Acquisition simultaneous

The AEBIL system simultaneously carries out acquisition and processing of 2 main sets of data ... 

This means an acquisition rate of 64 channels simultaneously, and 128 data channels as 2 frequencies are used. The acquisition speed is 140 points per second for each channel, meaning practically 6 to 12 points per rod mm. Since the method was developed 10 years ago, the processing and analysis time of this amount of information (20 Mbytes average) was long and difficult. 

The measurement of surface forces calls for a rigid apparatus that exhibits a high force sensitivity as well as distance measurement and control on a subnanometre scale [38]. Most SFAs make use of an optical interference teclmique to measure distances and hence forces between surfaces. Alternative distance measurements have been developed in recent years—predominantly capacitive techniques, which allow for faster and simpler acquisition of an averaged distance [H, 39, 40] or even allow for simultaneous dielectric loss measurements at a confined interface. 

With such aTOF-imaging SSIMS instrument, the useful mass range is extended beyond 10000 amu the mass resolution, m/Am, is -10000 with simultaneous detection of all masses and within each image, all masses can be detected. The number of data generated in a short time is enormous, and very sophisticated data acquisition systems are required to handle and process the data. 

The advantage of the imaging mode is fast data acquisition. Because all pixels are projected and detected simultaneously the measurement time for one distribution is extremely low. 

Greatly enhanced sensitivity with very short measuring time is the major advantage of PFT (pulse Fourier transform) experiments. In the CW (continuous wave) experiment, the radiofrequency sweep excites nuclei of different Larmor frequencies, one by one. For example, 500 s may be required for excitation over a 1-KHz range, while in a PFT experiment a single pulse can simultaneously excite the nuclei over 1-KHz range in only 250 jits. The PFT experiment therefore requires much less time than the CW NMR experiment, due to the short time required for acquisition of FID signals. Short-lived unstable molecules can only be studied by PFT NMR. 

The INEPT experiment can be modified to allow the antiphase magnetization to be precessed for a further time period so that it comes into phase before data acquisition. The pulse sequence for the refocused INEPT experiment (Pegg et al., 1981b) is shown in Fig. 2.13. Another delay, A. is introduced and 180° pulses applied at the center of this delay simultaneously to both the H and the C nuclei. Decoupling during data acquisition allows the carbons to be recorded as singlets. The value of Z), is adjusted to enable the desired type of carbon atoms to be recorded. Thus, with D, set at V4J, the CH carbons are recorded at VsJ, the CH2 carbons are recorded and at VeJ, all protonated carbons are recorded. With D3 at %J, the CH and CH ( carbons appear out of phase from the CH2 carbons. 

Optical emision spectra nowadays are simply measured using a fiber optic cable that directs the plasma light to a monochromator, which is coupled to a photodetector. By rotating the prism in the monochromator a wavelength scan of the emitted light can be obtained. Alternatively, an optical multichannel analyzer can be used to record (parts of) an emission spectrum simultaneously, allowing for much faster acquisition. A spectrometer resolution of about 0.1 nm is needed to identify species. 

In addition to the Mossbauer data, SDDs allow the simultaneous acquisition of the XRF spectrum, thus providing data on the sample s elemental composition. A new control- and readout-electronics for MIMOS llA allows spectra acquisition at highest possible count rates available at a total detector area of 360 mm. ... 

Fig. 1.4 Phase encoding scheme in three ween the rf pulses and before the acquisition of dimensions. Three pulsed gradients in ortho- the echo signal. In practice, the gradients are gonal directions are applied and are varied often applied simultaneously. The indices 1, 2 independently of each other (symbolized by the and 3 represent orthogonal directions with no diagonal line). The actual timing of the gradi- priority being given to a particular choice of ents is arbitrary provided they are placed bet- combinations.

The data acquisition is performed using an ADC board (PC-414G3, DATEL, USA). Because the ADC board has 14-bit resolution, simultaneous two-channel acquisition capability up to 1 MHz sampling rate and 32 Kword FIFO buffer memory, it has sufficient performance for most MRI applications. 

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