Structures of processors for calculating the instant Walsh spectrum

The work is devoted to the development of circuits for fast Walsh transform processors of the serialparallel type. The fast Walsh transform processors are designed for decoding error-correcting codes and synchronization; their use can reduce the cost of calculating the instantaneous Walsh spectrum by almost 2 times. The class of processors for computing the instantaneous spectrum according to Walsh is called serialparallel processors. Circuits of the fast Walsh transform processors of serial-parallel type have been developed. A comparative analysis of the constructed graphs of the fast Walsh transform processors is carried out. A method and a processor for calculating the Walsh transform coefficients are proposed, which allows increasing the speed of the transformations performed. When calculating the conversion coefficients using processors of parallel, serial and serial-parallel types, it was found that controllers of the serial-parallel type require 2(N–1) operations when calculating the instantaneous spectrum according to Walsh. The results obtained can be used in the design of discrete information processing devices, in telecommunication systems when coding signals for their noise-immune transmission and decoding, which ensures the optimal number of operations, and therefore the optimal hardware costs.

Wigner Distribution Analysis Applied to Lehmer’s Conjecture on the Ramanujan tau Function

Wigner distribution is a tool for signal processing to obtain instantaneous spectrum of a signal. By using Wigner distribution analysis, another representation of the Euler product can be obtained for Dirichlet series of the Ramanujan tau function. From which, it can be proved that the Ramanujan tau function never become zero for all numbers.

Evaluation of the Impact of Doppler Effect on Quality of HSR Radiocommunications

The article proposes a methodology for evaluating radio signal distortions caused by Doppler effect (DE; also, Doppler shift) under the conditions of highspeed train traffic (HSR, high-speed rail). The objective of the work is to develop criteria for assessing quality of radiocommunications with moving objects in HSR environment. For this, a technique is proposed for calculating the probability of an error arising from Doppler effect. A rationale for relevance of the topic is that radiocommunications are used on railways for controlling train traffic and ensuring safety and achieving required quality of radio signals is a major challenge. Quality assessment is especially important for organization of broadband communication channels with locomotive drivers using mobile networks. To solve this problem, a model for assessing quality of radiocommunication influenced by DE is considered. Distortions of signals in a radio channel due to DE are proposed to be estimated using the reduced dispersion of the total error, which consists of two components: dynamic and interference. Calculations of the total reduced signal error and the error probability for speeds above 100 km/h are described. Estimates of the effect of DE on a coherent receiver, in which errors may occur due to changes in duration of radio pulses, are suggested. Effectiveness of the receiver’s automatic frequency control (AFC) system is analysed as a means of challenging DE. For this, the concept of an instantaneous spectrum of parasitic frequency modulation due to DE was introduced and quality of radio communication was calculated using the reduced dispersion of the total error. The efficiency of using AFC has been proven after comparing the evaluations of reception quality with and without AFC in the form of the ratio of error probabilities. The features of the use of mobile communications on railways under the conditions of DE are formulated.

Wigner Distribution Analysis and the Riemann Hypothesis

Wigner distribution is a tool for signal processing to obtain instantaneous spectrum of a signal. From which, another representation of the Euler product can be obtained for Dirichlet series of the Mobius function, which leads to the proof of the Riemann hypothesis

The Parameter Study of Instantaneous Spectrum of Spatially Varying Ground Motion

In this paper ,the parameter study of the instantaneous spectrum model is transformed to that of strength envelope model and instantaneous frequency model, based on the real ground motion array data, the statistical analysis result of the parameter of multipoint ground motion at local sites indicate that the most parameters are associated with projection distance and soil layer thickness, and the regression model and the value selection of various parameters provided in this paper can also be used for the reference of artificial synthesis of multipoint ground motion.

Environmental Sound Recognition Using Time-Frequency Intersection Patterns

Environmental sound recognition is an important function of robots and intelligent computer systems. In this research, we use a multistage perceptron neural network system for environmental sound recognition. The input data is a combination of time-variance pattern of instantaneous powers and frequency-variance pattern with instantaneous spectrum at the power peak, referred to as a time-frequency intersection pattern. Spectra of many environmental sounds change more slowly than those of speech or voice, so the intersectional time-frequency pattern will preserve the major features of environmental sounds but with drastically reduced data requirements. Two experiments were conducted using an original database and an open database created by the RWCP project. The recognition rate for 20 kinds of environmental sounds was 92%. The recognition rate of the new method was about 12% higher than methods using only an instantaneous spectrum. The results are also comparable with HMM-based methods, although those methods need to treat the time variance of an input vector series with more complicated computations.