Journal articles: 'Doppler frequency shift'

1

Kremkau, F. W. "Doppler shift frequency data." Journal of Ultrasound in Medicine 6, no. 3 (March 1987): 167. http://dx.doi.org/10.7863/jum.1987.6.3.167.

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Пензин, Максим, Maksim Penzin, Николай Ильин, and Nikolay Ilyin. "Modeling of Doppler frequency shift in multipath radio channels." Solar-Terrestrial Physics 2, no. 2 (August 10, 2016): 66–76. http://dx.doi.org/10.12737/21000.

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We discuss the modeling of propagation of a quasi-monochromatic radio signal, represented by a coherent pulse sequence, in a non-stationary multipath radio channel. In such a channel, signal propagation results in the observed frequency shift for each ray (Doppler effect). The modeling is based on the assumption that during propagation of a single pulse a channel can be considered stationary. A phase variation in the channel transfer function is shown to cause the observed frequency shift in the received signal. Thus, instead of measuring the Doppler frequency shift, we can measure the rate of variation in the mean phase of one pulse relative to another. The modeling is carried out within the framework of the method of normal waves. The method enables us to model the dynamics of the electromagnetic field at a given point with the required accuracy. The modeling reveals that a local change in ionospheric conditions more severely affects the rays whose reflection region is in the area where the changes occur.

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Milan, S. E., M. Lester, and N. Sato. "Multi-frequency observations of E-region HF radar aurora." Annales Geophysicae 21, no. 3 (March 31, 2003): 761–77. http://dx.doi.org/10.5194/angeo-21-761-2003.

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Abstract. Multi-frequency observations of E-region coherent backscatter from decametre waves reveal that auroral echoes tend to comprise two spectral components superimposed, one at low Doppler shifts, below 250 ms-1, and the other Doppler shifted to near the ion-acoustic speed or above, up to 800 ms-1. The low Doppler shift component occurs at all look directions; Doppler shifts near the ion acoustic speed occur when looking at low flow angles along the direction of the electron drift in the electrojet, and Doppler shifts in excess of the ion acoustic speed occur at intermediate flow angles. The latter population appears most commonly at radar frequencies near 10–12 MHz, with its occurrence decreasing dramatically at higher frequencies. The velocity of the high Doppler shift echoes increases with increasing radar frequency, or irregularity wave number k. The velocity of the low Doppler shift population appears to be suppressed significantly below the line-of-sight component of the electron drift. Initial estimates of the altitude from which scatter occurs suggest that the high Doppler shift echoes originate from higher in the E-region than the low Doppler shift echoes, certainly in the eastward electrojet. We discuss these observations with reference to the theories of de/stabilization of two-stream waves by electron density gradients and electrostatic ion cyclotron waves excited by field-parallel electron drifts.Key words. Ionosphere (ionospheric irregularities)

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Zhou, Chang, Zhen-Bo Zhu, and Zi-Yue Tang. "A Novel Waveform Design Method for Shift-Frequency Jamming Confirmation." International Journal of Antennas and Propagation 2018 (July 2, 2018): 1–13. http://dx.doi.org/10.1155/2018/1569590.

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Shift-frequency jamming is generally used to form range false targets for ground-based early-warning radar systems; the frequency shift value of such interference is larger than the Doppler shift value of the moving target, and the key element to suppress the shift-frequency jamming is the frequency shift value estimation. However, in the low- or medium-pulse repetition frequency (PRF) mode, it is challenging to estimate the accurate frequency shift due to the velocity ambiguity. To solve this problem, a novel sparse Doppler-sensitive waveform is designed based on the ambiguity function theory, where the basic idea is to design a waveform sensitive to a specific Doppler but insensitive to other Dopplers; therefore, this waveform can recognize the specific Doppler of the target unambiguously. To apply the designed waveform in practice, the detection and estimation processing flow is provided based on the waveform diversity technique and the family of the sparse Doppler-sensitive waveforms. Simulation experiments are presented to validate the efficiency of the proposed method, and we conclude that the advantage of this method is that it can be used to confirm the specific Doppler of the target unambiguously with few pulses even under the condition of a low PRF.

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Cheng, Zi-Mo, Shu-Tian Xue, Yan-Chao Lou, Pei Wan, Zhi-Cheng Ren, Jianping Ding, Xi-Lin Wang, and Hui-Tian Wang. "Rotational Doppler shift tripling via third-harmonic generation of spatially structured light in a quasi-periodically poled crystal." Optica 10, no. 1 (January 3, 2023): 20. http://dx.doi.org/10.1364/optica.474243.

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The rotational Doppler effect—the angular version of the Doppler effect—shows a frequency shift phenomenon happening when light passes through a rotating object and its angular momentum is changed. The rotational Doppler effect has been widely studied with various light waves based on different angular momentum transform mechanisms and successfully utilized to detect the rotation of objects. However, these studies are mostly limited to linear optics. As the rotational Doppler effect is closely related to the frequency degree of freedom and frequency conversion always happens in nonlinear optics, it is of great significance to explore the rotational Doppler effect in nonlinear optics. Although nonlinear rotational Doppler phenomena have been observed in second-harmonic generation with circularly polarized Gaussian fundamental light and a rotating nonlinear crystal, there is still the open challenge of how to realize Doppler frequency shift conversion (similar to conventional nonlinear frequency conversion), such as doubling or tripling. Here we report the experiment observation of rotational Doppler shift conversion in nonlinear optics. We demonstrate the tripling of a rotational Doppler frequency shift in third-harmonic generation of a spatially structured fundamental wave. Frequency shifts can be extracted from the intensity beating signals with the interference of two components of vector fields with opposite topological charges and the measured modulation frequency of the beating signal for the generated third harmonic. Our results will excite more research on nonlinear optics with spatially structured light, and our method may create opportunities for precision measurement of frequency shifts.

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Eska, Andrita Ceriana. "Doppler Shift Effect at The Communication Systems with 10 GHz around Building." JURNAL INFOTEL 12, no. 4 (November 25, 2020): 129–33. http://dx.doi.org/10.20895/infotel.v12i4.483.

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This research described the Doppler shift effect for the communication systems. The mobile station moves with various velocities around the building’s environment. Doppler’s shift influences the communication systems. The frequency communication was used 10 GHz and its influenced by atmospheric attenuation. This research consisted of propagation with LOS and NLOS conditions, mobile station velocity variation, height buildings variation, and transmitter power variation. This research described frequency maximum at Doppler shift, coherence time, and signal to noise ratio. More increase Doppler shift of coherence time caused signal noise ratio to decrease.

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Schier, Walter. "Doppler frequency shift of sound apparatus." Physics Teacher 49, no. 4 (April 2011): 246–47. http://dx.doi.org/10.1119/1.3566040.

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Dang, Qun, and Xiao Li Lei. "Doppler Frequency Shift Tolerance Extension in Burst Spread Spectrum Communication System." Advanced Materials Research 443-444 (January 2012): 237–40. http://dx.doi.org/10.4028/www.scientific.net/amr.443-444.237.

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A method to extend Doppler frequency discrimination tolerance is proposed for quick acquirement PN-code and Doppler frequency in TDMA burst spread spectrum communication system. According to Doppler’s different impacts on the correlation Peak and data demodulation, PN-code is acquired through single channel matched-filters, and parallel multi-channel correlators are used in the data demodulation branch channel. Thus, with using frame head prior information in data channel instead of traditional Cross-Product Automatic Frequency Control (CPAFC), the Doppler frequency shift discrimination tolerance is extended. Simulation and experiment show that frequency and PN-code can be acquired in several data periods, and synchronous time and the resources consumption are effectively reduced.

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Jiang, Wei, and Tian Le. "Joint Estimation of Doppler Frequency Shift and Doppler Frequency Rate Based on Interpolation." Journal of Electronics & Information Technology 35, no. 1 (February 17, 2014): 166–71. http://dx.doi.org/10.3724/sp.j.1146.2012.00716.

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Wu, Guizhou, Min Zhang, Fucheng Guo, and Xuebing Xiao. "Direct Position Determination of Coherent Pulse Trains Based on Doppler and Doppler Rate." Electronics 7, no. 10 (October 22, 2018): 262. http://dx.doi.org/10.3390/electronics7100262.

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Direct Position Determination (DPD) of coherent pulse trains using a single moving sensor is considered in this paper. Note that when a large observation window and relative maneuvering course between emitter and receiver both exist, the localization accuracy of Doppler frequency shift only based DPD will decline because of the noticeable Doppler frequency shift variations. To circumvent this problem, a Doppler frequency shift and Doppler rate based DPD approach using a single moving sensor is proposed in this paper. First, the signal model of the intercepted coherent pulse trains is established where the Doppler rate is taken into consideration. Then, the Maximum Likelihood based DPD cost function is given, and the Cramer–Rao lower bound (CRLB) on localization is derived whereafter. At last, the Monto Carlo simulations demonstrate that in one exemplary scenario the Doppler frequency shift variations are noticeable with a large observation window and the proposed method has superior performance to the DPD, which is only based on the Doppler frequency shift.

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11

Roy, Dipankar. "Doppler frequency shift in a refractive atmosphere." Journal of Aircraft 24, no. 9 (September 1987): 577–86. http://dx.doi.org/10.2514/3.45481.

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12

Wang, Zhong-Yue. "Non-Doppler frequency shift of Newton waves." Optik 174 (December 2018): 676–83. http://dx.doi.org/10.1016/j.ijleo.2018.08.006.

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Du, Xiao Jing, Wen Bo Zhang, and Song Bo Wang. "Analysis of the Impact on Doppler Frequency Shift of the Signal Caused by Receiver’s High Dynamic Environment." Applied Mechanics and Materials 568-570 (June 2014): 176–79. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.176.

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The Doppler frequency shift of the signal received from receiver carrier in high dynamic environment which means high speed and high acceleration represents different changing rules. The changing rules can make the positioning accuracy become worse and even make the receiver unable to track the signal. On the basis of modeling and simulation of three high dynamic carriers including the aircraft, satellite and ballistic missile, the changing rules of Doppler frequency shift were analyzed using the calculation equation of the Doppler frequency shift. The results show that for the high dyanmic carriers, the larger the velocity of the carrier is, the larger corresponding Doppler frequency shift is and the larger the acceleration of the carrier is, the larger corresponding changing rate of Doppler frequency shift is.

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Gibson, Graham M., Ermes Toninelli, Simon A. R. Horsley, Gabriel C. Spalding, Euan Hendry, David B. Phillips, and Miles J. Padgett. "Reversal of orbital angular momentum arising from an extreme Doppler shift." Proceedings of the National Academy of Sciences 115, no. 15 (March 26, 2018): 3800–3803. http://dx.doi.org/10.1073/pnas.1720776115.

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The linear Doppler shift is familiar as the rise and fall in pitch of a siren as it passes by. Less well known is the rotational Doppler shift, proportional to the rotation rate between source and receiver, multiplied by the angular momentum carried by the beam. In extreme cases the Doppler shift can be larger than the rest-frame frequency and for a red shift, the observed frequency then becomes “negative.” In the linear case, this effect is associated with the time reversal of the received signal, but it can be observed only with supersonic relative motion between the source and receiver. However, the rotational case is different; if the radius of rotation is smaller than the wavelength, then the velocities required to observe negative frequencies are subsonic. Using an acoustic source at ≈100 Hz we create a rotational Doppler shift larger than the laboratory-frame frequency. We observe that once the red-shifted wave passes into the “negative frequency” regime, the angular momentum associated with the sound is reversed in sign compared with that of the laboratory frame. These low-velocity laboratory realizations of extreme Doppler shifts have relevance to superoscillatory fields and offer unique opportunities to probe interactions with rotating bodies and aspects of pseudorelativistic frame translation.

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Metzner, Walter, Shuyi Zhang, and Michael Smotherman. "Doppler-shift compensation behavior in horseshoe bats revisited: auditory feedback controls both a decrease and an increase in call frequency." Journal of Experimental Biology 205, no. 11 (June 1, 2002): 1607–16. http://dx.doi.org/10.1242/jeb.205.11.1607.

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SUMMARY Among mammals, echolocation in bats illustrates the vital role of proper audio-vocal feedback control particularly well. Bats adjust the temporal,spectral and intensity parameters of their echolocation calls depending on the characteristics of the returning echo signal. The mechanism of audio-vocal integration in both mammals and birds is, however, still largely unknown. Here, we present behavioral evidence suggesting a novel audio-vocal control mechanism in echolocating horseshoe bats (Rhinolophus ferrumequinum). These bats compensate for even subtle frequency shifts in the echo caused by flight-induced Doppler effects by adjusting the frequency of their echolocation calls. Under natural conditions, when approaching background targets, the bats usually encounter only positive Doppler shifts. Hence, we commonly believed that, during this Doppler-shift compensation behavior,horseshoe bats use auditory feedback to compensate only for these increases in echo frequency (=positive shifts) by actively lowering their call frequency below the resting frequency (the call frequency emitted when not flying and not experiencing Doppler shifts). Re-investigation of the Doppler-shift compensation behavior, however, shows that decreasing echo frequencies(=negative shifts) are involved as well: auditory feedback from frequencies below the resting frequency, when presented at similar suprathreshold intensity levels as higher echo frequencies, cause the bat's call frequency to increase above the resting frequency. However, compensation for negative shifts is less complete than for positive shifts (22% versus 95%),probably because of biomechanical restrictions in the larynx of bats. Therefore, Doppler-shift compensation behavior involves a quite different neural substrate and audio-vocal control mechanism from those previously assumed. The behavioral results are no longer consistent with solely inhibitory feedback originating from frequencies above the resting frequency. Instead, we propose that auditory feedback follows an antagonistic push/pull principle, with inhibitory feedback lowering and excitatory feedback increasing call frequencies. While the behavioral significance of an active compensation for echo frequencies below RF remains unclear, these behavioral results are crucial for determining the neural implementation of audio-vocal feedback control in horseshoe bats and possibly in mammals in general.

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Wu, Kang, Yi Jun Chen, Zhuang Ping Qi, Hui Jie Liu, and Xu Wen Liang. "Hardware Implementation of Doppler Shift Estimation and Compensation in LEO Satellite Communication." Advanced Materials Research 791-793 (September 2013): 2076–80. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.2076.

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In the low earth orbit (LEO) satellite communication systems, in which receiver and transmitter are not fixed and have significant relative velocity, the fast time-varying Doppler frequency shift is high, which degrades the performance of acquisition and tracking. Doppler frequency shift and Doppler frequency rate can be calculated by the terrestrial system based on the satellite orbit and the relative velocity. In this paper, we introduce the Doppler compensation principle and the realization of Doppler shift estimation and compensation on an universal wireless signal processing platform. The experimental results showed that the Doppler compensation model have high accuracy, which is positively correlated with the Doppler frequency rate.

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Borisova, T. D., N. F. Blagoveshchenska, I. V. Moskvin, M. T. Rietveld, M. J. Kosch, and B. Thidé. "Doppler shift simulation of scattered HF signals during the Tromsø HF pumping experiment on 16 February 1996." Annales Geophysicae 20, no. 9 (September 30, 2002): 1479–86. http://dx.doi.org/10.5194/angeo-20-1479-2002.

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Abstract. Comparisons between bistatic scatter measurements and simulation results during the Tromsø HF pumping experiment on 16 February 1996 are made. Doppler measurements of an HF diagnostic signal scattered from the field-aligned irregularities (FAIs) in the auroral E-region were carried out on the London – Tromsø – St. Petersburg path at 9410 kHz from 21:00 to 22:00 UT. The scattered signals were observed both from natural and artificial ionospheric irregularities located in the vicinity of Tromsø. To simulate the Doppler frequency shifts, fd , of scattered signals, a radio channel model, named CONE, was developed. The model allows for ray tracing, group and phase paths, and Doppler frequency shift calculations. The calculated Doppler shifts were analyzed for dependence on the magnitude and direction of plasma velocities in the scattering volume. It was found that the velocity components in the north-south direction are crucial for explaining the Doppler frequency shifts of the scattered diagnostic signals. To simulate fd , real velocities obtained from the EISCAT UHF radar at an altitude of 278 km and from the digital all-sky imager during the experiment were employed. The simulation results of Doppler frequency shift variations with time are in reasonable agreement with the experimental Doppler shifts of scattered signals on the London – Tromsø – St. Petersburg path.Key words. Ionosphere (active experiments; ionospheric irregularities) Radio science (ionospheric propagation)

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Gaitan, Michael, Jon Geist, Benjamin J. Reschovsky, and Ako Chijioke. "Characterization of laser Doppler vibrometers using acousto-optic modulators." ACTA IMEKO 9, no. 5 (December 31, 2020): 361. http://dx.doi.org/10.21014/acta_imeko.v9i5.1001.

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We report on a new approach to characterize the performance of a laser Doppler vibrometer (LDV). The method uses two acousto-optic modulators (AOMs) to frequency shift the light from an LDV by a known quantity to create a synthetic velocity shift that is traceable to a frequency reference. Results are presented for discrete velocity shifts and for sinusoidal velocity shifts that would be equivalent to what would be observed in an ideal accelerometer vibration calibration. The method also enables the user to sweep the synthetic vibration excitation frequency to characterize the bandwidth of an LDV together with its associated electronics.

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Cao, Xin Liang, Wei Cui, and Meng De Wang. "An Extracting Algorithm of Ultrasonic Doppler Shift for Multiphase Fluid Flow Measurement." Applied Mechanics and Materials 494-495 (February 2014): 817–20. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.817.

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Because of the complexity for the frequency measurement about echo signal of ultrasonic Doppler flow, the acquisition methods directly affect the accuracy of Doppler frequency shift. The algorithm of power spectrum extraction has accurate to detection echo Doppler frequency of stationary signal for the flow-velocity measurement. The key is to obtain relative useful frequency information from complex echo velocity. This study is based on the principle of Doppler velocity measurement, by studying the average frequency algorithm of echoes, and the Fourier transform method is adopted to identify Doppler signal frequency and Doppler frequency shift which was polluted by aliasing noise. The MATLAB simulation results show: the useful frequency to obtain reliable, accurate, and also laid the foundation for the measurement of multiphase flow non-stationary signals.

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Keating, A. W., O. W. Henson, M. M. Henson, W. C. Lancaster, and D. H. Xie. "Doppler-shift compensation by the mustached bat: quantitative data." Journal of Experimental Biology 188, no. 1 (March 1, 1994): 115–29. http://dx.doi.org/10.1242/jeb.188.1.115.

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Quantitative data for Doppler-shift compensation by Pteronotus parnellii parnellii were obtained with a device which propelled the bats at constant velocities over a distance of 12 m. The bats compensated for Doppler shifts at all velocities tested (0.1-5.0 ms-1). The main findings were (1) that compensation was usually accomplished by a progressive lowering of the approximately 61 kHz second harmonic constant-frequency component of emitted sounds in small frequency steps (93 +/- 72 Hz); (2) that the time needed to reach a steady compensation level averaged 514 +/- 230 ms and the number of pulses required to reach full compensation averaged 10.78 +/- 5.16; (3) that the animals compensated to hold the echo (reference) frequency at a value that was slightly higher than the resting frequency and slightly lower than the cochlear resonance frequency; (4) that reference frequency varied as a function of velocity, the higher the velocity of the animal, the higher was the reference frequency (slope 55 Hz m-1s-2); and (5) that the mean reference frequency was always an undercompensation. The average amount of undercompensation was 15.8%. There was a significant difference (P < or = 0.005) in Doppler-shift compensation data collected at velocities that differed by 0.1 ms-1. A velocity difference of 0.1 ms-1 corresponds to a Doppler-shift difference of about 35 Hz in the approximately 61 kHz signals reaching the ear.

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Cao Kang, 曹康, 姜成昊 Jiang Chenghao, 朱精果 Zhu Jingguo, 杜鹃 Du Juan, 乔治 Qiao Zhi, and 叶征宇 Ye Zhengyu. "激光多普勒移频特性研究." Infrared and Laser Engineering 50, no. 11 (2021): 20210116. http://dx.doi.org/10.3788/irla20210116.

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Hu, Fei, Chang Qing Shen, Fang Liu, Ao Zhang, and Fan Rang Kong. "Doppler Shift Elimination Method Based on Instantaneous Frequency Estimation for the Wayside Acoustic Signal." Applied Mechanics and Materials 333-335 (July 2013): 510–15. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.510.

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The phenomenon of Doppler Shift leads to the difficulty for fault diagnosis of train bearings with a high moving speed. So the elimination of the Doppler shift should be implemented firstly. A Doppler Shift elimination method for the wayside acoustic signal is proposed. The instantaneous frequency estimation based on STFT was applied to attain the IF vector. According to the acoustic theory of Morse, the data fitting was then carried out to achieve the fitting IFs, with which the re-sampling sequence could be established to eliminate Doppler Shift. To demonstrate the validity of this method, an experiment with the synthetic signal containing several frequency components had been carried out. The results show that the re-sampled signal was revised without Doppler Shift.

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Chang, Qing Wen, Xiao Hong Shen, and Juan Chang. "Research on the Doppler Shift Mitigation Scheme for OFDM Underwater Acoustic Communication." Applied Mechanics and Materials 135-136 (October 2011): 820–25. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.820.

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Doppler shift decreases the estimation accuracy of carrier frequency and may result in divergent estimation. It thus degrades the performance of orthogonal frequency division multiplexing (OFDM) underwater acoustic (UWA) communication system. In this paper, the two-step Doppler shift mitigation scheme[4] was adopted to mitigate the Doppler effect. The innovation lied in the second step in which an enhanced carrier frequency offset (CFO) two-time estimation approach on basis of the pilot was proposed to improve the Doppler shift mitigation scheme. In addition, the new Doppler shift mitigation scheme with the proposed approach was implemented in the OFDM communication system under the simulated multipath-spread channel environment. The experiment results show that the new scheme is able to improve the performance of OFDM UWA communication significantly.

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Пензин, Максим, Maksim Penzin, Николай Ильин, and Nikolay Ilyin. "Modeling of Doppler frequency shift in multipath radiochannels." Solnechno-Zemnaya Fizika 2, no. 2 (June 17, 2016): 57–63. http://dx.doi.org/10.12737/16505.

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We discuss the modeling of propagation of a quasi-monochromatic radio signal, represented by a coherent pulse sequence, in a non-stationary multipath radio channel. In such a channel, signal propagation results in the observed frequency shift for each ray (Doppler effect). The modeling is based on the assumption that during propagation of a single pulse a channel can be considered stationary. A phase change in the channel transfer function is shown to cause the observed frequency shift in the received signal. Thus, instead of measuring the Doppler frequency shift, we can measure the rate of change in the mean phase of one pulse relative to another. The modeling is carried out within the framework of the method of normal waves. The method enables us to model the dynamics of the electromagnetic field at a given point with the required accuracy. The modeling reveals that a local change in ionospheric conditions more severely affects the rays whose reflection region is in the area where the changes occur.

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Biglieri, E., F. Abrishamkar, and Y. C. Jou. "Doppler frequency shift estimation for differentially coherent CPM." IEEE Transactions on Communications 38, no. 10 (1990): 1659–63. http://dx.doi.org/10.1109/26.61433.

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Liu, Peng, Nobuyoshi Kouguchi, and Ying Li. "Velocity Measurement of Coherent Doppler Sonar Assisted by Frequency Shift, Kalman Filter and Linear Prediction." Journal of Marine Science and Engineering 9, no. 2 (January 21, 2021): 109. http://dx.doi.org/10.3390/jmse9020109.

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Velocity is vital information for navigation and oceanic engineering. Coherent Doppler sonar is an accurate tool for velocity measurement, but its use is limited due to velocity ambiguity. Velocity measured by frequency shift has no velocity ambiguity, yet its measurement error is larger than that of coherent Doppler sonar. Therefore, coherent Doppler sonar assisted by frequency shift is used to accurately measure velocity without velocity ambiguity. However, the velocity measured by coherent Doppler sonar assisted by frequency shift is affected by impulsive noise. To decrease the impulsive noise, Kalman filter and linear prediction are proposed to improve the velocity sensing accuracy. In this method, the Kalman filter is used to decrease measurement error of velocity measured by frequency shift, and linear prediction is used to remove the impulsive noise generated by a wrong estimate of the integer ambiguity. Lab-based experiments were carried, and the results have shown that coherent Doppler sonar assisted by frequency shift, Kalman filter and linear prediction can provide accurate and precise velocity with short time delay in a large range of signal to noise ratio.

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Zhao, Rui, and Yan Wen Wang. "Under Low SNR Condition Rapidly Varying Doppler Frequency Offset Influence on Carrier Frequency Acquisition and Simulation Analysis." Advanced Materials Research 912-914 (April 2014): 1489–95. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1489.

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The Quickly changed Doppler frequency offset is calculated and researched under low SNR during mobile satellite communications receiver carrier capture process. Firstly, current carrier frequency offset calculation technology is introduced, and the influence of the Doppler shift caused by the carrier capture is analyzed; Secondly, carrier frequency offset acquisition affected by changing rate of Doppler frequency offset is analyzed. Its mainly considered that first order changing rate and second order changing rate affect carrier acquisition. The changing rate would seriously reduces non-coherent accumulation number during carrier frequency offset estimation at low SNR; Finally, carrier frequency offset caused by the rate of change of the first order and second-order Doppler shift is analyzed and researched. It is demonstrated that platform effort caused by Doppler frequency offset can be improved, and the efficiency of the carrier capture increased through sampling points N reasonable by MATLAB simulation.

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Dong, Shao Feng, Bao Qiang Du, and Wei Zhou. "Real-Time Measurement Method of Doppler Based on GPS Carrier Signals." Applied Mechanics and Materials 226-228 (November 2012): 2050–55. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2050.

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According to Doppler effect of satellite on the time synchronization technology between satellite and the ground station, a real-time measurement method of Doppler is proposed based on GPS carrier signals. Using Doppler observations from GPS receiver, the method can real-timely measure Doppler frequency shift of GPS including dynamic Doppler and media Doppler whose error can be timely modified in the receiver end. Simulation results show that the frequency shift caused by dynamic Doppler, a main influencing factor in the course of transmission of time-frequency signal by GPS satellite, is between plus or minus several thousands Hz. Comparing to traditional measurement method of Doppler, the method makes it possible to fast track phase of signal in large dynamic range in synchronous technology.

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Liu, Bei Jia, Xiao Wang, Xue Zhi Tan, and Yang Yu. "An Adaptive Channel Estimation Based on Polynomial Fitting for LTE Uplink in High Doppler Spread Scenario." Advanced Materials Research 756-759 (September 2013): 3522–26. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.3522.

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Channel estimation plays a crucial role in improving the overall system performance in long term evolution (LTE) systems. However, it is demonstrated that conventional channel estimation algorithms have poor performance in the presence of a large Doppler frequency shift. To mitigate the adverse effect of Doppler frequency shift on transmission signals, an adaptive anti-Doppler shift method based on polynomial fitting for LTE uplink is proposed in this paper. Furthermore, an adaptive strategy is exploited to improve estimation accuracy and reduce estimation mean square error (MSE), achieving better system performance. Simulations results validate the effectiveness of anti-Doppler algorithm.

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Tamura, T., and A. Fronek. "Shear-Layer Detection in Poststenotic Flow by Spectrum Analysis of Doppler Signals." Journal of Biomechanical Engineering 110, no. 4 (November 1, 1988): 320–25. http://dx.doi.org/10.1115/1.3108448.

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Spectrum analysis of the Doppler signals was performed 0.5 tube diameters downstream from an axisymmetric constriction with an area reduction of 80 percent in steady flow at a jet Reynolds number of 2840. Both pulsed and continuous wave (CW) Doppler spectra showed significant reverse flow components in the separated flow. The pulsed Doppler spectra exhibited sudden changes when the sample volume crossed the shear layer between the center jet and the separated flow. A power spectrum equation was theoretically derived from continuity of flow to define the Doppler shift frequency for the shear layer velocity. The CW Doppler spectrum showed a minimum spectrum density at a frequency which equalled the shear layer Doppler shift frequency derived from the equation. The pulsed spectra exhibited the sudden changes at the same frequency as well.

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Dong, Ji Gang, Da Jun Sun, and Wei Wei Fan. "The Study and Implementation of the Anti-Doppler Technology of AUV Communication System." Applied Mechanics and Materials 536-537 (April 2014): 999–1004. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.999.

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Due to the complexity of the underwater acoustic channel, a reliable mobile underwater acoustic communication system must have high resistance to Doppler and multi-path extension. In this paper, an AUV underwater acoustic control and communication system based on frequency-hopping frequency-shift keying (FH-FSK) is proposed. The system uses pulse pair method to estimate Doppler frequency shift, and analyzes the performance of the algorithm via simulation. The system has been developed based on chip OMAP-L138, with lake test conducted. Result of the tests shows that the system can estimate and compensate the Doppler frequency shift generated by the platform's movement precisely, and has strong resistance to interference to transmit AUV control messages effectively.

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Kang, Bochao, Xu Li, Yangyu Fan, Jian Zhang, Dong Liang, and Yongsheng Gao. "Wideband microwave Doppler frequency shift measurement based on acousto-optic frequency shift and DP-QPSK receiver." Measurement 178 (June 2021): 109388. http://dx.doi.org/10.1016/j.measurement.2021.109388.

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Lu, Bing, Wei Pan, Xihua Zou, Xianglei Yan, Lianshan Yan, and Bin Luo. "Wideband Doppler frequency shift measurement and direction ambiguity resolution using optical frequency shift and optical heterodyning." Optics Letters 40, no. 10 (May 11, 2015): 2321. http://dx.doi.org/10.1364/ol.40.002321.

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Smotherman, Michael, and Walter Metzner. "Effects of Echo Intensity on Doppler-Shift Compensation Behavior in Horseshoe Bats." Journal of Neurophysiology 89, no. 2 (February 1, 2003): 814–21. http://dx.doi.org/10.1152/jn.00246.2002.

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Echolocating horseshoe bats respond to flight-speed induced shifts in echo frequency by adjusting the frequency of subsequent calls. Under natural conditions, Doppler effects may force the frequency of a returning echo several kilohertz above the original emission frequency. By lowering subsequent call frequencies, the bat can return echo frequencies to within a narrow spectral bandwidth to which its highly specialized auditory system is most sensitive. While Doppler-shift compensation (DSC) behavior specifically refers to frequency compensation, other parameters of the returning echo, such as delay, duration, and interaural time and intensity differences have been shown to influence DSC performance. Understanding the nature of these influences has already led to a better appreciation of the neurophysiology of DSC. Here we provide a quantitative analysis of the effects of a prominent feature of the returning echo, its intensity, on DSC performance in horseshoe bats. Although DSC performance generally tolerates echo attenuation up to approximately 40 dB relative to the outgoing emission intensity, a systematic decline in DSC performance can be observed over this range. Generally, the effects of echo attenuation are characterized by a reduction in 1) the overall amount of compensation relative to the size of the shift in echo frequency and 2) the rate at which the bat responds to perceived echo shifts. These effects appear to be the consequence of a systematic shift in the range of echo frequencies capable of inducing DSC behavior. In particular, the reference frequency (the minimum shift in echo frequency that will elicit DSC behavior) appears to be highly sensitive to echo intensity. Every 10-dB reduction in echo intensity shifts the reference upward nearly 250 Hz. Our results indicate that, even at the highest intensity levels, relatively minor changes in echo intensity critically influence frequency compensation during normal DSC. We conclude with a discussion of how these results might impact echolocation behavior of horseshoe bats under natural and experimental conditions.

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Huang, Chongjia, and Erwin H. W. Chan. "All-Optical Pulsed Signal Doppler Frequency Shift Measurement System." IEEE Photonics Journal 13, no. 6 (December 2021): 1–7. http://dx.doi.org/10.1109/jphot.2021.3118679.

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Lariontsev, E. G. "Quantum interference of biphotons with a Doppler frequency shift." Quantum Electronics 46, no. 8 (August 31, 2016): 749–52. http://dx.doi.org/10.1070/qel16096.

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Landolt, Andrin, and Thomas Roesgen. "Global Doppler frequency shift detection with near-resonant interferometry." Experiments in Fluids 47, no. 4-5 (June 2, 2009): 733–43. http://dx.doi.org/10.1007/s00348-009-0688-4.

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Clayton, H. J., P. Fines, and A. H. Aghvami. "Kalman algorithm frequency estimator for dynamic Doppler shift environments." Electronics Letters 29, no. 7 (1993): 597. http://dx.doi.org/10.1049/el:19930400.

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Wang, Chen, and Jonathan D. Ellis. "Dynamic Doppler Frequency Shift Errors: Measurement, Characterization, and Compensation." IEEE Transactions on Instrumentation and Measurement 64, no. 7 (July 2015): 1994–2004. http://dx.doi.org/10.1109/tim.2014.2377991.

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Lin, Xiao, and Baile Zhang. "Normal Doppler Frequency Shift in Negative Refractive‐Index Systems." Laser & Photonics Reviews 13, no. 12 (November 4, 2019): 1900081. http://dx.doi.org/10.1002/lpor.201900081.

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Vergados, Panagiotis, and Spiros D. Pagiatakis. "Preliminary results on the sensitivity of atmospheric bending angles retrieved from COSMIC radio occultations to Doppler frequency shift and satellite velocity variationsThis article is one of a series of papers published in this Special Issue on the theme GEODESY." Canadian Journal of Earth Sciences 46, no. 8 (August 2009): 597–610. http://dx.doi.org/10.1139/e09-010.

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We describe and present preliminary results from an independent bending-angle algorithm implementation for the calculation of radiowave bending angles propagated from a Global Positioning System (GPS) to a Low Earth Orbiting (LEO) satellite. The algorithm utilizes raw atmospheric excess phases and satellite kinematics to determine Doppler frequency shifts of the GPS signals from which bending-angle profiles are derived. The intent is twofold: (a) perform a series of sensitivity studies to investigate the effect of Doppler frequency shift and satellite velocity variations on bending-angle profiles; and (b) examine and compare our results against the bending-angle profiles provided by the Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) Data Analysis and Archive Centre (CDAAC). In this paper, we employ the same GPS observations as by CDAAC to analyze various occultation events in 2006, 2007, 2008, and 2009. Our principal finding is that radiowave bending angles exhibit an inversely proportional behaviour to orbital velocity variations while they change proportionally to the variations of Doppler frequency shift. Our studies also reveal that bending angles are more sensitive to orbital velocity than to Doppler frequency shift variations and show “wave-like” structures in the upper part of the atmosphere, unlike COSMIC-derived profiles. We discuss the differences between our derived bending-angle profiles and the COSMIC-derived profiles, emphasizing the advantages of our algorithm implementation.

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Jomtarak, Rangsan, Preecha P. Yupapin, and Jalil Ali. "Doppler shift velocimetry using two point probe nested-microring resonators." Journal of Nonlinear Optical Physics & Materials 24, no. 01 (March 2015): 1550003. http://dx.doi.org/10.1142/s0218863515500034.

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In this paper, a micro Doppler shift velocimeter using two nested-microring resonators incorporating two gratings is designed and simulated. Two wavelength light pulse can be generated by a single input wavelength source after travelling through the two defect grating. Whispering gallery mode of light pulses are localized within the nested-microring resonators, which can be used to form the two point probe Doppler shift velocimeter. The shifted frequency (velocity) can be obtained by the difference of optical path length between two point probes, where the relative velocity of Doppler frequency shift velocimeter can be obtained. The light absorption behaviors can also be investigated by the different light output spectrum. The obtained simulation results shows that the relative velocities of the reflection and transmission light intensities are ranged from 104 m/s to 105 m/s, which can be useful for Doppler frequency shift velocimeter and sensors, where the micro-optical device and multi-functions are the advantages.

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Li, Fulong, Xiaohong Shen, Ling Wang, and Haiyan Wang. "Research of Mobile Underwater Acoustic Communication of M-Ary Combining FDM and Piecewise-LFM." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 704–13. http://dx.doi.org/10.1051/jnwpu/20193740704.

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Aiming at the countering doppler shift, a mobile underwater acoustic communication scheme of M-ary via FDM-PLFM is proposed. The cross-correlation between piecewise linear frequency modulation(PLFM) and traditional LFM signal is analyzed based on the cross-correlation function. Combining with frequency division multiplexing(FDM), the spectrum utilization of traditional underwater acoustic LFM communication scheme is improved. With the underwater acoustic LFM communication scheme, the new scheme does not require the doppler frequency shift compensation at the low doppler shift. The simulation results show that the present scheme has lower bit error rate than that for the traditional underwater acoustic M-ary LFM communication method under higher data rate conditions.

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Zong, Zhu Lin, Jian Hao Hu, and Li Dong Zhu. "Estimation of Doppler Parameter for Formation-Flying Satellite SAR System." Applied Mechanics and Materials 44-47 (December 2010): 3473–77. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.3473.

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In formation-flying satellite SAR system, especially the satellites are LEO or MEO, Doppler frequency shift of SAR echo has a character of long-range changes and quick time variation. Because of this, imaging with high quality become difficulty. Based on the theories and methods of universal gravitation, the relative positions and velocities between every satellite and the ground detection center can be computed, then the Doppler frequency shift for formation-flying satellite SAR system can be estimated that only need to known the parameters of satellite orbit, the working frequency and the azimuth of antenna of master satellite radar. The simulation results show that by using this method, the scope of Doppler frequency shift can be reduced to a very small range, about two in a thousand compared to original echo.

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Ebara, Hironori, Akihiro Takita, Tomohiko Azami, and Yusaku Fujii. "Development of Material Tester Using Pendulum." Key Engineering Materials 497 (December 2011): 176–81. http://dx.doi.org/10.4028/www.scientific.net/kem.497.176.

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The requirements for evaluating the mechanical characteristics of materials have increased in the various industrial, research and the applications such as materials testing. Therefore, the authors have proposed a method for measuring force acting a material using pendulum [1]. In the Material tester, the mechanical characteristics of material against small force are measured by means of the pendulum mechanism based on the levitation mass method (LMM) [2,3,4].In the LMM, the Doppler shift frequency is measured for measuring the inertial force. The Doppler shift frequency of a laser beam reflected from the mass is accurately measured by using optical interferometer. The velocity, position, acceleration and inertia force of the mass are calculated from the measured time-varying Doppler shift frequency. Thus, the accurate measure of frequency makes that of force.

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Gogolev, I. V. "Doppler Stretch and Delay Statistical Performance Comparison for Wideband and Narrowband Signal Model." Journal of the Russian Universities. Radioelectronics, no. 1 (April 17, 2018): 13–18. http://dx.doi.org/10.32603//1993-8985-2018-21-1-13-18.

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Narrowband approximation of Doppler effect by a frequency shift is inappropriate for some problems of radiolocation, hydro acoustics or passive location. In this case it is necessary to use Doppler stretch (time-scaling) as a signal parameter. Statistical performance of joint Doppler stretch and delay for arbitrary spectral width signal without narrowband approximations is derived in this paper.Narrowband and wideband parameters relations are investigated for triangle impulse with linear spectral modulation. Besides, Fisher Information Matrices (FIM) differences are analyzed. In the narrowband limit consideration of results in well-known FIM of Doppler shift and delay estimation are proposed. Another feature of wideband FIM is reference time dependence on time delay variance. Transition from Doppler stretch to Doppler frequency shift considering narrowband limitations results in translation invariant FIM.The article shows that reference time variance of delay estimation is related to estimated parameter modification and velocity influence on delay. Also, estimation variances in narrowband signal model differ from wideband parameter variances by magnitude of spectrum width to central frequency ratio.

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Xu, Bing, and Lei Dou. "Novel acquisition of global positioning system signals based on parameter prediction and the chirp z-transform." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 8 (June 6, 2016): 1391–401. http://dx.doi.org/10.1177/0954410016652151.

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The acquisition stage in global positioning system receivers provides a coarse estimation of the Doppler shift and the code phase of the incoming signals. The accuracy of the estimation, especially the Doppler shift, greatly influences the subsequent tracking loops. Based on the parameter prediction and the chirp z-transform algorithm, a novel acquisition approach to acquire the Doppler shift accurately is proposed. The code phase and the Doppler shift are predicted first according to the desired trajectory of the vehicle and satellite ephemeris. Then, frequency refinement of the code-stripped signal is conducted within a small interval around the predicted Doppler shift by using the chirp z-transform algorithm. To reduce the computational load, the data sequence is down-sampled with an integrate and dump accumulator without degrading the performance of the proposed algorithm. Results indicate that, with only 1 ms sampled data, the proposed algorithm can achieve a high-frequency accuracy. Besides, the proposed algorithm can acquire signals with the carrier-to-noise ratio down to 31 dB-Hz.

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Wang, Zhihao, Ying Luo, Kaiming Li, Hang Yuan, and Qun Zhang. "Micro-Doppler Parameters Extraction of Precession Cone-Shaped Targets Based on Rotating Antenna." Remote Sensing 14, no. 11 (May 26, 2022): 2549. http://dx.doi.org/10.3390/rs14112549.

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Micro-Doppler is regarded as a unique signature of a target with micro-motions. The sophisticated recognition of the cone-shaped targets can be realized through the micro-Doppler effect. However, it is difficult to extract the micro-motion features perpendicular to the radar line of sight (LOS) effectively. In this paper, a micro-Doppler parameters extraction method of the cone-shaped targets is put forward based on the rotating antenna. First, a new radar configuration is proposed, in which an antenna rotates uniformly on a fixed circle, thus producing Doppler frequency shift. Second, the expression of the micro-Doppler frequency shift induced by the precession cone-shaped target is derived. Then, the micro-Doppler curves of point scatterers at the cone top and bottom are separated by the smoothness of the curves, and the empirical mode decomposition (EMD) method is utilized for the detection and estimation of the coning frequency. Finally, the micro-motion components perpendicular to the radar LOS are inverted by the peak of micro-Doppler frequency curve. Simulation results prove the effectiveness and robustness of the proposed method.

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Bonnefous, O., and P. Pesqué. "Time Domain Formulation of Pulse-Doppler Ultrasound and Blood Velocity Estimation by Cross Correlation." Ultrasonic Imaging 8, no. 2 (April 1986): 73–85. http://dx.doi.org/10.1177/016173468600800201.

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The Doppler effect is usually described as a frequency shift of the backscattered signals from moving targets with respect to the frequency transmitted. Recently, real-time blood flow imaging has become possible thanks to the development of a new velocity estimator based on phase-shift measurements of successive echoes. However, this method suffers from the well-known limitations of pulse-Doppler instruments. A new formulation is presented which describes the pulse-Doppler effect on the successive echoes from a cloud of moving targets as a progressive translation in time due to the displacement of the scatterers between two excitations. This approach allows us to generate efficiently computer-simulated data in order to evaluate accurately the various processing techniques. Furthermore, it leads to a novel class of velocity estimators in the time domain which measure the time shifts which are proportional to the local blood velocity. Among them, the cross correlation of the received rf signals turns out to be well suited. A local cross-correlation function is first calculated from a consecutive pair of range-gated echoes and the time shift is then determined by searching for the time position with the maximum correlation. The time-correlation technique is shown to provide accurate velocity profiles with broadband transducers. Moreover, the classical velocity limitation of pulse-Doppler is overcome because there is no ambiguity in measuring a time shift instead of a phase shift. These major advantages should make quantitative flow mapping possible and more reliable.

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Liu, Lianyun, Xiaojie Cheng, Xu Zheng, Yi Qiu, and Zhiyong Hao. "Experimental and numerical study of the rotational Doppler shift in acoustic waves using static microphones." Physics of Fluids 34, no. 4 (April 2022): 047109. http://dx.doi.org/10.1063/5.0087181.

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The rotational Doppler shift in acoustic waves carrying orbital angular momentum (OAM) has been applied in experiments to demonstrate the Zel'dovich amplification, which is analogously linked with the black hole radiance. However, rotating microphones used in the published experiments are difficult to assemble and intrinsically weak in the frequency response at frequencies around 0 Hz. To circumvent the limitations, this paper proposes an experimental method to study the rotational Doppler shift in acoustic OAM waves using static microphones. The Doppler shifted signals viewed by a rotating observer were extracted from the original acoustic signals at frequencies around 100 Hz, where the microphones had flat frequency response. The measured results not only demonstrated the extreme Doppler shift to a negative frequency but also showed that the acoustic amplitudes were very low when the Doppler shifted frequency was 0 Hz. This phenomenon was explained by showing in a time-domain numerical simulation that the wave was co-rotating with the observer. In addition, the characteristics of the simulated pressure contours of the rotating wave have been discussed. The proposed methods can further be used to study the physics related to the wave carrying OAM, such as the acoustic super-radiance.

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Journal articles on the topic 'Doppler frequency shift'

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