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Technolgy of materials preparation for the high sensitivity infrared detectors
Novotný, Jan ; Zelinka, Jiří ; Franc, J.
Single crystals of triglycine sulphate (TGS) doped with L-alanin, lysin and with Co.sup.2+.sup., Cd.sup.2+.sup. and PO.sub.4./sub..sup.3-.sup. were grown from aqueous solutions by means of slow cooling method. Concentration of doping elements varied from 5 to 20mol. per cent. Morphology, domain structure and P-E hysteresis loops have been investigated. TGS single crystals doped with Co.sup.2+.sup. and PO.sub.4./sub..sup.3-.sup. show the inernal fields as high as 217 kV/m with peculiarities in the hysteresis loops. The best hysteresis loop has been obtained on TGS crystal doped with Lysin and Cd.sup.2+.sup. ions.
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Estimation of the parameters of quartz oscillators
Čermák, Jan
The main parameters of quartz oscillators are frequency accuracy, frequency drift, and frequency (phase) stability. Methods used to estimate these parameters depend on the oscillator quality and measurements capability of the calibration laboratory. The issue is demonstrated on the measurements performed within the National Time and Frequency Standard.
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Frequency synthesizers with sigma-delta modulation
Kroupa, Věnceslav František ; Štursa, Jarmil
We shall discus basic parameters of the steering signal. This signal is built in the sigma-delta modulator and controls pulse removing in the PLL frequency synthesizer. We shall investigate the dependence of these parameters on sigma-delta modulator order and give spurious phase spectrum of the fractional-N synthesizer with a low-pass filter of high degree.
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