Rate 3/4 coded 16-QAM for uplink applications

First phase development of an advanced modulation technology which synergistically combines coding and modulation to achieve 2 bits per second per Hertz bandwidth efficiency in satellite demodulators is nearing completion. A proof-of-concept model is being developed to demonstrate technology feasibility, establish practical bandwidth efficiency limitations, and provide a data base for the design and development of engineering model satellite demodulators. The basic considerations leading to the choice of 4 x 4 quadrature amplitude modulation (16-QAM) and its associated coding format are discussed, along with the basic implementation of the carrier and clock recovery, automatic gain control, and decoding process. Preliminary performance results are presented. Spectra for the modulated signal shows the effects of the square root Nyquist filters in the modulation. Bit error rate (BER) results for the encoder/decoder subsystem show near ideal results, although power consumption is high and baseband BER performance of the Nyquist filter set is poor. Recommendations regarding the present system to improve BER performance and acquisition speed are given

Optimal controlled random tests

Controlled random tests, methods of their generation, main criteria used for their synthesis, such as the Hamming distance and the Euclidean distance, as well as their application to the testing of both hardware and software systems are discussed. Available evidences suggest that high computational complexity is one of the main drawbacks of these methods. Therefore we propose a technique to overcome this problem. In the paper we propose the algorithm for optimal controlled random tests generation. Both experimental and analytical investigation clearly show the high efficiency of proposed solution especially for the multi-run tests with small number of iterations. The given tests can be applied for hardware and software testing but it seems they may be particularly interesting from the perspective of the effective detection of pattern sensitive faults in RAMs

Methods of synthesis of controlled random tests

Controlled random tests, methods of their generation, main criteria used for their synthesis, such as the Hamming distance and the Euclidean distance, as well as their application to the testing of both hardware and software systems are discussed. Available evidences suggest that high computational complexity is one of the main drawbacks of these methods. Therefore we propose a technique to overcome this problem. A method for synthesizing multiple controlled random tests based on the use of the initial random test and addition operation has been proposed. The resulting multiple tests can be interpreted as a single controlled random test. The complexity of its construction is significantly lower than the complexity of the construction of classical random tests. Examples of generated tests as well as estimates of their effectiveness compared to other solutions have been presented in experimental studies

Universal Address Sequence Generator for Memory Built-in Self-test

This paper presents the universal ad-dress sequence generator (UASG) for memorybuilt-in-self-test. The studies are based on the proposed universal method for generating address se-quences with the desired properties for multirun march memory tests. As a mathematical model, a modification of the recursive relation for quasi-random sequence generation is used. For this model, a structural diagram of the hardware implementation is given, of which the basis is a storage device for storing so-called direction numbers of the generation matrix. The form of the generation matrix determines the basic properties of the generated ad-dress sequences. The proposed UASG generates a wide spectrum of different address sequences, including the stand-ard ones, such as linear, address com-plement, gray code, worst-case gate delay, 2i, next address, and pseudoran-dom. Examples of the use of the pro-posed methods are considered. The result of the practical implementation of the UASG is presented, and the main characteristics are evaluated

Turbulent cross-field transport of non-thermal electrons in coronal loops: theory and observations

<p><b>Context:</b> A fundamental problem in astrophysics is the interaction between magnetic turbulence and charged particles. It is now possible to use Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations of hard X-rays (HXR) emitted by electrons to identify the presence of turbulence and to estimate the magnitude of the magnetic field line diffusion coefficient at least in dense coronal flaring loops.</p> <p><b>Aims:</b> We discuss the various possible regimes of cross-field transport of non-thermal electrons resulting from broadband magnetic turbulence in coronal loops. The importance of the Kubo number K as a governing parameter is emphasized and results applicable in both the large and small Kubo number limits are collected.</p> <p><b>Methods:</b> Generic models, based on concepts and insights developed in the statistical theory of transport, are applied to the coronal loops and to the interpretation of hard X-ray imaging data in solar flares. The role of trapping effects, which become important in the non-linear regime of transport, is taken into account in the interpretation of the data.</p> <p><b>Results:</b> For this flaring solar loop, we constrain the ranges of parallel and perpendicular correlation lengths of turbulent magnetic fields and possible Kubo numbers. We show that a substantial amount of magnetic fluctuations with energy ~1% (or more) of the background field can be inferred from the measurements of the magnetic diffusion coefficient inside thick-target coronal loops.</p&gt

ПСЕВДОИСЧЕРПЫВАЮЩЕЕ ТЕСТИРОВАНИЕ ОЗУ

Modern RAM tests and methods for their generation are analyzed and investigated. The wide application of pseudoexhaustive tests as the main test procedure for modern computer systems has been proved. The main estimates and metrics for so kind of tests are obtained. The values of analytical estimates have been validated by the experimental investigations.Анализируются методы тестирования современных запоминающих устройств, в том числеоперативных запоминающих устройств (ОЗУ), обосновывается применение псевдоисчерпывающих тестов для обнаружения сложных неисправностей памяти. Формулируется необходимое условие генерирования псевдоисчерпывающего теста для заданного количества запоминающих ячеек ОЗУ. Показывается, что задача генерирования псевдоисчерпывающего теста на базе многократных тестов ОЗУ с изменяемыми адресными последовательностями сводится к комбинаторной задаче собирателя купонов. Приводятся оценки минимальной, максимальной и средней кратности многократного теста для обеспечения исчерпывающего множества комбинаций для заданного числа ячеек ОЗУ, что подтверждает возможность формирования псевдоисчерпывающего теста для заданного числа ячеек ОЗУ

МНОГОКРАТНЫЕ УПРАВЛЯЕМЫЕ ВЕРОЯТНОСТНЫЕ ТЕСТЫ

Controlled Random Tests and methods for their generation have been analyzed and investigated. The similarities of all known controlled random testing approaches are shown. A new method and algorithm for Multiple Controlled Random Tests have been proposed and analyzed.Рассматриваются однократные управляемые вероятностные тесты, методы их формирования, а также их применение для тестирования средств вычислительных систем. Показываются основные недостатки построения однократных вероятностных тестов. Предлагается метод построения многократных управляемых вероятностных тестов на базе исходного однократного теста. Анализируются различные численные метрики для построения как однократных, так и многократных управляемых вероятностных тестов

Псевдоисчерпывающее тестирование запоминающих устройств на базе маршевых тестов типа March A

The relevance of testing of memory devices of modern computing systems is shown. The methods and algorithms for implementing test procedures based on classical March tests are analyzed. Multiple March tests are highlighted to detect complex pattern-sensitive memory faults. To detect them, the necessary condition that test procedures must satisfy to deal complex faults, is substantiated. This condition is in the formation of a pseudo-exhaustive test for a given number of arbitrary memory cells. We study the effectiveness of single and double application of tests like MATS ++, March C– and March A, and also give its analytical estimates for a different number of k ≤ 10 memory cells participating in a malfunction. The applicability of the mathematical model of the combinatorial problem of the coupon collector for describing multiple memory testing is substantiated. The values of the average, minimum, and maximum multiplicity of multiple tests are presented to provide an exhaustive set of binary combinations for a given number of arbitrary memory cells. The validity of analytical estimates is experimentally shown and the high efficiency of the formation of a pseudo-exhaustive coverage by tests of the March A type is confirmed.Показывается актуальность тестирования запоминающих устройств современных вычислительных систем. Анализируются методы и алгоритмы реализации тестовых процедур на базе классических маршевых тестов. Выделяются многократные маршевые тесты, позволяющие обнаруживать сложные кодочувствительные неисправности памяти. Для их обнаружения обосновывается необходимое условие, которому должны удовлетворять тестовые процедуры для покрытия сложных неисправностей. Это условие заключается в формировании псевдоисчерпывающего теста для заданного количества произвольных ячеек памяти. Исследуется эффективность однократного и двукратного применения тестов типа MATS++, March C- и March A, а также приводятся ее аналитические оценки для различного количества k ≤10 ячеек памяти, участвующих в неисправности. Обосновывается применимость математической модели комбинаторной задачи собирателя купонов для описания многократного тестирования памяти. Приводятся значения средней, минимальной и максимальной кратности многократных тестов для обеспечения исчерпывающего множества двоичных комбинаций для заданного числа произвольных ячеек памяти. Экспериментально показывается справедливость аналитических оценок и подтверждается высокая эффективность формирования псевдоисчерпывающего покрытия тестами типа March A