Fourier Transforms in PhysiCs: Diffraction Macroscopic information in the far field provides microscopic(invis ible) information about the grating D 信号与系统
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Fourier Transforms in Physics: Crystallography What if the target is more complicated than a grating? target mage 信号与系统
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Fourier Transforms in Physics: Crystallography Part of image at angle g has contributions for all parts of the target target Image 信号与系统
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Fourier Transforms in PhysiCS: Crystallography The phase of light scattered from different parts of the target un- dergo different amounts of phase delay Phase at a point a is delayed (i.e, negative) relative to that at 0 p=__2sin 8 入 信号与系统
信号与系统
. o ADTMF signal consists of the sum of 1209Hz1336Hz1477Hz two sinusoids-or tones- with frequencies taken from two mutually 697 exclusive groups. These frequencies were chosen to prevent any harmonics from being incorrectly detected by the receiver as some other dme frequency. Each pair of tones contains Y 852Hz one frequency of the low group(697 Hz, 770 Hz, 852 HZ, 941 Hz) and one frequency of the high group (1209 Hz, 1336 Hz, 1477Hz) and represents a unique symbol. The frequencies allocated to the push-buttons of the telephone pad are shown below 信号与系统
❖ A DTMF signal consists of the sum of two sinusoids - or tones - with frequencies taken from two mutually exclusive groups. These frequencies were chosen to prevent any harmonics from being incorrectly detected by the receiver as some other DTMF frequency. Each pair of tones contains one frequency of the low group (697 Hz, 770 Hz, 852 Hz, 941 Hz) and one frequency of the high group (1209 Hz, 1336 Hz, 1477Hz) and represents a unique symbol. The frequencies allocated to the push-buttons of the telephone pad are shown below: 信号与系统