Digital image processing is the use of computer algorithms to improve image quality, to extract or add information. Image compression is a part of image processing and is used to reduce the quantity of data to store. This paper presents the implementation of image compression operations on low cost embedded systems (Raspberry Pi 3, Arduino Uno R3). Motivated by the work of Tchagna et al. (DOI: 10.5815/ijigsp.2018.11.05), we proposed within this paper a real-time implementation of the compression algorithm on embedded boards. Our investigation in this paper is to make a real-time compression system able to capture an image, apply compression algorithm and save compression image on an SD card (for Arduino or Raspberry) or sent directly compressed image to cloud. Compression system with a Raspberry Pi basically used a webcam USB camera to capture the images, the compression function based on python language, and a function to store compressed image to an SD card or to Cloud. The compression system with Arduino used an SD card where the image to be compressed are stored, an external SRAM chip, and an Ethernet shield. The proposed hardware system can decompress the image. In opposition to the approach adopted in the literature, all the results presented within this work use the vector quantization. Eight images have been used to evaluate and compared the compression time for each board according to codebook size used during vector quantization step. Based on our results, we remark that compression and decompression time using Raspberry Pi is lower than compression and decompression time using Arduino. Raspberry Pi offers many possibilities and its processor is bigger than Arduino processor. This justifies the obtained compression and decompression time using Raspberry Pi compared to those with Arduino.
A virtual coincidence unit, a virtual counter and a virtual timer were developed via a software in this study. Different frequency signals supplied from a function generator were sent to a real coincidence unit. The same signals were transmitted to the virtual coincidence unit via a digitizer. Output signals of the real and virtual coincidence units were counted by real and the virtual counters. Count periods were set through real and virtual timers. For different count periods, coincidence counts obtained from the virtual counter were compared with those of the real one. It was seen that obtained results were highly compatible with each other for low frequency (25 – 55 Hz) signals.
The special point is found in frequency characteristics of one model of an oscillatory contour about which it wasn't reported earlier in the scientific literature. The point settles down at a frequency, the smaller resonant frequency of a contour. The module of an impedance doesn't depend on the size of active resistance at this frequency. Physical interpretation of the phenomenon doesn't exist at the moment and it is main question. The aim of this article is the complete description of the properties system with the observed effect - results of calculations of existence region of the module are for the first time given in it. For comparison two models of an oscillatory contour are considered. Existence region of the impedance is essentially different for the considered models. Phase charts of an impedance are calculated with same aim. Results of the research can be used in the electrical and the electronic engineering and textbooks for profound studying of electrical equipment.
Due to the fact that the traditional Digital Electronic Technology (hereinafter referred to as DET) experiments bear sufficient reference material, elaborate design plan and complete design circuits (which makes it difficult for the students to design some experiments by themselves innovatively), but fail to bear enough experimenting methods, combined with the requirements raised by the competitions for experiment case teaching of elementary curriculums on electronic engineering and technique, in order to make some changes to the traditional experiment teaching, the paper innovated a new experiment case for the design of Rock-paper-scissors Game. In the design, two methods, Digital-integrated-circuit method and programmable-techniques method, are adopted to make it come true. When adopting digital-integrated-circuit method, right integrated circuit components will be employed according to the game-designing plan, using the software of Proteus to simulate it first, followed by debugging and testing of the hardware circuits on the bread board. The programmable-techniques method can describe the functions of the game on the development platform of the software of Quartus II by programming, adopting HDL (hardware description language). After right simulation, the programs will be downloaded onto FPGA experimental boxes or development board to realize the design of the game. The experimental case of Rock-paper-scissors Simulation Game is interesting and novel, which tends to stimulate the students to explore new world, study and innovate new things on their own. The adoption of the two methods will not only further enhance students’ knowledge application ability and engineer practice ability, but also help them better understand the difference of an experiment between the traditional and modern method, which will, in turn, understand the significance and value of programmable techniques in digital system designing.
This paper focuses on the Binary Phase Shift Keying Digital Modulation Technique for Noiseless and Noisy Transmission with the following objectives:(i) to design a BPSK system (ii) to show the modulation and demodulation of a BPSK technique through a noiseless channel and (iii) to show the modulation and demodulation of the same technique through a noisy channel. A model-based design methodology was employed in this work. The entire idea was modelled in Matlab/Simulink environment. The results obtained after analysis and simulation show good system design and specifications. Demodulated bits will be in error if transmission channel is noisy.
Combined techniques consisting of traditional linear filtering and total variation de-noising are studied to de-noise images polluted with composite noises from different sources. Series and parallel approaches are compared theoretically. Some further discussions are given about parameters and their effect on the optimization problem. A simultaneous method is proposed and simulated using the convex optimization toolbox, comparing different alternative methods with respect to signal to noise ratio and error covariance matrix. The proposed method could be used to enhance the smoothing performance.
在n-Rayleigh信道下，研究了使用发射天线选择(TAS)和正交空时分组码(STBC)的多输入多输出(MIMO)系统的平均符号误码率(ASEP)性能。基于标量加性高斯白噪声(AWGN)信道的方法，得到了系统使用多进制正交幅度调制(MQAM)和多进制相移键控调制(MPSK)，在接收端的信噪比的表达式。然后对不同条件下的ASEP性能做了数值仿真，仿真结果表明：随着发射天线或接收天线数的增加，系统的ASEP性能得到了很好的改善，当使用QPSK调制，SNR = 12 dB，(3,3; 6)系统的误码率是2 × 10−3, (4,4; 8)系统的误码率是2 × 10−4, (5,5; 10)系统的误码率是2 × 10−5。The average symbol error probability (ASEP) of multiple-input multiple-output (MIMO) systems employing transmit antenna selection (TAS) and orthogonal space-time block code (STBC) under n-Rayleigh fading channels is investigated in this paper. Based on the scalar additive white Gaus-sian noise (AWGN) channel approach, the exact form expressions of the signal-to-noise ratio (SNR) at the receiving end are derived for multiple quadrature amplitude modulation (MQAM), and mul-tiple phase shift keying modulation (MPSK). Then the ASEP performance under different conditions is evaluated through numerical simulations. Simulation results show that: the ASEP performance can be improved with the increase of the number of transmit antennas or receive antennas, when SNR = 12 dB, the ASEP of (3,3; 6) with QPSK is 2 × 10−3, (4,4;8) is 2× 10−4, (5,5; 10) is 2 × 10−5.
In order to mitigate the interference between macrocell mobile stations (mMSs) and femtocells and allocate the spectrum efficiently, a graph coloring based clustering algorithm for channel allocation is proposed in this paper. Under the premise of guaranteeing the SINR requirements of mMSs, the algorithm determines the initial set of subchannels which can be used for each femtocell. Then according to the constructed interference graph of the femtocell networks, each femtocell mobile station(fMS) is allocated all the available spectrum resources dynamically. In this paper, we use an improved cluster algorithm to ensure the SINR of mMSs and maximize the femtocell throughput. Simulation results show that the proposed algorithm can reduce the outage probability of mMSs as well as improve the total throughput.
According to the theory of continuous-time filter design,a new sampled-data wavelet filter implementation based on switched-current bilinear integrator and inverse follow-the-leader feedback(IFLF) structure is presented.First,the wavelet frequency domain function is approximated by Maclaurin series.Next,the wavelet filter whose impulse response is the wavelet approximation function is designed using an IFLF structure with switched-current bilinear integrator as the main building blocks.By controlling the various clock frequencies of the filters with the same system architecture,the continuous wavelet transform can be implemented.Simulations demonstrate that the designed circuits have simple structure,easily adjustment scales of wavelet function and very low passband sensitivity.
BiCMOS Circuits which have both advantages of CMOS circuits and bipolar Circuits have been paid more and more attention.A novel general structure and design method for pulse-triggered flip-flops based on BiCMOS technique are proposed and two kinds of D flip-flops according to the structure are presented.The results carried out by Hspice using TSMC 180nm show the proposed circuits have correct logic functions and advantages of high speed,low power and strong drive ability.Compared with existing designs,the proposed BiCMOS pulse-triggered D flip-flops consume much less power and have much smaller PDP.
Inter-symbol interference(ISI) will be caused when Faster-Than-Nyquist(FTN) signaling is applied,and it will degrade the system performance according to the traditional communication theory.In 1975,however,Mazo told us that system performance will not be degraded as long as the transmission rate is not beyond 25% faster than the Nyquist rate,because the minimum euclidean distance is not changed though ISI exists.In this paper,a realization scheme in AWGN channel based on two-stage equalization for FTN transmission system is proposed,which is composed of a linear minimum mean square error(MMSE) equalizer followed by a windowed Chase equalizer.Simulation results show that the receive scheme can work normally and keep the BER performance invariable if the transmission rate is not beyond 25% faster than Nyquist,which validates the theory of Mazo through experiment.
In order to solve the conflict between scarcity of the spectrum resources and the urgent demand for high capacity digital communication systems,the bandwidth efficiency of the digital communication systems should be high.In this paper,a new band-pass digital modulation technologies-1/2Continous phase Chirp Keying(1/2-CPCK),whose energy is highly concentrated,are analyzed.The segmented Chirp signals serve as the waveform samples of modulated signals,which make use of the features that frequency between modulated signals transmits smoothly to improve bandwidth efficiency.The paper introduces the mathematical models of 1/2-CPCK and its power spectral density,the energy concentration of modulated signals is analyzed.The BER of the 1/2-CPCK digital communication system is analyzed by simulation.Theoretical analysis and simulation results show that the energy and bandwidth efficiency of 1/2-CPCK are high,1/2-CPCK digital communication system has better adaptation to additive white Gaussian noise channel.
The bottleneck of UWB technology used in satellite communication field is the interference problem between UWB satellite communication systems and narrowband systems.The time and frequency characteristics of sinusoidal modulation Gaussian pulse used in satellite channel are investigated.UWB satellite communication emulate system is finished and the bit error characteristic in condition of interference between UWB satellite communication systems and narrowband systems is evaluated.Key factors that affect interference are gained and UWB system design parameters that suit with transmission in satellite communication channel are put forward.The feasibility of sharing frequency spectrum between these two kinds of systems is demonstrated.
A method based on interpolating sampling technology is proposed in this paper to achieve high precision time difference measurement in TDOA location system.Compared with traditional methods,this method converts the clock quantization error’s measurement to the phase measurement of reference signals,thus completely eliminating the traditional methods’ principle error.Theoretical analysis and MATLAB simulation are discoursed fully in the paper.Results show that a time difference measure precision within 70 ps can be achieved under the current device performance.This technology can also be used for the clock synchronization of base stations in TDOA location system.The clock synchronization error will be effectively reduced.So the positioning accuracy shall be further improved as well.
This paper addresses the problem of Subspace method that it may fail when the channel order is overestimated.An enhanced Subspace method is presented,which is robust to channel order overestimation.Firstly,overmodel is studied,and a new theorem is derived and proved,which indicates that a weighting matrix can remove the influence of the overestimated order to Subspace method.Then,the weighting matrix can be approximated by an exponential sequence.Compared to Subspace method,the proposed algorithm has the same computational cost and is more robust to channel order overestimation.Simulations demonstrate the effectiveness of the algorithm.
In allusion to the excellent performance for high SNR and error spread for low SNR,DS-VCC-DDEA is researched based on the proposition of VCC-DDEA and DFE-VCC-DDEA in Narrow-Band HF(High Frequency) single serial tone data communication,which is realized by switching the equalization algorithm between VCC-DDEA and DFE-VCC-DDEA guided by the real-time SNR estimation from the current frame.DS-VCC-DDEA not only abandons the hypothesis that the channel coefficients is constant for DDEA in the frame,but also avoids the short-back of DFE equalizer,and can fetch the integral performance improvement for different SNR.Simulation validates its advantage to DDEA,VCC-DDEA and DFE-VCC-DDEA.
An optimization design of damping control for unified power flow controller on the tradeoff between delay margin and damping ratio is proposed.In order to solve the problem that supplementary damping controller obtained by conventional design can not effectively damping interval frequency oscillation in the case of communication latency,a UPFC damping control time-delay model with considering time varying and stochastic feature of the communication latency,which is based on classical UPFC damping control model,is constructed.A delay-dependent stability criterion for power system with less conservativeness is derived according to the Lyapunov-Krasovskii stability theory,which unveils interactive influence mechanism among damping controller parameters,delay margin and damping performance,and helps to optimize conventional damping controller design.Simulations demonstrates that UPFC damping controller designed by the proposed method can effectively damp interval frequency oscillation as well as endure a certain communication latency,which overcomes the disadvantages of conventional damping controller in the case of longer communication latency.
Reconfigurable system is an excellent solution for video decoding,which has shown great advantages in both flexibility and high performance,reaching a satisfactory tradeoff between GPPs(General Purpose Processors) and ASICs.But high-profile 1080p real-time decoding is still a hard work,which contains computing-intensive tasks,such as IDCT(Inverse Discrete Cosine Transform),MC(Motion Compensation),Intra-prediction,deblocking.These tasks take 80% complexity in H.264.This paper gives out a plan to map the tasks on a certain coarse-grade reconfigurable processor,called REMUS,achieving better results than Ganesan and D.Peng’s works.IDCT in a micro-block executes in no more than 192 cycles,intra-prediction 389 cycles,MC 320cycles and deblocking 704 cycles,met the timing requirement of H.264 1080p high profile real-time decoding at 200MHz.
The Orthogonal Matching Pursuit(OMP) algorithm is one of the sparse channel estimation methods based on compressed sensing.Multipath energy leakage due to the non-integer multipath delay will always lead to multipath number increasing and bring difficulties to detection.In this paper,we investigate the termination criterion of the OMP algorithm and design one based on noise variance which can be obtained by estimation.The OMP algorithm based on noise variance(NV-OMP) can jointly detect the channel multipath number and estimate the channel state information.The stimulation results show that,compared with the OMP algorithm based on known sparsity,the NV-OMP algorithm is more robust in non-integer multipath delay environment,and hence is more suitable for practical applications.Moreover,the influence of noise variance estimation on the performance of the new OMP algorithm is also presented.
A low-pass R-MOSFET-C filter with a tunable cutoff frequency is proposed in the paper.In the filter,a MOSFET is employed to replace the resistor in a typical topology of the RC active filter to achieve the tunable and ultra-low cutoff frequency,which is suitable for medical applications.The filter is implemented in UMC 0.13um CMOS technology with a 1.2V supply voltage.The simulation results show that the cutoff frequency ranges from 0.2Hz to 292.8Hz as the gate voltage of the MOSFET is tuned from 0.6V to 0.84V.
