Journal articles: 'Digital frequency modulation and demodulation'

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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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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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BERNHARDT, PAUL A. "COMMUNICATIONS USING CHAOTIC FREQUENCY MODULATION." International Journal of Bifurcation and Chaos 04, no. 02 (April 1994): 427–40. http://dx.doi.org/10.1142/s0218127494000289.

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Chaotic Frequency Modulation (CFM) provides the basis for a nonlinear communications system with (1) good noise suppression and (2) analogue signal encryption for private and secure communications links. CFM is a generalization of conventional Wideband Frequency Modulation (WFM) where the information about modulation samples mk are contained in the lengths of the periods pk for the kth cycle of the WFM waveform. A WFM modulator produces waveform periods described by an invertible function of the form pk=F(mk). Chaotic FM uses a map of the pulse periods to produce a noise-like pulse train even with a constant signal. The basis for CFM is a function pk=F(mk; pk−1, pk−2, …, pk−i), where i is the dimensionality of the map. A practical realization for a CFM transmitter employs an autonomous chaotic relaxation oscillator (ACRO) circuit for use as a chaotic voltage-controlled oscillator (CVCO). The ACRO is simple to construct, consisting of only two capacitors, one inductor, a bistable nonlinear element, and a modulated current source. The CVCO period (pk) is a nonlinear function of the current (mk) and the two previous pulse periods. Demodulation requires the use of at least three successive waveform-periods. Experimental and theoretical studies of the CVCO circuit have shown that (1) the ACRO return maps of pulse periods are embedded in three dimensions, (2) chaotic outputs are difficult to decode without prior knowledge of the circuit parameters, and (3) demodulation may be accomplished with a digital signal processor.

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Li, Chen Wu, Jian Zhang, Qin Xie, and Xiao Hong Zhang. "Carrier Modulation Technology Based on Orthogonal Frequency Division Multiplexing." Advanced Materials Research 774-776 (September 2013): 1671–76. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.1671.

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This paper first analyzes the transmission characteristics of low-voltage power line channels with the focus on the study of carrier modulation technology regarding the power line communication part, then proposes the orthogonal frequency division multiplexing technology that serves for the digital communication of family network power line communication gateways, analyzes the OFDM system principle, actulizes OFDM modulation and demodulation through discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT), and build the OFDM simulation model. Finally, a specific plan of using power lines as the family network transmission media is proposed.

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Manning, Christopher J., and Peter R. Griffiths. "Step-Scanning Interferometer with Digital Signal Processing." Applied Spectroscopy 47, no. 9 (September 1993): 1345–49. http://dx.doi.org/10.1366/0003702934067630.

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A novel step-scan FT-IR spectrometer incorporating a digital signal processor for demodulation of the detector signal is described. The potential advantages of this method of signal processing are discussed and illustrated. The instrument is based on a commercial cube-corner interferometer which has been modified by replacement of the drive motor with a stepper motor-micrometer and piezoelectric transducer combination. The interferometer retardation is feedback controlled by a 486–50 personal computer, which also controls the digital signal processor and collects spectral data. More than one phase modulation frequency can be imposed simultaneously, allowing for a multiplex advantage in photoacoustic depth profiling. Digital signal processing allows for simultaneous demodulation of multiple frequencies which would normally require several lock-in amplifiers. Data that illustrate the feasibility of these concepts are presented. The suitability of this instrument for double-modulation step-scan FT-IR measurements such as polymer stretching and electrochemically modulated step-scan FT-IR is also discussed.

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Ghauri, Sajjad Ahmed. "KNN BASED CLASSIFICATION OF DIGITAL MODULATED SIGNALS." IIUM Engineering Journal 17, no. 2 (November 30, 2016): 71–82. http://dx.doi.org/10.31436/iiumej.v17i2.641.

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Demodulation process without the knowledge of modulation scheme requires Automatic Modulation Classification (AMC). When receiver has limited information about received signal then AMC become essential process. AMC finds important place in the field many civil and military fields such as modern electronic warfare, interfering source recognition, frequency management, link adaptation etc. In this paper we explore the use of K-nearest neighbor (KNN) for modulation classification with different distance measurement methods. Five modulation schemes are used for classification purpose which is Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), 16-QAM and 64-QAM. Higher order cummulants (HOC) are used as an input feature set to the classifier. Simulation results shows that proposed classification method provides better results for the considered modulation formats.

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Mayer, Kayol Soares, Candice Müller, Fernando Cesar Comparsi de Castro, and Maria Cristina Felippetto de Castro. "A New CPFSK Demodulation Approach for Software Defined Radio." Journal of Circuits, Systems and Computers 28, no. 14 (February 8, 2019): 1950243. http://dx.doi.org/10.1142/s0218126619502438.

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This paper proposes a new coherent Frequency-Shift Keying (FSK) demodulation technique for software defined radio platform, based on a new Digital Phase Locked Loop (DPLL) architecture. The proposed DPLL addresses the frequency dependence on classic DPLL architectures found in the literature. In classical approaches, the loop filter constants are dependent on the frequency level of the FSK transmitted symbols. The proposed approach applies a simpler feedback loop, with a single integrator and a phase detector architecture based on the small-angle approximation [Formula: see text], which resulted in a DPLL totally independent of frequency. The proposed demodulator has been implemented in Very High Speed Integrated Circuits (VHSIC) Hardware Description Language (VHDL) and evaluated for continuous-phase frequency shift keying (CPFSK) and Gaussian minimum shift keying (GMSK) signals. For CPFSK signals, the demodulator has been evaluated for 2, 4 and 8 frequency levels, with modulation indexes [Formula: see text], [Formula: see text] and [Formula: see text], respectively. For evaluation of GMSK signals, several Gaussian filter bandwidths were considered. In addition, a brief analysis for 2-CPFSK and GMSK is presented over multipath and carrier frequency offset. Results show that the proposed method presents a significantly reduced bit error rate when compared to other coherent methods presented in the literature.

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Drapcho, David L., Raul Curbelo, Eric Y. Jiang, Richard A. Crocombe, and William J. McCarthy. "Digital Signal Processing for Step-Scan Fourier Transform Infrared Photoacoustic Spectroscopy." Applied Spectroscopy 51, no. 4 (April 1997): 453–60. http://dx.doi.org/10.1366/0003702971940486.

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A software-based digital signal processing (DSP) method using the data system processor has been developed to demodulate the photoacoustic responses of a sample to the fundamental phase modulation frequency and its harmonic frequencies (up to the ninth harmonic) in step-scan FT-IR photoacoustic measurements, without the use of any additional hardware. The DSP algorithm and its sampling depth multiplexing advantages are compared to conventional hardware demodulation. Comparison of results from the DSP method to those from hardware demodulators are shown at both the phase modulation frequency and the harmonics, and application of the DSP method to step-scan photoacoustic measurements with phase modulation is discussed as it applies to obtaining depth profile information in heterogeneous materials.

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Li, Nan, Yi Nan Wang, Hong Shan Nie, Hong Qi Yu, and Hui Xu. "Biomaterial Impedance Analyzer Based on Digital Auto Balancing Bridge." Advanced Materials Research 291-294 (July 2011): 1259–62. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.1259.

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This paper presents the design method of a novel biomaterial impedance analyzer based on digital auto balancing bridge method. The system hardware mainly consists of FPGA, ADC, DACs and operational amplifiers. Many DSP algorithms such as direct digital frequency synthesis (DDS), digital phase sensitive demodulation (DPSD), digital modulation and digital filter are implemented in FPGA to realize the auto balancing function of the bridge circuit. Simulation results show that the system has good performance from low frequency to 10MHz. It is suitable for EIS application in biomaterial analysis.

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Aminah, Siti, Asep Deni Mulyadi, and Yuliadi Erdani. "The Wireless Acquisition Data System Simulator Design on Automatic Weather Monitoring Station." MOTIVECTION : Journal of Mechanical, Electrical and Industrial Engineering 1, no. 3 (September 1, 2019): 51–62. http://dx.doi.org/10.46574/motivection.v1i3.33.

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The Wireless Acquisition Data System Simulator Design on Automatic Weather Monitoring Station is means of collecting, monitoring, and controlling some long distance subsystems. Automatic weather monitoring station is device for receiving data by a censor in use to gauge some weather parameters. In this Research we develop an automatic weather monitoring station design simulator by creating a subsystem in the form of prototype, using Digital Pin and Analog Pin from the microcontroller. Sensor characteristics are considered to measure several weather parameters. The principles of a system function are it will have to collect data from some subsystems to accommodate in a database, able to control and deliver instructions to the subsystem. The communication system makes the use of radio frequency by means of Frequency Shift Keying (FSK) method through Handy Talky (HT), picked out because advantages of lower power consumptions and long range of transmission. Additional advantages are, although catastrophes, data communication using HT allows to keep fast transmission. The transmission of data using HT media require a signal converter by which HT is operated by analogue signal (sound), while censor and microcontroller by digital signal and, therefore, Modulation and Demodulation techniques are necessary. The Modulation functions to convert digital signal into analogue, and just the opposite to the Demodulation, the Modulation and Demodulation processes is using IC TCM3105. The results of the trial suggest that system design has proper functions, the communication process in this system is two-ways communication, the process was fast working in either transmitter mode or receiver mode.

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Tao, Qiu Xiang. "Based on Simulink the MSK Communication System Design and Research." Advanced Materials Research 1049-1050 (October 2014): 1954–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1954.

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Minimum shift keying (MSK) signal is constant envelope modulation technology, It has the characteristics of continuous phase, high frequency band utilization, is very attractive in the field of wireless communications digital modulation mode, the current in short wave, microwave and satellite communications have been adopted. This paper studies the working principle of MSK modulation and demodulation, and then build simulation module based on Simulink environment, through the simulation design to render the MSK system performance advantages.

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Wang, Jun, and Shuo Feng. "Design of Infrared Communication System Based on Phase-Locked Loop Frequency Modulation." Applied Mechanics and Materials 624 (August 2014): 561–66. http://dx.doi.org/10.4028/www.scientific.net/amm.624.561.

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The paper introduces a system using PLL frequency modulation and demodulation technique, and using infrared as the carrier to realize wireless communication. CD4046 is a common CMOS low-frequency phase locked loopintegrated circuit, and it has the characteristics of high VCOlinearity, tunable center frequency and acquisition frequency range, low power consumption and simple for use. The paper introduces the design scheme using the technique for infrared communication, and proposes a method using sing-chip microcontroller to control single channel to realize the simultaneous transmission of acoustic signal and digital signal, which has great practicability.

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Chen, Chien-Sheng, Chyuan-Der Lu, Ho-Nien Shou, and Le-Wei Lin. "Baseband Transceiver Design of a High Definition Radio FM System Using Joint Theoretical Analysis and FPGA Implementation." International Journal of Antennas and Propagation 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/580479.

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Advances in wireless communications have enabled various technologies for wireless digital communication. In the field of digital radio broadcasting, several specifications have been proposed, such as Eureka-147 and digital radio mondiale (DRM). These systems require a new spectrum assignment, which incurs heavy cost due to the depletion of the available spectrum. Therefore, the in-band on-channel (IBOC) system has been developed to work in the same band with the conventional analog radio and to provide digital broadcasting services. This paper discusses the function and algorithm of the high definition (HD) radio frequency modulation (FM) digital radio broadcasting system. Content includes data format allocation, constellation mapping, orthogonal frequency division multiplexing (OFDM) modulation of the transmitter, timing synchronization, OFDM demodulation, integer and fraction carrier frequency (integer carrier frequency offset (ICFO) and fractional CFO (FCFO)) estimation, and channel estimation of the receiver. When we implement this system to the field programmable gate array (FPGA) based on a hardware platform, both theoretical and practical aspects have been considered to accommodate the available hardware resources.

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Li, Nan, Jing Guo, Hong Shan Nie, Wei Yi, Hai Jun Liu, and Hui Xu. "Design of Embedded Bio-Impedance Analyzer Based on Digital Auto Balancing Bridge Method." Applied Mechanics and Materials 135-136 (October 2011): 396–401. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.396.

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This paper presented the design of a novel embedded bio-impedance analyzer based on digital auto-balancing bridge method. The hardware architecture of the system mainly consists of FPGA, ADC, DACs, USB controller and so on. Many DSP algorithms such as direct digital synthesis, digital phase sensitive demodulation, digital modulation and digital filter were implemented in FPGA to realize the auto balancing function of the bridge circuit. Simulation results show that the system has good performance from low frequency up to 10 MHz. For the advantages of cost-efficient and high stability, it is suitable for BIA application.

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Zhao, Jian Rui, Ning Liu, and Yu Hua Wu. "Design of Digital Communication System of XCTD Based on FSK." Applied Mechanics and Materials 644-650 (September 2014): 3972–75. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.3972.

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According to the problem of expendable conductivity temperature depth profile (XCTD) of transmission signal waveform distortion and undistinguishable information caused by cable time-varying parameters and influence of seawater. This paper designed a based on FSK (Frequency shift keying) of digital communication system. It used single-chip modem chip FX604 used in FSK modulation and demodulation of the signal. And it implements the digital signal transmission on thin wire communication on the water. The system overcomes unfavorable conditions about transmission channel and marine environment. The circuit is easy and practical.

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Sadchenko, Andrey, and Oleg Kushnirenko. "QPSK-Modulation Modem Invariant to the Rotation of the Signal Constellation Plane." Electrical, Control and Communication Engineering 14, no. 2 (December 1, 2018): 149–56. http://dx.doi.org/10.2478/ecce-2018-0018.

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AbstractIn order to increase the efficiency of dedicated frequency channels, i.e. to increase the specific data transfer rate, multipositional quadrature phase shift keying (QPSK, aka 4-PSK) should be used. The problems with QPSK signal demodulation is a rotation of the signal constellation plane by an angle multiple of 90° and a slow response of the carrier oscillation recovery scheme. The study considers the existing methods for eliminating the phase ambiguity of the recovered carrier frequency in typical QPSK modems, and identifies the shortcoming of a low-speed response oscillation recovery circuit. The authors propose a QPSK demodulator circuit with a fast adjustment of the reference oscillator, which is due to the fact that no loop filter is used in the feedback and that a digital calculator of the required phase shift is used. An algorithm for the frame synchronization restoration with the simultaneous elimination of the phase ambiguity multiple of 90° was also developed using synthesized binary sequences with an ideal non-periodic autocorrelation function (NACF) at even shifts that do not have the rotary symmetry property. The phase ambiguity elimination algorithm proposed in the article can be used as an alternative to standard modems with differential coding.

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Sotnik, О., S. Marchenko, V. Litvinenko, and О. Syanov. "RADIO COMMUNICATION CHANNEL WITH FREQUENCY MODULATED SIGNAL BASED ON PROGRAMMABLE LOGICAL INTEGRATED CIRCUIT." Collection of scholarly papers of Dniprovsk State Technical University (Technical Sciences) 1, no. 38 (September 8, 2021): 75–83. http://dx.doi.org/10.31319/2519-2884.38.2021.9.

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This paper presents the results of an experimental study of a radio communication channel (RF) with a frequency-modulated signal based on a programmable logic integrated circuit (FPGA). The work highlights the features of hardware and software implementation of algorithms for the synthesis of frequency-modulated signal and demodulation of this signal using FPGA in real time. The software part is made in the development environment of ISE WebPack 14.7 in Verilog language with the ability to visualize the results of GTKWave. Hardware implementation is performed on the basis of FPGA (Spartan-6) using a debug board from Alinx AX309. The experimental study consists of two stages of the study of the FM oscillator modulator and the synchronous FM oscillator demodulator. In the course of research, the amplitude spectral characteristics of the signals (amplitude spectra) were obtained: at the output of the modulator and demodulator of the frequency-modulated signal, which have good agreement with the simulation results. The quality of the hardware synchronous demodulation of the FM signal based on the phase tuning system was confirmed by the result of the obtained spectrum of the restored information signal, in which the ratio between the first harmonic and the second is 51.87 dBm. When obtaining the results of experimental studies of the RH system, it was found necessary to take into account the peculiarities of the arithmetic of integers, which make errors in the hardware implementation of DSP algorithms. Thus, the use of programmable logic integrated circuits at the present stage of development of telecommunications and radio engineering opens wide opportunities for the construction of high-speed digital RH systems with parallel signal processing in real time.

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Liu, Qiao Ping, Yan Ning Yang, and Wei Xia Li. "Application of OFDM Technology in 4G Mobile Network." Applied Mechanics and Materials 631-632 (September 2014): 851–55. http://dx.doi.org/10.4028/www.scientific.net/amm.631-632.851.

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OFDM (Orthogonal Frequency Division Multiplexing) is a special kind of multi-carrier digital modulation technique. Each OFDM subcarrier exists orthogonality and great use of spectrum resources. To a certain extent, the problem of shortage of spectrum resources will be eased in the future. OFDM has a good ability to resist inter symbol interference and fight against frequency selective fading, and be able to adapt to the future wireless high-speed data transmission without distortion. Each channel modulation and demodulation with FFT and IFFT is easy to implement and meet the need of the business in the wireless communication system. The paper introduces the basic principle of OFDM technology, describes the advantages of OFDM and the defects needed to be overcome. Moreover, we analyzes the characteristics of 4G technology and discusses the application of OFDM in 4G mobile network.

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Zheng, Zi Wei. "Iterative Channel Estimation for the Chinese Digital Television Terrestrial Broadcasting Systems with the Multiple-Antenna Receivers." Advanced Engineering Forum 6-7 (September 2012): 439–44. http://dx.doi.org/10.4028/www.scientific.net/aef.6-7.439.

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Orthogonal frequency division multiplexing is an effective against multipath fading and high data throughput wireless channel transmission technology. Assistance with the inverse fast Fourier transform and fast Fourier transform operation, orthogonal frequency division multiplexing modulation and demodulation operations of the system convenient and convenient hardware implementation, orthogonal frequency division multiplexing, so in the modern digital television terrestrial broadcasting the system is widely used to support high performance bandwidth-efficient multimedia services. Broadband multi-carrier orthogonal frequency division multiplexing with multi-antenna and multi-antenna receiving system, to increase the diversity gain and improve the capacity of the system in different multipath fading channel. Accurate channel estimation in a simple channel equalization and decoding of broadband multi-carrier orthogonal frequency division multiple-antenna receiver and channel estimation accuracy and multiplexing system is very important, is the key to the performance of the overall broadband multi-carrier orthogonal frequency division multiplexing system in the multi-antenna receiver bit error rate. In this paper, iterative channel estimation to plan for digital terrestrial television broadcasting broadband multi-carrier orthogonal frequency division multiple antenna receiver multiplexing system proposal.

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Sun, Jin-cai, Wei-jie Zhu, Yi-yun Sun, and Hui Xiao. "A new method of demodulating the digital frequency modulation signals." Journal of Marine Science and Application 2, no. 2 (December 2003): 5–10. http://dx.doi.org/10.1007/bf02918657.

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Al-Nuaimi, Dhamyaa H., Ivan A. Hashim, Intan S. Zainal Abidin, Laith B. Salman, and Nor Ashidi Mat Isa. "Performance of Feature-Based Techniques for Automatic Digital Modulation Recognition and Classification—A Review." Electronics 8, no. 12 (November 26, 2019): 1407. http://dx.doi.org/10.3390/electronics8121407.

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The demand for bandwidth-critical applications has stimulated the research community not only to develop new ways of communication, but also to use the existing spectrum efficiently. Networks have become dynamic and heterogeneous. Receivers have received various signals that can be modulated differently. Automatic modulation classification (AMC) is a key procedure for present and next-generation communication networks, and facilitates the demodulation process at the receiver side. Under the presence of noise from the channel, the transmitter and receiver with its unknown parameters, such as carrier frequency, phase offset, signal power, and timing information, have become cumbersome because detecting the modulation scheme of the received signal is a complicated procedure. Two main methods, namely maximum likelihood functions and the signal statistical feature-based (FB) approach, are used for the automatic classification of modulated signals. In this study, a comprehensive survey of various modulation techniques based on FB approach is conducted. In this research, a number of basic features that are usually used in determining and discriminating modulation types were investigated. The classifier that was used in the discrimination process is studied in detail and compared to other types of classifiers to help the reader determine the limitations associated with the FB approach. Both classifiers and basic features were compared, and their advantages and disadvantages were investigated based on previous researches to determine the best type of classifier and the set of features in relation to each discrimination environment. This work serves as a guide for researchers of AMC to determine the suitable features and algorithms.

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Will, Christoph, Sarah Linz, Sebastian Mann, Fabian Lurz, Stefan Lindner, Robert Weigel, and Alexander Koelpin. "A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation." Advances in Radio Science 15 (October 25, 2017): 249–58. http://dx.doi.org/10.5194/ars-15-249-2017.

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Abstract. Precise position measurement with micrometer accuracy plays an important role in modern industrial applications. Herewith, a guided wave Six-Port interferometric radar system is presented. Due to limited matching and discontinuities in the radio frequency part of the system, the designers have to deal with DC offsets. The offset voltages in the baseband lead to worse relative modulation dynamics relating to the full scale range of the analog-to-digital converters and thus, considerably degrade the system performance. While common cancelation techniques try to estimate and extinguish the DC offsets directly, the proposed radar system is satisfied with equalizing both DC offsets for each of the two differential baseband signal pairs. Since the complex representation of the baseband signals is utilized for a subsequent arctangent demodulation, the proposed offset equalization implicates a centering of the in-phase and quadrature (I/Q) components of the received signal, which is sufficient to simplify the demodulation and improve the phase accuracy. Therefore, a standard Six-Port radar system is extended and a variable phase shifter plus variable attenuators are inserted at different positions. An intelligent algorithm adjusts these configurable components to achieve optimal I/Q offset cancelation.

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Hilario, Jovencio, David Drapcho, Raul Curbelo, and Timothy A. Keiderling. "Polarization Modulation Fourier Transform Infrared Spectroscopy with Digital Signal Processing: Comparison of Vibrational Circular Dichroism Methods." Applied Spectroscopy 55, no. 11 (November 2001): 1435–47. http://dx.doi.org/10.1366/0003702011953810.

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Digital signal processing (DSP) has been implemented in a step-scan FT-IR spectrometer in a modification that enables processing of high-frequency polarization modulation signals. In this work, direct comparison is made between vibrational circular dichroism (VCD) spectra measured on the same instrument, with the same samples, under the same conditions, using this new DSP method and a conventional rapid-scan technique (employing a lock-in amplifier for demodulation). In this initial test, both techniques generated high-quality VCD for solution phase, rigid chiral molecules such α-pinene and camphor. Noise and reproducibility of known spectral features, as well as enhancing signal measurability and discrimination, were used as criteria for the selection of optimal DSP measurement parameters. Both DSP and rapid-scan VCD methods produced qualitatively reasonable spectra for biologically related molecules such as poly-γ-benzyl-L-glutamate, poly-L-proline, and duplex RNA homopolymer. In most cases, the DSP method had a slight signal-to-noise advantage based on standard deviations of the noise trace data over the rapid-scan measurement, but the final results did depend on the details of the data collection and the phase correction methods inherent in both methods.

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Gao, Zhenyi, Bin Zhou, Xiang Li, Lei Yang, Qi Wei, and Rong Zhang. "A Digital-Analog Hybrid System-on-Chip for Capacitive Sensor Measurement and Control." Sensors 21, no. 2 (January 9, 2021): 431. http://dx.doi.org/10.3390/s21020431.

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Sensors based on capacitance detection are common in the field of inertial measurement and have the potential for miniaturization and low power consumption. In order to control and process such sensors, a novel digital-analog hybrid system-on-chip (SoC) is designed and implemented. The system includes a capacitor to voltage (C/V) conversion circuit and a band-pass sigma-delta modulator (BPSDM) as the analog-to-digital converter (ADC). The digital signal is processed by the dedicated circuit module based on the least mean square error demodulation (LMSD) algorithm on the chip. The low-power Cortex-M3 processor supports software implementation of control algorithms and circuit parameter configuration. The control signal is output through a digital BPSDM. The chip was taped out under SMIC 180 nm Complementary Metal Oxide Semiconductor (CMOS) technology and tested for performance. The result shows that the maximum operating frequency of the chip is 105 MHz. The total area is 77.43 mm2. When the system clock is set to 51.2 MHz, the static power consumption and dynamic power consumption of the digital system are 18 mW and 54 mW respectively.

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Gao, Zhenyi, Bin Zhou, Xiang Li, Lei Yang, Qi Wei, and Rong Zhang. "A Digital-Analog Hybrid System-on-Chip for Capacitive Sensor Measurement and Control." Sensors 21, no. 2 (January 9, 2021): 431. http://dx.doi.org/10.3390/s21020431.

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Sensors based on capacitance detection are common in the field of inertial measurement and have the potential for miniaturization and low power consumption. In order to control and process such sensors, a novel digital-analog hybrid system-on-chip (SoC) is designed and implemented. The system includes a capacitor to voltage (C/V) conversion circuit and a band-pass sigma-delta modulator (BPSDM) as the analog-to-digital converter (ADC). The digital signal is processed by the dedicated circuit module based on the least mean square error demodulation (LMSD) algorithm on the chip. The low-power Cortex-M3 processor supports software implementation of control algorithms and circuit parameter configuration. The control signal is output through a digital BPSDM. The chip was taped out under SMIC 180 nm Complementary Metal Oxide Semiconductor (CMOS) technology and tested for performance. The result shows that the maximum operating frequency of the chip is 105 MHz. The total area is 77.43 mm2. When the system clock is set to 51.2 MHz, the static power consumption and dynamic power consumption of the digital system are 18 mW and 54 mW respectively.

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Chen, Bo, Yangyu Fan, Zhou Tian, Wuying Wang, Bochao Kang, Wei Jiang, and Yongsheng Gao. "An Ultra-Wideband Microwave Photonic Channelized Receiver with Zero-IF Architecture." Applied Sciences 10, no. 1 (December 19, 2019): 30. http://dx.doi.org/10.3390/app10010030.

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A scheme for realizing a zero-intermediate frequency (IF) channelized receiver using a dual-polarization quadrature phase-shift keying (DP-QPSK) modulator and a narrow-band optical filter is proposed. The channelized system only requires one optical frequency comb to achieve zero-IF multi-channel reception of wideband signals, and the spacing of the optical frequency comb only needs to be equal to the sub-channel width, which is very easy to implement. It is found that using photonic IQ demodulation and balanced detection and reception technology can not only eliminate many disadvantages of the traditional zero-IF receiver, including local oscillator (LO) leakage, direct current (DC) offset, even-order distortion, and in-phase/quadrature (I/Q) imbalance, but also reduce the bandwidth and sample rate of the analog-to-digital converter (ADC). It is theoretically proven that the radio frequency (RF) signal with a bandwidth of 3 GHz can be divided into five sub-channels with a bandwidth of 600 MHz and finally demodulated to I/Q basebands, which are also verified with simulation.

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Mijarez, Rito, David Pascacio, Ricardo Guevara, and Joaquin Rodriguez. "Signal processing algorithm for thermal drift compensation in high-temperature down-hole instrumentation systems." Transactions of the Institute of Measurement and Control 39, no. 8 (February 17, 2016): 1161–68. http://dx.doi.org/10.1177/0142331216630360.

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Down-hole oil and gas industry requirements for measuring thermodynamic and geophysical parameters, for instance pressure, temperature, vibration and multiphase flow, are challenging. Accomplishing these necessities requires a complete signal communications chain of high-performance components and effective signal processing communication techniques to provide system reliability. Nevertheless, noise interference, cable attenuation and thermal drift of the front-end passive electronic elements can lead to poor signal-to-noise ratio (SNR) and possibly loss of the communication link. This paper describes a signal processing algorithm implemented in a bidirectional communication system that exchanges data from a down-hole high pressure and high-temperature (HPHT) measurement tool to the surface installation. The communication channel is a multi-conductor coaxial logging cable also used as a power supply transmission line. The instrumentation system consists of a proprietary down-hole measurement tool, composed of an HPHT sensor and a high-temperature digital signal processor (DSP)-based electronic device; located in the surface installation is a data-acquisition equipment. The system employs a signal processing algorithm, based on the frequency domain SNR characterization of the whole communication chain, which determines in real time the optimal carrier frequency that is automatically implemented in the selected modulation/demodulation technique. The obtained laboratory test results of the down-hole tool, using changes in temperature from 25° to 185°C, provide a firm basis for testing and evaluating the system in the field.

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Cho, Seongho, and Daejin Park. "Robust Intra-Body Communication Using SHA1-CRC Inversion-Based Protection and Error Correction for Securing Electronic Authentication." Sensors 20, no. 21 (October 24, 2020): 6056. http://dx.doi.org/10.3390/s20216056.

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The explosive increase in the number of IoT devices requires various types of communication methods. This paper presents secure personal authentication using electrostatic coupling Intra-body communication (IBC) based on frequency shift keying (FSK) and error correction. The proposed architecture uses GPIO for a transmitter and analog-to-digital conversion (ADC) for a receiver. We mplemented FSK modulation, demodulation, data protection, and error correction techniques in the MCU software without applying hardware devices. We used the characteristic that the carrier signal is 50% duty square wave for 1-bit error correction and applied a method of randomly inverting SHA1 hash data to protect user authentication data during transmission. The transmitter modulates binary data using a square wave as a carrier signal and transmits data through the human body. The receiver demodulates the signal using ADC and decrypts the demodulated binary data. To determine the carrier frequency from ADC results, we applied a zero-crossing algorithm which is used to detect edge characteristics in image processing. When calculating the threshold value within the zero-crossing algorithm, we implemented an adaptive threshold setting technique utilizing Otsu’s binarization technique. We found that the size of the electrode pad does not affect the signal strength, but the distance between the electrode pad and the skin has a significant effect on the signal strength. Our results show that binary data modulated with a square wave can be successfully transmitted through the human body, and, when 1-bit error correction is applied, the byte error rate on the receiver side is improved around 3.5% compared to not applying it.

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Carlowitz, Christian, Thomas Girg, Hatem Ghaleb, and Xuan-Quang Du. "Efficient Ultra-High Speed Communication with Simultaneous Phase and Amplitude Regenerative Sampling (SPARS)." Frequenz 71, no. 9-10 (September 26, 2017): 449–61. http://dx.doi.org/10.1515/freq-2017-0163.

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Abstract For ultra-high speed communication systems at high center frequencies above 100 GHz, we propose a disruptive change in system architecture to address major issues regarding amplifier chains with a large number of amplifier stages. They cause a high noise figure and high power consumption when operating close to the frequency limits of the underlying semiconductor technologies. Instead of scaling a classic homodyne transceiver system, we employ repeated amplification in single-stage amplifiers through positive feedback as well as synthesizer-free self-mixing demodulation at the receiver to simplify the system architecture notably. Since the amplitude and phase information for the emerging oscillation is defined by the input signal and the oscillator is only turned on for a very short time, it can be left unstabilized and thus come without a PLL. As soon as gain is no longer the most prominent issue, relaxed requirements for all the other major components allow reconsidering their implementation concepts to achieve further improvements compared to classic systems. This paper provides the first comprehensive overview of all major design aspects that need to be addressed upon realizing a SPARS-based transceiver. At system level, we show how to achieve high data rates and a noise performance comparable to classic systems, backed by scaled demonstrator experiments. Regarding the transmitter, design considerations for efficient quadrature modulation are discussed. For the frontend components that replace PA and LNA amplifier chains, implementation techniques for regenerative sampling circuits based on super-regenerative oscillators are presented. Finally, an analog-to-digital converter with outstanding performance and complete interfaces both to the analog baseband as well as to the digital side completes the set of building blocks for efficient ultra-high speed communication.

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Turovsky, O. L., and O. A. Khakhlyuk. "SYNTHESIS AND ANALYSIS OF THE PHASE SYNCHRONIZATION SYSTEM UNDER THE REDUCTION OF PERMANENT DYNAMIC ERRORS IN THE CARRIER FREQUENCY TRACKING MODE." Visnyk Universytetu “Ukraina”, no. 1 (28) 2020 (2020): 90–99. http://dx.doi.org/10.36994/2707-4110-2020-1-28-08.

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The successful solution of the problem of further improving the efficiency of communication systems largely depends on the quality of operation of systems and devices that are part of them. Phase synchronization systems are widely implemented in various radio engineering devices of communication, radar and control technology, as well as in the device of precise magnetic recording. In particular, in phase-coherent telecommunications and control systems, they are used to restore the carrier and clock frequencies and for coherent demodulation of analog and digital signals with angular modulation. The issues of increasing the efficiency of the phase synchronization system of phase-coherent telecommunication and control systems in radio engineering devices are considered in the work. Namely, the results of synthesis and analysis of the scheme of construction of the combined system of phase synchronization under the condition of reduction of constant dynamic errors during monitoring of the carrier frequency, the phase of which is modulated by a deterministic Doppler signal are presented. As a result of research it is established that the synthesis of the open channel in the combined synchronization systems allows to realize them on invariant schemes which provide reduction of constant dynamic errors by increase of the order of astatism. The use as an open communication frequency discriminator, allows to increase the order of astatism of the combined system synchronization system to the second order. The open channel is made in the form of parallel (serial) connection of two links of the frequency discriminator with the proposed transfer function allows to increase the order of astatism to the third and higher order and does not affect the stability of the system. The analysis of the proposed schemes showed that the effect on the phase error dispersion of the synchronization system can be achieved by changing the parameters of the broken link of the scheme of construction of the specified system.

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Buhaiov, M. V., B. V. Molodetsky, I. O. Mykhailiuk, and V. V. Hordiichuk. "METHOD OF SIGNAL PARAMETERS ESTIMATION OF RADIOSTATIONS WITH FAST FREQUENCY HOPPING SPREAD SPECTRUM." Проблеми створення, випробування, застосування та експлуатації складних інформаційних систем, no. 17 (December 30, 2019): 14–26. http://dx.doi.org/10.46972/2076-1546.2019.17.02.

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Modern special-purpose radios utilize ultra-short burst mode with frequency hopping spread spectrum. Such digital radios operate, as a rule, in the fast frequency hopping spread spectrum mode and use a considerable number of frequency channels with frequency separation between adjacent channels, which is significantly less than the spectrum width of the frequency element. The main modulation in such radios is frequency manipulation. The identification of signals with fast frequency hopping spread spectrum and frequency manipulation is performed by estimating the speed of frequency tuning, the speed of information transmission, the number of frequency channels and the step of the frequency grid and comparing the obtained values with the corresponding characteristics of known radio stations with fast frequency hopping spread spectrum. The time limits and the duration of the frequency elements are calculated by the envelope of the received signal. For this purpose, a suitable method has been developed, which consists in filtering the envelope by means of a moving average window for suppression of the noise component and threshold processing. The threshold value is selected by the given probability of its exceeding by noise sample. The proposed approach to determining the time limits of frequency elements does not require any a priori signal information. To determine the frequencies of the frequency elements periodogram estimates are used. An exponential extrapolation of the discrete power spectrum was used to increase the frequency resolution at a fixed window length of the fast Fourier transform. It is shown that in order to uniquely determine the step of the frequency grid and the diversity of frequency manipulation frequencies, it is necessary to analyze the number of frequency elements not less than the number of frequency channels. By analyzing the histogram of the differences of sorted frequency vector of the frequency elements, determine the frequency grid, frequency diversity and the multiplicity of frequency manipulation. An approximate estimate of the number of frequency channels is calculated as the ratio of the magnitude of the frequency vector of the frequency elements to the step of the frequency grid. As a rule, symbol transmission at frequency manipulation is carried out at orthogonal frequencies, so it can be roughly assumed that the symbolic speed is equal to the frequency diversity of the frequency manipulation. The baud rate can be set only after signal demodulation and bit stream analysis, which can determine the frame structure and the number of service and information bits. The proposed method provides the estimation of the values of the parameters necessary for the identification of radio stations of signal parameters with a relative error not exceeding 0.3%, with values of signal to noise ratio not lower than 5 dB.

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van Kleunen, Wouter A. P., Niels A. Moseley, Paul J. M. Havinga, and Nirvana Meratnia. "Proteus II: Design and Evaluation of an Integrated Power-Efficient Underwater Sensor Node." International Journal of Distributed Sensor Networks 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/791046.

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We describe the design and evaluation of an integrated low-cost underwater sensor node designed for reconfigurability, allowing continuous operation on a relatively small rechargeable battery for one month. The node uses a host CPU for the network protocols and processing sensor data and a separate CPU performs signal processing for the ultrasonic acoustic software-defined Modulator/Demodulator (MODEM). A Frequency Shift Keying- (FSK-) based modulation scheme with configurable symbol rates, Hamming error correction, and Time-of-Arrival (ToA) estimation for underwater positioning is implemented. The onboard sensors, an accelerometer and a temperature sensor, can be used to measure basic environmental parameters; additional internal and external sensors are supported through industry-standard interfaces (I2C, SPI, and RS232) and an Analog to Digital Converter (ADC) for analog peripherals. A 433 MHz radio can be used when the node is deployed at the surface. Tests were performed to validate the low-power operation. Moreover the acoustic communication range and performance and ToA capabilities were evaluated. Results show that the node achieves the one-month lifetime, is able to perform communication in highly reflective environments, and performs ToA estimation with an accuracy of about 1-2 meters.

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Hatai, Indranil, and Indrajit Chakrabarti. "A New High-Performance Digital FM Modulator and Demodulator for Software-Defined Radio and Its FPGA Implementation." International Journal of Reconfigurable Computing 2011 (2011): 1–10. http://dx.doi.org/10.1155/2011/342532.

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This paper deals with an FPGA implementation of a high performance FM modulator and demodulator for software defined radio (SDR) system. The individual component of proposed FM modulator and demodulator has been optimized in such a way that the overall design consists of a high-speed, area optimized and low-power features. The modulator and demodulator contain an optimized direct digital frequency synthesizer (DDFS) based on quarter-wave symmetry technique for generating the carrier frequency with spurious free dynamic range (SFDR) of more than 64 dB. The FM modulator uses pipelined version of the DDFS to support the up conversion in the digital domain. The proposed FM modulator and demodulator has been implemented and tested using XC2VP30-7ff896 FPGA as a target device and can operate at a maximum frequency of 334.5 MHz and 131 MHz involving around 1.93 K and 6.4 K equivalent gates for FM modulator and FM demodulator respectively. After applying a 10 KHz triangular wave input and by setting the system clock frequency to 100 MHz using Xpower the power has been calculated. The FM modulator consumes 107.67 mW power while FM demodulator consumes 108.67 mW power for the same input running at same data rate.

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Fu, Gang, Jian Hua Lin, and Qian He. "Demodulating Method of Frequency Predictable Digital FM Signal." Applied Mechanics and Materials 644-650 (September 2014): 4595–98. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.4595.

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This paper presents a new method for strong background noise of known frequency signal estimation method is then applied to the demodulated digital FM signal. This new method only needs to know the frequency of the demodulated carrier signal phase information without the need to complete the digital FM demodulation signal. Computer simulations show that the method has more than non-coherent demodulation noise immunity, and has a very strong ability of anti-phase fluctuations. Thus, the demodulation method has good prospects for engineering applications.

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Anderson, B. G. "Frequency switching time measurement using digital demodulation." IEEE Transactions on Instrumentation and Measurement 39, no. 2 (April 1990): 353–57. http://dx.doi.org/10.1109/19.52514.

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Li, Ke, Chunping Hou, Yonghong Hou, and Jinlin Fu. "New cooperative frequency domain differential modulation and demodulation." Journal of Systems Engineering and Electronics 22, no. 6 (December 2011): 892–96. http://dx.doi.org/10.3969/j.issn.1004-4132.2011.06.003.

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Dosiek, Luke. "Extracting Electrical Network Frequency From Digital Recordings Using Frequency Demodulation." IEEE Signal Processing Letters 22, no. 6 (June 2015): 691–95. http://dx.doi.org/10.1109/lsp.2014.2368516.

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Garanin, M. V., and L. A. Shalimov. "Digital Demodulation of Multiple Frequency-Shift Keying Signals." Telecommunications and Radio Engineering 63, no. 3 (2005): 245–50. http://dx.doi.org/10.1615/telecomradeng.v63.i3.80.

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Glushkov, A. N., V. P. Lintvinenko, B. V. Matveev, O. V. Chernoyarov, and K. S. Kalashnikov. "Digital noncoherent demodulation of the frequency-modulated signals." Applied Mathematical Sciences 9 (2015): 6925–34. http://dx.doi.org/10.12988/ams.2015.510664.

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Al-Rawi, Muhanned. "Data-Aided Carrier Recovery with QPSK Modulation." Scientific Bulletin 24, no. 1 (June 1, 2019): 14–22. http://dx.doi.org/10.2478/bsaft-2019-0002.

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Abstract Digital communication has proven to be the most efficient method of data transmission especially where long distances are involved. This led to the invention of more sophisticated methods of communication ranging from mobile handset communication to more advanced satellite communication. The speeds of passing information have been improving over the years and real time video communication has been made possible with digital devices. Various methods of digital data transmission are employed based on the information to be transmitted. This paper focuses on carrier recovery in digital communication systems, especially those based on Quadrature Phase Shift Keying (QPSK) modulation and demodulation scheme. The design being implemented is that of coherent demodulation for QPSK scheme using SIMULINK design tool. Performance of QPSK is also investigated to make a comparison and the suitability of the scheme to use in digital data transmission applications.

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Medvedev, Andrei, Andrei Berezhnoi, Aleksei Kudryashov, and Leonid Liokumovich. "Precise digital demodulation for fiber optic interferometer sensors." International Journal of Modern Physics: Conference Series 41 (January 2016): 1660139. http://dx.doi.org/10.1142/s2010194516601393.

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Different methods are used in the interferometer sensors for target signal extraction. Digital technologies provide new opportunities for precise signal detection. We have developed the principle of signal demodulation using an additional harmonic phase modulation and digital signal processing. The principle allows implementation of processing algorithms using different ratios between modulation and discretization frequencies. The expressions allowing calculation of the phase difference using the inverse trigonometric functions were derived. The method was realized in LabVIEW programming environment and was demonstrated for various signal shapes.

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Yang, Zhang Cheng, and Xiang Lin Wang. "Analysis on Anti-Noise Performance of Frequency Modulation System Based on MATLAB Simulation." Applied Mechanics and Materials 543-547 (March 2014): 2426–30. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.2426.

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The popularity of internet technology has brought the change very big to the life and production of modern humans, the current Internet technology application has penetrated into people in every aspect of modern life, has become an indispensable part of people's life. Firstly, system model of the current network communication to dissect, analyzes the architecture of network communication system, modulation and demodulation principle is applied to design the FM communication signal modulation system network communication in the Internet technology, the non coherent demodulation method to build FM demodulation system, realize the demodulation process through differential device, the anti noise performance of the method of frequency modulation system of MATLAB simulation experiments, the experimental results show that the method of anti noise performance significantly, to a certain extent, provide theoretical basis and technical support for the research in this field.

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Jang, In-Gyu, Sung-Hyun Lee, and Yong-Hwa Park. "A Parallel-Phase Demodulation-Based Distance-Measurement Method Using Dual-Frequency Modulation." Applied Sciences 10, no. 1 (December 31, 2019): 293. http://dx.doi.org/10.3390/app10010293.

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Time-of-flight (ToF) measurement technology based on the amplitude-modulated continuous-wave (AMCW) model has emerged as a state-of-the-art distance-measurement method for various engineering applications. However, many of the ToF cameras employing the AMCW process phase demodulation sequentially, which requires time latency for a single distance measurement. This can result in significant distance errors, especially in non-static environments (e.g., robots and vehicles) such as those containing objects moving relatively to the sensors. To reduce the measurement time required for a distance measurement, this paper proposes a novel, parallel-phase demodulation method. The proposed method processes phase demodulation of signal in parallel rather than sequentially. Based on the parallel phase demodulation, 2π ambiguity problem is also solved in this work by adopting dual frequency modulation to increase the maximum range while maintaining the accuracy. The performance of proposed method was verified through distance measurements under various conditions. The improved distance measurement accuracy was demonstrated throughout an extended measurement range (1–10 m).

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Yamada, Osamu. "Fundamental Technologies for Digital TV Broadcasting. (7). Digital Modulation and Demodulation Techniques." Journal of the Institute of Television Engineers of Japan 48, no. 7 (1994): 876–85. http://dx.doi.org/10.3169/itej1978.48.876.

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R. Udawant, Sandip, and Satyawati Magar. "Modulation and Demodulation of Image Processing by Using GMSK." International Journal of Engineering & Technology 7, no. 3.27 (August 15, 2018): 233. http://dx.doi.org/10.14419/ijet.v7i3.27.17883.

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Today digital communication is widely used in telecommunication sector in which the information is coded in the form of bits. There are many techniques that are implemented for modulation in digital communication some of them are BPSK, QPSK, M-ary PSK, GMSK. While transmitting an image there is always a challenge to retain the quality of an image by using these digital modulation techniques. In this paper GMSK technique is used for transmitting an image. The GMSK modulation technique is widely used in GSM techniques. By using GMSK modulation technique, which carries the information with high data rate and this is very important for image transmission. The proposed system gives better results than other modulation techniques like BPSK and M-ary PSK.

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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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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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Shen, Wei, and Biyang Wen. "A New Demodulation and Modulation Method Designed for FMCW Radar." Journal of Electrical and Computer Engineering 2010 (2010): 1–6. http://dx.doi.org/10.1155/2010/897429.

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An efficient demodulation method designed for FMCW (Frequency-Modulated Continuous Wave) radar is presented. It is a kind of modified DFT (IDFT) algorithm; the spectrum segment of interest can be easily extracted from the original signal without calculating the whole DFT/FFT. It provides fast demodulation and extraction of desired frequency bands in our HFSWR (High-Frequency Surface Wave Radar) system. The proposed approach enhances the performances of radar system and reduces the computing complexity. The new structure could also be inversely used for signal modulation. And also arbitrary sampling rate conversion could be achieved with the combination of forward and backward structure.

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Zhou, Fan, Xin Xin Geng, and Xiao Yu Zhang. "An Improved QPSK Signal's Algorithm Design and Simulation of its Modulation and Demodulation." Advanced Materials Research 912-914 (April 2014): 1146–49. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1146.

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QPSK, a modulation mode with a high frequency band utilization ratio and a strong anti-noise immunity,is widely used in the field of military and satellite communication. This article based on the analysis of the traditional QPSK signal modulation and demodulation mechanism, proposes an improved QPSK signal modulation and demodulation algorithm, and have a further in-depth analysis of the feasibility of this algorithm. Finally, by MATLAB software simulation testing, simulation results shows that the algorithm can accurately generate a QPSK signal and complete a rapidly demodulation of a QPSK signal.

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Yang, Chaozhong, Yulin Wang, Shifeng Li, and Wenhe Yan. "Experimental Study of a Signal Modulation Method to Improve eLORAN Data Channel Communications." Sensors 20, no. 22 (November 14, 2020): 6504. http://dx.doi.org/10.3390/s20226504.

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There are mainly two types of data modulation methods used for enhanced LOng-RAnge Navigation (eLORAN) systems: pulse position modulation (PPM) and supernumerary interpulse modulation (SIM). The typical application for PPM is tri-state PPM (3S-PPM), also known as Eurofix. The typical application for SIM is ninth pulse modulation. Both of these methods are phase modulation methods. Phase modulation coding, a very mature technology, is used at present. To achieve a better demodulation success rate of eLORAN digital modulation signals at longer distances, a method of using the transmitting station duplex mode to transmit a digital modulation pulse group after LORAN-C transmitting a pulse group is proposed to realize modulation pulse on–off modulation. In this method, a broadcasting experiment was performed on the BPL (The call sign of eLORAN time service system in China) broadcaster station. After monitoring, a good receiving demodulation effect was initially obtained.

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Journal articles on the topic 'Digital frequency modulation and demodulation'

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