Coding Of Signals Research Articles

A Study on the TT&C Engineering Telemetry Test

This paper uses the theoretical analysis of communication and signal system to calculate the power spectrum of NRZ code and PSK signal, which reveals the bandwidth selection problem often used in equipment, and derives the most commonly used calculation conversion formula in calibration. Finally, the analysis and compared two calibration methods.

Application of Coded Excitation Signals for Measurement of Rock Ultrasonic Wave Velocity

The accurate measurement of ultrasonic velocity requires the detected waveforms to have a high signal-to-noise ratio (SNR). Coded excitation technique (CET) can improve the SNR without resolution loss. This study introduces the basic principles of phase-coded technology and gives a synthetic and experimental evaluation of Barker and Golay codes. All the results show that CET can increase the SNR, but the gain in SNR (GSNR) is lower than the theoretical value. The velocity measurements on red sandstone and granite verify that the Barker code has better pulse compression performance than the Golay code. Besides, the application of Barker-coded signals on the velocity monitoring of uniaxially compressed rock proves that the Barker CET is reliable.

“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.

Hetero-contact microstructure to program discerning tactile interactions for virtual reality

Helping to reconstruct and restore tactile perception motivates the continuous development of functional materials, sensing structures, and manufacturing strategies. Coding and use of mechanotransduction signals from artificial tactile perception make a vital contribution to provide tactile feedback for robots, prosthetics, and rehabilitation therapy. Here we propose a hetero-contact microstructure (HeCM) to fabricate tactile sensor by using silver nanowires@polyurethane scaffold combined with layered carbon fabric. The synergistically perceiving of the HeCM enables the mechanosensational range of tactile sensor to be programmatically and significantly enhanced by >100% compared to the one of the common counterpart. The as-designed sensor characterizes high sensitivity, fast response time, and reproducible electromechanical properties to identify static and dynamic external pressure changes. Actual fingertip events can be converted into visual or audio interactive feedback in virtual reality by the intelligent sensor, demonstrating the feasibility and practicality of design concept and great potential of the sensor for human-interactive system.

On High-Resolution Adaptive Sampling of Deterministic Signals

In this work, we study the topic of high-resolution adaptive sampling of a given deterministic and differentiable signal and establish a connection with classic approaches to high-rate quantization. Specifically, we formulate solutions for the task of optimal high-resolution sampling, counterparts of well-known results for high-rate quantization. Our results reveal that the optimal high-resolution sampling structure is determined by the density of the signal-gradient energy, just as the probability density function defines the optimal high-rate quantization form. This paper has three main contributions: The first is establishing a fundamental paradigm bridging the topics of sampling and quantization. The second is a theoretical analysis of nonuniform sampling, for arbitrary signal dimension, relevant to the emerging field of high-resolution signal processing. The third is a new practical approach to nonuniform sampling of one-dimensional signals that enables reconstruction based only on the sampling time points and the signal extrema locations and values. Experiments for signal sampling and coding showed that our method outperforms an optimized tree-structured sampling technique.

The fine-grained statistical structure of speech is congruent with nonlinear peripheral auditory processing

Efficient coding of sensory signals takes advantage of statistical regularities in sensory data. Cochlear filter in mammals are known to reflect the overall statistical structure of speech, in line with the hypothesis that low-level sensory processing provides efficient codes for information contained in natural stimuli. Recently, some efforts have been made to describe this correspondence in more detail. The study of the statistical structure of speech over different acoustic classes demonstrates that frequency selectivity should not be fixed to achieve maximum efficiency. On the other hand, cochlear signal processing is nonlinear as frequency selectivity decreases with sound intensity level. Both effects are greater in the high frequencies. In the present study, these two facts are shown to be consistent in the case of a parametric method based on Gabor dictionaries (Gaussian-modulated sinusoids) and in a simplified setting. A model with fewer constrains is also introduced for future experiments to validate this hypothesis in a more general context.

Simultaneous Multi-Frequency Phase-Coded Microwave Signal Generation at Six Different Frequencies Using a DP-BPSK Modulator

An approach to the generation of a multi-frequency phase-coded microwave signal at six different microwave carrier frequencies using a laser diode and a dual-polarization binary phase-shift keying (DP-BPSK) modulator is proposed and experimentally demonstrated. The key component in the proposed system is the DP-BPSK modulator, which consists of two dual-drive Mach–Zehnder modulators (DD-MZMs) that are driven by a binary coding signal and a microwave reference signal. By controlling the bias points of the DD-MZMs, and the power of the coding signal and the microwave reference signal, phase-coded microwave signals at six different frequencies are generated at the output of a photodetector. An experiment is performed. A multi-frequency phase-coded microwave signal at six different carrier frequencies in a frequency range from 1 to 19.5 GHz is generated. The performance in terms of phase recovery accuracy and pulse compression capability is evaluated. The interferences between different channels are also evaluated and no significant interferences are observed.

Photonic generation of microwave frequency shift keying signals using a dual-polarization quadrature phase shift keying modulator

A novel method to generate microwave frequency shift keying (FSK) signals based on a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is proposed and verified by a simulation. In this simulation work, the DP-QPSK modulator is employed to produce two orthogonally polarized double-sideband modulated signals with a wavelength spacing that is four times of the radio frequency driving frequency. Then, the signals are sent into a polarization modulator driven by a binary coding signal for complementary phase modulations. After that, a microwave FSK signal with frequency multiplication factors of four for bit ‘1’ and eight for bit ‘0’ is successfully generated through photodetection. The proposed system exhibits good stability and frequency tunability. Thanks to the high frequency multiplication factors, this method can find potential applications in high-frequency communication systems.

Simulation of the effect of bit assignment to multi-hypothesis pictures per group for motion compensated video compression (MCVC)

This paper describes the Lagrange based formulation of bit-assignment for multi-hypothesis frames over number of pictures in a group for motion compensated video compression. Theoretical insight on bit assignment is accomplished by applying Lagrange multiplier and its cost function for a real-time computational analysis. Video signals are compressed at optimal bit allocation for qualitative reconstruction at the decoder (receiver) depending upon the number of hypothesis used in coding the signal. This has made multi-hypothesis motion compensation (MHMC) a great process in the prediction of the actual signal through the combination of more than one motion compensated prediction (MCP). Optimal Bits were allocated to multi-hypothesis frames using MATLAB to optimize the number of hypothesis frames per group of pictures (GOP) decoded for an improved signal compression. Simulation results show that an optimal bit assignment of the range 0.089 bpp to 0.159 bpp was realized with eight numbers of hypotheses frames per (GOP). This implies that varying number of hypotheses actualizes optimal bit assignment for motion compensation. This shows a qualitative signal compression performance analysis for high technology motion pictures in communication services and storage processes. It also addresses a better prediction due to greater time correlation between hypotheses and helps in the improvement of coding and reconstruction quality of video signals. Key words: Bit-rate, frame, Group of Pictures (GOP), Motion Compensation,multi-hypothesis, Video Compression.

An implicit and reliable neural measure quantifying impaired visual coding of facial expression: evidence from the 22q11.2 deletion syndrome

Although various psychiatric disorders present with social-cognitive impairment, a measure assessing social-cognitive processes implicitly and reliably, with high selectivity and with enough signal-to-noise ratio (SNR) for individual evaluation of any population at any age, is lacking. Here we isolate a neural marker quantifying impaired visual coding of facial expression in individuals with 22q11.2 deletion syndrome (22q11DS) using frequency-tagging with electroencephalography (EEG). Twenty-two 22q11DS participants and 22 healthy controls were presented with changes of facial expression displayed at low, moderate, and high intensities every five cycles in a stream of one neutral face repeating 6 times per second (i.e., at a 6 Hz base rate). The brain response to expression changes tagged at the 1.2 Hz (i.e., 6 Hz/5) predefined frequency was isolated over occipito-temporal regions in both groups of participants for moderate- and high-intensity facial expressions. Neural sensitivity to facial expression was reduced by about 36% in 22q11DS, revealing impaired visual coding of emotional facial signals. The significance of the expression-change response was estimated for each single participant thanks to the high SNR of the approach. Further analyses revealed the high reliability of the response and its immunity from other neurocognitive skills. Interestingly, response magnitude was associated with the severity of positive symptoms, pointing to a potential endophenotype for psychosis risk. Overall, the present study reveals an objective, selective, reliable, and behavior-free signature of impaired visual coding of facial expression implicitly quantified from brain activity with high SNR. This novel tool opens avenues for clinical practice, providing a potential early biomarker for later psychosis onset and offering an alternative for individual assessment of social-cognitive functioning in even difficult-to-test participants.

Adaptive Reed–Solomon coding and envelope detection of photonic vector signal in V-band radio over fiber system

In this paper, a millimeter-wave radio-over-fiber (RoF) system based on adaptive Reed–Solomon (RS) coding scheme and envelope-detector-based (ED-based) down-conversion for 16-quadrature amplitude modulation (16-QAM) vector signal are proposed and experimentally investigated, which makes the ROF systems simpler, lower-cost and more robust to the phase noise of the generated millimeter-wave signals compared with the conventional system. The transmission of RS-coded 16-QAM vector signals with the bit rate of 2-Gb/s and 4-Gb/s at 60-GHz over 20-km standard single mode fiber (SSMF) and 2-m wireless distance are successfully achieved. RS coding module is adaptively performed via the last received codeword error rate (CER) estimated by the output of the first RS encoder. The experimental results show that the post-FEC bit error rate (BER) of 1×10−8 can be obtained by adaptive RS coding scheme with the flexible and optimum code rate and redundancies.

A Method of Fault Location Detection on Branched Power Transmission Lines

Using a method with different signal-to-noise ratios to search for a location of a fault location in branched power-transmission lines (PTLs) is considered in the work. A simulation model of a branched PTL is developed in the MATLAB software package. The relative error of fault location determination by changing the signal-to-noise ratio on the PTL and simulating different types of faults is studied in the simulation model. Three simulated pulses are used as the location signal: a single rectangular pulse, chirp signal, and Barker code with changing pulse width. It is revealed that choosing the location signal results in the maximum achievable accuracy of fault detection. Using the Barker code provides determination of fault location with an error of 0.2% and signal-to-noise ratio of more than 27 dB.

Time diversity scheme and adaptive signal clipping with blanking applied to G3 systems for narrowband power‐line communications

SummaryIn this paper, an investigation into the behavior of modern narrowband power‐line communication systems when concatenated with both a fountain code named Luby transform code and a combination of nonlinear preprocessing techniques called signal clipping with blanking is presented. The new systems can be used in applications such as the automatic meter reading component of smart grid technology. Testing is performed on a range of systems provided by the G3 standard and the results show that a bit error rate improvement can be achieved with the correct encoder/decoder settings. The recommended settings include an adaptive technique that uses Gaussian elimination for Luby transform code decoding and code rates that depend on the system specifications used. From there, it is shown that a further improvement is achieved when both the Luby transform code and adaptive signal clipping/blanking based on signal power are combined. It is found that these modifications present a complexity trade‐off, which is higher on the receiver side. This added complexity can be well‐tolerated in automatic meter‐reading systems because of the star topology and asymmetric nature of the network, which has a centralized agent acting as a receiver that collects data from various transmitter nodes.

A triple-frequency cycle slip detection and correction method based on modified HMW combinations applied on GPS and BDS

By taking advantage of the additional combined signals introduced by triple-frequency GNSS, we propose a cycle slip detection and correction method based on the traditional extra-wide-lane Hatch–Melbourne–Wubbena (HMW) combination and also modified HMW combinations. Instead of using the combined code signals directly in the traditional HMW combination, the modified HMW combination adopts the original code signals and one combined phase signal with corrected cycle slips to eliminate the ionospheric bias and reduce the effect of the noise induced by the code measurement. To determine the optimally combined signals and the corresponding coefficients in the modified HMW combination, four constrained conditions are proposed based on the maximum acceptable ionospheric bias and measurement noise of the combination in the process of cycle slip detection. Two optimally combined signals are selected; however, the second best signal cannot maintain a 100% success rate when epoch intervals are increased, due to the effect of the remaining ionospheric bias. To solve this problem, a scale factor is introduced to balance the corrected percentage of the ionospheric bias and the amplification of the measurement noise. These selected signals are further tested with real triple-frequency GPS and BDS observations. Results show that the proposed method can provide a 100% success rate in detecting cycle slips in the observations with large epoch intervals (up to 30 s) from medium earth orbit satellites with elevation angles above 5°, as well as inclined geosynchronous orbit and geostationary orbit satellites with elevation angles above 20°.

Coding of Probe Signals in the Tomography of Acoustic Nonlinear Parameters

Different ways of coding radiated signals that probe a tomographized object such as a liquid medium are compared in order to reconstruct the spatial distribution of acoustic nonlinear parameters using a small number of transducers. The results from reconstructing model nonlinear scatterers are discussed. The region of spatial frequencies available for reconstruction is analyzed.

Switching plasmonic Fano resonance in gold nanosphere-nanoplate heterodimers.

The interference between spectrally overlapping superradiant and subradiant plasmon resonances generates plasmonic Fano resonance, which allows for attractive applications such as electromagnetically induced transparency, light trapping, and refractometric sensing with high figures of merit. The active switching of plasmonic Fano resonance holds great promise in modulating optical signals, dynamically harvesting light energy, and constructing switchable plasmonic sensors. However, structures enabling the active control of plasmonic Fano resonance have rarely been achieved because of the fabrication complexity and cost. Herein we report on the realization of active plasmonic Fano resonance switching on Au nanosphere-nanoplate heterodimers. The active switching is enabled by varying the refractive index of a layer of polyaniline that fills in the gap between the Au nanosphere and the Au nanoplate. A reversible spectral shift of 20 nm is observed on the individual heterodimers during switching. The maximal spectral shift decreases as the interparticle gap distance is enlarged, showing a strong dependence of the spectral shift on the local electric field intensity enhancement in the gap region. This trend agrees with the predicted dependence of the refractive index sensitivity on the local field intensity enhancement. Our results provide insights into the development of plasmonic structures supporting actively switchable Fano resonances, which can lead to new technological applications, such as switchable cloaking and display, dynamic coding of optical signals, color sorting and filtering. The Au heterodimers with polyaniline in the gap can also be applied for the sensing of local environmental parameters such as pH values and heavy metal ions.

BASIC SIGNAL CODING METHODS BASED ON GALA CODES

The theoretical basics of data-free encoding of data based on recurrent GK-codes are presented, analysis and comparison of existing coding methods and their protocols with the proposed method, the principle of GK-codes formation based on Galois code sequence and transmission of coded data-free data are substantiated. The theoretical foundations and principles of signaling codes used to manipulate bit-oriented data streams in computer system information channels are proposed, taking into account the extent of signal space utilization and signal shape, the rate of message transmission and the degree of error protection. The RSSC provides effective symmetric coding in the form of Galois codes of sequences of zeros and units of a data block, with unambiguous determination of their number that can be used to detect and correct errors after data transmission on computer systems. A special feature of the structure of this special processor is the symmetrical formation of Galois data bit signs. Moreover, the start of the Galois generator occurs according to the appearance of the first bit of zero or one in the data stream. New methods of signal-free bit encoding of bit-oriented information flows using Galois field codes have been proposed, which enable the detection and correction of one-time errors without inputting excess data streams transmitted in an optical channel. Formalization of functional structures of modules of processors of formation of hopeless codes has been formalized, as well as structures of special processors and their components have been developed, which perform the formation of Galois signal corrective codes and implement their algorithmic modeling.

Piecewise constant signal and image denoising using a selective averaging method with multiple neighbors

Piecewise constant signals and images are an important kind of data. Typical examples include bar code signals, logos, cartoons, QR codes (Quick Response codes), and text images, which are widely used in both general commercial and automotive industry use. One previous work called a general selective averaging method (GSAM) was introduced to remove noise from them. It chooses homogeneous neighbors from the two closest pixels (one pixel at each side) to update the current pixel. One limitation is that it suffered from appearing sparse noisy pixels in the denoised result when the noise level is high. In this paper, we try to solve this problem by proposing a selective averaging method with multiple neighbors. To update the intensity value at each pixel, the proposed algorithm averages more homogeneous neighbors selected from a large domain, which is based on the property of the local geometry of signals and images. This greatly reduces sparse noisy pixels left in the final result by GSAM. Similarly, our method adopts the Neumann boundary condition at edges, and thus preserves edges well. In 1D case, some theoretical results are given to guarantee the convergence of our algorithm. In 2D case, except eliminating additive Gaussian noise, this algorithm can be used for restoring noisy images corrupted by speckle noise. Intensive experiments on both gray and color image denoising demonstrate that the proposed method is quite effective for piecewise constant image denoising and achieves superior performance visually and quantitatively.

Машинная классификация сигналов числового кода в электротехнических системах локомотивной сигнализации

Машинная классификация сигналов числового кода в электротехнических системах локомотивной сигнализации

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation