Journal articles: 'Delay-Doppler'

1

Raney, R. K. "The delay/Doppler radar altimeter." IEEE Transactions on Geoscience and Remote Sensing 36, no. 5 (1998): 1578–88. http://dx.doi.org/10.1109/36.718861.

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Harmon, John K., Raymond E. Arvidson, Edward A. Guinness, Bruce A. Campbell, and Martin A. Slade. "Mars mapping with delay-Doppler radar." Journal of Geophysical Research: Planets 104, E6 (June 1, 1999): 14065–89. http://dx.doi.org/10.1029/1998je900042.

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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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McMillan, Malcolm, Alan Muir, Andrew Shepherd, Roger Escolà, Mònica Roca, Jérémie Aublanc, Pierre Thibaut, Marco Restano, Américo Ambrozio, and Jérôme Benveniste. "Sentinel-3 Delay-Doppler altimetry over Antarctica." Cryosphere 13, no. 2 (March 1, 2019): 709–22. http://dx.doi.org/10.5194/tc-13-709-2019.

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Abstract. The launch of Sentinel-3A in February 2016 represented the beginning of a new long-term series of operational satellite radar altimeters, which will provide Delay-Doppler altimetry measurements over ice sheets for decades to come. Given the potential benefits that these satellites can offer to a range of glaciological applications, it is important to establish their capacity to monitor ice sheet elevation and elevation change. Here, we present the first analysis of Sentinel-3 Delay-Doppler altimetry over the Antarctic ice sheet, and assess the accuracy and precision of retrievals of ice sheet elevation across a range of topographic regimes. Over the low-slope regions of the ice sheet interior, we find that the instrument achieves both an accuracy and a precision of the order of 10 cm, with ∼98 % of the data validated being within 50 cm of co-located airborne measurements. Across the steeper and more complex topography of the ice sheet margin, the accuracy decreases, although analysis at two coastal sites with densely surveyed airborne campaigns shows that ∼60 %–85 % of validated data are still within 1 m of co-located airborne elevation measurements. We then explore the utility of the Sentinel-3A Delay-Doppler altimeter for mapping ice sheet elevation change. We show that with only 2 years of available data, it is possible to resolve known signals of ice dynamic imbalance and to detect evidence of subglacial lake drainage activity. Our analysis demonstrates a new, long-term source of measurements of ice sheet elevation and elevation change, and the early potential of this operational system for monitoring ice sheet imbalance for decades to come.

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Jiann-Ching Guey and M. R. Bell. "Diversity waveform sets for delay-Doppler imaging." IEEE Transactions on Information Theory 44, no. 4 (July 1998): 1504–22. http://dx.doi.org/10.1109/18.681325.

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Zhang, Yan, Zunwen He, Wancheng Zhang, Limin Xiao, and Shidong Zhou. "Measurement-Based Delay and Doppler Characterizations for High-Speed Railway Hilly Scenario." International Journal of Antennas and Propagation 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/875345.

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This paper presents results for delay and Doppler spread characterization in high-speed railway (HSR) hilly scenario. To investigate the propagation characteristics in this specific terrain, a measurement campaign is conducted along the “Guangzhou-Shenzhen” HSR in China. A wideband channel sounder with 40 MHz bandwidth is used to collect raw data at 2.4 GHz band. The delay spread and Doppler frequency features are analyzed based on measured data. It is found that there are abundant multipath components (MPCs) in this scenario. We present the relationship between the delay spreads and the transceiver distances. The measured route can be divided into four areas with different delay and Doppler characteristics. Finally, a tapped delay line (TDL) model is proposed to parameterize the channel responses in the HSR hilly environment, which is supposed to provide criterions for evaluations of the radio interface and development of wireless communication system.

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Müller-Bender, D., A. Otto, and G. Radons. "Resonant Doppler effect in systems with variable delay." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2153 (July 22, 2019): 20180119. http://dx.doi.org/10.1098/rsta.2018.0119.

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We demonstrate that a time-varying delay in nonlinear systems leads to a rich variety of dynamical behaviour, which cannot be observed in systems with constant delay. We show that the effect of the delay variation is similar to the Doppler effect with self-feedback. We distinguish between the non-resonant and the resonant Doppler effect corresponding to the dichotomy between conservative delays and dissipative delays. The non-resonant Doppler effect leads to a quasi-periodic frequency modulation of the signal, but the qualitative properties of the solution are the same as for constant delays. By contrast, the resonant Doppler effect leads to fundamentally different solutions characterized by low- and high-frequency phases with a clear separation between them. This is equivalent to time-multiplexed dynamics and can be used to design systems with well-defined multistable solutions or temporal switching between different chaotic and periodic dynamics. We systematically study chaotic dynamics in systems with large dissipative delay, which we call generalized laminar chaos. We derive a criterion for the occurrence of different orders of generalized laminar chaos, where the order is related to the dimension of the chaotic attractor. The recently found laminar chaos with constant plateaus in the low-frequency phases is the zeroth-order case with a very low dimension compared to the known high dimension of turbulent chaos in systems with conservative delay. This article is part of the theme issue ‘Nonlinear dynamics of delay systems’.

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Yoshida, Soshi, Kazuma Hase, Olga Heim, Kohta I. Kobayasi, and Shizuko Hiryu. "Horseshoe bats use not changes in echo delay but Doppler shift to perceive approaching objects." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A146. http://dx.doi.org/10.1121/10.0010922.

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Echolocating bats use echo delay for target ranging and Doppler shift information for relative velocity recognition. However, how they perceive moving objects remains unclear. To investigate this question, we played back echolocation pulses in real-time as virtual echoes to Japanese horseshoe bats ( Rhinolophus ferrumequinum nippon ) on a perch in a flight room. Since echoes coming back from an approaching object are theoretically characterized by both changes in echo delay and the presence of Doppler shift, we reproduced an artificial approaching object by encoding these two acoustic parameters in the virtual echoes. As a result, only Doppler shift evoked bats flight reaction, showing that they use only Doppler shift and not change in echo delay to perceive approaching objects. Also, we played back only constant frequency (CF) component and confirmed that they use the CF component to detect Doppler shift. Furthermore, as a response to the Doppler shift in the perceived echo, bats increased the bandwidth of the terminal component of their pulse. Surprisingly, this response occurred in the very first pulse after Doppler shift, which indicates bats can adapt their echolocation pulse characteristics to changing situations within a pulse. [This work was supported by JSPS KAKENHI Grant Nos. 18H03786 and 16H06542.]

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Cherrak, Omar, Hicham Ghennioui, Nadege Thirion Moreau, and El Hossein Abarkan. "Blind separation of complex-valued satellite-AIS data for marine surveillance: a spatial quadratic time-frequency domain approach." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 3 (June 1, 2019): 1732. http://dx.doi.org/10.11591/ijece.v9i3.pp1732-1741.

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<p>In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation.</p>

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10

Li, Li. "Joint Estimation of Doppler and Time Delay of Wideband Echoes for LFM Pulse Radar Based on Fractional Correlation in Impulse Noise Environment." Advanced Materials Research 989-994 (July 2014): 3706–9. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.3706.

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A new method to estimate the Doppler and multipath time delay is presented in impulse noise environment. First, the Doppler is estimated by energy cumulation of multipath component based on fractional lower-order-frational correlation transform. Then, an order-reduced signal is reconstructed combining the Doppler with the prior knowledge of the transmitted signal, and the echoes signal is converted to many single-frequency signals. Finally, the multipath time delay is obtained by the fractional lower-order power spectrum method. The method is adapted for low SNR noise, can restrain the affection of the cross-items, and has a high time-delay estimation resolution. Some computer simulations are given in this paper and the results show that the new method is valid.

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11

Chen, Shengyao, Feng Xi, and Zhong Liu. "A general sequential delay-Doppler estimation scheme for sub-Nyquist pulse-Doppler radar." Signal Processing 135 (June 2017): 210–17. http://dx.doi.org/10.1016/j.sigpro.2017.01.012.

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12

Chieh-Fu Chang and M. R. Bell. "Frequency-coded waveforms for enhanced delay-doppler resolution." IEEE Transactions on Information Theory 49, no. 11 (November 2003): 2960–71. http://dx.doi.org/10.1109/tit.2003.818408.

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13

Park, Hyuk, Daniel Pascual, Adriano Camps, Francisco Martin, Alberto Alonso-Arroyo, and Hugo Carreno-Luengo. "Analysis of Spaceborne GNSS-R Delay-Doppler Tracking." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 7, no. 5 (May 2014): 1481–92. http://dx.doi.org/10.1109/jstars.2014.2322198.

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14

Stein, S. "Differential delay/Doppler ML estimation with unknown signals." IEEE Transactions on Signal Processing 41, no. 8 (1993): 2717–19. http://dx.doi.org/10.1109/78.229901.

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15

Fish, Alexander, Shamgar Gurevich, Ronny Hadani, Akbar M. Sayeed, and Oded Schwartz. "Delay-Doppler Channel Estimation in Almost Linear Complexity." IEEE Transactions on Information Theory 59, no. 11 (November 2013): 7632–44. http://dx.doi.org/10.1109/tit.2013.2273931.

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16

Friedlander, Benjamin. "An Efficient Parametric Technique for Doppler-Delay Estimation." IEEE Transactions on Signal Processing 60, no. 8 (August 2012): 3953–63. http://dx.doi.org/10.1109/tsp.2012.2198818.

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17

Ge, Jian. "Fixed Delay Interferometry for Doppler Extrasolar Planet Detection." Astrophysical Journal 571, no. 2 (June 1, 2002): L165—L168. http://dx.doi.org/10.1086/341226.

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18

Walstead, Sean. "Delay-Doppler characteristics of surface interacting underwater sound." Journal of the Acoustical Society of America 142, no. 4 (October 2017): 2496. http://dx.doi.org/10.1121/1.5014113.

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19

Li, Li. "Joint Estimation of Doppler and Multipath Time Delay of Wideband Echoes for LFM Pulse Radar Based on Fractional Correlation." Applied Mechanics and Materials 543-547 (March 2014): 2400–2403. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.2400.

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A new method based on fractional correlation theory for estimating the Doppler and multipath time delay of the wideband echoes for LFM pulse radar by only one pulse signal is presented. First, the Doppler is estimated by energy cumulation of multipath component based on fractional correlation transform. Then, an order-reduced signal is reconstructed combining the Doppler with the prior knowledge of the transmitted signal, and the echoes signal is converted to many single-frequency signals. Finally, the multipath time delay is obtained by the dechirping method. The method is adapted for low SNR noise, can restrain the affection of the cross-items, and has a high time-delay estimation resolution. Some computer simulations are given in this paper and the results show that the new method is valid.

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20

Li, Jie, Fangjiong Chen, Songzuo Liu, Hua Yu, and Fei Ji. "Estimation of Overspread Underwater Acoustic Channel Based on Low-Rank Matrix Recovery." Sensors 19, no. 22 (November 15, 2019): 4976. http://dx.doi.org/10.3390/s19224976.

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In this paper, the estimation of overspread, i.e., doubly spread underwater acoustic (UWA) channels of strong dispersion is considered. We show that although the UWA channel dispersion causes the degeneration of channel sparsity, it leads to a low-rank structure especially when the channel delay-Doppler-spread function is separable in delay and Doppler domain. Therefore, we introduce the low-rank criterion to estimate the UWA channels, which can help to improve the estimation performance in the case of strong dispersion. The estimator is based on the discrete delay-Doppler-spread function representation of channel, and is formulated as a low-rank matrix recovery problem which can be solved by the singular value projection technique. Simulation examples are carried out to demonstrate the effectiveness of the proposed low-rank-based channel estimator.

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21

Wang, Ke, Chan-Tong Lam, and Benjamin K. Ng. "Positioning Information Based High-Speed Communications with Multiple RISs: Doppler Mitigation and Hardware Impairments." Applied Sciences 12, no. 14 (July 13, 2022): 7076. http://dx.doi.org/10.3390/app12147076.

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In this paper, we consider a multiple reconfigurable intelligent surface (RIS)-assisted system using positioning information (PI) to explore the potential of Doppler effect mitigation and spectral efficiency (SE) enhancement in high-speed communications (HSC) in the presence of hardware impairments (HWI). In particular, we first present a general multi-RIS-assisted system model for HSC with HWI. Then, based on PI, different phase shift optimization strategies are designed and compared for maximizing SE, eliminating Doppler spread, and maintaining a very low delay spread. Moreover, we compare the performance of different numbers of RISs with HWI in terms of SE and delay spread. Finally, we extend our channel model from line-of-sight to the Rician channel to demonstrate the effectiveness and robustness of our proposed scheme. Numerical results reveal that the HWI of RISs increases the delay spread, but has no impact on Doppler shift and spread. Additionally, the multiple RIS system not only suffers a more severe delay spread, but is limited in SE due to the HWI. When the number of RISs increases from 2 to 16, the range of average spectral efficiency and delay spread are from 4 to 4.6 Bit/s/Hz and from 0.7 μs to 2.5 μs, respectively. In contrast to conventional RIS-assisted systems that require channel estimation, the proposed PI-based RIS system offers simplicity without compromising effectiveness and robustness in both SE enhancement and Doppler mitigation.

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Ilyin, M. Yu, A. A. Kim, I. S. Razuvaeva, and N. V. Sotnikova. "RADIO-PHOTON MULTILOOP DELAY LINE FOR MONITORING AND VERIFICATION OF TECHNICAL PARAMETERS OF DOPPLER RADAR SYSTEM." Issues of radio electronics, no. 7 (July 20, 2018): 44–50. http://dx.doi.org/10.21778/2218-5453-201-7-44-50.

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One of them actual problems of development doppler radar is technical parameters quality control. Especially it concerns the development of reference standards for sounding and imitation of Doppler shifts of the carrier frequencies of the radar, which is difficult and economically unprofitable task. The article considers the possibility of measuring and controlling the technical parameters of meteorological Doppler radars using the time delay multi-loop radio-photon system for imitation distance and Doppler shift. A method for controlling the range, spatial resolution, blind zone, sensitivity of the receiver, as well as the accuracy of determining the wind speed along the beam is proposed on the basis of data obtained as a result of the calibration bench for metrological control of laser meteorological locators prototype development. Methods for checking the trace standards and Doppler shifts in a radio-photon imitation multi-loop time delay line are proposed.

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Yongsheng, Zhao, Hu Dexiu, Zhao Yongjun, and Liu Zhixin. "Moving target localization for multistatic passive radar using delay, Doppler and Doppler rate measurements." Journal of Systems Engineering and Electronics 31, no. 5 (October 2020): 939–49. http://dx.doi.org/10.23919/jsee.2020.000071.

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Xiao, Xuebing, and Fucheng Guo. "Joint Estimation of Time Delay, Doppler Velocity and Doppler Rate of Unknown Wideband Signals." Circuits, Systems, and Signal Processing 38, no. 1 (April 13, 2018): 85–104. http://dx.doi.org/10.1007/s00034-018-0816-6.

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Liu, Xiang, Deborah Cohen, Tianyao Huang, Yimin Liu, and Yonina Eldar. "Unambiguous Delay-Doppler Recovery From Random Phase Coded Pulses." IEEE Transactions on Signal Processing 69 (2021): 4991–5004. http://dx.doi.org/10.1109/tsp.2021.3105921.

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26

Rodriguez-Alvarez, Nereida, Dennis M. Akos, Valery U. Zavorotny, Jeffrey A. Smith, Adriano Camps, and Christopher W. Fairall. "Airborne GNSS-R Wind Retrievals Using Delay–Doppler Maps." IEEE Transactions on Geoscience and Remote Sensing 51, no. 1 (January 2013): 626–41. http://dx.doi.org/10.1109/tgrs.2012.2196437.

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Harmon, J. K. "Planetary delay-Doppler radar and the long-code method." IEEE Transactions on Geoscience and Remote Sensing 40, no. 9 (September 2002): 1904–16. http://dx.doi.org/10.1109/tgrs.2002.803731.

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Li, MengJiao, Wen‐Qin Wang, and Zhi Zheng. "Communication‐embedded OFDM chirp waveform for delay‐Doppler radar." IET Radar, Sonar & Navigation 12, no. 3 (January 3, 2018): 353–60. http://dx.doi.org/10.1049/iet-rsn.2017.0369.

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Campbell, James D., Amer Melebari, and Mahta Moghaddam. "Modeling the Effects of Topography on Delay-Doppler Maps." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 13 (2020): 1740–51. http://dx.doi.org/10.1109/jstars.2020.2981570.

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30

Jiong Li and Yanfei Wang. "Doppler Shift Mitigating Algorithm for Quadrature Phase Delay Estimator." IEEE Transactions on Instrumentation and Measurement 58, no. 8 (August 2009): 2743–46. http://dx.doi.org/10.1109/tim.2009.2016291.

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31

Guccione, Pietro. "Comparison of Processing Algorithms for a Delay/Doppler Altimeter." IEEE Geoscience and Remote Sensing Letters 5, no. 4 (October 2008): 764–68. http://dx.doi.org/10.1109/lgrs.2008.2005274.

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32

Reyes, Hector, Naima Kaabouch, and Wen-Chen Hu. "Spectrum Channel Characterization Using Delay and Doppler Spread Parameters." Journal of Communications 9, no. 3 (2014): 234–40. http://dx.doi.org/10.12720/jcm.9.3.234-240.

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33

Myers, Glen A. "Doppler shift viewed as a result of variable delay." Physics Teacher 26, no. 5 (May 1988): 284–85. http://dx.doi.org/10.1119/1.2342531.

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34

Zheng, Le, and Xiaodong Wang. "Super-Resolution Delay-Doppler Estimation for OFDM Passive Radar." IEEE Transactions on Signal Processing 65, no. 9 (May 1, 2017): 2197–210. http://dx.doi.org/10.1109/tsp.2017.2659650.

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35

Grieco, Giuseppe, Ad Stoffelen, Marcos Portabella, Maria Belmonte Rivas, Wenming Lin, and Fran Fabra. "Quality Control of Delay-Doppler Maps for Stare Processing." IEEE Transactions on Geoscience and Remote Sensing 57, no. 5 (May 2019): 2990–3000. http://dx.doi.org/10.1109/tgrs.2018.2879059.

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36

Li, Xuan, Xiaochuan Ma, Shefeng Yan, and Chaohuan Hou. "Joint Doppler and time delay estimation by compressed sampling." Journal of the Acoustical Society of America 131, no. 4 (April 2012): 3482. http://dx.doi.org/10.1121/1.4709139.

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37

Sidi, Alon Y., and Anthony J. Weiss. "Delay and Doppler Induced Direct Tracking by Particle Filter." IEEE Transactions on Aerospace and Electronic Systems 50, no. 1 (January 2014): 559–72. http://dx.doi.org/10.1109/taes.2013.120326.

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38

Zhang, Xudong, Hongbin Li, and Braham Himed. "Maximum Likelihood Delay and Doppler Estimation for Passive Sensing." IEEE Sensors Journal 19, no. 1 (January 1, 2019): 180–88. http://dx.doi.org/10.1109/jsen.2018.2875664.

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McPhee, Hamish, Lorenzo Ortega, Jordi Vilà-Valls, and Eric Chaumette. "On the accuracy limits of misspecified delay-Doppler estimation." Signal Processing 205 (April 2023): 108872. http://dx.doi.org/10.1016/j.sigpro.2022.108872.

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Yongqiang, Guo, Wu Yumin, and Liu Hui. "Construction of Waveform Library in Cognitive Radar." Polish Maritime Research 24, s2 (August 28, 2017): 22–29. http://dx.doi.org/10.1515/pomr-2017-0060.

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Abstract Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT) is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB) of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.

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Walter, Michael, Dmitriy Shutin, and Uwe-Carsten Fiebig. "Joint Delay Doppler Probability Density Functions for Air-to-Air Channels." International Journal of Antennas and Propagation 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/814218.

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Recent channel measurements indicate that the wide sense stationary uncorrelated scattering assumption is not valid for air-to-air channels. Therefore, purely stochastic channel models cannot be used. In order to cope with the nonstationarity a geometric component is included. In this paper we extend a previously presented two-dimensional geometric stochastic model originally developed for vehicle-to-vehicle communication to a three-dimensional air-to-air channel model. Novel joint time-variant delay Doppler probability density functions are presented. The probability density functions are derived by using vector calculus and parametric equations of the delay ellipses. This allows us to obtain closed form mathematical expressions for the probability density functions, which can then be calculated for any delay and Doppler frequency at arbitrary times numerically.

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Pugolovkin, K. A., E. A. Efimova, E. A. Dombrovskaya, I. Yu Platonova, and A. A. Solov’ev. "Transcranial Doppler ultrasound is a diagnostic and predicting tool for movement disorders in children after hypoxic ischemic encephalopathy." Russian Journal of Woman and Child Health 4, no. 3 (2021): 254–59. http://dx.doi.org/10.32364/2618-8430-2021-4-3-254-259.

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Aim: to assess brain circulation in the regions supplied by the basilar artery (BA) in children with movement disorders and motor skill delay in the late rehabilitative period after hypoxic ischemic encephalopathy and its importance for the objectivity of clinical data and evaluation of rehabilitative effect. Patients and Methods: 28 children (mean age one year seven months) with movement disorders and motor skill delay (after hypoxic ischemic CNS lesion in the perinatal period) without lower extremity paraparesis or Willis circle abnormalities (by Doppler ultrasound) were examined. Doppler ultrasound was performed using the suboccipital approach at 3–8 months with 3–4-month intervals. The parameters of blood flow in BA, i.e., resistivity index (RI) and mean blood flow velocity (Vm), were measured. Retrospectively, children were divided into three groups based on motor skill delay severity (mild, moderate, or severe) and time for standing unaided to walking. Mean values in the groups and relative deviations (increase/decrease) from reference values in a given age group were compared. Results: motor skill delay severity and predicting time for standing unaided to walking correlated with RI and Vm. RI was a diagnostically valuable parameter whose reference values differed from motor skill delay severity. Isolated increase in Vm and normal RI were reported in children with motor skill delay 1–3 months before standing unaided to walking. This type of blood circulation is a transitional one during clinical improvement in some children. Conclusions: a set of instrumental data allow for describing motor skill delay severity depending on RI deviations from normal values in the regions supplied by BA. The sequence of brain circulation parameter changes is in line with the clinical course, e.g., RI normalization and further gradual recovery of blood flow velocity. KEYWORDS: movement disorders, motor skill delay, Transcranial Doppler ultrasound, basilar artery, resistivity index RI, mean blood flow velocity Vm. FOR CITATION: Pugolovkin K.A., Efimova E.A., Dombrovskaya E.A. et al. Transcranial Doppler ultrasound is a diagnostic and predicting tool for movement disorders in children after hypoxic ischemic encephalopathy. Russian Journal of Woman and Child Health. 2021;4(3):254–259 (in Russ.). DOI: 10.32364/2618-8430-2021-4-3-254-259.

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CHEN, Shengyao, and Feng XI. "Cramer-Rao bounds for the joint delay-Doppler estimation of compressive sampling pulse-Doppler radar." Journal of Systems Engineering and Electronics 29, no. 1 (February 2018): 58–66. http://dx.doi.org/10.21629/jsee.2018.01.06.

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Shui, Yishui, Fang Li, Junyi Yu, Wei Chen, Changzhen Li, Kun Yang, and Fuxing Chang. "Vehicle-to-Vehicle Radio Channel Characteristics for Congestion Scenario in Dense Urban Region at 5.9 GHz." International Journal of Antennas and Propagation 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/1751869.

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This paper reports the results of a car-following measurement of the wireless propagation channel at 5.9 GHz on a seriously congested urban road in Wuhan, China. The small-scale amplitude-fading distribution was determined to be a Ricean distribution using the Akaike information criterion. This result shows that this car-following scenario can be regarded as a line-of-sight radio channel. Moreover, the statistical K-factor features follow a Gaussian distribution. According to the power delay profile and average power delay profile, we found that street buildings in this dense urban environment contributed to very strong reflection phenomena. The impact of a powerful reflection is analyzed through path loss, delay, and Doppler spreads in the channel statistical properties. In the frequency domain, we observe a U-shape delay-Doppler spectrum that proved that the dense urban scenario consists of scattering channels. All these results are summarized in tabular form that will be useful in the modeling of vehicle-to-vehicle wireless communication systems.

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Li, Lian Jie, Jia Hao Deng, and Jin Liu. "Doppler Radio Fuze Signal Processing Method Based on the Extraction of Instantaneous Frequency." Applied Mechanics and Materials 411-414 (September 2013): 1033–39. http://dx.doi.org/10.4028/www.scientific.net/amm.411-414.1033.

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To get accurate frequency information from doppler signal is very difficult. In order to improve accuracy of doppler radio fuze, a design scheme which is not only using doppler signal amplitude information but also using doppler frequency information, and comprehensive and these two aspects of information give out the fuze work distance. The solution we give out in this paper is that we realize the STFT by application of parallel process mass on FPGA and together with quick frequency selection mechanism. Then we could get the frequency information from the doppler signal. Test results show that by using short time window Fourier transform, we could realize time-frequency analysis of doppler signal in allow system time delay.

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Ren, Sun, Zhang, and Zhao. "The Effect of Light Source Line Width on the Spectrum Resolution of Dual-Frequency Coherent Detection Signals." Sensors 19, no. 23 (November 29, 2019): 5264. http://dx.doi.org/10.3390/s19235264.

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In this paper, the power spectrum resolution problem of dual-frequency coherent mixing signals is analyzed when the Doppler frequency difference is small. The power spectrum function formula of the four optical coherent mixing signals is obtained using statistical theory and the Wiener–Khinchin theorem. The influence of delay time and light source line width on the power spectrum of dual-frequency coherent signals is analyzed using this formula. The results show that delay time only affects the peak of the power spectrum of the coherent signal. An increase in the line width of the light source broadens the signal power spectrum and reduces the peak value. The necessary condition for distinguishing the Doppler frequency difference is that the theoretical Doppler frequency difference is greater than 1/5 times the line width of the light source.

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Lubeigt, Corentin, Lorenzo Ortega, Jordi Vilà-Valls, Laurent Lestarquit, and Eric Chaumette. "Joint Delay-Doppler Estimation Performance in a Dual Source Context." Remote Sensing 12, no. 23 (November 27, 2020): 3894. http://dx.doi.org/10.3390/rs12233894.

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Evaluating the time-delay, Doppler effect and carrier phase of a received signal is a challenging estimation problem that was addressed in a large variety of remote sensing applications. This problem becomes more difficult and less understood when the signal is reflected off one or multiple surfaces and interferes with itself at the receiver stage. This phenomenon might deteriorate the overall system performance, as for the multipath effect in Global Navigation Satellite Systems (GNSS), and mitigation strategies must be accounted for. In other applications such as GNSS reflectometry (GNSS-R) it may be interesting to estimate the parameters of the reflected signal to deduce the geometry and the surface characteristics. In either case, a better understanding of this estimation problem is directly brought by the corresponding lower performance bounds. In the high signal-to-noise ratio regime of the Gaussian conditional signal model, the Cramér-Rao bound (CRB) provides an accurate lower bound in the mean square error sense. In this article, we derive a new compact CRB expression for the joint time-delay and Doppler estimation in a dual source context, considering a band-limited signal and its specular reflection. These compact CRBs are expressed in terms of the baseband signal samples, making them especially easy to use whatever the baseband signal considered, therefore being valid for a variety of remote sensors. This extends existing results in the single source context and opens the door to a plethora of usages to be discussed in the article. The proposed CRB expressions are validated in two representative navigation and radar examples.

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Zhang, Yang, Qunfei Zhang, Chengbing He, Yi Zhou, and Lianyou Jing. "Delay-Doppler domain decision feedback turbo equalization for OTFS modulation." Physical Communication 52 (June 2022): 101699. http://dx.doi.org/10.1016/j.phycom.2022.101699.

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Su, Jun, Yaan Li, Wasiq Ali, Xiaohua Li, and Jing Yu. "Underwater 3D Doppler-Angle Target Tracking with Signal Time Delay." Sensors 20, no. 14 (July 10, 2020): 3869. http://dx.doi.org/10.3390/s20143869.

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The traditional target tracking is a process of estimating the state of a moving target using measurement information obtained by sensors. However, underwater passive acoustic target tracking will confront further challenges, among which the system incomplete observability and time delay caused by the signal propagation create a great impact on tracking performance. Passive acoustic sensors cannot accurately obtain the target range information. The introduction of Doppler frequency measurement can improve the system observability performance; signal time delay cannot be ignored in underwater environments. It varies with time, which has a continuous negative impact on the tracking accuracy. In this paper, the Gauss–Helmert model is introduced to solve this problem by expanding the unknown signal emission time as an unknown variable to the state. This model allows the existence of the previous state and current state at the same time, while handling the implicit equations. To improve the algorithm accuracy, this paper further takes advantage of the estimated state and covariance for the second stage iteration and propose the Gauss–Helmert iterated Unscented Kalman filter under a three-dimensional environment. The simulation shows that the proposed method in this paper shows superior estimation accuracy and more stable performance compared with other filtering algorithms in underwater environments.

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Zhao, Lei, Wen-Jing Gao, and Wenbin Guo. "Sparse Bayesian Learning of Delay-Doppler Channel for OTFS System." IEEE Communications Letters 24, no. 12 (December 2020): 2766–69. http://dx.doi.org/10.1109/lcomm.2020.3021120.

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Journal articles on the topic 'Delay-Doppler'

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