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Signal Processing
Published in Stephen Horan, Introduction to PCM Telemetering Systems, 2018
Now that high pass and low pass filters have been achieved, cascading high pass and low pass sections can synthesize a band pass filter. This may not give an ideal response but will be workable. An example of this concept is illustrated in Figure 5.23. The device is composed of a low pass active filter building block followed by a high pass active filter building block. The band pass filter is designed by choosing cutoff frequencies for the low pass and the high pass filter sections and treating them as two independent design problems. The low pass stage has its cutoff frequency at the upper cutoff frequency of the band pass filter. The high pass stage has its cutoff frequency at the lower cutoff frequency. If we place the low pass filter section with its cutoff at the lower cutoff of the band pass and the high pass filter section with its cutoff at the upper cutoff of the band pass, we will have changed the filter into a band reject or notch filter.
Filters
Published in Hernando Lautaro Fernandez-Canque, Analog Electronics Applications, 2016
Hernando Lautaro Fernandez-Canque
The bandwidth of a band-pass filter is given as the difference between the high- and low-frequency cutoffs. In a band-pass filter is it usual to specify the middle frequency of the filter, fo, and a quality factor of a band pass is defined in terms of fo as Quality factor=Q=foBW(20.6)
Bandwidth, Sampling, and Error Propagation
Published in Clarence W. de Silva, Sensor Systems, 2016
Bandwidth has different meanings depending on the particular context and application. For example, when studying the response of a device, the bandwidth relates to the fundamental resonant frequency and correspondingly to the speed of response of the device for a given excitation. In band-pass filters, the bandwidth refers to the frequency band (passband) of the signal components that are allowed through the filter, while the frequency components outside the band are rejected. With respect to measuring instruments such as sensor systems, bandwidth refers to the range frequencies within which the instrument measures a signal accurately (operating frequency range). As a particular note, if a signal passes through a band-pass filter, we know that its frequency content is within the bandwidth of the filter, but we cannot determine the actual frequency content of the signal on the basis of that observation. In this context, the bandwidth appears to represent a frequency uncertainty in the observation (i.e., the larger the bandwidth of the filter, the less certain is our knowledge about the actual frequency content of a signal that passes through the filter). In digital communication networks (e.g., the Internet), the bandwidth denotes the capacity (information capacity) of the network in terms of information rate (bits/s). In this chapter, we will address various interpretations of bandwidth. The present focus, however, is on instrument bandwidth and control bandwidth. Within that focus, bandwidth directly concerns some form of largest possible operating “speed” such as the speed of response of a dynamic system and the speed of control.
Evaluation of the airport runway flexible pavement macro-texture using digital image processing technique (DIPT)
Published in International Journal of Pavement Engineering, 2022
Omid Ghaderi, Mohammad Abedini
Butterworth band-pass filter is a type of signal processing filter. There are generally three different forms of frequency filters: low-pass, high-pass and band-pass filters. Low-pass filters (LPF) only pass the low spatial frequency details of the input image, effectively smoothing the sharp intensity changes in the image. In contrast, high-pass filters (HPF) yield edge enhancement or edge detection in the spatial domain, because of high frequencies content of edges. Areas of rather constant grey-level consist of mainly low frequencies and are therefore suppressed. Band-pass filters leave the desired band of frequencies unchanged by multiplying an LPF and an HPF in the frequency domain. A band-pass filter is defined by setting two cut-off frequencies (f0 and f1; f0 > f1) as borders of band-pass for low-pass and high-pass filtering process that attenuating all frequencies smaller than f0 and higher than f1 and passes the frequencies between these two cut-offs. Band-pass filters could be used for edge enhancement by suppressing low frequencies while noises are reduced at the same time (Gonzalez and Woods 2008, Qidwai and Chen 2009).
Modeling and Performance Improvement of Fractional-Order Band-Pass Filter Using Fractional Elements
Published in IETE Journal of Research, 2023
K. Biswal, S. Swain, M. C. Tripathy, S. K. Kar
Band-pass filter is a series-based device that perfectly permits and rejects quantified frequencies of the input signal [1–3]. Also, it can be designed by integrating a high-pass and a low-pass filter, respectively. Active band-pass filter differs slightly, as it is a frequency perceptive filter circuit [4,5] used in analog electronic systems. It is used to distinct a signal at one perfect frequency, or a range of signals that lies within a certain “band” or range of frequencies [6,7]. This group of frequencies is set between the lower cutoff frequency (ƒL) and the higher cutoff frequency (ƒH), while attenuating any signals outside of these two points. In a band-pass filter, the quality factor (Q) of the circuit is illustrated by the inclusive width of the actual pass-band between the upper and lower 3 dB corner points [8] of the filter. Q-factor signifies the portion of selectivity of the band-pass filter toward a specified range of frequencies, whereas it is inversely proportional to the bandwidth [3] of the filter. The impedance function of these electrical elements is modeled by fractional-order differential equations [1]. The most important advantage of a fractional-order system over its integer-order counterpart is that it possesses infinite memory [2]. In this paper, we seek to generalize the use of fractional-order capacitors and inductors in designing a fractional-order band-pass filter of (α+β)th order. In recent times, it has been reported that the fabrication of fractional capacitor (also called fractance, constant phase element etc.) obeys fractional calculus [1] and can be used as two terminal passive devices used in analog circuits [8,9].
Interpreting geology from geophysics in poly-deformed and mineralised terranes; the Otago Schist and the Hyde-Macraes Shear Zone
Published in New Zealand Journal of Geology and Geophysics, 2019
Casey C. Blundell, Robin Armit, Laurent Ailleres, Steven Micklethwaite, Adam Martin, Peter Betts
Band pass filters are used to isolate wavelengths between selected frequencies. Low-pass filters (i.e. upward continuation) result in the attenuation of high-frequency wavelengths associated with shallow sources and enhancement of low-frequency, long wavelength features. A high-pass (downward continuation) suppresses long-wavelengths and enhances shallow short wavelength features. High-pass filters cannot be practically applied very far, as short-wavelength (high frequency) anomalies have characteristically low amplitudes, and the transform quickly becomes unstable.