Journal articles: 'Doppler spread'

1

Benani, Abdelmoumen, Andre Carr, and Martin Quenneville. "Doppler spread technique." IEEE Vehicular Technology Magazine 4, no. 1 (March 2009): 78–86. http://dx.doi.org/10.1109/mvt.2008.931621.

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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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Bu, Linsheng, Wanyu Chang, Defeng Chen, and Tuo Fu. "Deep learning-based Doppler-spread target detection with attention mechanism." Journal of Physics: Conference Series 2906, no. 1 (November 1, 2024): 012023. https://doi.org/10.1088/1742-6596/2906/1/012023.

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Abstract In radar systems, Doppler spread issues commonly arise in space small target detections when integration is adopted during a long coherent processing interval (CPI). Even with precise compensation for translational effects, phase variations introduced by changes in target observation attitudes (TOA) can still cause the target’s echo energy to spread across multiple Doppler cells. As the TOA undergoes several periods over a CPI, the echo energy disperses into equidistant Doppler cells within a range cell in the range-Doppler (RD) map, which poses challenges for traditional methods and results in degraded detection performance. Leveraging the convolutional neural network’s ability to autonomously extract data features, we propose a neural network based on the Doppler auto-correlation attention mechanism (DAAM) to enhance detection accuracy and precisely estimate target positions by exploiting the sparse characteristics of the target Doppler spectrum. Training and testing are conducted using an RD map dataset, and experimental results demonstrate the network’s advanced performance in both target detection and position estimation.

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Krasny, L., H. Arslan, D. Koilpillai, and S. Chennakeshu. "Doppler spread estimation in mobile radio systems." IEEE Communications Letters 5, no. 5 (May 2001): 197–99. http://dx.doi.org/10.1109/4234.922758.

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5

Howard, S. J., and K. Pahlavan. "Doppler spread measurements of indoor radio channel." Electronics Letters 26, no. 2 (1990): 107. http://dx.doi.org/10.1049/el:19900074.

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KO, Y. C. "Doppler Spread Estimation in Mobile Communication Systems." IEICE Transactions on Communications E88-B, no. 2 (February 1, 2005): 724–28. http://dx.doi.org/10.1093/ietcom/e88-b.2.724.

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Hines, Colin O. "The Doppler spread theory and parameterization revisited." Journal of Atmospheric and Solar-Terrestrial Physics 66, no. 11 (July 2004): 949–56. http://dx.doi.org/10.1016/j.jastp.2004.02.005.

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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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9

Bhadouria, Vijay Singh, Monika Agrawal, and Ritesh Kumar. "An unsupervised clustering-based scale-lag receiver design approach for the doubly selective underwater acoustic channel." Journal of the Acoustical Society of America 152, no. 1 (July 2022): 342–53. http://dx.doi.org/10.1121/10.0012349.

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This paper details the architecture of a novel scale-lag rake receiver for the doubly selective underwater acoustic (UWA) channel. The shallow UWA channel is known to have a large Doppler spread. The cause of this is primarily due to the large spread of the angle of arrival of the received signal's paths. The Doppler scale value is dependent on the angle of arrival of the received signal. The Doppler spread is significant, and multiple Doppler scales are present in the UWA channel. Therefore, the receivers operating with only a single Doppler scale compensation perform sub-optimally. The optimal receiver should incorporate all possible Doppler scales for better performance. The receiver needs to have multiple sampling rates to incorporate all Doppler scales. It is usually done by having multiple receive channels, one for each sampling rate. It requires tremendous resources as its complexity increases exuberantly. This paper shows that these Doppler scales are clustered and that an optimal receiver is implemented using fewer receiver channels, each corresponding to one such cluster. It reduces the receiver's complexity. The simulation results demonstrate that using the Doppler scale value associated with the path of the highest magnitude per cluster yields the best performance.

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10

Rice, Joseph, Paul Baxley, Homer Bucker, Richard Shockley, Dale Green, John Proakis, and John Newton. "Doppler spread in an undersea acoustic transmission channel." Journal of the Acoustical Society of America 103, no. 5 (May 1998): 2782. http://dx.doi.org/10.1121/1.422266.

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11

Baddour, K. E., and N. C. Beaulieu. "Robust Doppler spread estimation in nonisotropic fading channels." IEEE Transactions on Wireless Communications 4, no. 6 (November 2005): 2677–82. http://dx.doi.org/10.1109/twc.2005.858362.

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12

Huang, Pengda, Dinesh Rajan, and Joseph Camp. "An Autoregressive Doppler Spread Estimator for Fading Channels." IEEE Wireless Communications Letters 2, no. 6 (December 2013): 655–58. http://dx.doi.org/10.1109/wcl.2013.091113.130593.

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13

Okada, Minoru, Hideaki Takayanagi, and Heiichi Yamamoto. "Array antenna assisted doppler spread compensator for OFDM." European Transactions on Telecommunications 13, no. 5 (September 2002): 507–12. http://dx.doi.org/10.1002/ett.4460130511.

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14

Frigyes, I., B. G. Molnár, R. Vallet, Z. Herczku, and Z. Bodnár. "Doppler spread characteristics of satellite personal communication channels." International Journal of Satellite Communications 19, no. 3 (May 2001): 251–62. http://dx.doi.org/10.1002/sat.685.

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15

Lee, Chan-Ho, Young-Gwang Seo, and Ji-Won Park. "PRF Selection Algorithm to Avoid Clutter Doppler Spread." Journal of Korean Institute of Electromagnetic Engineering and Science 36, no. 1 (January 2025): 31–37. https://doi.org/10.5515/kjkiees.2025.36.1.31.

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16

Bu, Linsheng, Tuo Fu, Defeng Chen, Huawei Cao, Shuo Zhang, and Jialiang Han. "Doppler-Spread Space Target Detection Based on Overlapping Group Shrinkage and Order Statistics." Remote Sensing 16, no. 18 (September 13, 2024): 3413. http://dx.doi.org/10.3390/rs16183413.

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The Doppler-spread problem is commonly encountered in space target observation scenarios using ground-based radar when prolonged coherent integration techniques are utilized. Even when the translational motion is accurately compensated, the phase resulting from changes in the target observation attitude (TOA) still leads to extension of the target’s echo energy across multiple Doppler cells. In particular, as the TOA change undergoes multiple cycles within a coherent processing interval (CPI), the Doppler spectrum spreads into equidistant sparse line spectra, posing a substantial challenge for target detection. Aiming to address such problems, we propose a generalized likelihood ratio test based on overlapping group shrinkage denoising and order statistics (OGSos-GLRT) in this study. First, the Doppler domain signal is denoised according to its equidistant sparse characteristics, allowing for the recovery of Doppler cells where line spectra may be situated. Then, several of the largest Doppler cells are integrated into the GLRT for detection. An analytical expression for the false alarm probability of the proposed detector is also derived. Additionally, a modified OGSos-GLRT method is proposed to make decisions based on an increasing estimated number of line spectra (ENLS), thus increasing the robustness of OGSos-GLRT when the ENLS mismatches the actual value. Finally, Monte Carlo simulations confirm the effectiveness of the proposed detector, even at low signal-to-noise ratios (SNRs).

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17

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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18

Yang, Guang, Feng Zhou, Gang Qiao, Yunjiang Zhao, Yufei Liu, Yinheng Lu, and Yuanan He. "Optimized Doppler Estimation and Symbol Synchronization for Mobile M-ary Spread Spectrum Underwater Acoustic Communication." Journal of Marine Science and Engineering 9, no. 9 (September 13, 2021): 1001. http://dx.doi.org/10.3390/jmse9091001.

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In mobile underwater acoustic (UWA) communications, the Doppler effect causes severe signal distortion, which leads to carrier frequency shift and compresses/broadens the signal length. This situation has a more severe impact on communication performance in the case of low signal-to-noise ratio and variable-speed movement. This paper proposes a non-data-aided Doppler estimation method for M-ary spread spectrum UWA communication systems in mobile scenarios. The receiver uses the spread spectrum codes dedicated to transmitting signals with different frequency offsets as local reference signals. Correlation operations are performed symbol by symbol with the received signal. The decoding and Doppler estimation of the present symbol are achieved by searching the correlation maximum in the code domain and frequency domain. The length of the current symbol is corrected for the next symbol synchronization using the estimated Doppler coefficient. To optimize the process of Doppler estimation and symbol synchronization, a heuristic search method is used. By adjusting the Doppler factor search step size, setting the threshold value, and using the Doppler factor estimation of the previous symbol, the search range can be significantly reduced and the computational complexity decreased. The Fisher-Yates shuffle algorithm is used to traverse the search range to ensure reliability of the results. Simulation results show that enlarging the frequency-domain search step size in some degree does not affect the decoding accuracy. On 15 May 2021, a shallow-water mobile UWA spread spectrum communication experiment was conducted in Weihai, China. The horizontal distance between the transmitter and the receiver is 3.7–4.0 km, and the communication rate is 41.96 bits per second. The transmitting ship moves at a speed of 0–3 m/s, and the bit error rate (BER) is lower than 1e−3, which is better than that of the sliding correlation despreading method with average Doppler compensation.

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19

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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TAO, X., C. ZHANG, and J. LU. "Doppler Diversity in MC-CDMA Systems with T-ZCZ Sequences for Doppler Spread Cancelation." IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E90-A, no. 11 (November 1, 2007): 2361–68. http://dx.doi.org/10.1093/ietfec/e90-a.11.2361.

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21

Wu, Xing Cun, Ping Gong, Hai Jun Song, and Hui Zhi Zou. "An FFT-Based Approach for Carrier Frequency Domain Acquisition in Spread Spectrum TT&C System." Applied Mechanics and Materials 135-136 (October 2011): 211–16. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.211.

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Acquisition time of precision ranging code is long under the conditions of large Doppler shift, the carrier frequency domain FFT-based fast acquisition theory was analyzed, and the method of carrier Doppler compensation estimates to complete the PN code Doppler compensation was directly used in spread spectrum ranging signal acquisition. Comparing with the traditional parallel acquisition approach, the Doppler frequency estimation accuracy and acquisition speed is greatly improved, the acquisition time is shorter than long code segment with the traditional parallel acquisition method. Comparing with the method of short code supporting for long code, the channel energy is saved.

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22

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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23

Cai, Fei, and Meiyu Tang. "Dim Range-Spread Target Detection for Stepped-Frequency Radar Using a Bernoulli Extended Target Filter." Sensors 25, no. 5 (February 26, 2025): 1426. https://doi.org/10.3390/s25051426.

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Stepped-frequency radar is an important high range resolution radar. It can achieve wide overall bandwidth with narrow instant bandwidth. When the signal-to-noise ratio is low, detection and tracking become challenging due to dense false alarms and the range-Doppler coupling problem. In this paper, a new methodology is presented to address this problem. A Bernoulli extended target filter is used for joint detection and tracking of a dim range-spread target. The results of coherent processing are thresholded firstly using a low threshold, and the range-Doppler coupled detections generated by multiple scatterers, together with the false alarms, are fed to the Bernoulli filter. By appropriately modeling the range-Doppler coupling, the range spread, and the false alarms in the state and measurement models, the filter can detect the target effectively. Simulation results show that good detection performance is obtained and the range-Doppler coupling is decoupled simultaneously.

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24

Yoon, Eunchul, Soonbum Kwon, Unil Yun, and Sun-Yong Kim. "Doppler Spread Estimation Based on Machine Learning for an OFDM System." Wireless Communications and Mobile Computing 2021 (September 21, 2021): 1–15. http://dx.doi.org/10.1155/2021/5586029.

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In this paper, we propose a Doppler spread estimation approach based on machine learning for an OFDM system. We present a carefully designed neural network architecture to achieve good performance in a mixed-channel scenario in which channel characteristic variables such as Rician K factor, azimuth angle of arrival (AOA) width, mean direction of azimuth AOA, and channel estimation errors are randomly generated. When preprocessing the channel state information (CSI) collected under the mixed-channel scenario, we propose averaged power spectral density (PSD) sequence as high-quality training data in machine learning for Doppler spread estimation. We detail intermediate mathematical derivatives of the machine learning process, making it easy to graft the derived results into other wireless communication technologies. Through simulation, we show that the machine learning approach using the averaged PSD sequence as training data outperforms the other machine learning approach using the channel frequency response (CFR) sequence as training data and two other existing Doppler estimation approaches.

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SHENG, Bin, Pengcheng ZHU, and Xiaohu YOU. "An Enhanced Doppler Spread Estimation Method for OFDM Systems." IEICE Transactions on Communications E95.B, no. 12 (2012): 3911–14. http://dx.doi.org/10.1587/transcom.e95.b.3911.

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Yanovsky, F. J., C. M. H. Unal, H. W. J. Russchenberg, and L. P. Ligthart. "Doppler-Polarimetric Weather Radar: Returns from Wide Spread Precipitation." Telecommunications and Radio Engineering 66, no. 8 (2007): 715–27. http://dx.doi.org/10.1615/telecomradeng.v66.i8.20.

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27

Eller, Anthony I., and Ellen M. Daley. "Effects of scattering‐induced frequency spread on Doppler performance." Journal of the Acoustical Society of America 98, no. 5 (November 1995): 2912. http://dx.doi.org/10.1121/1.414197.

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28

Mohammadkarimi, Mostafa, Ebrahim Karami, Octavia A. Dobre, and Moe Z. Win. "Doppler Spread Estimation in MIMO Frequency-Selective Fading Channels." IEEE Transactions on Wireless Communications 17, no. 3 (March 2018): 1951–65. http://dx.doi.org/10.1109/twc.2017.2787539.

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Zhang, Wei, Huiyong Li, Guohao Sun, and Zishu He. "Enhanced Detection of Doppler-Spread Targets for FMCW Radar." IEEE Transactions on Aerospace and Electronic Systems 55, no. 4 (August 2019): 2066–78. http://dx.doi.org/10.1109/taes.2019.2925433.

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Hong Zhang and A. Abdi. "Cyclostationarity-based doppler spread estimation in mobile fading channels." IEEE Transactions on Communications 57, no. 4 (April 2009): 1061–67. http://dx.doi.org/10.1109/tcomm.2009.04.070255.

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31

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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32

Reddi, C. R., M. S. S. R. K. N. Sarma, and K. Niranjan. "HF Doppler radar observations of low-latitude spread F." Radio Science 44, no. 3 (May 9, 2009): n/a. http://dx.doi.org/10.1029/2007rs003777.

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ZHANG, P., X. XU, G. BI, X. CAO, and J. ZHAO. "Iterative Joint Correlation Interval Selection and Doppler Spread Estimation." IEICE Transactions on Communications E89-B, no. 11 (November 1, 2006): 3156–59. http://dx.doi.org/10.1093/ietcom/e89-b.11.3156.

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34

Capoglu, I. R., Ye Li, and A. Swami. "Effect of Doppler spread in OFDM-based UWB systems." IEEE Transactions on Wireless Communications 4, no. 5 (September 2005): 2559–67. http://dx.doi.org/10.1109/twc.2005.853978.

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35

Robertson, Patrick, and Stefan Kaiser. "Analysis of Doppler Spread Perturbations in OFDM(A) Systems." European Transactions on Telecommunications 11, no. 6 (November 2000): 585–92. http://dx.doi.org/10.1002/ett.4460110609.

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36

Ra, HyungIn, Changhyun Youn, and Kiman Kim. "High-Reliability Underwater Acoustic Communication Using an M-ary Cyclic Spread Spectrum." Electronics 11, no. 11 (May 26, 2022): 1698. http://dx.doi.org/10.3390/electronics11111698.

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Multipath propagation, frequency selective fading, low-propagation velocity, and narrow bandwidth are all characteristics of underwater acoustic channels. Doppler shifts and diffusions can occur as a result of the low transmission speed of an acoustic signal, which can be caused by the movement of ocean currents or the transceiver. Furthermore, frequency selective fading and excessive noise interference can disrupt underwater acoustic communication on a continual basis. Because of its high anti-interference ability and high confidentiality, spread spectrum technology is commonly adopted in underwater acoustic communications. Although the direct sequence spread spectrum method has a low data rate, it is advantageous in a multipath propagation channel environment or an environment with a low signal-to-noise ratio (SNR). This advantage is suitable for long-distance transmission or LPD (Low Probability of Detection) communication, and the direct sequence spread spectrum method is applied. In this paper, we propose a highly reliable M-ary cyclic spread spectrum technique by superimposing the M-ary spread spectrum, an extension of the direct sequence spread spectrum technique, and cyclic shift keying. Furthermore, by estimating the Doppler frequency using M-ary spread spectrum codes and performing synchronization correction of the ensuing symbol based on the estimation results, higher performance can be attained. Simulations and experiments showed that the M-ary cyclic spread spectrum method can reduce Doppler estimation and synchronization error accumulation while maintaining a high data rate. Furthermore, the MCSS method had a lower bit error rate than the standard spread spectrum method.

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Zhao, Pengyu, Xiaoyong Wang, Kai Zhang, Yanliang Jin, and Guoxin Zheng. "Doppler Modeling and Simulation of Train-to-Train Communication in Metro Tunnel Environment." Sensors 22, no. 11 (June 4, 2022): 4289. http://dx.doi.org/10.3390/s22114289.

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The communication system of urban rail transit is gradually changing from train-to-ground (T2G) to train-to-train (T2T) communication. The subway can travel at speeds of up to 200 km/h in the tunnel environment, and communication between trains can be conducted via millimeter waves with minimum latency. A precise channel model is required to test the reliability of T2T communication over a non-line-of-sight (NLoS) Doppler channel in a tunnel scenario. In this paper, the description of the ray angle for a T2T communication terminal is established, and the mapping relationship of the multipath signals from the transmitter to the receiver is established. The channel parameters including the angle, amplitude, and mapping matrix from the transmitter to the receiver are obtained by the ray-tracing method. In addition, the channel model for the T2T communication system with multipath propagations is constructed. The Doppler spread simulation results in this paper are consistent with the RT simulation results. A channel physics modelling approach using an IQ vector phase shifter to achieve Doppler spread in the RF domain is proposed when paired with the Doppler spread model.

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Tu, Xingbin, Shaojian Yang, Jie Xi, Yulin Jiang, Wei Yan, and Fengzhong Qu. "Doubly-spread channel equalization based on channel shortening in mobile underwater acoustic communications." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A249. http://dx.doi.org/10.1121/10.0023447.

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The shallow water environments and the movement of autonomous underwater vehicles contribute to the distortion of acoustic signals in both the delay and Doppler domains. Numerous studies have focused on eliminating the distortion in underwater acoustic communications but have struggled to find an optimal trade-off between performance and computational complexity, rendering them impractical for marine engineering applications. In our research, we propose a channel-shortening equalization scheme based on frequency-domain decision feedback equalization (FD-DFE) to address this issue. This approach leverages FD-DFE to reduce the number of multipaths and decreases the Doppler spread of the channel. A time-domain decision feedback equalization based on recursive least squares (RLS-DFE) is then employed to eliminate residual delay and Doppler spreads. The mismatch between the block- and symbol-wise equalization is minimized by an overlapping subblock structure. Numerical simulations have demonstrated the effectiveness of this scheme. Error-free transmissions with a data rate of up to 6 kbps were achieved in a reservoir experiment between an autonomous underwater helicopter (AUH) and a shore-base receiving node.

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Ricci, Stefano. "Switching Power Suppliers Noise Reduction in Ultrasound Doppler Fluid Measurements." Electronics 8, no. 4 (April 11, 2019): 421. http://dx.doi.org/10.3390/electronics8040421.

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Ultrasound Doppler techniques are widely employed in detecting the velocity of moving fluids both in medical and industrial applications. Echo Doppler electronics systems include a highly sensitive front-end suitable to processing the very low power ultrasound echoes received by the transducer. Moreover, the front-end input bandwidth typically ranges between 100 kHz and 10 MHz, which is the same frequency range where modern switching regulators work. Thus, the front-end is particularly prone to the noise produced by the suppliers that power the board itself. Electromagnetic interference (EMI) filters and spread-spectrum modulation of the switching regulator frequency help, but the results are often not optimal, and unacceptable artifacts are visible in the Doppler spectrum. In this paper a spread-spectrum modulation is proposed that concentrates the switching noise in the low-frequency range of the Doppler spectrum (e.g., 0–100 Hz). This range is removed by the high-pass clutter filter normally used in velocity Doppler investigations, thus switching noise and artifacts are eliminated. The method is verified through mathematical simulations and tested in measurements carried out with a research Doppler system. An example is presented in which the artifacts present during the investigation of a 0.4-m/s flow in a 25.4-mm diameter pipe are effectively removed by the proposed method.

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40

Sadrieh, Seyed Nima, Ali Broumandan, and Gérard Lachapelle. "Doppler Characterization of a Mobile GNSS Receiver in Multipath Fading Channels." Journal of Navigation 65, no. 3 (April 4, 2012): 477–94. http://dx.doi.org/10.1017/s037346331200015x.

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Global Navigation Satellite Systems (GNSS) Doppler measurements are commonly used for velocity-based relative positioning and aiding Inertial Navigation Systems (INS) in signal degraded environments. The aim of this paper is to characterise the Doppler measurements in GNSS harsh multipath environments. In multipath fading situations such as indoor and urban canyon environments, multipath components arrive to the receiver antenna from different paths and directions. These give rise to various Doppler shifts that cause errors in the velocity solution. In this work the Doppler measurements discrepancy characterised by Doppler spread in multipath environments is investigated. By assuming a ‘sphere of scatterers’ model and considering the antenna gain pattern, the theoretical Power Spectral Density (PSD) observed by a receiver is formulated. The theoretical findings are examined using two sets of measurements in dense multipath environments. Global Positioning System (GPS) live signals using non-isotropic antennas with different orientations are used for this purpose. Different motion directions are also examined using different data sets. An Assisted GPS (A-GPS) approach is utilised where the code phase and the navigation data bits are provided by a nearby outdoor antenna. By applying a ‘Block Processing’ technique, an epoch-by-epoch Doppler and velocity estimation is implemented. Herein, the Doppler and velocity measurements accuracy in addition to the Doppler spread characterization are studied. As shown both theoretically and experimentally, in harsh multipath environments the PSD of the observed signals is a function of the scatterers' geometry and the antenna gain pattern. The Doppler estimation accuracies in multipath and multipath-free cases are compared for different ranges of Carrier-to-Noise ratio (C/N0). Theoretical and experimental results revealed inaccurate Doppler estimation and poor Doppler-derived velocity solutions in dense multipath environments.

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Amalia, Nisa Noor, Khoirul Anwar, and Nachwan Mufti Adriansyah. "PENINGKATAN KINERJA FUTURE RAILWAY MOBILE COMMUNICATION SYSTEM UNTUK KERETA CEPAT INDONESIA DENGAN SINGLE INPUT MULTIPLE OUTPUT - DOPPLER SPREAD COMPENSATOR." TEKTRIKA - Jurnal Penelitian dan Pengembangan Telekomunikasi, Kendali, Komputer, Elektrik, dan Elektronika 6, no. 1 (July 21, 2022): 28. http://dx.doi.org/10.25124/tektrika.v6i1.4071.

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Future railway mobile communication system (FRMCS) merupakan sistem pensinyalan kereta cepat berbasis the fifth telecommunication generation new radio (5G NR) third generation partnership project (3GPP) TS 22.289 dan European telecommunication standard institute (ETSI) TR 103 459. Pergerakan kereta yang cepat mengakibatkan kerusakan sinyal akibat adanya pergeseran frekuensi yang dirasakan oleh penerima, sehingga mengganggu sistem komunikasi kereta cepat. Untuk mendukung pensinyalan kereta cepat yang baik dan berkapasitas besar, makalah ini mengusulkan single input multiple output (SIMO) dengan Doppler spread compensator (DSC) untuk memanfaatkan space diversity kanal antara transmitter dan receiver yang terletak di atas gerbong kereta. SIMODSC yang diusulkan memiliki dua antena array paralel yang berjarak 5? = 1.6 m di atas gerbong kereta. Evaluasi SIMO-DSC yang diusulkan dilakukan dengan rangkaian simulasi komputer untuk kinerja bit error rate (BER) terhadap signal to noise power ratio (SNR), frame error rate (FER) terhadap SNR, dan BER terhadap normalized Doppler spread ( fdTs) pada model kanal kereta Indonesia. Hasil penelitian menunjukkan bahwa SIMO-DSC mampu menghilangkan Eefek Doppler secara signifikan, dan meningkatkan performansi FRMCS meskipun pada kecepatan 1000 km/jam. Kata Kunci: DSC, Efek Doppler, SIMO

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Kumar, B. T. Vikram, P. Velayudhan Nair, and P. B. Rao. "HF doppler observations on the occurrence of equatorial spread-F." Journal of Earth System Science 94, no. 3 (November 1985): 261–67. http://dx.doi.org/10.1007/bf02839203.

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Ghogho, M., A. Swami, and T. S. Durrani. "Frequency estimation in the presence of Doppler spread: performance analysis." IEEE Transactions on Signal Processing 49, no. 4 (April 2001): 777–89. http://dx.doi.org/10.1109/78.912922.

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Hagfors, T., and E. Tereshchenko. "Two-dimensional chirp mapping of delay and Doppler spread targets." Radio Science 26, no. 5 (September 1991): 1199–203. http://dx.doi.org/10.1029/91rs01414.

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Marsden, R. F., and R. G. Ingram. "Correcting for Beam Spread in Acoustic Doppler Current Profiler Measurements." Journal of Atmospheric and Oceanic Technology 21, no. 9 (September 2004): 1491–98. http://dx.doi.org/10.1175/1520-0426(2004)021<1491:cfbsia>2.0.co;2.

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Po-Ying Chen and Hsueh-Jyh Li. "An iterative algorithm for Doppler spread estimation in LOS environments." IEEE Transactions on Wireless Communications 5, no. 6 (June 2006): 1223–28. http://dx.doi.org/10.1109/twc.2006.1638638.

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Castrellon, Mario, David Muñoz, Cesar Vargas, Claudio Lopez, and David Covarrubias. "Doppler spread for Gaussian scatter density environments employing smart antennas." AEU - International Journal of Electronics and Communications 61, no. 9 (October 2007): 631–36. http://dx.doi.org/10.1016/j.aeue.2006.12.010.

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Ramakrishnan, D., and J. Krolik. "Adaptive Radar Detection in Doubly Nonstationary Autoregressive Doppler Spread Clutter." IEEE Transactions on Aerospace and Electronic Systems 45, no. 2 (April 2009): 484–501. http://dx.doi.org/10.1109/taes.2009.5089536.

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Roy, Sébastien, Huu Tuê Huynh, and Paul Fortier. "Compound Doppler Spread Effects of Subscriber Motion and Scatterer Motion." AEU - International Journal of Electronics and Communications 57, no. 4 (January 2003): 237–46. http://dx.doi.org/10.1078/1434-8411-54100166.

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Luo, T., Z. Wen, J. Li, and H. H. Chen. "Saturation throughput analysis of WAVE networks in Doppler spread scenarios." IET Communications 4, no. 7 (2010): 817. http://dx.doi.org/10.1049/iet-com.2009.0071.

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Journal articles on the topic 'Doppler spread'

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