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Threat Mitigation
Published in Ron Burch, Resilient Space Systems Design: An Introduction, 2019
FHSS systems are more complicated than traditional single frequency systems because both the transmitter and the receiver must be precisely synchronized in time so as to hop according to a random code that defines the sequence of frequencies that each must use concurrently. Cryptographic devices are required to provide these secure codes. Spread spectrum waveforms can provide another type of robustness. By spreading their energy over a wide bandwidth, detection of the signal becomes more difficult as the peak signal power approaches the channel noise level. This class of waveform exhibits a low probability of detection (LPD) and a low probability of intercept (LPI). LPD waveforms are less susceptible to jamming, resulting in a measure of avoidance that also reduces the likelihood that it can be monitored.
Pulse-Code Modulation Codec-Filters
Published in Jerry D. Gibson, The Communications Handbook, 2018
Michael D. Floyd, Garth D. Hillman
The PCM codec-filter itself has many opportunities to contribute to the idle channel noise level. The input high-pass filter often is third order, whereas both the input and the output low-pass filters are typically fifth-order elliptic designs. The potential for noise generation is proportional to the order of the filter. The ADC and DAC arrays have many components that are controlled by sequencing digital circuits. The power supply rejection capability of PCM codec-filters once dominated the noise level of the channel. The power supply rejection ratio of these devices has been improved to a level where the device is virtually immune to power supply noise within the allowable power supply voltage range. This performance was attained by differential analog circuit designs in combination with tightly controlled matching between on-chip components.
High Dynamic Range, 100 km Digital Radio-over-Fiber Links
Published in Chi H. Lee, Microwave Photonics, 2017
Vincent J. Urick, Frank Bucholtz, Eric E. Funk
The MER, the SNR per symbol, is an excellent figure of merit for the evaluation of channel quality. In a RoF link, the measured MER will be influenced by both the RF noise figure and IMD. IMD manifests itself as in increase in both adjacent-channel and in-channel noise. In a single channel RoF system, it is in-channel noise that will degrade the MER. While Equation 6.16 gives the IMD in an IMDD link with two RF tones, an equivalent analytic expression for the distortion of a QAM signal is beyond the scope of this work. In electronically amplified QAM systems adjacent channel noise measurements can be used to predict the mean in-channel noise level [74]. The relationship between in channel and adjacent channel distortion has not yet been clearly established for a RoF system employing IMDD. However, adjacent channel power measurements can be used as a figure of merit in a QAM RoF system.
Distributional Spectrum Series (DSS) with Beamforming in 5G Communication System
Published in IETE Journal of Research, 2023
Dipali Bansal, Malay Ranjan Tripathy, Prasad Shastry
This section explains how the suggested optimization algorithm's results, which are shown in the 5G software solution, were validated. The functions for the method were created in the MATLAB tool for the version of 2018a for this analysis section, and all the algorithm stages were built in the “m-script” functions and run using the widely used system topology of the 5G system. The initial values of the channel noise level in the communication line as well as the system parameters were initialized and verified in that signal. By computing comparative parameters to indicate the effectiveness of the DSS algorithm in comparison to another current optimization model, this part also illustrates the performance of the proposed optimization model. The suggested work may be contrasted with the current Independently Tailored Architecture-Slicing Architecture (ITNSA) system that is mentioned in [20]. In this paper, the author uses a similar approach to find the shortest path with Recursive Spectral Classification (RSC) algorithm as shown in paper [23].