History and prospects of the application of X-ray in seed production and seed studies

A retrospective analysis of the history of the application of the method of radiography in the course of studies of the structure of seeds for the purposes of seed production and seed studies was carried out. It is shown that the beginning of X-ray studies of seeds is directly related to the development in the late 70s of the last century in the Special Design Bureau for X-ray Instruments, Leningrad Association of Electronic Instrumentation “Svetlana” of a specialized X-ray apparatus based on the X-ray emitter REIS with a voltage of 25 kV. The methodological part of the research was provided by the leading specialized enterprises of our country, now they are FSBSI API, FSBI Research Institute for Storage Problems of the Federal Reserve FSBSI FSVC. In the early 2000s, ETU “LETI”, represented by a small enterprise of the Technopark LETI, CJSC “ELTECH-Med”, actively joined the research. LETI is associated with the transition to digital receivers of X-ray images, which made it possible to fundamentally increase the efficiency of research by employees of CJSC “ELTECH-Med” together with specialists from Agrophysical Research Institute, FSBI Research Institute for Storage Problems of the Federal Reserve, FSBSI FSVC developed a number of technical means for obtaining digital 2 and 3 dimensional X-ray images of seeds.

A Novel Design of Matched Filter for Digital Receivers

In this paper, a brief review regarding introduction to the digital signal processing techniques particularly Digital Pulse Compression and Linear Frequency Modulation involved in matched filtering and some designs being used is presented. Also, the matched filter being developed is discussed by highlighting its pros and cons. The introduction of matched filter in the communication receivers has simplified the design of the system. The matched filter has improved the signal to noise ratio of the receiver system and hence has become an important element in the communication system. This paper also presents the possible challenges; the matched filter design and simulation results in MATLAB have shown satisfactory outputs of the receiver.

CHARACTERISTICS OF DIGITAL AGC IN FIXED-POINT OPERATIONS

Introduction. Nowadays, communication systems are mostly digital. One of the tasks of automatic gain control in digital receivers is to maintain analog signals at the appropriately fixed level, which prevents saturation of the analogto-digital converter. Most numerical algorithms are based on floating point arithmetic, and digital automatic gain control is usually implemented using fixed-point arithmetic devices such as programmable logic chips and signal processors. As consequence of fixed-point arithmetic and hardware constraints usage, the out-put significant bits should be truncated correctly. Although many studies mention digital automatic gain control, its characteristics are not considered in detail in terms of the finite capacity of calculators.Objective. The purpose of the study is to analyze dynamic characteristics of digital automatic gain control implemented on a computer for operations on numbers with fixed-point.Materials and methods. Within the frames of the study in Matlab software was developed a mathematical model of digital automatic gain control. The model was implemented on a programmable logic chip.Results. The paper shows the difference in characteristics and features of the digital automatic gain control during operations on fixed-point numbers. The study provides the assessment of the effect of fixed-point signals on the stability of the digital automatic gain control and includes the analysis of causes of spurious oscillations of the control signal.Conclusion. The study proposes the algorithm for compensation of the control signal oscillations by means of correction of the reference level of the digital automatic gain control. Further is required to verify the proposed algorithm on real signals. The results of the study are relevant in development of digital receivers for communication systems of various purposes.