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Networks and Advanced Technologies
Published in John Rhodes, Videoconferencing for the Real World, 2001
BRI-ISDN provides dial-up service on two 64 kbps (B) channels, and a separate signaling or data (D) channel of 16 kbps. Each B channel may be used separately for phone, data, or video communication, or the channels can be combined to form a single, higher-speed 128 kbps connection. Many basic desktops video systems employ a single BRI circuit to provide basic videoconferencing and data collaboration. BRI service is inexpensive, sometimes costing less than the two analog business phone lines it replaces. Multiple BRI connections can be combined to create a higher-speed communications link of 256 kbps, 384 kbps, or 512 kbps. This is accomplished with the assistance of an Inverse Multiplexer, or IMUX.
Nonlinear Echo Cancellation
Published in Andrzej Borys, Nonlinear Aspects of Telecommunications, 2018
connections for transmission of packetized data; that is, data packets used in data networks. The digital subscriber loop as shown in Figure 2.13 and described above occurs in the integrated services digital network (ISDN), which integrates voice and data services to provide them to the customer over a common facility.40,48 At its basic level, the ISDN provides transmission rate of 144 kbit/s for each direction. This rate is described as the basic interface and called 2B+D, which means that the interface consists of two B channels at 64 kbit/s each and one channel D at 16 kbit/s. The B channels are devoted to transmission of the digital voice and/or data, while the D channel is an additional channel for data, which can be transmitted at a lower rate (4 times lower, 64 kbit/s: 4 = 16 kbit/s, than in the B channel). Additionally, framing and control data are transmitted at the rate of 16 kbit/s, which gives altogether 144 + 16 = 160 kbit/s. With regard to Figure 2.13, that means that the transmission rates are 160 kbit/s on the subscriber loop in each direction. Moreover, the transmission on the digital subscriber loop is the so-called baseband transmission,40 that is, without the use of carriers. This is because the frequency characteristic of the two-wire connection of the digital subscriber loop in Figure 2.13 has a shape of a lowpass filter. For example, to transmit at the rate of 160 kbits/s, it must provide bandwidth at least in the range of 0 40 kHz.24 On the other hand, the voiceband channel can be considered as a passband channel, having the character of a bandpass filter. It provides bandwidth in the range of 300 3300 Hz. By the way, comparing the bandwidth 3300 300 = 3000 Hz with the previous value of 40 kHz for the digital subscriber loop, note that the bandwidth provided by the voiceband channel is much smaller than that provided by the digital subscriber loop. This is rather the rule. Communication between two full-duplex voiceband data modems is shown schematically in Figure 2.14. In this figure, two modems are connected to the public telephone network via two wires representing telephone channels of bandpass frequency characteristic with the passband in the range mentioned just before; that is, between 300 3300 Hz. They work in the full-duplex mode of operation.
A new colour image copyright protection approach using evolution-based dual watermarking
Published in Journal of Experimental & Theoretical Artificial Intelligence, 2021
Saad M. Darwish, Osama F. Hassan
The cover image is converted to YCbCr colour space as it is better to model the human colour perception. This type of colour space allows more precise colour detectors to be created since colour intensity is removed when viewing the Cr or Cb vectors (Advith et al., 2016; X. Liu et al., 2016; Lusson et al., 2013). Herein, the embedding is performed in Y, and Cb as the luminance channel represents the intensity of the image. It is the ideal space for data hiding whenever tolerance against JPEG compression and noise addition are the most important concerns; whereas the chrominance channel, Cb channel has more ability to defeat various types of attacks compared to chrominance space Cr [1].
Measuring the imaginary-time dynamics of quantum materials
Published in Philosophical Magazine, 2020
S. Lederer, D. Jost, T. Böhm, R. Hackl, E. Berg, S. A. Kivelson
Figure 1 shows the Raman spectra of overdoped in the channel [essentially s-wave, panel (a)] and the [ d-wave-like, panel (b)]. The spectra are constant and temperature independent (to within ) at energies above 700 cm. Below 700 cm the intensity increases upon cooling, with the spectra (Figure 1 (b)) displaying a slightly stronger variation. Figure 2 shows the same data, but now presented as a function of scaled variables. Sufficiently close to certain quantum-critical points, one expects critical response functions to exihibit scaling, which would mean that scaling the data at various T and ω as in the figure would collapse the data onto a single curve. The data in the B channel shows an approximate version of such a scaling collapse; the A data somewhat less so.
Multiresolution generative adversarial networks with bidirectional adaptive-stage progressive guided fusion for remote sensing image
Published in International Journal of Digital Earth, 2023
Yuanyuan Wu, Yuchun Li, Mengxing Huang, Siling Feng
The experimental outcomes on the QB data with the degraded resolution are presented in Figure 8, where the red-green–blue band represents the R-G-B channel. Figure 8(a) presents the degraded-resolution PAN image (L_PAN). Figure 8(b) is an interpolated MS image by a bicubic approach (EXP). Figure 8(c–k) illustrate the results of the GSA, BDSD, SFIM, MTF-GLP-HPM, RED-cGAN, PsGAN, PGMAN, DIGAN, and BPF-MGAN models, and Figure 8(l) depicts the ground truth (GT). Figure 8(a) and Figure 8(c–l) have a spatial resolution of 2.4 m. To more expediently observe the effects among various models, the mean absolute error map (MAEM) acquired between the fused results and the GT is depicted in Figure 9.