scholarly journals A Novel Sample Based Quadrature Phase Shift Keying Demodulator

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Asraf Mohamed Moubark ◽  
Sawal Hamid Md Ali
Keyword(s):  
Phase Noise ◽  
Signal To Noise Ratio ◽  
Local Oscillator ◽  
Coherent Detection ◽  
Signal Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Incoming Signal ◽  
Shift Keying ◽  
Low Pass

This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10−6, whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.

ANALYTICAL MODELING AND SIMULATION OF PHASE NOISE IN BISTATIC SYNTHETIC APERTURE RADAR SYSTEMS

2006 ◽  
Vol 06 (03) ◽  
pp. L297-L303 ◽  
Author(s):  
WENQIN WANG
Keyword(s):  
Synthetic Aperture Radar ◽  
Phase Noise ◽  
Local Oscillator ◽  
Synthetic Aperture ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Noise Simulation ◽  
Low Pass ◽  
Bistatic Synthetic Aperture Radar ◽  
Aperture Radar

The requirement of phase noise imposed on the stable local oscillator for bistatic synthetic aperture radar (SAR) is much more severe than in the monostatic cases. So accurate phase noise simulation is of great importance during the design and development of bistatic SAR systems. This letter concentrates on the impacts of limited oscillator stability between bistatic transmitter and receiver, and presents an analytical model of phase noise that solves some drawbacks implicitly present in the previously proposed models. This model uses the Gaussian noise as the input of a hypothetical low-pass filter and its output is then considered as phase noise. Finally, some simulation results are provided to demonstrate the validity of this model.

A Rotor Flux Observer Based on Nonlinear Quadrature Double Compensation

2011 ◽  
Vol 128-129 ◽  
pp. 25-29
Author(s):  
Bo Fan ◽  
Xing Li ◽  
Jie Xin Pu ◽  
Jian Wei Ma ◽  
Ju Wei Zhang
Keyword(s):  
Induction Motor ◽  
Electromotive Force ◽  
Signal Frequency ◽  
Quick Response ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Flux Observer ◽  
Low Pass ◽  
Rotor Flux ◽  
Order Change

In order to solve the problem of integration saturation drift and hardship in compensation quantity calculation exist in rotor flux observation of induction motor, a rotor flux observer based on nonlinear quadrature double compensation method is presented in this paper. The quantity of compensation is determined dynamically according to the quadrature level between flux and back electromotive force. Through the order change of compensation and low-pass filter, quick response of flux when signal frequency leaps is realized. The simulation result shows that the method can improve the flux waveform, realize the accurate and swift track of flux.

scholarly journals Audio Watermarking Combined with Compressive Sampling Based on QIM and DST-QR Techniques

2019 ◽  
Vol 19 (1) ◽  
pp. 20
Author(s):  
Irma Safitri ◽  
Gelar Budiman ◽  
Arfidianti Kartika Meiza Putri
Keyword(s):  
Signal To Noise Ratio ◽  
Transformation Process ◽  
Compressive Sampling ◽  
Audio Watermarking ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Digital Copyright ◽  
Sine Transform ◽  
Low Pass ◽  
Speed Change

Abuse is not only done to copy or distribute data but also to the digital copyright labels. There is a way to protect data by inserting or hiding a piece of certain information, namely a watermarking technique. In this paper, we propose audio watermarking with Quantization Index Modulation (QIM) method as an embedding process combined with Compressive Sampling (CS), Discrete Sine Transform (DST) and QR decomposition. Binary image is used as a watermark inserted in host audio. DST is used for transformation process from time domain to frequency domain, while QR is used to decompose onedimension matrix into two-dimension matrix. Meanwhile, CS is used to obtain the compressed watermark file which is done before the embedding process. QIM method is used to embed the watermark file to the audio host file. Simulation results indicated that the proposed audio watermarking technique has good robustness against some attacks such as Low Pass Filter (LPF), resampling and linear speed change. In addition, it provides good performance in terms of imperceptibility with Signal to Noise Ratio (SNR) > 20 dB and capacity C = 689 bps.

The Human Controller as an Adaptive, Low Pass Filter

1967 ◽  
Vol 9 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Gordon H. Robinson
Keyword(s):  
Signal To Noise Ratio ◽  
Noise Signal ◽  
Manual Control ◽  
Future Research ◽  
Research Needs ◽  
Descriptive Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Independent Variables ◽  
Low Pass

Data is presented on the ability of a human controller to track a signal contaminated with noise. Signal frequencies and signal-to-noise ratio are the independent variables. An optimal, adaptive filter is presented for comparison. A descriptive model is derived based on known human characteristics in manual control. Future research needs are discussed.

Weak Signal Detection System Based on Lock-in Amplifier Technology

2013 ◽  
Vol 389 ◽  
pp. 489-493
Author(s):  
Yong Lv ◽  
Chun Hui Niu ◽  
Yue Qiang Li ◽  
Qing Shan Chen ◽  
Xiao Ying Li ◽  
...  
Keyword(s):  
Signal Detection ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
Weak Signal ◽  
Weak Signal Detection ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Phase Sensitive ◽  
Lock In

In order to detect the weak signal deeply buried in the noise, a weak signal detection system based on lock-in amplifier is proposed. The system includes the preamplifier circuit, active low pass filter circuit, AC amplifying circuit and phase sensitive demodulation circuit. Test results show that it can greatly increase the signal-to-noise ratio (SNR) up to 12.7db.

A 2nd-Order Continuous Time Delta-Sigma Modulator for Photoplethysmography Analog Front-End

2020 ◽  
Author(s):  
Eka Fitrah Pribadi ◽  
Rajeev Kumar Pandey ◽  
Paul C.-P. Chao
Keyword(s):  
Transfer Function ◽  
Continuous Time ◽  
Supply Voltage ◽  
Signal To Noise Ratio ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Delta Sigma Modulator ◽  
Delta Sigma ◽  
Low Pass ◽  
Order Continuous

Abstract A brief presents a 2nd order continuous-time delta-sigma modulator (CT-DSM) using a low pass filter to reduce the slew rate requirement of the output swing of the first integrator. By adding the low pass filter, the desired transfer function of the CT-DSM is altered. Thus a feed-forward based compensation circuit is introduced to transform the altered transfer function to the original condition. The CT-DSM is designed with a bandwidth of 100 Hz to satisfy the requirement of photoplethysmogram (PPG) detection. The CT-DSM is simulated using CMOS 180 nm technology with the layout area 460 μm × 460 μm. The circuit uses a 1.8 V supply voltage and consumes 35.61 μW. The signal-to-noise ratio of the CT-DSM is 101.2 dB, while the SFDR is 99.1 dB.

scholarly journals QIM - Based Audio Watermarking with Combination Technique of DCT-QR-CPT

2019 ◽  
Vol 7 (1) ◽  
pp. 112 ◽  
Author(s):  
RENDY DWI RENDRAGRAHA ◽  
GELAR BUDIMAN ◽  
IRMA SAFITRI
Keyword(s):  
Signal To Noise Ratio ◽  
Audio Watermarking ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Opinion Score ◽  
Low Pass ◽  
Band Pass ◽  
Speed Change ◽  
Index Modulation

ABSTRAKAudio watermarking adalah teknik memasukkan informasi ke dalam file audio dan untuk melindungi hak cipta data digital dari distribusi ilegal. Makalah ini memperkenalkan audio stereo watermarking berdasarkan Quantization Index Modulation (QIM) dengan teknik gabungan Discrete Cosine Transform (DCT) - QRCartesian Polar Transform (CPT). Host audio dibagi menjadi beberapa frame, selanjutnya setiap frame ditransformasi oleh DCT, kemudian output DCT diuraikan menjadi matriks orthogonal dan matriks segitiga menggunakan metode QR. Selanjutnya, CPT mengubah dua koefisien kartesian dari matriks segitiga (R) pada posisi (1,1) dan (2,2) menjadi koefisien polar. Setelah itu, penyisipan dilakukan pada koefisien polar oleh QIM. Hasil simulasi menunjukkan bahwa imperseptibilitas audio terwatermark berkualitas baik dengan Signal to Noise Ratio (SNR)> 20, Mean Opinion Score (MOS)> 4 dan tahan terhadap serangan seperti Low Pass Filter (LPF) dan Band Pass Filter (BPF) dengan cut off 25-6k, resampling, Linear Speed Change (LSC) dan MP3 Compression dengan rate diatas 64 kbps.Kata kunci: Audio Watermarking, CPT, DCT, QIM, QR ABSTRACTAudio watermarking is a technique for inserting information into an audio file and to protect the copyright of digital data from illegal distribution. This paper introduces a stereo audio watermarking based on Quantization Index Modulation (QIM) with combined technique Discrete Cosine Transform (DCT) – QR – Cartesian Polar Transform (CPT). Each frame of a host audio is transformed by DCT, then DCT output is decomposed using QR method. Next, CPT transform two cartesian coefficients from triangular matrix (R) in position (1,1) and (2,2) to polar coefficients. After that, embedding is executed on polar coefficients by QIM. The simulation result shows that the imperceptibility is good with Signal to Noise Ratio (SNR)>20, Mean Opinion Score (MOS)>4 and it is robust against attacks such as Low Pass Filter (LPF) and Band Pass Filter (BPF) with cut off 25-6k, Resampling, Linear Speed Change and MP3 Compression with rate 64 kbps and above. Keywords: Audio Watermarking, CPT, DCT, QIM, QR

scholarly journals Measurement Accuracy Enhancement via Radio Frequency Filtering in Distributed Brillouin Sensing

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2878 ◽  
Author(s):  
Cheng Feng ◽  
Stefan Preussler ◽  
Jaffar Emad Kadum ◽  
Thomas Schneider
Keyword(s):  
Radio Frequency ◽  
Noise Reduction ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Rf Filters ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Optical Time ◽  
Rf Signal

In this article, we demonstrate the noise reduction and signal to noise ratio (SNR) enhancement in Brillouin optical time-domain analyzers (BOTDA). The results show that, although the main noise contribution comes from the Brillouin interaction itself, a simple low pass filtering on the detected radio frequency (RF) signal reduces remarkably the noise level of the BOTDA traces. The corresponding SNR enhancement depends on the employed cut-off frequency of the low pass filter. Due to the enhancement of the SNR, a mitigation of the standard deviation error of the Brillouin frequency shift (BFS) has been demonstrated. However, RF filters with low cut-off frequency could lead to distortions on the trace signals and therefore detection errors on a non-uniform BFS. The trade-off between the noise reduction and the signal distortion as well as an optimal cut-off frequency are discussed in detail.

scholarly journals Enhancing SNR and generating contrast for cryo-EM images with convolutional neural networks

2020 ◽  
Author(s):  
Eugene Palovcak ◽  
Daniel Asarnow ◽  
Melody G. Campbell ◽  
Zanlin Yu ◽  
Yifan Cheng
Keyword(s):  
Image Processing ◽  
High Frequency ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Low Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Processing Pipeline ◽  
Visual Contrast ◽  
Low Pass

AbstractIn cryogenic electron microscopy (cryo-EM) of radiation-sensitive biological samples, both the signal-to-noise ratio (SNR) and the contrast of images are critically important in the image processing pipeline. Classic methods improve low-frequency image contrast experimentally, by imaging with high defocus, or computationally, by applying various types of low-pass filter. These contrast improvements typically come at the expense of high-frequency SNR, which is suppressed by high-defocus imaging and removed by low pass filtration. Here, we demonstrate that a convolutional neural network (CNN) denoising algorithm can be used to significantly enhance SNR and generate contrast in cryo-EM images. We provide a quantitative evaluation of bias introduced by the denoising procedure and its influences on image processing and three-dimensional reconstructions. Our study suggests that besides enhancing the visual contrast of cryo-EM images, the enhanced SNR of denoised images may facilitate better outcomes in the other parts of the image processing pipeline, such as classification and 3D alignment. Overall, our results provide a ground of using denoising CNNs in the cryo-EM image processing pipeline.

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