Noise detection

SPC techniques offer the advantage of low noise detection, providing / -values of 1-2 times lower than in analog detection. Although this can in principle result in four times faster acquisition speed this gain in speed is not realized in practice. In SPC, the comparatively high dead-times of detectors and electronics limits the acquisition speed. SPC system should be operated at count rates below the inverse of the dead-time of the system (electronics... 

Figure 5.17 An illustration of signal and noise. Detection limit is defined as the concentration that produces a signal that is double the noise level. 

The energy of the emitted radiation is strongly dependant on the material composition and may be somewhere in the total spectrum from the very ultra violet to the far infra-rad. Not all these wavelengths are suited for imaging, since low noise detection with a photomultiplier has to be possible as well therefore imaging is restricted to those wavelengths which are in the detectable range of the photomultiplier. 

In addition to the fiber sensors, there have been numerous reports on remote fiberless optical detection of pollution from stationary sources. Mobile remote sensors can have cost advantages over on-site instruments and also are much more versatile. Pollutants in smokestack emissions have been identified by irradiation with a laser from a mobile unit equipped with a telescope, a monochromator, and low-noise detection electronics. The gases and particles in the plume scatter the laser light in various directions. A fraction is scattered back to the receiver and analysed to detect the amount and type of gas in the plume. Many of these methods await their application to fiber-optic sensing schemes which are inherently safer than direct laser spectroscopic schemes. 

For hermetically sealed microcircuits several screen tests should be performed before delidding the package. A particle impact noise detection test (FIND [MIL-STD-883 Method 2020 or MEL STD-750D, Method 2052-2]) is recommended. This shake test combines a series of shocks and vibrations and, through an attached transponder, acoustically detects any loose particles (for example, chips of cured adhesive, solder, wire, ceramic, or loose plating) that have detached and can cause shorted or open circuits and damage or breakage of thin wires and connections. 

Particle Impact Noise Detection Test, MIL-STD-883, Method 2020.7. 

Figure 1 Determination of optimal ludferase quantity and background BRET. Luciferase titrations are plotted as a function of the amount of transfected energy donor DNA, in the absence of energy acceptor (fluorescent protein). The resulting BRET ratio (black circles) is plotted on the left Y axis, and the luminescence counts (white circles) are plotted on the right Y axis. The detected BRET ratio decreases to reach a background value that is stable over increasing luminescence, and that must be deduced from experimental BRET ratios to obtain BRETnet- This instrument-dependent stable background BRET is due to bleeding of the donor emission into the acceptor emission channel (note the scale difference between the BRET and BRET systems). The higher BRET ratios at too low luminescence counts are due to noise detection in the acceptor emission channel.

Third, noise detection is a common cause of false detection in the absence of tachycardia. Lead problems such as insulation breaks or conductor fracture can cause high-frequency signals that lead to spurious discharges (Fig. 20.8). 

Fig. 20.8 Top Noise detected on the ventricular channel leads to false detection of ventricular fibrillation. Bottom Daily monitoring of lead impedance in the same patient shows a sudden increase in resistance. In this case the patient was notified remotely via a home monitoring system and came to the pacemaker clinic before an inappropriate shock was delivered.

Rosenthal ME, and Paskman C. Noise detection during bradycardia pacing with a hybrid nonthoracotomy implantable cardioverter defibrillator system incidence and clinical significance. Pacing Clin Electrophysiol 1998 21 1380-1386. 

Analysis of electrochemical current noise Detection of pitting corrosion defects, signatures of specific corrosion types (pitting or crevice vs general) W(Mxl et al. (2002), Sulyma and Roy (2010h), Monticelli et al. (1998)... 

Tan, Y., 2009. Sensing locahsed corrosion by means of electrochemical noise detection and analysis. Sens. Actuators B 139, 688—698. 

Particle impact noise detection (PIND) tests, where each hybrid part or IC with a cavity where the die was unglassivated (insulated with a glass coating. Fig. 7.160 shows an IC with cracks in this coating), was vibrated and transducers, mounted on the part would detect if there were any particles rattling around. Parts with loose pieces in them were rejected from the shipment. 

Particle impact noise detection testing (PIND) A test where cavity devices are vibrated and monitored for the presence of loose particles inside the device package via the noise the material makes. These loose particles may be conductive (such as gold flake particles from gold eutectic die attachment operations) and could result in short circuits. This is not required on a 100% basis for military class B devices. It is required for aU class S, or devices generally required for spacecraft application use. 

Introduction Detection of Binary Signals in Additive White Gaussian Noise Detection of M-ary Signals in Additive... 

BOR-60 (Russian Federation) hydrogen measuring, acoustic noise detection... 

Noise, Detection Limits, and Linearity Other Practical Considerations... 

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