Device under test

The temperature dependence of the fabricated open cavity FP device was evaluated experimentally. The sensor was placed in a programmable electric tubular furnace. The temperature of the furnace was increased from room temperature to 1,100°C at a step of 50°C. The cavity length as a function of the temperature is plotted in Fig. 7.11, where it increased nearly linearly following the increase of temperature. The temperature sensitivity of the particular FP device under test was estimated to be 0.074 nm °C 1 based on the linear fit of the measurement data. The equivalent coefficient of thermal expansion (CTE) of the fiber FP device was 2.4x10 6oC. ... 

EIS data is generally interpreted based on defining an appropriate equivalent circuit model that best fits the acquired data. The elements of the circuit model involve a specific arrangement of resistors, capacitors, and inductors that tacitly represent the physicochemical reality of the device under test. Under these circumstances the numerical value for chemical properties of the system can be extracted by fitting the data to the equivalent circuit model. Impedance measurements are typically described by one of two models ... 

In the literature on measuring the quality of audio devices one mostly finds measurement techniques that characterize the audio device under test. The characterization either has build in knowledge of human auditory perception or the characterization has to be interpreted with knowledge of human auditory perception. 

Figure 1.1 Overview of the basic philosophy used in the development of perceptual audio quality measurement techniques. A computer model of the subject is used to compare the output of the device under test (e.g. a speech codec or a music codec) with the ideal, using any audio signal. If the device under test must be transparent then the ideal is equal to the input.

In general, the quantities being determined by microwave measurements are complex reflection and transmission coefficients or complex impedances normalized to the impedances of the transmission lines connecting a network analyser and the device-under-test (dut). In addition to linear frequency domain measurements by means of a network analyser the determination of possible non-linear device (and thus material) properties requires more advanced measure-... 

The match between a simulator spectrum E s(A) and the reference AM 1.5G spectrum r(A) is never perfect, even for the best solar simulators. Furthermore, a spectral mismatch is introduced because the spectral responses St (A) of the device under test and Sr.(A) of the reference cell are not identical. In order to correct for this, a spectral mismatch factor M can be computed from... 

However, for relatively new types of solar cells such as the polymer-based solar cells described here, suitable stable reference cells cannot yet be fabricated. This implies that, for measurements concerning these cells, calibrated reference cells are used (Si, GaAs) with a different spectral response to the device under test, resulting in mismatch factors that deviate significantly from 1. It is therefore of the utmost importance to carry out the procedure as precisely as possible in order to minimise measurement errors. 

As long as this test pulse is low enough, no damage is done to the device under test, and we have a 100% screening process. For expensive ordnance items, the costs of this type of testing is more than offset by the increased lot yields. 

Force sensors are not used in general automotive applications. In agricultural machines a force sensor measures the load at the connection rod [1], Some force sensors are specially made for measuring forces during vehicle testing and validation. Often metal strain gauges are welded to the devices under test The data is sometimes needed for system development or to verify simulation results. The first and only mass production of torque sensors is in electrical steering systems [2]. 

Fig. 7.6. Sample Bell arrangement for feeding vapor to a device under test (DUT)...

A simplified diagram of a potentiostat is shown in Fig. 3.6. Most potentiostats have three or four test leads to be connected to the cell or device under test. The three leads that are always present are those for the working (WE), counter (CE), and reference (REF) electrodes. The optional fourth one is basically a second reference electrode which senses the potential of the working electrode. Depending on the manufacturer, it is labeled as SENSE or RE2 or REE2. If no fourth test lead is present, it means that it is internally connected to the working electrode connection. The potentiostat s aim in life is simple it measures the potential difference between the REF and SENSE inputs, and makes sure that it stays equal to the desired potential difference by adjusting the potential at the CE output. The desired potential... 

Device under test (DUT) A term used to describe the device being tested by the ATE. 

Measurement of level is fundamental to most audio specifications. Level can be measured either in absolute terms or in relative terms. Power output is an example of an absolute level measurement it does not require any reference. SNR and gain or loss are examples of relative measurements the result is expressed as a ratio of two measurements. Although it may not appear so at first, frequency response is also a relative measurement. It expresses the gain of the device under test as a function of frequency, with the midband gain, typically, as a reference. 

Harmonic distortion measurements excite the device under test with a sine wave and measure the spectrum of the output. Because of the nonhnearity of the transfer characteristic, the output is not sinusoidal. By using Fourier series, it can be shown that the output waveform consists of the original input sine wave plus sine waves at integer multiples (harmonics) of the input frequency. The spectrum of the... 

A common consideration for system-wide distortion measurements is that of distortion addition and cancellation in the devices under test. Consider the example given in Fig. 20.13. Assume that one... 

Multitone test techniques use carefully designed mixtures of tones applied simultaneously to the device under test (DUT). The individual tone elements have weU-defined frequency, phase, and amplitude relationships. The frequencies of multitone components are selected to avoid mathematically predictable harmonic and intermodulation products that would fall on or near any of the fundamentals. The phase of each tone is fixed, but randomly selected relative to each of the other tones. Amplitude relationships may vary, depending on the device under test. 

For noise and distortion measurements, the eight bins surrounding each fundamental in a multitone are set to zero. The remaining bins are plotted to represent the noise (and distortion) floor of the device under test. 

Multitone testing A measurement technique whereby an audio system is characterized by the simultaneous apphcation of a combination of sine waves to a device under test. 

There is a great body of statistical literature devoted to identifying the failure rate of devices under test. We just present a conceptual survey of rates. 

Drop out current (relay), 137 Dual in-line package (DIP), 252 Dump of computer data, 259 DUT (device under test), 152 DVD recording, 213, 255, 277... 

There are scores of microwave devices that need to be measured. The most common measurements tirat are done are the frequency measurements, but we are also interested in phase measurements depending on the device under test (DUT). We can use various equipments like spectrum analyzer, vector network analyzer, etc. [33]. Most of the devices that we measure will be two-port devices that is, the input is applied at one port and the output is taken at the other port. So we will basically be measuring devices, a group of devices that form a part of tiie system, and microwave circuits. 

In the fiber-optic thermometry probe technique, a temperahue sensor, consisting of a small amount of a temperature-sensitive material (manganese-activated magnesium fluorogermanate), is mounted on the end of a probe and is placed on the surface of the device under test (DUT). A filtered xenon flash lamp provides a blue-violet light to excite the phosphor on the probe to fluoresce. When excited by this wavelength of light, the phosphor in the sensor exhibits a deep red fluorescence. 

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