Clock Interval Research Articles

Evolutoin of algorithms for separation of optimal two mutually unorthogonal signals of binary phase modulation

A review of the results of the development of the methodology for the synthesis of the separation-demodulation algorithms of two mutually non-orthogonal binary phase modulation signals in the length of the information clock interval, synchronous and asynchronous according to the clock points, with continuous and intermittent radiation. The evolution of algorithms for optimal separation of two mutually non-orthogonal signals of binary phase modulation has the following sequence: signals are mutually synchronous by clock points (communication channel – with constant parameters, non-seeding oscillations are represented by functions integrated with the square; the signals are mutually synchronous in clock points, the second interfering signal is intermittent; signals are mutually asynchronous in clock points; the signals are mutually asynchronous in clock points, the second interfering signal is intermittent; signals are mutually synchronous in clock points, both signals are discontinuous. At the same time, the minimum probability of an error in the estimation of the discrete information parameter of the first (useful) signal was assumed as the optimality criterion. The results of a comparative review of algorithms for the separation of two mutually non-orthogonal binary FM signals demonstrate their evolutionary nature. The identified main regularities make it possible to obtain descriptions of signal separation procedures with mismatched clock frequencies without performing intermediate signal processing procedures. The gradual process of complicating synthesis tasks led to the discovery of gradual regularities in the structures of the separation-demodulation algorithms of two binary FM signals, which provides an opportunity to formulate directions for further research, which should be based on the provisions of the theory of multi-user detection. Namely, the revealed regularities are the basis for conducting further research in order to solve similar problems with the gradual further complication of the initial conditions. Priority consideration in the future will be given to tasks that have theoretical interest and practical value: when both signals are characterized by non-stationary intermittent emission modes and are asynchronous in clock points; when they are characterized by packet transmission mode; when band-efficient types of modulation are used (MSK, GMSK – first of all).

Cyclostationary Characterization of Radiated Emissions in Digital Electronic Devices

Stochastic electromagnetic fields originating from processes in digital circuitry affect the operation of the circuit, increase the error rate in the transmission of digital signals, degrade the circuit's performance, yield malfunction of the system or even lead to a complete failure of the system's operation. Interference from stochastic fields are not only disruptive but are becoming more common due to the increasing complexity of modern electronics. Stochastic electromagnetic fields under common circumstances are due to a mixture of emissions from different sources, which makes a quantification of stochastic fields very challenging. Since digital signals are clocked, the ensemble averages of the electromagnetic field transients representing the digital signal exhibit a periodic time dependence with the period of the clock interval. The probabilistic model of the cyclostationary random process was composed by appropriate transformations of the initial discrete random process of the binary symbols. Exploiting the cyclostationary characteristics of stochastic fields greatly simplifies their analysis. The physical signal propagating along the transmission line is considered also a source of the radiating electromagnetic field which preserves the cyclostationary properties of the binary sequence. The stochastic process of the measured near-field emissions inherits probability characteristicsfrom the random process of the physical signal in the transmission line. This paper presents an approach for quantifying emissions and coupling of stochastic fields using their cyclostationary properties. For practical evaluation of cyclostationary characteristics the statistical cyclic averaging of the measured signals are used. The important feature of the statistical cyclic averaging procedure is its capability to distinguish cyclostationary signals from a mixture of stochastic processes such as stationary noise with deterministic signals and even from other cyclostationary signals with distinct cyclic frequencies. The measurement setup for observing electromagnetic emissions from printed circuit boards (PCBs) hosting digital electronic devices comprises an automated positioning system with a scanning near-field probe attached to the moving scanner head. This scanning near-field probe and a properly position fixed or also movable reference probe are connected to the inputs of a multi-channel digital oscilloscope for simultaneous and synchronous sampling and registering of the magnetic field components. The registered data from the oscilloscope was transferred to a data acquisition computer. After the postprocessing procedure, the spatial localization of distributed radiating sources on the surface of the PCB was performed in conjunction with determination of their average power characteristics and specified cyclic frequencies. The proposed cyclic averaging was applied to the spatial separation of radiating sources with different bit rates and for the quantitative characterization of crosstalk and coupling between transmission lines carrying the data sequencesand subsequent estimation of bit error rate (BER) caused by the crosstalk using their cyclostationary properties.

Influence of synchronization errors оn the noise immunity of coherent reception of M-PSK signals

Signals with multiple phase-shift keying (M-PSK) have long been successfully used for highspeed information transfer in many applications – a number of adopted protocols of IEEE 802.11 wireless networks, digital satellite television DVB-S, DVB-S2/S2X systems, cellular networks CDMA and others. The most important characteristic of such systems is their noise immunity, which depends not only on the propagation conditions of radio waves in the communication channel, but also on the quality of operation of the component nodes of the information transmission systems themselves. The paper investigates the influence of the inaccuracy of estimating the frequency and phase of the carrier and the inaccuracy of the clock synchronization system on the noise immunity of coherent reception of M-PSK signals. Analytical expressions were obtained by statistical radio engineering methods. The expressions allow calculating the dependence of the probability of a bit error on the signal-to-noise ratio for various errors of the receiver auxiliary systems. In this case, the magnitudes of the errors were assumed to be either constant (static error) or dynamically changing (dynamic error). The dynamic errors were modeled using the Monte Carlo method, and the dynamic errors themselves were assumed to be Gaussian random variables. It is shown that the inaccuracy of estimating these parameters strongly influences the noise immunity of the coherent reception of the M-PSK signal, and this effect increases with increasing signal positionality. Estimates of the maximum permissible errors of the analyzed systems are given. When M-PSK signals are received, a tolerable value of the frequency of the reference oscillations can be considered as a ∆ωTs value of about 0.05. The allowable inaccuracy of the carrier phase estimation depends on the positioning of the signal and varies from π/36–π/72 for 2PSK to π/180 for 32PSK. The allowable time offset of the clock moments can be considered the value of 3–5% of the clock interval duration.

ЗАВАДОСТІЙКІСТЬ МОДЕМА МНОЖИННОГО ДОСТУПУ ШУМОВИХ СИГНАЛІВ З УРАХУВАННЯМ ВПЛИВУ КВАДРАТИЧНОЇ СКЛАДОВОЇ

The current state of the development of the elemental base of radio systems stimulates both the improvement of the characteristics of existing traditional systems and the study of alternative methods of information transmission. The research of modems with the use of a signal with an extended spectrum as an information carrier is of great importance in improving the information transmission systems. The issue of improving the modems with noise signals involves an increase in the accuracy of theoretical analysis of noise immunity of the proposed methods of demodulating the signal information components. The demodulator, for which the analysis is carried out, is characterized by the fact that in the functional for the evaluation of the received information bit there are components with different probability distribution laws. The consideration of the quadratic component influence on the noise immunity of the modem of multiple access in the analysis is performed for the first time. The article investigates the noise immunity of the modem of multiple access, which uses noise Gaussian signals as a carrier. The analytical expressions for calculating the noise immunity of the modem, when every user of the system uses a binary digital demodulator of transmitted signal, are obtained. The noise immunity of the modem of multiple access is analyzed taking into account the influence of input components of the signal, which are approximated by Gaussian and Chi-squared laws of probability distribution. Theoretical estimations of the noise immunity of the digital modem of multiple access, checked on the simulation model, are obtained. Theoretical results of the analysis have allowed to determine the dependence of the noise immunity of the digital demodulator on the amount of input signal readings at the clock interval. The optimum values of the amount of input signal readings, depending on the number of users of the system and the excess of the signal over the interference in the additive Gaussian communication channel are established.

Immunity of coherent stroboscopic processing system of ultra wideband signals during synchronous mode

Analyze of the radio pulse stroboscopic schema work in “synchronous” mode was made at clock interval synchronization by the second harmonic of intermediate frequency. It’s introduced relationships describing the input radio signal’s amplitude relationship during the phase modulation transforming in time during work the converter in synchronous mode. The results of semi natural modeling of the radio pulse gating system qualitative agreement with theoretical calculations.

The approximation of optical signals by short laser pulses in the form of a hyperbolic secant

At present time have been developed methods to improve the signal bandwidth of fiber-optical transmission systems (FOTS). A special case of such methods is considered in earlier works of the author. The essence of the proposed methods is to transfer more than one bit of information in one clock interval. The fundamental complexity of the implementation of such methods is the need to form a low-frequency component (envelope) of an optical signal of a given shape. A solution to this problem is proposed using a single laser pulse. In this case, the laser pulse is fed to the inputs of optical amplifiers, and from their outputs - to the inputs of delay lines with a precision step. As a result of the summation of the signals from the outputs of the delay lines, an approximant of a given optical signal is formed. This article assumes that the laser pulse has the form of a hyperbolic secant. A proof of the convergence of the corresponding approximants to functions of a given type is given. A numerical analysis confirming the solutions has been also performed. It is shown that the rate of convergence is of the order of 1/N, where N is the number of approximating pulses (the number of delay lines). It is shown that the proposed solutions are consistent with the characteristics of modern FOTS and can be implemented at the existing technological level of manufacturing optical components.

Quantum Key Distribution with Temporal Coding of Time-Bin Qubits

In this study, we demonstrate the possibility of realizing the quantum key distribution system by temporal coding of time-bin qubits that are prepared and measured using unbalanced Mach-Zehnder interferometers. We also show that, to exclude a clear a priori identification of time-bin qubits with equal bases, their encoding with the symbols 0 and 1 can be accomplished by delaying one of them by half the clock interval. The uniqueness of measurements of qutrits in this algorithm is shown to be based on the ability of quantum particles in β-states to interfere with the probability amplitudes at the ports of the system interferometers, as well as the absence of collisions of signaling states of the qutrits in adjacent clock intervals. We describe a method for controlling such collisions, including those that are based on qubits prepared from quasi-one-photon coherent laser states.

Pipeline Reconfigurable DSP for Dynamically Reconfigurable Architectures

Dynamically reconfigurable architectures, such as NATURE, achieve high logic density and low reconfiguration latency compared to traditional field-programmable gate arrays. Unlike fine-grained NATURE, reconfigurable DSP block incorporated NATURE architecture achieves significant improvement in performance for mapping compute-intensive arithmetic operations. However, the DSP block fails to fully exploit the potential provided by the run-time reconfiguration. This paper presents a pipeline reconfigurable DSP architecture to target the NATURE platform that supports temporal logic folding. The proposed approach allows the DSP pipeline stages to be reconfigured independently such that different functions can be performed distinctively and individually at every clock interval during runtime. In addition, a multistage clock gating technique is also used in the design to minimize the power consumption. We also extend NanoMap tool for mapping circuits on NATURE platform to exploit the pipeline-level reconfigurability of our proposed DSP block to enable efficient resource sharing and area/power reduction. Simulation results on 13 benchmarks show that the proposed approach enables area-delay improvement of up to 3.6\(\times \) compared to the fine-grained NATURE architecture. The proposed architecture also delivers 31.42% reduction in area and a maximum of 4.18\(\times \) improvement in power-delay compared to existing NATURE architecture. We also observe an average improvement of 29 and 54.13% in performance and area when compared to commercial Xilinx Spartan-3A DSP platform, thereby allowing the designers to tune the circuit implementations for the area, power, or performance benefits.

BDS Precise Point Positioning for Seismic Displacements Monitoring: Benefit from the High-Rate Satellite Clock Corrections.

In order to satisfy the requirement of high-rate high-precision applications, 1 Hz BeiDou Navigation Satellite System (BDS) satellite clock corrections are generated based on precise orbit products, and the quality of the generated clock products is assessed by comparing with those from the other analysis centers. The comparisons show that the root mean square (RMS) of clock errors of geostationary Earth orbits (GEO) is about 0.63 ns, whereas those of inclined geosynchronous orbits (IGSO) and medium Earth orbits (MEO) are about 0.2–0.3 ns and 0.1 ns, respectively. Then, the 1 Hz clock products are used for BDS precise point positioning (PPP) to retrieve seismic displacements of the 2015 Mw 7.8 Gorkha, Nepal, earthquake. The derived seismic displacements from BDS PPP are consistent with those from the Global Positioning System (GPS) PPP, with RMS of 0.29, 0.38, and 1.08 cm in east, north, and vertical components, respectively. In addition, the BDS PPP solutions with different clock intervals of 1 s, 5 s, 30 s, and 300 s are processed and compared with each other. The results demonstrate that PPP with 300 s clock intervals is the worst and that with 1 s clock interval is the best. For the scenario of 5 s clock intervals, the precision of PPP solutions is almost the same to 1 s results. Considering the time consumption of clock estimates, we suggest that 5 s clock interval is competent for high-rate BDS solutions.

Complete bifurcation analysis of a chaotic attractor in an electric circuit with piecewise‐smooth characteristics

We investigate the bifurcation phenomena of chaotic attractors observed in electric circuits with piecewise‐smooth characteristics. First, we present a circuit model whose switching action depends on its own state and on the clock interval. Next, we explain the behavior of the waveform. Following this, we sample the waveform at every clock period to define the return map, which is vital for a detailed understanding of the circuit dynamics. Finally, bifurcation phenomena of chaotic attractors are classified into four cases with a focus on the invariant interval. In particular, we discuss the characteristics of each bifurcation phenomenon, and then clarify the bifurcation structure of the chaotic attractor. Moreover, some of the numerical results are verified experimentally. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Meander Delay Compensation in High-Speed Digital Multilayer Packages

The routing of multi-trace digital signal buses in printed circuit boards often results in mismatches in the lengths of the lines. This results in mismatched propagation time, referred to as “timing skew” in a digital system. A common method that is used to compensate for this is to add meander sections of line to lengthen the signal path length. Many advanced circuit board design tools have the capability to perform this compensation automatically. Advanced Ball Grid Array (BGA) packages are fabricated using fine-line multilayer laminate substrates or they are built up using multilayer wafer-scale processes. The design tools for these types of packages have evolved from printed circuit board tools and typically use the same methods and principles. It is very common in BGA packages for high-speed digital applications to use meander trace patterns to match the trace lengths of high speed bus interconnections either from the chip to the solder balls or between chips in a multi-chip package. However, electromagnetic simulation of these packages shows that despite the use of these techniques to match the physical length of the traces, electrical lengths often vary by as much as a factor of two. Examples of such packages are presented and analyzed. The resulting timing skew is not a significant problem in most current applications, since the overall delay is small compared with the clock interval. But with emerging applications pushing well beyond 10Gb/s, timing skew in packages will be an important consideration. The reasons for the ineffectiveness of meander delay compensation are discussed, and are demonstrated by some simple simulations.

BIFURCATION ANALYSIS IN A PWM CURRENT-CONTROLLED H-BRIDGE INVERTER

This paper introduces the complete bifurcation analysis in a PWM current-controlled H-Bridge inverter in a wide parameter space. First, we briefly explain the behavior of the waveform in the circuit in terms of the switched dynamical system. Then, the consecutive waveform during the duration of the clock interval is exactly discretized, and the return map is defined for the rigorous analysis. Using the map, we derive the one- and two-dimensional bifurcation diagrams, and discuss the specific property of each bifurcation phenomena in the circuit.

Parallel stream cipher for secure high-speed communications

Due to ongoing improvements in high-speed communications, the speed of data encryption must also increase. Accordingly, this paper proposes an PS-LFSR with an m(⩾2)-times faster shifting during one clock interval and a parallel stream cipher that is faster by paralleling many similar keystream generators using the PS-LFSRs. Finally, an m-parallel SUM-BSG with 8-parallel for detail is proposed as a design example of the proposed parallel stream cipher. When compared with a conventional stream cipher, the properties of the proposed cipher exhibited the same crypto-degree with m-times faster processing.

The drift chamber electronics and readout for the NA48 experiment at the CERN SPS

A drift chamber readout system for a bout 8000 channels with continuous sensitivity, i.e. concurrent data recording and readout, is described. Drift times are measured in bins of 1.56 ns with respect to a continuously running 40 MHz clock. The clock interval of 25 ns is divided into 16 bins by means of a 16-element delay chain. The length of this chain is linked to the clock interval by a phase-locked loop. An ASIC chip was developed to perform time measurements and data storage for 16 channels. In an asynchronous readout of this chip, data are tranferred to intermediate buffers, for use in a first-level trigger and eventual final readout. The design of the electronics is described and results from data-taking runs are presented.

A statistical model for delay-fault testing

The authors propose a statistical model for measuring delay-fault coverage. The model provides a figure of merit for delay testing in the same way that fault coverage provides one for the testing of single stuck-at faults. The mode measures test effectiveness in terms of the propagation delay of the path to be tested, the size of the delay defect, and the system clock interval, and then combines the data for all delay faults to measure total delay-fault coverage. The authors also propose a model for measuring the defect level as a function of the manufacturing yield and the predictions of the statistical delay-fault coverage model. >

On Delay Fault Testing in Logic Circuits

Correct operation of a logic circuit requires propagation delays of all paths in the circuit to be smaller than the intended clock interval. Random or deterministic tests, conducted at the normal clocking rate, can be used to insure that path delays in manufactured circuits meet the specifications. Algorithms, based on a five-valued logic system, to accurately calculate the detection probability of path delay faults by random delay tests as well as to derive deterministic tests to detect path delay faults are proposed. The results can be used to determine the test length for a desired confidence level in testing a path fault when random tests are used, and to generate a test set for a list of delay faults when deterministic tests are used.

Adjustment errors of feedback guided human forearm movements elicited by random position signal sequences.

The effects of visual and auditory relevant feedback on human forearm movements elicited by random position signal sequences were examined. We observed the adjustment error sequences when the arm moved briskly and accurately to the target position. As the results, the mean adjustment errors for each speed (clock interval) of random position signal sequence are different in the left-right target positions, and also different in the flexion-extension movements. In faster speed (1 s), the adjustment errors are approximately flat as compared with those in other speeds, on the other hand, in moderate speed (2 s) or slower speed (3 s), these indicate a upward tendency from left to right positions, and also indicate a upward tendency from flexion to extension movements. However, in the reaction times, the moving times, and the adjusting times, there are no significant differences for the left-right target positions and for the flexion-extension movements.

Arc scan ultrasonic transducer array

A plurality of transducers is arranged successively on a common impedance matching layer of a resilient material. Each transducer comprises an elongated piezoelectric element having a width expansion vibrational mode, a pair of first and second electrodes attached to opposite surfaces of the element across its thickness and an elongated block of an impedance matching material disposed between the second electrode and the common impedance matching layer. The common impedance matching layer is bent to take the shape of an arch to conform to the surface of a frame structure which is convexed in the direction of propagation of ultrasonic energy. The piezoelectric elements are secured to the frame so that they bridge the parallel side members of the frame. The piezoelectric members are divided into a plurality of subgroups, each composed of successively arranged elements. The piezoelectric elements of a given subgroup are selected and energized during each clock interval for transmission of focused ultrasonic energy. The subgroup to be selected is shifted linearly to the next by at least one element in response to successive clock pulses. Becuase of the convex shape of the array, the transmitted energy is successively angulated to provide arc scan.

Automatic rhythm generator

First Page

Multipath Propagation at 4, 6, and 11 GHz

Signals at 4, 6, and 11 GHz, transmitted over a 28.5-mile radio relay path in Ohio, were continuously monitored during the late summer of 1966. Previous publications have reported on the observed 4- and 6-GHz multipath fading statistics, and on the improvements available with space or frequency diversity. This paper presents data for the 11-GHz transmission, and, in combination with the earlier results, establishes an empirical frequency dependence for the amplitude statistics. A general treatment of the relationships between the factors underlying multipath propagation is intractable. However, based on the results in this and other papers, a general relationship is given for the probability of deep multipath fading which is linear in frequency, cubic in path length, and varies with meteorological-geographical factors. Temporal aspects of the Ohio data were also investigated at all frequencies, utilizing both a 1-hour and a 1-day clock time interval. It was found that the multipath fade time statistic can be described by a single parameter for either interval. A subset of the multipath fading hours was also analyzed using a 1-minute clock interval, with the result that the difference between the minute median fade and the hourly median fade is frequency independent, and normally distributed with a standard deviation of 5.5 dB.