Poisson Noise: The x-ray and gamma ray sources emitted number of photons per unit time. These sources are having random fluctuation of photons. Result gathered image has spatial and temporal randomness. This noise is also called as quantum (photon) noise or shot noise.

In electrical terms, noise is defined as the unwanted form of energy which tends to interface with the proper reception and the reproduction of transmitted signals. Electronic Devices unwanted random addition to the signal are considered as Noise. Their are various types of Noise presents.

Intensity noise at the shot noise level is obtained e.g. for a so-called coherent state, which may be approximated by the output of a laser at high noise frequencies. At lower noise frequencies, laser noise is normally much higher due to relaxation oscillations, mode hopping, excess pump noise, and other phenomena.

Thermal noise in an ideal resistor is approximately white, meaning that the power spectral density is nearly constant throughout the frequency spectrum (however see the section below on extremely high frequencies).

Which of broad classifications of noise are most difficult to treat? Explanation: Noise which is generated inside the receiver is very much difficult to handle. 5.

Thermal noise is a noise that is a result of the thermal agitation of electrons. The thermal noise power depends of the bandwidth and temperature of the surroundings.

The noise level is dependent only upon the temperature and the value of the resistance. Therefore the only ways to reduce the thermal noise content are to reduce the temperature of operation, or reduce the value of the resistors in the circuit.

The two options to reduce noise originating in DC/DC converters are π-filters and active devices such as LDOs or power filters. The π-filter is composed of two capacitors separated by an inductor or ferrite bead.

Intermodulation noise is due to the presence of the products of intermodulation. If a number of signals are passed through a non-linear device the result will be intermodulation products that are spurious frequency components. These components may be inside or outside the frequency band of interest for the device.

Crosstalk is the transmission of signals and noise due to coupling between lines, and is also called interference. The term “crosstalk” itself is evocative of the age of analog telephony, and of “talking across lines”. As a result of these, noise is induced.

Crosstalk delay: Crosstalk delay is same as noise but in this case both the nets are not in a steady state. there is some transition happening on both the nets. crosstalk delay depends on the propagating direction of the aggressor and victim nets which makes the transition slower or faster.

Induced noise is the noise generated in a circuit by a varying magnetic or electrostatic field produced by another circuit. Induced noise, just like any other electrical noise, degrades the useful signal and may lead to equipment errors, shutdown, or malfunction.

Design Methodology for How to Reduce Crosstalk

1. Configure your board layers so that two adjacent signal layers will have preferred routing directions that cross each other instead of running parallel to each other.
2. Use ground planes between two adjacent signal layers to reduce the chance of broadside coupling even more.

Crosstalk happens when the signal from one cable gets mixed up with the signal in another cable. This can happen when cables run too closely together. Some cables use shielding to help reduce the impact of crosstalk. If shielded cable is not used, cables should not be run directly near each other.

In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit or channel to another.

Near-end crosstalk (NEXT) is an error condition that can occur when connectors are attached to twisted pair cabling. NEXT is usually caused by crossed or crushed wire pairs. The error condition does not require that the wires be crushed so much that the conductors inside become exposed.

To obtain the crosstalk as a percentage of the offender voltage, take the difference of the induced voltages at the near (NEXT) or far (FEXT) end of the victim, and divide it by the difference between the positive and negative voltages on the offender.

Power sum near end crosstalk, abbreviated at PSNEXT, is simply a calculation that sums the NEXT measurement of all adjacent pairs. NEXT measures the crosstalk on each pair of a four-pair cable as affected by the other three pairs individually.

Far-End Crosstalk (FEXT) This crosstalk is similar to NEXT except that it appears at the opposite end of the cable from where the signal was sent. The signals at the far end of the transmitting pair are much weaker than the signals at the near end due to attenuation.

Crosstalk is a phenomenon, by which a logic transmitted in vlsi circuit or a net/wire creates undesired effect on the neighbouring circuit or nets/wires, due to capacitive coupling. Refer to the digram below to get a clear picture on the effect of coupling capacitance on functionality and timing of VLSI circuits.

Crosstalk. Older versions of UTP cable (for example, Category 3 or 5) are more susceptible to crosstalk than newer versions such as Cat 5e or Cat 6. Although data emanation can be a problem with UTP cable, it is more common with coaxial cable, as is vampire tapping.

The near-end far-end (ratio) interference can occur among the neighboring channels (four channels on each side of the desired channel). In an omni directional-cell system, if one channel is assigned to the middle cell of seven cells, next channels cannot be assigned in the same cell.