The aim of this chapter is to review: (1) the Sampling (Nyquist) Theorem; (2) the concept of aliasing; (3) the importance of antialiasing low-pass filtering for eliminating the effect of aliasing and appropriately determining the sampling frequency; (4) the advantages of properly chosen ...
To properly measure a signal, the digital sampling rate must be at least twice the highest frequency contained within that signal. This is known as the Nyquist sampling theorem. The aliasing phenomenon is not confined to MRI but is present in all types of technology, explaining audible distortion...
Throughout the series, the version of the sampling theorem I have used states that perfect reconstruction is possible when the sampling rate is equal to or greater than two times the highest frequency in the original signal—not the frequency of interest, not the dominant frequency, bu...
Click on theHelptab in the box on the right, then selectEducational Apps. TheImatestEducational app, illustrating the Sampling theorem. You can adjust the Frequency and Phase with sliders. By adjusting Frequency you can see how aliasing (output signal at a lower frequency than the input signal...
Equation 13, commonly called the sampling theorem, is the result for which we have been working. It shows that sampling in the time domain at intervals of T seconds replicates the spectrum of our unsampled signal every 1/T cycles per second. Fi gur e 2 shows ...
Chapter6Anti-aliasingMethodsandSampling StrategiesIntroduction: LastChapter5showedhowtoestimatethemaximumsamplingrateofan hardwareacquisitionstructure,startingfromitscharacteristicfeatures.The samplingtheorem,discussedinChapter3,provesthat,inordertoensurea correctsampling,acontinuoustimesignalmustbeupper-boundedinthe ...
采样频率,所以将stride从4调整为2,与之相应的将...kernel size也缩小(可以认为stride变小了,kernel没有必要看那么大范围了),这样修改前后,特征的变化情况如下图所示,第1层呈现了更多更具区分力的特征,第二2层的特征也更加清晰,没有aliasing...更多关于aliasing的内容,可以参见Nyquist–Shannon sampling theorem和...
According to the Nyquist sampling theorem, the sampling rate should be at least twice the maximum frequency component of the signal of interest. In other words, the maximum frequency of the input signal should be less than or equal to half of the sampling rate. How do you ensure that this...
An anti-aliasing filter (AAF) is a filter used before a signal sampler to limit the bandwidth of a signal to just about or persuade the Nyquist–Shannon sampling theorem above the band of interest. In the sight of the fact that the theorem states that an explicit reconstruction of the sign...
However, convolutional neural networks (CNNs) used as the backbone for object detection architectures typically neglect Nyquist's sampling theorem during down-sampling operations, resulting in aliasing and degraded performance. This is likely to be a particular issue for tiny objects that occupy very ...