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Continuous phase modulation

About: Continuous phase modulation is a research topic. Over the lifetime, 3199 publications have been published within this topic receiving 37245 citations. The topic is also known as: CPM.


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Patent
12 Mar 1980
TL;DR: In this article, a system for transmitting n-level data signals by means of an angle-modulated carrier having a constant amplitude and a continuous phase was proposed, where the constant amplitude enables amplification in non-linear transmitter output stages.
Abstract: A system for transmitting n-level data signals by means of an angle-modulated carrier having a constant amplitude and a continuous phase. The constant amplitude enables amplification in non-linear transmitter output stages. Associated with the n-levels are k(k>n) phase variations in accordance with such a rule, depending on preceding phase variations, that the spectrum of the angle-modulated signal becomes narrower. In a symbol interval the phase of the carrier changes by an amount from the sequence extending from -(k-1)π/n to (k+1)π/n in increments of 2π/n. The receiver is formed by a differential n-phase receiver. The system is used inter alia for radio transmission of digital information.

13 citations

Proceedings ArticleDOI
01 Jun 2014
TL;DR: An asymptotic analysis and optimization of coded CPM systems using both unstructured and protograph-based LDPC codes ensembles is derived and some simple rules to design good protograph codes with good threshold properties are provided.
Abstract: In this paper, we derive an asymptotic analysis and optimization of coded CPM systems using both unstructured and protograph-based LDPC codes ensembles. First, we present a simple yet effective approach to design unstructured LDPC codes : by inserting partial interleavers between LDPC and CPM, and allowing degree-1 and degree-2 variable nodes in a controlled pattern, we show that designed codes perform that can operate very close to the maximum achievable rates. Finally, the extension to protograph based codes is discussed. We provide some simple rules to design good protograph codes with good threshold properties.

13 citations

Journal ArticleDOI
TL;DR: This method can recover the phase of InSAR with the under-sampled problems caused by terrain abrupt change and so on, and is applied to phase retrieval of interferometric synthetic aperture radar with satisfactory results.
Abstract: Phase retrieval from single interference fringe is important and effective method in obtaining the real phase distribution. The original phase can be retrieved by the line integral of its gradient expressed as sine and cosine components, which were gained by the Hilbert transform twice from a single interference fringe pattern. However, this method fails when the phase transformation of the interference fringe is too fast. In this paper, a novel method to recover the continuous phase of the whole field is proposed to solve the above problems. The shear interference technique is introduced into the phase retrieval method to build an exponential 2-D complex light field of natural base for the phase slope obtained by the Hilbert transform. Then, the expressions of phase slopes in x- and y-directions are constructed as a discrete Poisson equation. Therefore, the calculation of phase retrieval is equivalent to solve the discrete Poisson equation mathematically. Finally, the real phase is gotten by the weighted discrete cosine transform (WDCT) of the discrete Poisson equation. The simulation results verify the validity of this method and show that the proposed method can achieve the phase retrieval of the phase discontinuity in x- and y-directions, which leads to the under-sampled problem. It can restore the whole field phase distribution rapidly and accurately. Moreover, this method is applied to phase retrieval of interferometric synthetic aperture radar (InSAR) with the under-sampled problem in this paper. The experimental results show that this method can recover the phase of InSAR with the under-sampled problems caused by terrain abrupt change and so on. Compared with other commonly used methods, it achieved satisfactory results. This method provides a new idea for solving the under-sampled problem in the phase retrieval from a single-frame interference fringe.

13 citations

Journal ArticleDOI
TL;DR: The W7-X stellarator as discussed by the authors employs a two-color CO2 (10.591 m) and CO (5.295 m) heterodyne-infrared interferometer as an electronic density measurement diagnostic.
Abstract: Interferometry is used for measuring line average electronic densities in fusion plasmas. The W7-X stellarator will employ a two-color CO2 (10.591 m) and CO (5.295 m) heterodyne-infrared interferometer as an electronic density measurement diagnostic. The frequency displacement is 40 MHz for the CO2 wavelength and 25 MHz for the CO, so these values will fix the heterodyne frequencies. Because the frequency gap between the two carriers is wide enough and the detector sensitivity is similar for both wavelengths, it is possible to use a single detector for the two signals; nevertheless, they should be split with filters. Traditionally, the intermediate-frequency signals should be filtered, downconverted to a lower frequency by the use of analog circuitry, and then processed. A new approach is proposed. The intermediate-frequency signals are directly sampled by means of high-speed analog-to-digital converters followed by a digital diplexer and a specific phase-meter processor implemented in a field-programmable gate array. Preliminary results from the W7-X infrared interferometer prototype, without plasma, are presented.

13 citations

Patent
01 Feb 1977
TL;DR: In this article, a phase lock loop system for phase modulated carrier pulse signals was proposed, in which the pulses are coded according to a plurality of N phases of the carrier.
Abstract: Demodulator for phase modulated carrier pulse signals or phase codes in which the pulses are coded according to a plurality of N phases of the carrier. It comprises a digital phase lock loop system for locking to a frequency equal to N times the carrier frequency which includes at least a two input phase detector, a loop integrator and a voltage controlled oscillator having an output connected to the first input of the phase detector, means for dividing by N the frequency of this oscillator and for generating a reference carrier signal. The phase codes are decoded by comparing the phases of the carrier of the phase codes to the phase of the reference signal. In order to derive from all the phase codes a train of synchronous pulses a multiphase shifter receives the carrier of the phase codes and locally generates a plurality of carriers having phase shifts equal to 0, 2π/N, 2×2π/N, . . . ([N/2]- 1) ×2π/N with respect to the carrier of the received phase code and means are provided for generating passing through zero pulses coinciding with the passage through zero of said received and locally generated carriers. Those of said passing through zero pulses which occur during the central part of each phase modulated carrier pulse are gated through gating means. These gated passing through zero pulses are applied to the second input of the phase detector.

13 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202241
202136
202060
201976
201870