Use Of Pseudo-random Sequences Research Articles

EVALUATING THE IMPACT OF CROSS-CORRELATION PROPERTIES OF COMPLEX SIGNALS ON THE CHARACTERISTICS OF SMART RADIO SYSTEMS

The article discusses modern problems and prospects for the development of "smart radio" systems using complex signals for effective use of the radio frequency spectrum. Cognitive radio systems use complex signals to efficiently use the radio frequency spectrum. It is emphasized that the ensemble size of complex signals is a key factor that affects various system characteristics such as immunity, data transmission efficiency, and spectral efficiency. Various methods can be used to increase the ensemble size of complex signals, including the use of pseudo-random sequences with low levels of sidelobes in the cross-correlation function, new complex signal generation algorithms (e.g., based on artificial intelligence), and new coding techniques that allow for increased ensemble size. without compromising data transmission efficiency. The choice of a specific approach to increasing the size of the ensemble of complex signals depends on the specific requirements of the cognitive telecommunication system. An important task is the development of new methods of generating complex signals with high interference-resistant properties, which allow to increase the size of the ensemble without compromising the quality of service. This task is important for the development of next-generation "smart radio" systems. The analysis of various methods of increasing the size of the ensemble of complex signals is presented. The maximum correlation immunity is calculated for different lengths of sequences and the results of research for five sequences are given: pseudorandom noise, nonlinear sequence, Galois sequence, Gold sequence and Kiyosaki sequence. This information can be used to select the optimal sequence taking into account the specific requirements of "smart radio" systems. The conclusions of the article can make a valuable contribution to the development of effective and productive telecommunication systems for future generations of "smart radio".

Adaptive Pseudo-Random Sequence Generation for Spread Spectrum Image Steganography

In this article we consider the ways of data hiding in digital images with the use of pseudorandom sequences and the spread spectrum technique. We propose a new way of the generation of sequences, which considers statistical properties of cover-images. This makes it possible to achieve a low correlation, which provides reliable and safe data hiding in digital images. The results of experimental researches show, that the bit error rate in restored messages is significantly reduced. At the same time, the distortions of cover-images remain the same.

Toward Energy-Efficient Stochastic Circuits Using Parallel Sobol Sequences

Stochastic computing (SC) often requires long stochastic sequences and, thus, a long latency to achieve accurate computation. The long latency leads to an inferior performance and low energy efficiency compared with most conventional binary designs. In this paper, a type of low-discrepancy sequences, the Sobol sequence, is considered for use in SC. Compared to the use of pseudorandom sequences generated by linear feedback shift registers (LFSRs), the use of Sobol sequences improves the accuracy of stochastic computation with a reduced sequence length. The inherent feature in Sobol sequence generators enables the parallel implementation of random number generators with an improved performance and hardware efficiency. In particular, the underlying theory is formulated and circuit design is proposed for an arbitrary level of parallelization in a power of 2. In addition, different strategies are implemented for parallelizing combinational and sequential stochastic circuits. The hardware efficiency of the parallel stochastic circuits is measured by energy per operation (EPO), throughput per area (TPA), and runtime. At a similar accuracy, the $8{\times}$ parallel stochastic circuits using Sobol sequences consume approximately 1% of the EPO of the conventional LFSR-based nonparallelized circuits. Meanwhile, an average of 70 (up to 89) times improvements in TPA and less than 1% runtime are achieved. A sorting network is implemented for a median filter (MF) as an application. For a similar image processing quality, a higher energy efficiency is obtained for an $8{\times}$ parallelized stochastic MF compared with its binary counterpart.

A new switched current circuit fault diagnosis approach based on pseudorandom test and preprocess by using entropy and Haar wavelet transform

This paper presents a new switched current (SI) circuit fault diagnosis approach based on pseudorandom test and preprocess by using entropy and Haar wavelet transform. The proposed method has the capability to detect and identify faulty transistors in SI circuit by analyzing its time response. The use of pseudorandom sequences as a stimulate signal to SI circuit reduces the cost of testing and the overhead of the test generation circuit, and using entropy and Haar wavelet transform to preprocess the time response for feature extraction drastically improves the fault diagnosis efficiency. For both actual experiment and analysis of switched current filters in Z transform (ASIZ) simulation, a low-pass, a band-pass SI filter and a clock feed-through cancellation circuit have been used as test examples to verify the effectiveness of the proposed method. The result shows that the accuracy of fault recognition achieved is about 100% by analyzing low-frequency approximations entropy and high-frequency details entropy. Therefore, it indicates that the presented method is superior than other methods.

Use of pseudo-random sequences and a single microphone to measure surface impedance at oblique incidence

The use of a pseudo-random sequence and a single microphone is suggested for the experimental determination of the acoustical properties (surface impedance, reflection coefficient, etc.) of sound-absorbing materials. An experimental system is developed with which the surface impedance and reflection coefficient at oblique incidence are determined from measurements of the impulse-response function sequentially at two locations close to the surface of the material using a pseudo-random sequence and a single microphone. This technique is validated using the measurement of a residual pressure-intensity index. The advantage of this technique is that it is possible to perform measurements of the surface properties of materials without phase-mismatch errors that occur with two-microphone methods. Models for estimating the surface impedance from plane-wave and spherical-wave hypotheses are reviewed and compared. Measurements of impedance at oblique incidence are carried out on a sheet of glass fiber in an anechoic room, as well as in a semi-reverberant room, and the results are compared. Surface impedances and reflection coefficients are presented as a function of angle of incidence. The proposed experimental system can be used to measure the acoustical properties of materials at oblique angles of incidence and in semi-reverberant environments.

Use of Pseudo-Random Sequences in the Synthesis of Kinoforms

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text R. H. Katyl, "Use of Pseudo-Random Sequences in the Synthesis of Kinoforms," Appl. Opt. 11, 198-199 (1972) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article