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相关概念视频

Upsampling01:22

Upsampling

180
Managing signal sampling rates is essential in digital signal processing to maintain signal integrity. A decimated signal, characterized by a reduced frequency range due to its lower sampling rate, can be upsampled by inserting zeros between each sample. This upsampling process expands the original spectrum and introduces repeated spectral replicas at intervals dictated by the new Nyquist frequency. To refine this zero-inserted sequence, it is passed through a lowpass filter with a cutoff...
180
Downsampling01:20

Downsampling

117
When considering a sampled sequence with zero values between sampling instants, one can replace it by taking every N-th value of the sequence. At these integer multiples of N, the original and sampled sequences coincide. This process, known as decimation, involves extracting every N-th sample from a sequence, thereby creating a more efficient sequence.
The Fourier transform of the decimated sequence reveals a combination of scaled and shifted versions of the original spectrum. This...
117
Aliasing01:18

Aliasing

104
Accurate signal sampling and reconstruction are crucial in various signal-processing applications. A time-domain signal's spectrum can be revealed using its Fourier transform. When this signal is sampled at a specific frequency, it results in multiple scaled replicas of the original spectrum in the frequency domain. The spacing of these replicas is determined by the sampling frequency.
If the sampling frequency is below the Nyquist rate, these replicas overlap, preventing the original...
104
Bandpass Sampling01:17

Bandpass Sampling

147
In signal processing, bandpass sampling is an effective technique for sampling signals that have most of their energy concentrated within a narrow frequency band. This type of signal is known as a bandpass signal. The key principle of bandpass sampling involves sampling the signal at a rate that is greater than twice the signal's bandwidth to prevent aliasing.
A bandpass signal has a spectrum with a lower frequency limit, denoted as ω1, and an upper frequency limit, denoted as ω2....
147
Sampling Theorem01:15

Sampling Theorem

271
In signal processing, the analysis of continuous-time signals, denoted as x(t), often involves sampling techniques to convert these signals into discrete-time signals. This process is essential for digital representation and manipulation. A critical component in sampling is the train of impulses, characterized by the sampling interval and the sampling frequency. The relationship between these parameters and the original signal's properties dictates the success of the sampling process.
271

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相关实验视频

Updated: May 21, 2025

Three-dimensional Optical-resolution Photoacoustic Microscopy
08:31

Three-dimensional Optical-resolution Photoacoustic Microscopy

Published on: May 3, 2011

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通过使用频域中的累积功率差异来选择光声图像的下方采样因子的方法.

Shihao Tang1, Min Wan1, Yameng Zhang2

  • 1Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China.

Journal of biophotonics
|March 19, 2025
PubMed
概括

这项研究引入了一种新方法,即累积功率差 (CPD),用于快速选择光声显微镜 (PAM) 成像的最佳设置. CPD有助于改善图像质量评估,并减少需要进行广泛的先前测试.

关键词:
这是光学成像.摄影声学技术的使用.采样研究是采样研究.频谱分析是一种频谱分析.

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Last Updated: May 21, 2025

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科学领域:

  • 生物医学成像技术 生物医学成像技术
  • 在光学成像系统中,光学成像
  • 摄影声学 摄影声学

背景情况:

  • 光声显微镜 (PAM) 是一种非侵入性成像技术.
  • PAM的一个主要限制是由于空间采样稀疏,其成像速度较慢.
  • 为PAM选择最佳的下方采样因子需要进行广泛的先前实验.

研究的目的:

  • 提出一个新的频域评估指数,累积功率差 (CPD).
  • 为了快速选择PAM的最佳下方采样因子.
  • 为了克服缓慢的成像速度和PAM中广泛的参数调节的局限性.

主要方法:

  • 开发并应用了累积功率差异 (CPD) 评估指数.
  • 利用CPD分析小鼠耳朵和大脑下方采样的光声学图像.
  • 与已建立的图像质量指标 (如PCC,MSE和SSIM) 相关联的CPD.

主要成果:

  • 随着下方采样因子的增加,观察到图像质量的下降趋势.
  • CPD与PCC/MSE/SSIM有显著的相关性 (p < 0.001).
  • CPD有效地评估光声学图像质量,并量化下方采样导致的质量损失.

结论:

  • CPD 能够快速,准确地选择 PAM 的最佳下方采样因子.
  • 这种方法有助于在没有事先检查的情况下对下方采样图像进行质量评估.
  • 该研究扩大了PAM的应用范围,并支持其临床潜力.