Journal articles: 'Demodulation'

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Skorodumovs, A. "SDPSK-Specific Demodulation Method for the Nanortu Field-Programmable Gate Array / SDPSK-Specifiska Demodulācijas Metode Nanortutm Programmētajām Loģiskajām Integrācijas Shēmām." Latvian Journal of Physics and Technical Sciences 50, no. 1 (February 1, 2013): 84–90. http://dx.doi.org/10.2478/lpts-2013-0006.

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The software-defined radio (SDR) solutions inpart flexibility to the satellite applications when the devices are physically inaccessible after the launch. The nanoRTU FPGA-based controller (AAC Microtec) may be programmed to serve as a software-defined differential phase shift keying (SDPSK) modem backend to be used in satellites for communication with the Earth. The modem consists of two units - a modulator and a demodulator. A fully functional symmetric SDPSK modulator for nanoRTU FPGA has already been implemented. The next step of the modem implementation is the development of demodulator. In order to implement such facilities, the existing demodulation techniques should be reviewed in order to propose the appropriate method in which the demodulator would be capable of demodulating a signal, and, at the same time, would be resource-efficient. The author describes a valid method of specific SDPSK signal demodulation for the nanoRTU FPGA.

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Wang, Zhe, Zhi Hong Yin, and Ming Xu Zhang. "Research of Fiber Bragg Grating Sensor Demodulating Technology with Lab VIEW." Applied Mechanics and Materials 236-237 (November 2012): 1211–15. http://dx.doi.org/10.4028/www.scientific.net/amm.236-237.1211.

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Combining the virtual instrument technology with the fiber Bragg grating sensing technology, a new fiber Bragg grating sensing demodulation system based on Lab VIEW has been designed. The unbalanced Mach-Zehnder interferometer demodulation technology has been used in this system to translate the fiber Bragg grating wavelength signals in which the strain information is contained into the phase signals，and transfer it to the virtual instrument based on Lab VIEW with the high speed data acquisition card，then conduct process operations and results display [1]. At last, the value of measured strain can be obtained. Compared with the conventional demodulations system，the accuracy this interferometer demodulation system’s measurement has been increased greatly. At the same time, it solves the problem of high cost, large volume and only displays the wavelength with the conventional demodulations system.

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Mu, Shi Guang, Jin Rong Bai, and Xiu Feng Shi. "Optimization and Simulation of Demodulation and Decoding of the LDPC-BICM-ID System." Applied Mechanics and Materials 701-702 (December 2014): 1088–92. http://dx.doi.org/10.4028/www.scientific.net/amm.701-702.1088.

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In the bit interleaving coded modulation (BICM-ID) solution,includes the demodulator and decoder into the iteration and decoding process, and the decoding is completed between demodulator and decoder. In studies, it have been found that the oscillation is generated on logarithmic likelihood ratio (LLR) because the soft information generated by all previous BP iterations is ignored in this solution, so that the BP soft information output by the final BP iterative decoding is not always reliable. In this paper, the above problem is solved by optimizing the iterative demodulation and decoding solution. Aiming at this problem, this paper firstly puts forward a kind of optimization scheme about iterative demodulation and decoding, then the simulation analysis, the result show that, under the premise of ensuring the system complexity basically unchanged, can improve the demodulation and decoding performance of LDPC coded modulation and demodulation system.

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Chen, Yuren, Yang Yu, Yan Xu, Zhencheng Wang, Ning Li, Wenjie Xu, and Zhenrong Zhang. "Seawater Dual Parametric Fiber Optic Temperature and Pressure Sensors Demodulated by Machine Learning Method." Journal of Physics: Conference Series 2718, no. 1 (March 1, 2024): 012049. http://dx.doi.org/10.1088/1742-6596/2718/1/012049.

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Abstract By employing polydimethylsiloxane (PDMS) characterized by elevated thermo-optical and elastic-optical coefficients for encapsulating an optical microfiber coupler integrated with a sagnac loop (OMCSL) structure, which exhibits large abrupt field characteristics, a fiber optic sensor capable of simultaneously measuring seawater temperature and pressure can be created. Nevertheless, the utilization of the traditional sensitivity matrix method (SMM) for demodulating the sensor led to unstable and considerably erroneous demodulation results. To enhance the accuracy of the demodulation process, this paper investigates and employs a machine learning method (MLM) for sensor demodulation. This paper centers on the investigation and application of MLM for sensor demodulation. The experimental results exhibit a significant decrease in demodulation error attained via MLM when contrasted with the traditional SMM.

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Chen, Xian Qing, Shu Bo Song, and Wu Zhou. "Demodulation of a M-Ray Position Phase Shift Keying System Using Multi-Class Support Vector Machine Classification." Applied Mechanics and Materials 687-691 (November 2014): 3840–43. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.3840.

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In this paper, we introduce a new approach for nonlinear demodulation based on multi-class support vector machine (SVM) classification. We propose to measure the performance of this demodulator with different M which is the parameter of M-ray position phase shift keying (MPPSK) modulation, and compare with other demodulation technique. During demodulation, a few sampling points are chosen for multi-class SVM training and testing, which can reduce the complexity of system. Simulation results show that this new approach significantly outperforms the method of using Phase Locked Loop (PLL) demodulation by 10dB, and also better than Back Propagation Artificial Neural Networks (ANN-BP) classification demodulation. With the growth of M, the data rate increased and the performance become a little worse, but less bit SNR is used to achieve the same Symbol Error Rate (SER) as small M. So, it is an effective method to get better performance by using multi-class SVM classification technique for demodulation in MPPSK system.

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Peng, Kang-Chun, and Chan-Hung Lee. "A Novel Quadrature-Tracking Demodulator for LTE-A Applications." Wireless Communications and Mobile Computing 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/8712414.

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This work develops an advanced quadrature-tracking demodulation technique for coherently demodulating the orthogonal frequency-division multiplexing (OFDM) signal of LTE-A systems. To overcome the fact that traditional coherent demodulators are extremely sensitive to the quadrature imbalance of a system, especially an OFDM system, the proposed architecture uses a novel quadrature phase-locked loop (QPLL) to track simultaneously the in phase (I-phase) and the quadrature phase (Q-phase) of the received signal. This advanced quadrature-tracking demodulator is realized using TSMC 0.18 μm CMOS technology and hybrid circuits. Experimental results indicate that the developed quadrature-tracking demodulator, which operates at 2.1~2.5 GHz, can effectively demodulate an 18 Mbps LTE-A signal, even with a 15 degree quadrature imbalance.

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Zhu, Shou Zhong, Zheng Liu, and Wen Li Jiang. "Counteraction of Constant Modulus Demodulation Scheme for Mixing Space Borne AIS Signals." Applied Mechanics and Materials 340 (July 2013): 523–28. http://dx.doi.org/10.4028/www.scientific.net/amm.340.523.

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Demodulation scheme was proposed in satellite systems to received Automatic Identification Systems (AIS) signals, with the potential presence of other interfering signals. The counteraction of constant modulus demodulation scheme, referred to as CCMDS, yields a set of single short signals based on the prior information of AIS after estimating the frequency, code rate and modulation index. It demodulates the corresponding short codes according to the constant modulus characters of GMSK signals. The proposed demodulation scheme is simple and easy to implement. Simulations show the satisfying performance and engineering value in demodulating the mixing AIS signals.

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Li, Peng Fei, Jin Ping Li, and Xin Zhao. "Design and Simulation of 2PSK Modem." Applied Mechanics and Materials 321-324 (June 2013): 2914–18. http://dx.doi.org/10.4028/www.scientific.net/amm.321-324.2914.

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Based on the principle of the modulation and demodulation of Binary Phase Shift Keying(2PSK),a mathematical model for the modulation and demodulation of the 2PSK was built and the carrier signal was designed using the technology of Direct Digital Synthesis (DDS).Then,a model to simulate the hardware circuit of the modulation and demodulation of 2PSK was built,and then analyzed in Matlab and Modelsim.Simulation results show that the model not only properly realizes the function of 2PSK modulator-demodulator,but it also simplifies the hardware circuit and reduces the programming time.

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PAVLOV, I. I., M. C. PAVLOVA, E. S. ABRAMOVA, S. S. ABRAMOV, A. KHAN, and YU S. SHCHERBAKOV. "MODIFIED INVARIANT AMPLITUDE MODULATION WITH TWO REFERENCE SIGNALS." T-Comm 17, no. 6 (2023): 13–22. http://dx.doi.org/10.36724/2072-8735-2023-17-6-13-22.

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The model of modified invariant amplitude modulation and demodulation with two reference signals considered in the article belongs to the field of systems, networks and devices of telecommunications and radio engineering and can be used in radio transmitting devices, telecommunication systems and devices where an amplitude-modulated transmitted signal is required for transmission through a communication channel. The achieved technical result of the modified invariant amplitude modulation and demodulation with two reference signals is aimed at the possibility of forming an amplitude-modulated transmitted signal with increased noise immunity characteristics to a specific type of interference. Algorithms of modified invariant amplitude modulation and demodulation with two reference signals are proposed, and based on these algorithms, block diagrams of a modified invariant amplitude modulator and a demodulator with two reference signals were developed. In order to obtain experimental data for the analysis of a modified invariant amplitude modulation and demodulation with two reference signals when it is affected by interference in the communication channel, the communication system was simulated and the necessary data calculated in Matlab. Additive white Gaussian noise was chosen as an interference in the communication channel. The article presents a simplified block diagram of the communication system of the experimental model. To compare the results, modified invariant amplitude modulation and demodulation with two reference signals will be used as a modulator and demodulator, in the first case, and in the second case, amplitude modulation and demodulation. As a result, estimates of the dependence of the standard deviation on the value of the signal-to noise ratio and the probability of a bit error on the value of the signal-to-noise ratio were obtained. The standard deviation for modified invariant amplitude modulation and demodulation with two reference signals has significantly lower values than the standard deviation for amplitude modulation and demodulation. The transmission of information with the same reliability through a communication channel with a modified invariant amplitude modulation with two reference signals requires a significantly higher signal-to-noise ratio than transmission through a communication channel with amplitude modulation.

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Grzesiak, Krystian, and Zbigniew Piotrowski. "NN-Based 8FSK Demodulator for the Covert Channel." Sensors 22, no. 19 (September 21, 2022): 7181. http://dx.doi.org/10.3390/s22197181.

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In this article, a superposition-based covert channel and its demodulator were proposed and examined. As a covert waveform, an 8FSK modulation was selected. The impact of the channel estimation error and resulting imperfect SIC operation (successive interference cancelation) on the covert information demodulation process was considered. Especially for this imperfection, an NN-based demodulator was proposed. The superiority of this solution over the traditional 8FSK correlator-based receiver was examined for various cases, including the hard- and soft-decision detectors. It was proven that, although NN does not provide BER values equal to zero, even for the perfect SIC, it generally overcomes the traditional correlator-based 8FSK demodulator. Simulation results showed that the NN-base demodulator, in the case of additional covert channel coding, provides error-free demodulation, even for four-times greater channel gain error.

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Jiménez, Abimael, Ángel Sauceda, Antonio Muñoz, José Duarte, and José Mireles. "FPGA-Based Hardware Implementation of Homodyne Demodulation for Optical Fiber Sensors." Photonics 10, no. 3 (February 28, 2023): 258. http://dx.doi.org/10.3390/photonics10030258.

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Homodyne demodulation is a convenient technique for signal detection in interferometric sensors. The demodulation process is typically developed using analog circuits. However, to improve the performance of the demodulator, a digital system must be employed. In this study, we developed an optical fiber sensor by combining: (a) a Michelson interferometer, (b) a micro-electro-mechanical system (MEMS) device, and (c) a field-programmable gate array (FPGA)-based interrogator. Signal processing was integrated into the FPGA-embedded system. The homodyne demodulation algorithm was implemented with hardware modules developed in the hardware description language (HDL) to provide a portable, low-cost, and scalable digital system. The present study successfully demonstrates the development and validation of an FPGA-based interrogator capable of processing interferograms through a homodyne demodulation scheme. The experimental results reveal proper displacement measurements of the proof-mass MEMS and the low amount of hardware resources used. The displacement measurements obtained from the system matched those obtained from a certified characterization system. As the system can be easily reconfigured to the required measured signal, a similar measurement methodology can be developed using other demodulation schemes and optical fiber sensors.

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Yan, Hao, Xiaoping Liao, Chenglin Li, and Chen Chen. "A Cascaded MEMS Amplitude Demodulator for Large Dynamic Range Application in RF Receiver." Micromachines 12, no. 12 (December 5, 2021): 1515. http://dx.doi.org/10.3390/mi12121515.

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An amplitude demodulator with a large dynamic range, based on microelectromechanical systems (MEMS), is proposed in this paper. It is implemented as a cascade of a capacitive and a thermoelectric sensor. Two types of the transducer can improve the measurement range and enhance the overload capacity. This MEMS-based demodulation is realized by utilizing the square law relationship and the low-pass characteristic during the electromechanical and thermoelectric conversion. The fabrication of this device is compatible with the GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that this MEMS demodulator can realize the direct demodulation of an amplitude modulation (AM) signal with a carrier frequency of 0.35–10 GHz, and cover the power range from 0 to 23 dBm. This MEMS demodulator has the advantages of high power handling capability and zero DC power consumption.

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Xue, Ke, Tao Yu, Yanlin Sui, Yongkun Chen, Longqi Wang, Zhi Wang, Jun Zhou, Yuzhu Chen, and Xin Liu. "Research and Implementation of a Demodulation Switch Signal Phase Alignment System in Dynamic Environments." Sensors 23, no. 22 (November 13, 2023): 9144. http://dx.doi.org/10.3390/s23229144.

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In the space gravitational wave detection mission, inertial sensors play the role of providing an inertial reference for the laser interferometric measurement system. Among them, the capacitance sensor serves as the core key technology of the inertial sensor, used to measure the relative position of the test mass (TM) in the electrode cage. The capacitance sensor utilizes synchronous demodulation technology to extract signals from the AC induction signal. When the phase of the demodulation switch signal is aligned, the synchronous demodulator can most effectively filter out noise, thus directly influencing the performance of the capacitance sensor. However, since the TM is in a suspended state, the information read by the capacitance sensor is dynamic, which increases the difficulty of demodulation phase alignment. In light of this, a method is proposed for achieving the phase alignment of the demodulation switch signal in a dynamic environment. This is accomplished by adjusting the phase of the demodulation switch signal, and subsequently computing the phase difference between the AC induction signal and the demodulation switch signal. At the same time, a measurement and evaluation method for phase deviation is also proposed. Ultimately, an automatic phase alignment system for the demodulation switch signal in dynamic environments is successfully implemented on an FPGA platform, and tests are conducted on a hexapod PI console platform to simulate dynamic environments. The experimental results demonstrate that the system accurately achieves phase alignment in the static environment, with a phase deviation of 0.1394 rad. In the simulated dynamic environment, the phase deviation is 0.1395 rad.

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Lu, Huali, Xunhua Huang, Chenji Guo, Jiayang Xu, Jiannan Xu, Hui Hao, Hua Zhao, Wanchun Tang, Peng Wang, and Hongpu Li. "Orbital-angular-momentum beams-based Fizeau interferometer using the advanced azimuthal-phase-demodulation method." Applied Physics Letters 121, no. 24 (December 12, 2022): 241102. http://dx.doi.org/10.1063/5.0122253.

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A stably acquiring and accurately demodulating interferogram is crucial for the interferometer to achieve ultra-high precision and sensitivity measurements. In this study, a robust orbital angular momentum (OAM) beams-based Fizeau interferometer is proposed and experimentally demonstrated, which is more compact and stable than the OAM interferometers with other structures due to the common optical path characteristic. In accordance with such an interferometric scheme, a phase-demodulation method operated in the domain of the OAM complex spectrum is also proposed and demonstrated in this study. In contrast to other phase-demodulation techniques, the proposed phase-demodulation technique neither requires phase shifters or phase modulators nor brings spectral leakage, which provides a robust alternative enabling to accurately and quickly extract the phase from the OAM interferogram. As a proof-of-concept of the proposed scheme, tiny displacements ranging from 0 to 800 nm were measured. The proposed OAM beams-based Fizeau interferometer and the corresponding azimuthal phase demodulation method may provide a feasible way for exploring further applications of the OAM-based interferometer in metrology.

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Zhou, Jing, and Duandan Liang. "Intelligent Matching of the Control Voltage of Delay Line Interferometers for Differential Phase Shift Keying-Modulated Optical Signals." Photonics 8, no. 10 (October 6, 2021): 428. http://dx.doi.org/10.3390/photonics8100428.

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In optical communications, differential phase shift keying (DPSK) provides a desired modulation format that offers high tolerance to nonlinear effects in high-speed transmissions. A DPSK demodulator converts the phase-coded signal into an intensity-coded signal at receivers. One demodulation scheme is called balanced detection and is based on a tunable delay line interferometer (DLI). Demodulation performances are determined by the phase delay generated by the DLI, while the phase delay is controlled by a tunable driving voltage on the DLI device. However, a problem in the dynamic adjustment of the control voltage prevents the application of DPSK demodulators. The receivers need to scan the whole control voltage range of the DLI and find the control voltage that maximizes the demodulation performance, but the scan-based method needs to undergo a very long searching time. In our work, we found that the relation between DLI control voltages and demodulation performance can be predicted rapidly by a feedforward neural network (FNN). In this paper, we propose a new method to quickly locate the best DLI control voltage based on an FNN. We also verify the proposed method in simulations and telecommunication systems, and the results show that the proposed method can significantly improve the efficiency of resolving the best demodulation voltages.

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Wang, Chun, Dong Ling Peng, and Ge Zhu. "Energy Operator Demodulation Method and Its Application in Gears Fault Diagnosis." Advanced Materials Research 403-408 (November 2011): 2972–80. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.2972.

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Base on the analysis of the localization of the demodulation methods, a new optimizing arithmetic model, the energy operator optimizing arithmetic, is put forward first. Through theoretical analysis and engineering application, this new arithmetic is compared with the classic arithmetic, Hilbert demodulating method, from the precision, sensitivity, anti-jamming, complexion and some other fields by experiments. At last, this dissertation validates that the high-frequency resonance technique based on energy operator optimizing arithmetic which combine with LabView is availability with gear fault diagnosis that increase the frequency resolution of demodulation spectrum.

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Liu, Xiao Jian, Wei Xu, and Jue Wang. "LDPC Coded PPM and Iterative Detection for Free-Space Optical Links." Applied Mechanics and Materials 651-653 (September 2014): 444–50. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.444.

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The pulse position modulation, which has the advantage of average energy efficiency and bandwidth efficiency, is an attractive modulation scheme for free-space optical communication. An important practical issue is to employ an efficient channel coding to this modulation. In this view, we consider the use of low density parity-check code together with iterative soft demodulation and channel decoding at the receiver. In particular, we discuss the calculation of the soft information at the demodulator to accommodate the LDPC decoder. We show that the proposed scheme is quite efficient against demodulation errors due to the receiver noise.

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Harcombe, David M., Michael G. Ruppert, and Andrew J. Fleming. "A review of demodulation techniques for multifrequency atomic force microscopy." Beilstein Journal of Nanotechnology 11 (January 7, 2020): 76–91. http://dx.doi.org/10.3762/bjnano.11.8.

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This article compares the performance of traditional and recently proposed demodulators for multifrequency atomic force microscopy. The compared methods include the lock-in amplifier, coherent demodulator, Kalman filter, Lyapunov filter, and direct-design demodulator. Each method is implemented on a field-programmable gate array (FPGA) with a sampling rate of 1.5 MHz. The metrics for comparison include the sensitivity to other frequency components and the magnitude of demodulation artifacts for a range of demodulator bandwidths. Performance differences are demonstrated through higher harmonic atomic force microscopy imaging.

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Sud, Seema. "High Order Chirp Rate Shift Keying Modulation Using the Fractional Fourier Transform." European Journal of Engineering Research and Science 2, no. 4 (April 14, 2017): 1. http://dx.doi.org/10.24018/ejers.2017.2.4.314.

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In this paper, we discuss an improved demodulation scheme using the Fractional Fourier Transform (FrFT) for a modulation scheme employing chirp rate shift keying (CrSK). CrSK in conjunction with the FrFT enable very high order, e.g. more than 32-ary modulation schemes to be achievable with good bit error rate (BER) performance, even in the absence of coding, thereby overcoming limitations of traditional schemes including phase shift keying (PSK) or QAM (quadrature amplitude modulation). By using an FrFT-based demodulator, we expand our demodulation degrees of freedom from a single (e.g. frequency) axis to an entire time-frequency domain, called the Wigner Distribution (WD). We show how the proposed demodulation scheme using the FrFT improves over past approaches by more than 7 dB, enabling us to achieve close to 4-ary performance with a 32-ary modulation scheme. This enables future systems to operate at 5 bits/s/Hz bandwidth efficiency, enhancing bandwidth utilization for future generation, high data rate, applications, such as internet.

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Harcombe, David M., Michael G. Ruppert, Michael R. P. Ragazzon, and Andrew J. Fleming. "Lyapunov estimation for high-speed demodulation in multifrequency atomic force microscopy." Beilstein Journal of Nanotechnology 9 (February 8, 2018): 490–98. http://dx.doi.org/10.3762/bjnano.9.47.

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An important issue in the emerging field of multifrequency atomic force microscopy (MF-AFM) is the accurate and fast demodulation of the cantilever-tip deflection signal. As this signal consists of multiple frequency components and noise processes, a lock-in amplifier is typically employed for its narrowband response. However, this demodulator suffers inherent bandwidth limitations as high-frequency mixing products must be filtered out and several must be operated in parallel. Many MF-AFM methods require amplitude and phase demodulation at multiple frequencies of interest, enabling both z-axis feedback and phase contrast imaging to be achieved. This article proposes a model-based multifrequency Lyapunov filter implemented on a field-programmable gate array (FPGA) for high-speed MF-AFM demodulation. System descriptions and simulations are verified by experimental results demonstrating high tracking bandwidths, strong off-mode rejection and minor sensitivity to cross-coupling effects. Additionally, a five-frequency system operating at 3.5 MHz is implemented for higher harmonic amplitude and phase imaging up to 1 MHz.

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Sud, Seema. "High Order Chirp Rate Shift Keying Modulation Using the Fractional Fourier Transform." European Journal of Engineering and Technology Research 2, no. 4 (April 14, 2017): 1–5. http://dx.doi.org/10.24018/ejeng.2017.2.4.314.

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In this paper, we discuss an improved demodulation scheme using the Fractional Fourier Transform (FrFT) for a modulation scheme employing chirp rate shift keying (CrSK). CrSK in conjunction with the FrFT enable very high order, e.g. more than 32-ary modulation schemes to be achievable with good bit error rate (BER) performance, even in the absence of coding, thereby overcoming limitations of traditional schemes including phase shift keying (PSK) or QAM (quadrature amplitude modulation). By using an FrFT-based demodulator, we expand our demodulation degrees of freedom from a single (e.g. frequency) axis to an entire time-frequency domain, called the Wigner Distribution (WD). We show how the proposed demodulation scheme using the FrFT improves over past approaches by more than 7 dB, enabling us to achieve close to 4-ary performance with a 32-ary modulation scheme. This enables future systems to operate at 5 bits/s/Hz bandwidth efficiency, enhancing bandwidth utilization for future generation, high data rate, applications, such as internet.

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Yang, Ye, Jiang Wu, Hao Wu, and Yu Wang. "Research on onboard multistage digital demultiplexer for satellite communication based on MF-TDMA system." Journal of Physics: Conference Series 2524, no. 1 (June 1, 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2524/1/012007.

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Abstract A new multicarrier multi-rate digital demultiplexer system structure based on MF-TDMA(Multi-Frequency Time Division Multiple Access) in a wideband satellite communication system is described. Compared with the traditional tree multicarrier demultiplexer method, the new structure uses a half-band filter instead of the quadrature mirror filter, which has three advantages: 1) It fully avoids the shortcomings of the traditional method, such as confusion distortion and amplitude distortion. 2) The computation to achieve filtering is reduced by nearly half. 3) It effectively improves the demodulation performance of the system. In this paper, the new structure performs the multistage digital demultiplexer and demodulation of the MF-TDMA signal. The results show no obvious signal distortion, which is demultiplexed by the new structure. The bit error rate of the demodulated signal is better than that of the traditional single carrier demodulator. The bit error rate is very close to the theoretical value of QPSK demodulation.

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Ruppert, Michael G., David M. Harcombe, Michael R. P. Ragazzon, S. O. Reza Moheimani, and Andrew J. Fleming. "A review of demodulation techniques for amplitude-modulation atomic force microscopy." Beilstein Journal of Nanotechnology 8 (July 10, 2017): 1407–26. http://dx.doi.org/10.3762/bjnano.8.142.

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In this review paper, traditional and novel demodulation methods applicable to amplitude-modulation atomic force microscopy are implemented on a widely used digital processing system. As a crucial bandwidth-limiting component in the z-axis feedback loop of an atomic force microscope, the purpose of the demodulator is to obtain estimates of amplitude and phase of the cantilever deflection signal in the presence of sensor noise or additional distinct frequency components. Specifically for modern multifrequency techniques, where higher harmonic and/or higher eigenmode contributions are present in the oscillation signal, the fidelity of the estimates obtained from some demodulation techniques is not guaranteed. To enable a rigorous comparison, the performance metrics tracking bandwidth, implementation complexity and sensitivity to other frequency components are experimentally evaluated for each method. Finally, the significance of an adequate demodulator bandwidth is highlighted during high-speed tapping-mode atomic force microscopy experiments in constant-height mode.

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Shvaychenko, V. B., V. M. Bakiko, V. V. Pilinsʹkyy, and SH Shalilekh. "Analysis of the influence of different types of modulation on the spectral composition of conducted interference." Electronics and Communications 16, no. 3 (March 28, 2011): 216–20. http://dx.doi.org/10.20535/2312-1807.2011.16.3.266788.

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The basic features of electromagnetic compatibility are analysed at use in telecommunication systems of different types of modulation. Models М-FSK, M-PSK modulations and demodulations are developed. By results of modelling recommendations for choice optimum parametres of methods of modulation and demodulation for maintenance of criterion of a noise-immunity are indicated

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Cai, Lin Jun, Zheng Ying Li, Zhi Hao Tang, Wei Meng, and Quan Liu. "A Novel Peak-Seek Algorithm Used in FBG Sensor Demodulation System for Vibration Monitoring." Applied Mechanics and Materials 160 (March 2012): 135–39. http://dx.doi.org/10.4028/www.scientific.net/amm.160.135.

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The FBG sensor technologies used for real-time monitoring of the mechanical vibration have attracted more and more concerns from both academic and industrial domains. In practical applications, the vibration frequency of the equipments generally reach up to a few hundred to several thousand Hz, however, the existing FBG demodulator is incompetent to meet the actual requirements of vibration monitoring in terms of demodulation speed and algorithm structures. To solve this problem while achieving a higher accuracy at a relatively lower computation cost, a novel adaptive semi-peak-seek algorithm based on state machine is proposed, which can be divided into three parts including data collection, data analysis and data verification. The experiment result shows that for the demodulation speed of 2 KHz, we can reach a demodulation accuracy of 1pm and a static noise within ±2pm. On the basis of a long term test, the stability error that less than 2pm and the system dynamic range of 0~ -30db are concluded, and the measurement error with the optical power attenuation is limited to 4pm. Thus, the proposed algorithm is capable to meet the requirements of high-speed demodulation devices in terms of speed, precision, stability and anti-interference properties.

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Li, Qinglong, Yong Xu, Qiao Li, Kun Peng, and Xian Zhang. "A Demodulation Circuit For Analog Front End Of Passive Tag Chip." Journal of Physics: Conference Series 2065, no. 1 (November 1, 2021): 012007. http://dx.doi.org/10.1088/1742-6596/2065/1/012007.

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Abstract The demodulation circuit designed in this paper is suitable for the analog front end of passive UHF RFID tag chip, which can handle ASK signals with large changes in amplitude, modulation depth and signal frequency. Its performance meets the requirements of standards ISO/IEC 18000-6C and GB/T 29768-2013. Envelope detection circuit and limiter circuit are simple in structure and do not consume power. The comparison reference voltage is taken according to the average value of the envelope high and low levels, and is less affected by the dynamic changes of the input signal. Changing the width-to-length ratio of the MOSFETs in the feedback path of the comparator can adjust the hysteresis, with strong noise suppression and controllable sensitivity. The demodulator is implemented with TSMC 0.18 μm standard CMOS process. The simulation results show that the ASK signal modulation depth that the demodulator can handle is as low as 30%, and the maximum pulse width demodulation error is only 0.43%.

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Chaudhari, Sandeep C., Yashwant Gupta, Ajith Kumar, Navnath D. Shinde, Sweta Gupta, and Ajay Vishwakarma. "Reducing Effects of Cross-Talk in a Radio Telescope Using Walsh Modulation." Journal of Astronomical Instrumentation 06, no. 01 (March 2017): 1641017. http://dx.doi.org/10.1142/s2251171716410178.

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Traditional Walsh technique is used to eliminate cross-talk in a array of radio telescope where achieving synchronization between modulator and demodulator without compromising sensitivity is a real challenge. The paper describes a novel approach named Walsh Delay Hunting (WDH) to synchronize independently running modulator and demodulator with no additional hardware. This approach is unique and can easily be implemented in any existing radio telescope with minimal changes, thus by putting Walsh modulator at telescope and demodulation can be done in digital back-end. The scheme greatly reduces antenna electronics and overhead of sending synchronizing Walsh start pulse back to center station and vice versa. The paper describes WDH method and its feasibility study for Giant Meterwave Radio Telescope (GMRT) along with test results. The modulator is a low cost CPLD-based module and demodulation is done in a Reconfigurable Open Architecture Computing Hardware (ROACH)-based digitizer and packetizer. The scheme requires noise injection facility before modulator, which GMRT has for antenna calibration.

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Weikert, O., and U. Zölzer. "A wireless MIMO CPM system with blind signal separation for incoherent demodulation." Advances in Radio Science 6 (May 26, 2008): 101–5. http://dx.doi.org/10.5194/ars-6-101-2008.

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Abstract. A multiple-input multiple-output (MIMO) wireless transmission system with continuous phase modulation (CPM) is considered. A novel MIMO CPM receiver with incoherent modulation is presented. The incoherent demodulation of CPM allows an uncomplicated handling of a frequency offset compared to coherent approaches requiring exact knowledge of the carrier frequency. Blind signal separation (BSS) is applied in the proposed MIMO CPM receiver to separate the signals without any knowledge of the MIMO channel. The BSS permits the demodulation of each separated signal by an incoherent CPM demodulator. For bandwidth efficient transmission partial response CPM and non-binary modulation is applied. The applicability of the proposed system is verified by simulation results.

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Глушков, А. Н., Ю. В. Литвиненко, Б. Н. Тишуков, and Е. В. Черноярова. "DIGITAL SIGNAL DEMODULATOR WITH AMPLITUDE-PHASE MANIPULATION." ВЕСТНИК ВОРОНЕЖСКОГО ГОСУДАРСТВЕННОГО ТЕХНИЧЕСКОГО УНИВЕРСИТЕТА 19, no. 5 (November 7, 2023): 115–20. http://dx.doi.org/10.36622/vstu.2023.19.5.016.

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исследуется оптимальный цифровой алгоритм когерентной демодуляции сигналов с амплитудно-фазовой манипуляцией (АФМ или APSK). Демодуляция фазы выполняется на основе фазового детектора сигналов с многопозиционной фазовой манипуляцией, а амплитуды символов определяются по откликам квадратурных каналов обработки сигнала. Проведен анализ алгоритма обработки сигнала с АФМ, рассмотрены временные реализации откликов демодулятора. Определена помехоустойчивость демодуляции для сигналов с двухуровневой АФМ для двух наиболее распространенных вариантов созвездий, оценены вероятности ошибочной демодуляции фазы и амплитуды сигнала, дан сравнительный анализ помехоустойчивости сигналов с различными созвездиями. Рассмотрена помехоустойчивость демодуляции сигналов с амплитудной относительно-фазовой манипуляцией (АОФМ), дан сравнительный анализ потерь в отношении сигнал/шум по сравнению с АФМ для различных вариантов созвездий. Проведено статистическое имитационное моделирование алгоритма демодуляции при воздействии шумовой помехи. Исследовано влияние на помехоустойчивость погрешностей оценки пороговых уровней принимаемых сигналов. Реализация демодулятора ориентирована на программируемые логические интегральные схемы (ПЛИС) the optimal digital algorithm for coherent demodulation of signals with amplitude-phase modulation (APSK) is investigated. Phase demodulation is performed on the basis of a phase detector of signals with multi-position phase manipulation, and the amplitudes of symbols are determined by the responses of quadrature signal processing channels. The analysis of the algorithm of signal processing with APSK is carried out, the time realizations of the responses of the de-modulator are considered. The noise immunity of demodulation for signals with a two-level APSK for the two most common variants of constellations is determined, the probabilities of erroneous demodulation of the phase and amplitude of the signal are estimated, a comparative analysis of the noise immunity of signals with different constellations is given. The noise immunity of demodulation of signals with amplitude relative-phase manipulation (ARFM) is considered, a comparative analysis of signal-to-noise losses in comparison with APSK for various constellation variations is given. Statistical simulation of the demodulation algorithm under the influence of noise interference is carried out. The influence of errors in the estimation of threshold levels of the received signals on the noise immunity is investigated. The implementation of the demodulator is focused on programmable logic integrated circuits (FPGAs)

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Daldal, Nihat, Zeynel Abidin Sezer, Majid Nour, Adi Alhudhaif, and Kemal Polat. "A New Generation Communication System Based on Deep Learning Methods for the Process of Modulation and Demodulation from the Modulated Images." Mathematical Problems in Engineering 2022 (May 28, 2022): 1–13. http://dx.doi.org/10.1155/2022/9555598.

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Demodulating the modulated signals used in digital communication on the receiver side is necessary in terms of communication. The currently used systems are systems with a variety of hardware. These systems are used separately for each type of communication signal. A single algorithm facilitates the classification and subsequent demodulation of signals without needing hardware instead of extra hardware cost and complex systems. This study, which aims to make modulation classification by using images of signals, provides this convenience. In this study, a classification and demodulation process is done by using images of digital modulation signals. Convolutional neural network (CNN), a deep learning algorithm, has been used for classification and recognition. Images of the signals of quadrate amplitude shift keying (QASK), quadrate frequency shift keying (QFSK), and quadrate phase shift keying (QPSK) digital modulation types at noise levels of 0 dB, 5 dB, 10 dB, and 15 dB were used. Thanks to this algorithm, which works without hardware, the success achieved is around 98%. Python programming language and libraries have been used in training and testing the algorithm. Demodulation processes of these signals have been performed for demodulation using the nonlinear autoregressive network with exogenous inputs (NARX) algorithm, an artificial neural network. As a result of using MATLAB, the NARX algorithm achieved approximately 94% success in obtaining the information signal. Thanks to the work done, it will be possible to classify and demodulate other communication signals without extra hardware.

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Mohamed Moubark, Asraf, and Sawal Hamid Md Ali. "A Novel Sample Based Quadrature Phase Shift Keying Demodulator." Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/107831.

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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.

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Liu, Zheng, Qiong Yao, Ji Xia, Gang Liu, Shuidong Xiong, and Qingkai Hou. "Five-Step Phase-Shift-Based Multiwavelength Averaging for Extrinsic Fabry–Perot Interferometric Sensors." Photonics 10, no. 10 (September 25, 2023): 1076. http://dx.doi.org/10.3390/photonics10101076.

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In order to address issues such as low demodulation accuracy, large demodulation errors, small dynamic range, and complex algorithms for the extrinsic Fabry–Perot interferometric (EFPI) sensor, a five-step phase-shift algorithm based on a multiwavelength (MW)-averaging method is proposed to improve demodulation speed, noise stability, dynamic range, and noise suppression. The proposed demodulation method utilizes white-light interferometry (WLI) technology to acquire the reflection spectra and extract the five-step phase-shift signals at Ns consecutive operating points. The demodulation results of Ns sets of five-step phase-shift signals are averaged to obtain the average demodulated phase and cavity length variation. Theoretical analysis demonstrates the significant effects of the MW demodulation method on demodulation parameter errors and noise suppression. Particularly, when the demodulation parameter θ = π/2 rad, the method exhibits excellent stability against demodulation parameter error-induced instability. Moreover, it greatly improves noise suppression and reduces noise fluctuations. Numerical simulations are conducted to validate the performance of the proposed demodulation method. Compared with the traditional single-wavelength (SW) five-step phase-shifting demodulation method, the MW demodulation method exhibits stronger noise- and harmonic-suppression capabilities as the number of averaging wavelengths Ns increases. The harmonic distortion of the MW demodulation method with Ns = 128 is 20 dB lower than that of the SW demodulation method, and the noise is 15 dB lower. Furthermore, the proposed method effectively suppresses the influence of demodulation parameter errors on signal demodulation. This proposed demodulation method has the potential for fast real-time dynamic demodulation. It has great significance and application in the field of weak signal detection in fiber-optic sensors with interferometer structures and has enormous advantages in noise-suppression in complex environments.

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Hou, Shumin, Ming Liang, Yi Zhang, and Chuan Li. "Vibration signal demodulation and bearing fault detection: A clustering-based segmentation method." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 11 (December 2, 2013): 1888–99. http://dx.doi.org/10.1177/0954406213514960.

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The resonance demodulation technique has been widely employed in vibration signal analysis. In order to construct a proper bandpass filter, the prior knowledge, i.e. the resonance frequency band of the mechanical system is required in the traditional demodulation method. However, as the collected vibration signal is often tainted by the background noise and interferences often with unknown frequency contents, it is difficult to identify the center frequency and the bandwidth of the filter. This paper introduces a clustering-based segmentation method to determine these parameters automatically. Envelope analysis is then applied to demodulating the vibration data. According to the simulated cases, the proposed approach is robust to Gaussian noise and interferences. Its effectiveness is further validated by applying it to detect rolling bearing faults based on experimental data.

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Kajur, Renuka, and K. V. Prasad. "Design and analysis of optimized CORDIC based GMSK system on FPGA platform." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 5 (October 1, 2020): 4679. http://dx.doi.org/10.11591/ijece.v10i5.pp4679-4686.

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The Gaussian minimum shift keying (GMSK) is one of the best suited digital modulation schemes in the global system for mobile communication (GSM) because of its constant envelop and spectral efficiency characteristics. Most of the conventional GMSK approaches failed to balance the digital modulation with efficient usage of spectrum. In this article, the hardware architecture of the optimized CORDIC-based GMSK system is designed, which includes GMSK Modulation with the channel and GMSK Demodulation. The modulation consists of non-return zero (NRZ) encoder, an integrator followed by Gaussian filtering and frequency modulation (FM). The GMSK demodulation consists of FM demodulator, followed by differentiation and NRZ decoder. The FM Modulation and demodulation use the optimized CORDIC model for an In-phase (I) and quadrature (Q) phase generation. The optimized CORDIC is designed by using quadrant mapping and pipelined structure to improve the hardware and computational complexity in GMSK systems. The GMSK system is designed on the Xilinx platform and implemented on Artix-7 and Spartan-3EFPGA. The hardware constraints like area, power, and timing utilization are summarized. The comparison of the optimized CORDIC model with similar CORDIC approaches is tabulated with improvements.

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Chen, Xianqing, and Lenan Wu. "Nonlinear Demodulation and Channel Coding in EBPSK Scheme." Scientific World Journal 2012 (2012): 1–7. http://dx.doi.org/10.1100/2012/180469.

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The extended binary phase shift keying (EBPSK) is an efficient modulation technique, and a special impacting filter (SIF) is used in its demodulator to improve the bit error rate (BER) performance. However, the conventional threshold decision cannot achieve the optimum performance, and the SIF brings more difficulty in obtaining the posterior probability for LDPC decoding. In this paper, we concentrate not only on reducing the BER of demodulation, but also on providing accurate posterior probability estimates (PPEs). A new approach for the nonlinear demodulation based on the support vector machine (SVM) classifier is introduced. The SVM method which selects only a few sampling points from the filter output was used for getting PPEs. The simulation results show that the accurate posterior probability can be obtained with this method and the BER performance can be improved significantly by applying LDPC codes. Moreover, we analyzed the effect of getting the posterior probability with different methods and different sampling rates. We show that there are more advantages of the SVM method under bad condition and it is less sensitive to the sampling rate than other methods. Thus, SVM is an effective method for EBPSK demodulation and getting posterior probability for LDPC decoding.

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Wang, Wenhua, Weina Wu, Zhengye Xiong, Wenqing Shi, Yuanzheng Luo, Xiuyun Tian, and Zhishan Chen. "Demodulation algorithm for optical fiber fabry-perot interference sensor." MATEC Web of Conferences 336 (2021): 04010. http://dx.doi.org/10.1051/matecconf/202133604010.

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In view of resolution of optical fiber Fabry-Perot (FP) interference sensor, this paper analyses and researches high resolution demodulation algorithms including fast Fourier transform demodulation algorithm, cross-correlation calculation demodulation algorithm, vernier demodulation algorithm. Through continuous improvement, the vernier demodulation algorithm has achieved a resolution of 0.084nm. And it has a resolution of 2.3Pa when the vernier demodulation algorithm was applied to osmotic pressure measurement.

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Li, Chengli, Jianguan Tang, Cheng Cheng, Longbao Cai, and Minghong Yang. "FBG Arrays for Quasi-Distributed Sensing: A Review." Photonic Sensors 11, no. 1 (January 22, 2021): 91–108. http://dx.doi.org/10.1007/s13320-021-0615-8.

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AbstractFiber Bragg grating (FBG) array is a powerful technique for quasi-distributed sensing along the entire length of sensing fiber with fast response and high precision. It has been widely used for temperature, strain, and vibration monitoring. In this review work, an overview on the recent advances of FBG arrays is conducted. Firstly, the fabrication methods of FBG array are reviewed, which include femtosecond laser system and online writing technique. Then, the demodulation techniques for FBG arrays are presented and discussed. Distributed static sensing can be performed by demodulating wavelength shift of each FBG, while phase demodulation techniques with low noise are employed for dynamic vibration sensing. Simultaneous distributed dynamic and static sensing system based on FBG array is also outlined. Finally, possible future directions are discussed and concluded. It is believed that the FBG array has great development potential and application prospect.

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Li, Xiao Juan, Ze Gui Chen, Zhi Yong Xie, Xiao Bin Liang, and Xian Long Zhao. "FBG Sensing Demodulation Technology Based on Acousto-Optic Tunable Filter." Applied Mechanics and Materials 513-517 (February 2014): 4257–60. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.4257.

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This paper describes FBG sensing demodulation technology which based on acousto-optic tunable filter, this technique solves the traditional FBG demodulation technique existing some problems such as slow demodulation speed and small number of driving FBG sensors. The demodulation technique has advantages with simple structure, low cost, wide wavelength range, high resolution and fast demodulation speed.

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Feng, Fei, Qi Jia, Chunhua Liu, and Kaibai Yue. "Study on phase demodulation algorithm of fiber optic pressure sensor based on nonlinear differential equation." AIP Advances 12, no. 9 (September 1, 2022): 095116. http://dx.doi.org/10.1063/5.0090883.

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Fiber optic Fabry–Pérot sensors have been widely developed with unique advantages, such as ease of reuse, resistance to electromagnetic interference, light weight, and their ability to work in extreme environments. There are many demodulation methods that can be applied to fiber optic Fabry–Pérot sensors, including the intensity demodulation method, spectral demodulation, and the phase carrier method, but these demodulation methods cannot meet the requirements that take into account range, speed, and dynamic and static demodulation capabilities. In view of these problems, this paper uses nonlinear differential equations to solve the problem of simultaneous measurement of a large number of ranges and dynamic and static parameters. The measuring interferometer in the demodulation module was built using a polarizing interferometer, which avoids the difficulty in optical wedge processing when using a Fizeau interferometer. Regarding the problems of high and low signal-to-noise ratios of the generated signal, for the problem that the introduction of dispersion in the crystal causes the demodulation result of the traditional demodulation method to be wrong, a nonlinear differential equation is proposed to achieve the correct demodulation of the fiber optic sensor: the slow demodulation speed problem. This paper designs the acquisition, transmission, and processing system based on digital signal processing and a field-programmable gate array, which provide a hardware platform for real-time demodulation. Finally, experiments to test the resolution, linearity, stability, and repeatability of the interferometer were carried out on the designed demodulation system.

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Liu, Xiao Peng, Yan Han, Dong Dong Zhong, and Ming Yu Wang. "The Design and Implement of a Receiver for FSK Signal." Applied Mechanics and Materials 190-191 (July 2012): 739–41. http://dx.doi.org/10.4028/www.scientific.net/amm.190-191.739.

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A novel frequency shift keying (FSK) receiver is presented, including receiving antennas, a low noise amplifier (LNA), band-pass filters (BPF) and a novel all-digital 2-level FSK demodulator. The Matlab simulation results of the all-digital FSK demodulator show that it can improve bit error ratio (BER) performance compared with pseudo-coherent FSK demodulation (PCFSK). The novel FSK demodulator defined using Verilog HDL is easy to be implemented on Field Programmable Gate Array (FPGA) and in CMOS integrated circuit. The whole FSK receiver designed and implemented on a PCB board can receive FSK signal and send the recovered data to computer through RS-232 interface.

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Rodriguez-Marmolejo, Ulises H., Miguel Mora-Gonzalez, Jesus Muñoz-Maciel, and Tania A. Ramirez-delreal. "FSD-HSO Optimization Algorithm for Closed Fringes Interferogram Demodulation." Mathematical Problems in Engineering 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/1576735.

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Due to the physical nature of the interference phenomenon, extracting the phase of an interferogram is a known sinusoidal modulation problem. In order to solve this problem, a new hybrid mathematical optimization model for phase extraction is established. The combination of frequency guide sequential demodulation and harmony search optimization algorithms is used for demodulating closed fringes patterns in order to find the phase of interferogram applications. The proposed algorithm is tested in four sets of different synthetic interferograms, finding a range of average relative error in phase reconstructions of 0.14–0.39 rad. For reference, experimental results are compared with the genetic algorithm optimization technique, obtaining a reduction in the error up to 0.1448 rad. Finally, the proposed algorithm is compared with a very known demodulation algorithm, using a real interferogram, obtaining a relative error of 1.561 rad. Results are shown in patterns with complex fringes distribution.

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Luo, Wenhao, Hong Zhang, Yan Liu, Xiaogang Wei, Xiaonan Zhang, Yanhua Wang, and Renfu Yang. "A dual-axis high-order harmonic and single-axis phase-insensitive demodulation atomic magnetometer for in situ NMR detection of Xe." Journal of Applied Physics 132, no. 14 (October 14, 2022): 144401. http://dx.doi.org/10.1063/5.0096583.

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Based on the parametric oscillation process, we demonstrate the dual-axis phase-sensitive demodulation (PSD) and single-axis phase-insensitive demodulation (PISD) for the atomic magnetometer in an in situ nuclear magnetic resonance (NMR) detection system, which can separate the precession signals of NMR from the oscillating magnetic fields. The two orthogonal magnetic fields can be detected simultaneously and independently by selecting the optimal demodulation phases with the traditional PSD method. The response signals of the parametric modulation magnetometer demodulated with high order harmonic signals are evaluated, which is a new exploration. The first order harmonic demodulation can present the best sensitivity about 250 fT/Hz1/2. The high order harmonic demodulation technology supplies a twofold 3 dB bandwidth. With the PISD method, a single-axis demodulation technique is proposed. The transverse nuclear spin precession magnetic fields can be extracted effectively with the demodulation R signal outputs by setting a specific longitudinal modulation magnetic field amplitude, which is a new demodulation strategy compared with the traditional demodulation method for the NMR system.

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43

Bhansali, Praful V., and Ron Potter. "Digital demodulation." IEEE Transactions on Instrumentation and Measurement IM-35, no. 3 (September 1986): 324–27. http://dx.doi.org/10.1109/tim.1986.6499218.

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Fu, Gang, Dong Xu Zhu, and Wen Jian Geng. "Research on Soft Demodulation of Telemetry Signal in Reentry Telemetry Environment." Applied Mechanics and Materials 543-547 (March 2014): 2555–58. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.2555.

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PCM/FM system is one of the most widely used in the missile and rocket telemetry system. For the problem that the breakthrough tradition demodulation method of demodulation threshold leaded by the telemetry signals low signal noise ratio (SNR) of target spacecraft reentry telemetry environment, a baseband complex rotating orthogonal MSD based soft PCM/FM signal demodulation method is studied combined with the PCM/FM signal phase characteristic. The corresponding synchronization algorithm is applied to ensure the smooth operation of the demodulation. The simulation and test results verify the soft demodulation algorithm can make reduce the demodulation threshold effectively.

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Chen, Xianqing, and Lenan Wu. "A Novel Detection Scheme for EBPSK System." Mathematical Problems in Engineering 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/956191.

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We introduce the extended binary phase shift keying (EBPSK) communication system which is different from traditional communication systems by using a special impacting filter (SIF) for demodulation. The joint detection technique is applied at the demodulator side in order to improve the performance of the system under intersymbol interference (ISI). The main advantage of the joint detection technique, when compared to conventional threshold approaches, lies in its ability to use the amplitude and the correlation between neighboring bits, thus significantly improving performance, with low complexity. Moreover, we concentrate not only on increasing the bit rate of the system, but also on designing a bandwidth efficient communication system. Simulation results show that this new approach significantly outperforms the conventional method of using threshold decision by from 3.5 to 5 dB. The new system also occupies a narrower bandwidth. So joint detection is an effective method for EBPSK demodulation under ISI.

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Zou, Hui Zhi. "Research on Fm Telemetry Signal Demodulation Based on Instantaneous Frequency Measurement." Applied Mechanics and Materials 602-605 (August 2014): 2225–28. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.2225.

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According instantaneous frequency measurement theory, we propose a new PCM/FM telemetry signal demodulation method. This paper introduces the basic principles of this demodulation method and implementation process, the influence of instantaneous frequency measurement accuracy and the impact of factors on the Doppler frequency demodulation performance is proposed to improve the accuracy and instantaneous frequency measurement method demodulation performance. Simulation results show that this method is superior demodulation performance, strong anti-jamming capability, ease of software programming and DSP devices to achieve.

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Zhang, Ziyang, Song Ye, Shu Li, Yuting Zhang, Wentao Zhang, Jiejun Wang, Xinqiang Wang, and Fangyuan Wang. "Optimal Demodulation Algorithm of Spatially Modulated Full-Polarization Imaging System." Photogrammetric Engineering & Remote Sensing 86, no. 12 (December 1, 2020): 761–66. http://dx.doi.org/10.14358/pers.86.12.761.

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Spatially modulated full-polarization imaging systems can obtain full Stokes parameter information by single imaging, with strong characteristics of real-time execution and stability. Since all the polarization information is modulated into an interferogram, demodulation becomes an essential step. As the resolution of the obtained image continuously increases, the data to be calculated also increase. Therefore, a higher speed for the demodulation process is requisite. This article proposes a local filtering method and bypasses the frequency centralization method in the frequency domain to improve the speed of demodulation. The demodulation time of an interferogram of size 1024×1024 pixels was reduced from 3.027 473 s to 0.134 637 s, increasing the speed of demodulation by 97.72%. Meanwhile, the demodulation time of an interferogram of size 6144×6144 pixels was reduced from 444.329 92 s to 4.637 069 s, increasing the speed of demodulation by 98.75%.

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Yao, Xue Lu, Gang Fu, and Ren Long Li. "Demodulation Method of Telemetry Signal Based on Virtual Radio." Advanced Materials Research 989-994 (July 2014): 3981–84. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3981.

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According to the characteristics of PCM / FM signal demodulation method is proposed based on virtual radio platform. This paper discusses in detail the basic principles of this demodulation method and implementation process, analyze the demodulation performance and complexity of the method. Simulation results show that the method for actually received PCM / FM demodulation signal has better performance.

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Fu, Gang, Yan Jun Wu, and Yue Feng. "Research on Demodulation of Pulse Code Modulated Signal Based on Instantaneous Frequency Measurement." Advanced Materials Research 989-994 (July 2014): 3997–4000. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3997.

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According instantaneous frequency measurement theory, we propose a new PCM / FM telemetry signal demodulation method. This paper introduces the basic principles of this demodulation method and implementation process, the influence of instantaneous frequency measurement accuracy and the impact of factors on the Doppler frequency demodulation performance is proposed to improve the accuracy and instantaneous frequency measurement method demodulation performance .

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Wang, Hui Bo, and Zhi Quan Li. "Research on Modulation Multiplexing System and Technique Employing Tilted Grating." Applied Mechanics and Materials 397-400 (September 2013): 1643–47. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1643.

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A dual demodulation technique based on tilted grating and InGaAs photodiode array is proposed; using the coupling modes of the cladding, a wavelength demodulation method with the tilted grating as the spectroscopic device is realized. This method can achieve that the demodulation of the channel in which the sensing information changed and the optimization of collection rules of the system. Two tunable F-P filters scan and demodulate the sensing path simultaneously to further improve the system response speed. Simulation analysis and experiments results indicate that the average demodulation time is 40ms and the average signal frequency can reach 15Hz. In addition, the demodulation bandwidth is 40nm, and its wavelength demodulation precision can reach 20pm. The system has advantages of the shorter delay time, and the demodulation time is immune to the number of channels, etc.. Therefore, this system is able to meet the smart requirement of some complex systems and large scale distributed intelligent system.

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Journal articles on the topic 'Demodulation'

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