Passband bandwidth is the difference between the upper and lower cutoff frequencies of, for example, an bandpass filter, a communication channel, or a signal spectrum.

Bandwidth typically refers to baseband bandwidth in the context of, for example, sampling theorem and Nyquist sampling rate, while it refers to passband bandwidth in the context of Nyquist symbol rate or Shannon-Hartley channel capacity for communication systems.

The 3 dB bandwidth of an electronic filter or communication channel is the part of the system's frequency response that lies within 3 dB of the response at its peak, which in the passband filter case is typically at or near its center frequency, and in the lowpass filter is near 0 hertz.

In communication systems, in calculations of the Shannon – Hartley channel capacity, bandwidth refers to the 3dB-bandwidth.

The fact that in equivalent baseband models of communication systems, the signal spectrum consists of both negative and positive frequencies, can lead to confusion about bandwidth, since they are sometimes referred to only by the positive half, and one will occasionally see expressions such as, where is the total bandwidth ( i. e. the maximum passband bandwidth of the carrier-modulated RF signal and the minimum passband bandwidth of the physical passband channel ), and is the positive bandwidth ( the baseband bandwidth of the equivalent channel model ).

Each character in the alphabet is represented by a series of bits, sent over a communication channel such as a telegraph wire or a radio signal.

In the presence of " communication noise " on the transmission channel ( air, in this case ), reception and decoding of content may be faulty, and thus the speech act may not achieve the desired effect.

In any communication model, noise is interference with the decoding of messages sent over a channel by an encoder.

* Decoding methods, methods in communication theory for decoding codewords sent over a noisy channel

Code division multiple access ( CDMA ) is a channel access method used by various radio communication technologies.

One of the concepts in data communication is the idea of allowing several transmitters to send information simultaneously over a single communication channel.

In their view, the computational medium in cyberspace is an augmentation of the communication channel between real people ; the core characteristic of cyberspace is that it offers an environment that consists of many participants with the ability to affect and influence each other.

Many communication channels are subject to channel noise ,</ ref >

This is combined with time domain statistical multiplexing ; i. e., packet mode communication, which makes it possible for several users to share the same frequency channel.

Such robustness is as essential for an electronic communication system as it is for a language ; properly building such robustness into communications is done by channel coding.

The most fundamental results of this theory are Shannon's source coding theorem, which establishes that, on average, the number of bits needed to represent the result of an uncertain event is given by its entropy ; and Shannon's noisy-channel coding theorem, which states that reliable communication is possible over noisy channels provided that the rate of communication is below a certain threshold, called the channel capacity.

Coding theory is concerned with finding explicit methods, called codes, of increasing the efficiency and reducing the net error rate of data communication over a noisy channel to near the limit that Shannon proved is the maximum possible for that channel.

* the mutual information, and the channel capacity of a noisy channel, including the promise of perfect loss-free communication given by the noisy-channel coding theorem ;

The former quantity indicates how easily message data can be compressed while the latter can be used to find the communication rate across a channel.

There is usually a trade-off between interrupt latency, throughput ( the average rate of successful message delivery over a communication channel ), and processor utilization.

In practice an analog signal is subject to electronic noise and distortion introduced by communication channels and signal processing operations, which can progressively degrade the signal-to-noise ratio.

Whilst distractions like background noise, poor lighting or an environment which is too hot or cold can all affect people's morale and concentration, which in turn interfere with effective communication.

Noise that physically disrupts communication, such as standing next to loud speakers at a party, or the noise from a construction site next to a classroom making it difficult to hear the professor.

* Errors: Disturbances ( noise ) in analog communications invariably introduce some, generally small deviation or error between the intended and actual communication.

* Copying: Because of the inevitable presence of noise, making many successive copies of an analog communication is infeasible because each generation increases the noise.

DSP processor ICs are found in every type of modern electronic systems and products including, SDTV | HDTV sets, radios and mobile communication devices, Hi-Fi audio equipments, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio processing and speech processing systems.

Fall back is a feature of a modem protocol in data communication whereby two communicating modems which experience data corruption ( due to line noise, for example ) can renegotiate with each other to use a lower-speed connection.

In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.

In a communication system, the receiver side BER may be affected by transmission channel noise, interference, distortion, bit synchronization problems, attenuation, wireless multipath fading, etc.

* Animal communication, a song or noise made by an animal such as:

A channel code contains redundancy to allow more reliable communication in the presence of noise.

In FM transmission, emphasis is the intentional alteration of the amplitude-vs .- frequency characteristics of the signal to reduce adverse effects of noise in a communication system.

This is an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.

Mode partition noise: In an optical communication link, is phase jitter of the signal caused by the combined effects of mode hopping in the optical source and intramodal distortion in the fiber.

High noise levels can block, distort, change or interfere with the meaning of a message in human, animal and electronic communication.

Phase or frequency modulated communication systems may suffer from phase noise due to synchronization problems and time-invariant channel conditions, caused by mobility, fading and doppler shift.

Deliberate generation of communication system noise and interference is called jamming.

Since the air is a continuum, the network of communication remains intact regardless of the positions or motions of the points ( the people ) in the net.

As shown in Figure 1, there is a connection for communication between every pair of points.

We assume for this illustration that the size of the land plots is so great that the distance between dwellings is greater than the voice can carry and that most of the communication is between nearest neighbors only, as shown in Figure 2.

Since the hazards of poor communication are so great, p can be justified as a habitable site only on the basis of unusual productivity such as is made available by a waterfall for milling purposes, a mine, or a sugar maple camp.

With troops dispersed on fields of battle rather than on the parade ground, it may seem that a certain amount of monitoring is automatically enforced by the lines of communication.

The connective system, or network, is tailored to meet the requirements of the objective, and it is therefore not surprising that a military body acting as a single coordinated unit has a different communication network than a factory, a college, or a rural village.

The existence of a community is a state of mind -- a conviction that goals and values are widely shared, that effective communication is possible, that mutual trust is reasonably assured.

One of the obstacles to the easy control of a 2-year-old child is a lack of verbal communication.

It is true, that nothing has been found comparable with electricity by communication ; ;

in working with these patients the therapist eventually gets to do some at least private mulling over of the possible meaning of a belch, or the passage of flatus, not only because he is reduced to this for lack of anything else to analyze, but also because he learns that even these animal-like sounds constitute forms of communication in which, from time to time, quite different things are being said, long before the patient can become sufficiently aware of these, as distinct feelings and concepts, to say them in words.

Partly this difference is due to the nature of verbal communication.

It is only fairly recently, however, that linguists have developed a systematic way of charting voices on paper in a way that tells even more about the speakers and about the success or failure of human communication between two people.

And while the meaning of the words is not in this instance altered, the quality of communication in both the second and third examples is definitely impaired.

Since the psychiatric interview, like any other interview, depends on communication, it is significant to note that the therapist in this interview was a man of marked skill and long experience.

As was noted earlier, it is important that in valid, objective study of this sort of communication, the interested sitter should be separated from the sensitive.

If communication with an entity on the `` other side '' is taking place, this too may assume the form of clairvoyant symbolism.

The first step toward the goal is the establishment of a new atmosphere of mutual good will and friendly communication on other than the polemical level.

The only way that I can see is through communication.

This is a virtue of which we have great need in a society where there seems to be an increasing lack of communication -- or even desire for communication -- between differing schools of thought.