the quietest movements of the hands, and most steering is done with the legs and seat.

Thus, instead of pulling or jerking the horse's head to change direction by force, a skilled rider indicates the desired direction by tightening and loosening the grip on the reins.

The calf of the leg is used to push the body of the horse in a certain direction while the other one is used as a pivot and to provide the correct amount of impulsion required to keep the horse moving. Likewise, when slowing or stopping, a rider sits deeper in the saddle and closes their hands on the reins, avoiding jerking on the horse or hauling back on the reins in a "heavy-handed" fashion.

Change of position of the seat and the pressure of the rider's seat bones are also extremely useful for turning, speeding up and slowing down. There are many factors in the bitting equation which must be considered to get a true estimate of the action and severity of a bit. Although some mouthpieces are marketed as "correction" a euphemism for "severe" bits or "training" implying a mild bit , the terms are relative.

The bit always rests on the sensitive bars of a horse's mouth. A hard-handed rider can make even the mildest bit painful, and a skilled, light-handed rider can ride in a much harsher mouthpiece without damaging the mouth or causing any distress in the horse. Additionally, the shank or ring has a great impact on the action of the mouthpiece. Snaffles are generally considered the mildest, curbs and gags the harshest. It is difficult, therefore, to compare a harsher-type bit with a mild mouthpiece such as a pelham with a rubber mullen mouth , and a milder-type bit with a harsher mouthpiece like a thin snaffle with a slow twist.

In general, however, the mouthpiece can have a marked difference on the severity. Snaffles with twisted wires are never considered mild, whereas a pelham with a low port could. All bits work with either direct pressure or leverage. Bits that act with direct pressure on the tongue and lips are in the general category of snaffle bits. Snaffle bits most commonly have a single jointed mouthpiece and act with a nutcracker effect on the bars, tongue and occasionally roof of the mouth.

However, any bit that operates only on direct pressure is a "snaffle" bit, regardless of mouthpiece. Bits that have shanks coming off the bit mouthpiece to create leverage that applies pressure to the poll, chin groove and mouth of the horse are in the category of curb bits.

Most curb bit mouthpieces are solid without joints, ranging from a straight bar with a slight arch, called a "mullen" mouthpiece, through a "ported" bit that is slightly arched in the middle to provide tongue relief, to the full spade bit of the Vaquero style of western riding which combines both a straight bar and a very high "spoon" or "spade" extension that contacts the roof of the mouth.

The length of the shank determines the degree of leverage put on the horse's head and mouth. Again, a bit with shanks and leverage is always a "curb" type bit, even when it has a jointed mouthpiece more commonly seen on a snaffle such bits are sometimes—incorrectly—called "cowboy snaffles".

All shanked bits require the use of a curb chain or curb strap for proper action and safe use. Some bits combine both direct pressure and leverage, the most common examples being the Pelham bit , which has shanks and rings allowing both direct and leverage pressure on a single bit and is ridden with four reins; [3] the Kimblewick or Kimberwicke , a hybrid bit that uses minimal leverage on a modified snaffle-type ring combined with a mouthpiece that is usually seen more often on curb bits, ridden with two reins; [13] and the double bridle , which places a curb and a snaffle bit simultaneously in the horse's mouth so that each may act independently of the other, ridden with four reins.

Another bit that combines direct pressure and leverage in a unique manner is the Gag bit , a bit derived from the snaffle that, instead of having a rein attached to the mouthpiece, runs the rein through a set of rings that attach directly to the headstall, creating extra pressure on the lips and poll when applied. Usually used for correction of specific problems, the gag bit is generally illegal in the show ring [14] and racecourse.

Bits and the behavior of horses while wearing bits have made their way into popular culture outside of the horse world.

From Wikipedia, the free encyclopedia. For other uses, see bit disambiguation. Archived from the original on The Whole Horse Catalog: Revised and Updated New York: Horse tack and other equine equipment. Saddles , component parts and accessories. Bits , bridles and hackamores. Bridle Hackamore Double bridle Bitless bridle.

Horse harness and carriages. Blinders or blinkers Shadow roll Bearing rein or overcheck. Tack accessories and training tools. Halter Lead tack Grooming tools Horse blanket Fly mask. Hobble device Picket line Twitch device Cattle crush. Historic or ceremonial equipment. Horseshoe Hoof boot Caulkins. Glossary of equestrian terms Category: Horse tack and equipment.

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