Time Code Research Articles

Temporal Up-Sampling of Planar Long-Range Doppler LiDAR Wind Speed Measurements Using Space-Time Conversion

Measurement campaigns in wind energy research are becoming increasingly complex, which has exacerbated the difficulty of taking optimal measurements using light detection and ranging (LiDAR) systems. Compromises between spatial and temporal resolutions are always necessary in the study of heterogeneous flows, like wind turbine wakes. Below, we develop a method for space-time conversion that acts as a temporal fluid-dynamic interpolation without incurring the immense computing costs of a 4D flow solver. We tested this space-time conversion with synthetic LiDAR data extracted from a large-eddy-simulation (LES) of a neutrally stable single-turbine wake field. The data was synthesised with a numerical LiDAR simulator. Then, we performed a parametric study of 11 different scanning velocities. We found that temporal error dominates the mapping error at low scanning speeds and that spatial error becomes dominant at fast scanning speeds. Our space-time conversion method increases the temporal resolution of the LiDAR data by a factor 2.4 to 40 to correct the scan-containing temporal shift and to synchronise the scan with the time code of the LES data. The mean-value error of the test case is reduced to a minimum relative error of 0.13% and the standard-deviation error is reduced to a minimum of 0.6% when the optimal scanning velocity is used. When working with the original unprocessed LiDAR measurements, the space-time-conversion yielded a maximal error reduction of 69% in the mean value and 58% in the standard deviation with the parameters identified with our analysis.

Double Full Diversity Massive Unitary Space–Time Codes for MIMO Channels

In this paper, we consider a flat fading noncoherent wireless communication system with double transmitter antennas and massive multiple receiver antennas, in which the channel coherence time is divided into four orthogonal time slots, and these are used within a complete transmission cycle. For such a system, we systematically design a family of noncoherent unitary space–time codes. Then, within this family and with the noncoherent maximum likelihood (ML) detector, we propose the design of an optimal unitary space-time code that minimizes the worst-case pairwise error probability (PEP) subject to a constraint on total transmission bits. A closed-form optimal solution is attained by first characterizing the optimal structure for any fixed bits on each parameter space and then finding an optimal bit assignment that further minimizes the worst-case PEP. Also, asymptotic PEP performance analysis on such an optimal code further shows that it enables full receiver-diversity gain when the number of the receiver antennas goes to infinity, with the increasing rate of the coding gain in terms of signal-to-noise ratio (SNR) being the number of the transmitter antennas. In other words, it also provides full diversity gain, i.e., the product of the number of the receiver antennas and the number of the transmitter antennas, when SNR goes to infinity. Therefore, we call such a code double full diversity code. One of the significant advantages of the proposed optimal design for our considered massive multiple-input multiple-output system is that it has no error floor with SNR increasing. Another significant advantage is that it enables a fast ML detector.

“Il flauto magico” still works: Mozart’s secret of ventilation

Background: Synchronisation/coupling between respiratory patterns and musical structure.
 Methods: Healthy professional musicians and members of the audience were studied during a performance of W.A. Mozart’s Piano Concerto KV 449. Electrocardiogram (ECG)/Heart Rate Variability (HRV) data recording (Schiller: MedilogWAR12, ECG-channels: 3, sampling rate: 4096 Hz, 16 Bit) was carried out and a simultaneous synchronized high definition video/audio recording was made. The breathing-specific data were subsequently extracted using Electrocardiogram-derived respiration (EDR; Software: Schiller medilogWDARWIN) from the HRV data and overlaid at the same time onto the musical score using FINALE 2011 notation software and the GIMP 2.0 graphics programme. The musical score was graphically modified graphically so that the time code of the breathing signals coincided exactly with the notated musical elements. Thus a direct relationship could be produced between the musicians’ breathing activity and the musical texture. In parallel with the medical/technical analysis, a music analysis of the score was conducted with regard to the style and formal shaping of the composition.
 Results: It was found that there are two archetypes of ideally typical breathing behaviour in professional musicians that either drive the musical creation, performance and experience or are driven by the musical structure itself. These archetypes also give rise to various states of synchronisation and regulation between performers, audience and the musical structure.
 Conclusions: There are two archetypes of musically-induced breathing which not only represent the identity of music and human physiology but also offer new approaches for multidisciplinary respiratory medicine.

Sensitivity to AM incoherence is affected by center frequency and modulation rate

Fine-grained sensitivity to frequency modulation (FM) at slow rates and low-frequency carriers is thought to be due to auditory-nerve phase locking (time code). Alternatively, a unitary code for FM at all rates and carrier frequencies could be based on cochlear conversion of FM to amplitude modulation (AM) (place code). One weakness of the place-coding theory is it cannot readily explain rate- and carrier-dependent trends in FM sensitivity. This study asked whether FM trends could potentially be explained by sensitivity to two AM envelopes that are out of phase (incoherent AM) at separate cochlear locations, thereby simulating the effects of FM. AM discrimination was assessed for two-component complexes centered at low (500 and 1500 Hz) and high (7000 Hz) frequencies, spaced 2/3 or 4/3 octaves apart, and modulated at slow (2 Hz) and fast (20 Hz) rates. Coherent and incoherent two-component AM detection was assessed for the same conditions. Preliminary results show that sensitivity to AM incoherence is best at low center frequencies and slow rates, consistent with trends traditionally found in FM detection that have been attributed to time coding. Findings suggest time coding may not be necessary to explain trends in FM sensitivity. [Work supported by NIH Grant R01DC005216.]

О взаимодействии культурных кодов в обрядовой традиции

The article analyzes the relationships of the verbal component with other elements in the ritual tradition of Tuvans of China, Russia and Mongolia. It is noted that among cultural codes the verbal element stands out with more functionality and semantic charge in performing the rites. The ritual word is closely related to actions performed by the participants of the ceremony (gestures, facial expressions, body movements). The verbal component is pronounced in a certain space and in environment suitable for it conditions that are associated with the spatial code of the ritual. The verbal element is also associated with the time code, since any ritual text is pronounced at a certain stage of the ritual, at observance of timeframe. The interaction of the verbal code with the character code is manifested in the fact that in the rites the text is prefer- ably recited by respected people. The unity of the food code is indicated not only with verbal code, but also with actional, spatial, object elements. In competitions and games the interdependence of verbal components and the game code is revealed. Colour and number elements in verbal code are less noticeable, but they are also used in ritual formulas. The object code has a close connection when the ritual attribute is used while pronouncing the ritual text. The connection of the sound and verbal aspects is expressed when during a ritual texts are pronounced with volume effect.

Filling the Gaps in the Law of Private Limited Companies in Ethiopia: Law, Contract and or Custom

Business people tie themselves under certain form of business organization’s chain and tackle commercial hurdles through collective efforts. In Ethiopia, present day witnessed proliferation of tremendous business organizations in all corners of the country. The structure of business organization chosen may, however, have an impact on how simple it is to obtain finances, how taxes are paid, how accounting records are kept, whether liability of members is limited or unlimited and the ways of. Like other forms of business organizations, Private limited company was introduced in Ethiopia in 1960 when the empire of Ethiopia adopted a comprehensive commercial code for the first time. The 1960 Commercial Code of Ethiopia has recognized six forms of business organization from which private limited company is the most popular and prevalent forms of business organization. Per Article 510/2 of the commercial code of Ethiopia, private limited company is a company whose members are liable only to the extent of their contribution. Yet, commercial code have not sufficiently address the issues of capital maintenance, valuation of in kind contribution, administration of paid up capital, shareholders general meeting, liquidation, founders, and expulsion and/or withdrawal of shareholders. Besides, absence of cross reference to provision of law of Share Company is another worst weakness of law of private limited company. This article has unveiled whether filling the gaps via contract, custom or law is possible. Accordingly, contract can solve the conundrums underlying it by inculcating to articles and memorandum of association, and corporate code of conduct. But, since custom on corporate governance is at an infancy stage, it is tricky to recommend customs as a way out. so the best option is to amend laws on private limited companies in a way that address the existing practical problems associated with such companies so as to make the Ethiopian law compatible with the current global affairs.

Time and communicative code of pilgrimage to the Kyiv-Pechersk Lavra (the second half of the 18th century)

The article deals with the time and communicative characteristics of pilgrimage to the Kyiv-Pechersk Lavra in the second half of the 18th century. The analysis of material donations made by pilgrims during the mid-70’s - the mid-80’s of the 18th century, allowed to identify two waves of pilgrimage activity: the first was made in May-June and the second – in August, which coincided with the activity of visiting other holy places of Kyiv. It was found out that in the Near and Far Caves pilgrims left donations: near relics; for sending prayers and typing into the list; wallet money and money for sprinkling; money for candles. In addition, in the Near Caves they gave offering near the exit from the cave labyrinth. It was established that the all sums grew during the peak of pilgrimage activity, but the proportionality between them varied throughout the year. The following categories of donations competed for the championship: in the month of less pilgrimage activity, the largest donations were collected for the sending of prayers and typing into the list. However, in the months, when the pilgrimage activity was high, the biggest share of the collected donates came from the relics.Different types of money donations allowed us to establish that communication around the relics of the reverend Fathers of the Caves was made through their direct honoring through worship and kissing, as well as through the order of the prayers and the recording into the cave list, sprinkling with holy water and probably drinking water from the cross of Reverend Mark Pechernik in the Near Caves.Taking into consideration the needs of the pilgrims, the Kyiv-Pechersk Lavra, equipping space around the shrines, corresponded to the specified set of “services” so that communication around the relics of the Reverend Fathers of the Caves provided to the pilgrims a sense of close contact with the relics and formed their religiosity.Keywords: pilgrimage, the Kyiv-Pechersk Lavra, 18th century.

ACC Theta Improves Hippocampal Contextual Processing During Remote Recall

Standard consolidation theory argues that over time memory recall becomes independent of the hippocampus. Multiple lines of research show that the medial frontal cortex, including the anterior cingulate cortex (ACC), is involved with contextual information processing and remote recall. We hypothesized interactions between the ACC and hippocampal area CA1 would change as memories became more remote. Animals were re-exposed to multiple environments at different retention intervals and during remote recall ACC-CA1 theta coherence increased. Theta-mediated communication from the ACC to CA1 regulates unit spike timing, gamma oscillations, and ensemble and single neuron information coding. Furthermore, since all our analyses pointed to the effects originating in the ACC, it is consistent with how one would expect memory readout to occur according to the standard consolidation model. In this case, the readout of the memory begins in the ACC and the effects can be observed in the CA1.

OAM Mode Selection and Space–Time Coding for Atmospheric Turbulence Mitigation in FSO Communication

Orbital angular momentum (OAM) multiplexing has recently received considerable interest in free space optical (FSO) communications. Propagating OAM modes through free space may be subject to atmospheric turbulence (AT) distortions that cause intermodal crosstalk and power disparities between OAM modes. In this paper, we are interested in multiple-input-multiple-output (MIMO) coherent FSO communication systems using the OAM. We propose a selection criterion for the OAM modes to minimize the impact of the AT. To further improve the obtained performance, we propose a space-time (ST) coding scheme at the transmitter. Through numerical simulations of the error probability, we show that the penalty from AT is completely absorbed for the weak AT regime, and considerable coding gains are obtained in the strong AT regime.

Signal power calibration of complex urban kinematic navigation system simulator based on C/N0 estimation

For a complex urban kinematic navigation system, which can realize the rapid deployment of the fire scene environment and provide an effective means for indoor positioning, it adopts Time Division Multiple Access and Code Division Multiple Access (TDMA + CDMA) signal structure to solve the problems of “near-far effect” of the ground-based navigation system and the weak indoor positioning signal. A simulator of the kinematic navigation system is a very important equipment for signal validation, receiver design and performance test. The simulator signal power precision is very essential for the validation of receiver signal power range and sensitivity. As a result, the simulator itself needs calibration, especially for the weak signal power. This paper deals with the time division weak signal power calibration of the simulator, which is based on the Carrier to Noise power density ratio (C/N0) estimation. Firstly, the kinematic navigation system simulator with its signal structure and power design is analyzed. Secondly, the architecture of the measurement system, where the calibration is carried out, is designed. Thirdly, a test strategy is designed to solve the problem of time division weak signal calibration, and then a description and comparison of three known C/N0 estimators is performed, which shows a clear gain in favour of the method “the correlator comparison method with varying noise”. Finally, a performance comparison between the estimation obtained from the receiver and the method proposed in this paper is done for two values of C/N0. From these results, it is concluded that the proposed method is precise and effective in time division weak signal power calibration.

Diagonal Space Time Block Coded Spatial Modulation

In this paper, a new Spatial Modulation (SM) scheme, called Diagonal Space Time Coded Spatial Modulation (DS-SM), is designed by embedding the Diagonal Space Time Code in SM. The DS-SM scheme still inherits advantages of SM while enjoying further benefits from spatial constellation (SC) designs. Based on rank and determinant criteria, a new set of four SC codewords is proposed for the DS-SM system with 4 transmit antennas to achieve the fourth-order diversity. Then a general design procedure for an even number of transmit antennas, larger than 4, is developed by cyclically shifting two rows of the SC codewords. Simulation results show that DS-SM surpasses several existing SM schemes at the same spectral efficiency and antenna configuration. DS-SM also exhibits better performance over the benchmark systems under spatially correlated channels. Complexity of DS-SM is also analyzed and compared with other SM schemes.

The relationship between time and place coding with cochlear implants with long electrode arrays.

The auditory system can theoretically encode frequencies by either the rate or place of stimulation within the cochlea. Previous work with cochlear implants has demonstrated that both changes in timing and place can be described as pitch changes but are perceptually orthogonal. Using multidimensional scaling, the present experiment extends the previous findings that timing and place changes are perceptually orthogonal into the cochlear apex using long 31-mm electrode arrays. However, temporal cues seem to be more reliable across subjects at the apex while place cues seem to be more reliable at the middle of the cochlea.

Random Access in Massive MIMO by Exploiting Timing Offsets and Excess Antennas

Massive multiple-input multiple-output (MIMO) systems, where base stations (BSs) are equipped with hundreds of antennas, are an attractive way to handle the rapid growth of data traffic. As the number of user equipments (UEs) increases, the initial access and handover in contemporary networks will be flooded by user collisions. In this paper, a random access protocol is proposed that resolves collisions and performs timing estimation by simply utilizing the large number of antennas envisioned in massive MIMO networks. UEs entering the network perform spreading in both time and frequency domains, and their timing offsets are estimated at the BS in closed form using a subspace decomposition approach. This information is used to compute channel estimates that are subsequently employed by the BS to communicate with the detected UEs. The favorable propagation conditions of massive MIMO suppress interference among UEs, whereas the inherent timing misalignments improve the detection capabilities of the protocol. Numerical results are used to validate the performance of the proposed procedure in massive MIMO networks, under uncorrelated and correlated fading channels. With $2.5 \times 10^{3}$ UEs that may simultaneously become active with probability 1%, a total of 16 frequency–time codes, and 100 antennas, a given UE is detected with probability 75%, and the accuracy of its timing estimate is on the order of few samples.

A Novel Robust and Low-Complexity Spacetime Codes for Industry 4.0 Systems

This paper proposes different robust and low-complexity space time codes which provide more reliability for industrial automation. An innovative synchronized uplink system configuration for an Industrial Environment is proposed. Mathematical framework for estimating the channel phase of each Slave Node (SN) is developed. Furthermore, the channel is practically estimated based on an innovative method using parallel sequence spread spectrum (PSSS) implemented in Universal Software Radio Peripheral (USRP). The proposed space time codes are applied in the uplink of an industrial communication system where the channel is modelled using Quasi Deterministic Radio Channel Generator (Quadriga) which follows a geometry-based stochastic approach. Simulation results exposed that the proposed codes surpass Alamouti code for Industrial Automation. The bit error rate (BER) performance demonstrates that the achieved coding gain for the proposed codes is higher than Alamouti code leading to more robust communication. Furthermore, a low complexity decoders based on minimum mean squared error (MMSE) and zero forcing (ZF) algorithms are designed at the receiver side. The proposed codes give a predominant execution against the state-of-the-art space time codes for Industry 4.0.

Performance Analysis of Adaptive Filter Channel Estimated MIMO OFDM Communication System

Advanced Communication Systems are wideband systems to support multiple applications such as audio, video and data so and so forth. These systems require high spectral efficiency and data rates. In addition, they should provide multipath fading and inter-symbol interference (ISI) free transmission. Multiple input multiple output orthogonal frequency division multiplexing (MIMO OFDM) meets these requirements Hence, MIMO-OFDM is the most preferable technique for long term evaluation advanced (LTE-A). The primary objective of this paper is to control bit error rate (BER) by proper channel coding, pilot carriers, adaptive filter channel estimation schemes and space time coding (STC). A combination of any of these schemes results in better BER performance over individual schemes. System performance is analyzed for various digital modulation schemes. In this paper,adaptive filter channel estimated MIMO OFDM system is proposed by integrating channel coding, adaptivefilter channel estimation, digital modulation and space time coding. From the simulation results, channel estimated 2×2 MIMO OFDM system shows superior performance over individual schemes.

Indexing videos: timing is everything

Indexing videos requires many of the same skills as indexing books or other materials. The main difference lies in the locator – time codes are used to guide the reader to the relevant point in the video. Jan Wright explains how this is done and provides helpful hints on how to manage a video indexing project.

RETUSS: Ensuring Traceability System between Class Diagram in UML and Java Source Code in Real Time

Ensuring of the traceability of deliverables is one of effective methods to secure the quality of software. It can verify that the requirements are reflected in the programs. But it has two problems: taking much labor and time, and causing mistakes by human handling. This paper has implemented RETUSS (Real-time Ensure Traceability between UML and Source-code System) in order to solve the above two problems. RETUSS can ensure traceability between Class diagram in UML and Java source code in real time.

Performance analysis of MIMO FSO link with Alamouti coding and switch-and-examine combining

Atmospheric turbulence is one of the main causes of degrading the quality of service in free-space optical (FSO) systems. The use of diversity techniques in an FSO system can minimize the fading effect which is caused by atmospheric turbulence. When diversity combining is applied at both the transmitter and the receiver ends, the system can mitigate the degradation more effectively. In this paper, we consider a $$2\times L$$ multiple-input multiple-output FSO system with on–off keying modulation where the link is affected by gamma–gamma fading. Alamouti space–time coding is implemented at the transmitter, while the receiver employs switch-and-examine combining. Analytical expressions for different performance metrics such as outage probability, average bit error rate and average capacity are derived using a moment-generating function-based approach. Numerical results are provided and are compared with Monte Carlo simulations.

Nearly optimal codebooks based on generalized Jacobi sums

Codebooks with small inner-product correlation are applied in many practical applications including direct spread code division multiple access (CDMA) communications, space–time codes and compressed sensing. It is extremely difficult to construct codebooks achieving the Welch bound or the Levenshtein bound. Constructing nearly optimal codebooks such that the ratio of its maximum cross-correlation amplitude to the corresponding bound approaches 1 is also an interesting research topic. In this paper, we firstly study a family of interesting character sums called generalized Jacobi sums over finite fields. Then we apply the generalized Jacobi sums and their related character sums to obtain two infinite classes of nearly optimal codebooks with respect to the Welch or Levenshtein bound. The codebooks can be viewed as generalizations of some known ones and contain new ones with very flexible parameters.

Эффективность передачи информации двухсимвольными ансамблями в симплексных системах связи на базе ТСК

The theory of electrical communication provides transmission of two types of information (messages): continuous messages and discrete. Continuous messages are characterized by an infinite number of their values on a finite time interval. An example of such a message may be the value of a quantity of the direction power of the microphone output: the greater the resolving power of the measuring device, the more different voltage values. Discrete messages (as opposed to continuous ones) are characterized by a finite number of values over an infinite time interval. For example, several volumes of a work of art have a finite number of characters (letters) that must be transferred. Advantages of digital methods of display, processing, transmission, accumulation and storage of information provide them with the primary use. Actually, various methods of digital conversion are used to increase the speed of information transfer - particularly, information compression. In this article were researched the efficiency of information transmission by two-character ensembles in simplex systems based on timed signal constructions. Timer coding, as opposed to positional, in which the information of the transmitted symbol is determined by the type of signal on the nyquist interval, keeps stored information in the length of several separate time segments of the signal tci and their mutual position. In this case, the duration of each of the signal segments is not less than the nyquist interval: t ci = t 0 + zD . Comparison of information parameters of two-character ensembles at positional and time coding had been made. Determined the information capacity of the nayquist element and the influence of the number of redundant elements ( r = n - m ) on entropy of the message at positional block coding. Optimal parameters of timed signal constructions for the code set affecting power were determined. Timer signal constructions are proposed as a code summarization mechanism, which provides transmission of information about the state of more than two sources in one codeword.