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1
Zhao, Hangyu, Yeping Lai, Yuhao Wang, and Hao Zhou. "High-Frequency Radar Cross Section of Ocean Surface for an FMICW Source." Journal of Marine Science and Engineering 9, no. 4 (April 15, 2021): 427. http://dx.doi.org/10.3390/jmse9040427.
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The frequency-modulated interrupted continuous waveform (FMICW) has been widely used in remotely sensing sea surface states by high-frequency ground wave radar (HFGWR). However, the radar cross section model of the sea surface for this waveform has not yet been presented. Therefore, the first- and second-order cross section models of the sea surface about this waveform are derived in this study. The derivation begins with the general electric field equations. Subsequently, the FMICW source is introduced as the radar transmitted signal to obtain the FMICW-incorporated backscattered electric field equations. These equations are used to calculate range spectra by Fourier transforming. Therefore, Fourier transformation of the range spectra calculated from successive sweep intervals gives the Doppler spectra or the power spectral densities. The radar cross section model is obtained by directly comparing the Doppler spectra with the standard radar range equation. Moreover, the derived first- and second-order radar cross section models for an FMICW source are simulated and compared with those for a frequency-modulated continuous waveform (FMCW) source. Results show that the cross section models for the FMICW and FMCW cases have different analytical expressions but almost the same numerical results.
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Laureti, Stefano, Marco Mercuri, David A. Hutchins, Felice Crupi, and Marco Ricci. "Modified FMCW Scheme for Improved Ultrasonic Positioning and Ranging of Unmanned Ground Vehicles at Distances < 50 mm." Sensors 22, no. 24 (December 15, 2022): 9899. http://dx.doi.org/10.3390/s22249899.
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Unmanned ground vehicles (UGVs) find extensive use in various applications, including that within industrial environments. Efforts have been made to develop cheap, portable, and light-ranging/positioning systems to accurately locate their absolute/relative position and to automatically avoid potential obstacles and/or collisions with other drones. To this aim, a promising solution is the use of ultrasonic systems, which can be set up on UGVs and can potentially output a precise reconstruction of the drone’s surroundings. In this framework, a so-called frequency-modulated continuous wave (FMCW) scheme is widely employed as a distance estimator. However, this technique suffers from low repeatability and accuracy at ranges of less than 50 mm when used in combination with low-resource hardware and commercial narrowband transducers, which is a distance range of the utmost importance to avoid potential collisions and/or imaging UGV surroundings. We hereby propose a modified FMCW-based scheme using an ad hoc time-shift of the reference signal. This was shown to improve performance at ranges below 50 mm while leaving the signal unaltered at greater distances. The capabilities of the modified FMCW were evaluated numerically and experimentally. A dramatic enhancement in performance was found for the proposed FMCW with respect to its standard counterpart, which is very close to that of the correlation approach. This work paves the way for the future use of FMCWs in applications requiring high precision.
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Eum, Soung-Hyun, and Woo-Jin Oh. "High Resolution FMCW Level Gauge with Narrowband FMCW Radar." Journal of the Korean Institute of Information and Communication Engineering 16, no. 5 (May 31, 2012): 899–905. http://dx.doi.org/10.6109/jkiice.2012.16.5.899.
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Xin, Qin, Zhihong Jiang, Pu Cheng, and Mi He. "Signal Processing for Digital Beamforming FMCW SAR." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/859890.
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According to the limitations of single channel Frequency Modulation Continuous Wave (FMCW) Synthetic Aperture Radar (SAR), Digital Beamforming (DBF) technology is introduced to improve system performance. Combined with multiple receive apertures, DBF FMCW SAR can obtain high resolution in low pulse repetition frequency, which can increase the processing gain and decrease the sampling frequency. The received signal model of DBF FMCW SAR is derived. The continuous antenna motion which is the main characteristic of FMCW SAR received signal is taken into account in the whole signal processing. The detailed imaging diagram of DBF FMCW SAR is given. A reference system is also demonstrated in the paper by comparing with a single channel FMCW SAR. The validity of the presented diagram is demonstrated with a point target simulation results.
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Yang, Jiewei, Tianxin Yang, Zhaoying Wang, Dongfang Jia, and Chunfeng Ge. "A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser." Sensors 20, no. 14 (July 9, 2020): 3834. http://dx.doi.org/10.3390/s20143834.
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Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW light are limited and diverse in terms of technical approaches and mechanisms. Due to a lack of characterization methods for linear FMCW lasers, it is difficult to compare and judge the generation systems in the same category. We propose a novel scheme for measuring the mapping relationship between instantaneous frequency and time of a FMCW laser based on a modified coherent optical spectrum analyzer (COSA) and digital signal processing (DSP) method. Our method has the potential to measure the instantaneous frequency of a FMCW laser at an unlimited sweep rate. In this paper, we demonstrate how to use this new method to precisely measure a FMCW laser at a large fast sweep rate of 5000 THz/s by both simulation and experiments. We find experimentally that the uncertainty of this method is less than 100 kHz and can be improved further if a frequency feedback servo system is introduced to stabilize the local CW laser.
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Huang, Tongxing, Chaoyang Zhang, Dun Lu, Qiuyu Zeng, Wenjie Fu, and Yang Yan. "Improving FMCW GPR Precision through the CZT Algorithm for Pavement Thickness Measurements." Electronics 11, no. 21 (October 29, 2022): 3524. http://dx.doi.org/10.3390/electronics11213524.
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Ground Penetrating Radar (GPR) application in road surface detection has been greatly developed in the past few decades, which enables rapid and economical estimation of pavement thickness and other physical properties in non-destructive testing (NDT) and non-contact testing (NCT). In recent years, with the rapid development of microwave and millimeter-wave solid-state devices and digital signal processors, the cost of Frequency-Modulated Continuous-Wave (FMCW) radar has dropped significantly, with smaller size and lighter weight. Thereafter, FMCW GPR is considered to be applied during pavement inspection. To improve the precision of FMCW GPR for NDT and NCT of pavement thickness, a Chirp Z-transform (CZT) algorithm is introduced to FMCW GPR and investigated in this paper. A FMCW + CZT GPR at 2.5 GHz with a bandwidth of 1 GHz was built, and laboratory and field experiments were carried out. The experimental results demonstrate that the FMCW + CZT GPR radar can obtain the sample thickness with low error and recognize subtle thickness variations. This method realizes the high precision thickness measurement of shallow asphalt pavement by FMCW radar with a narrow bandwidth pulse signal and would provide a promising low-cost measurement solution for GPR.
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Pal, Surendra. "FMCW – Radar Design." IETE Journal of Research 65, no. 4 (June 11, 2019): 576–77. http://dx.doi.org/10.1080/03772063.2019.1615392.
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Gu, Shanshan, Guangrong Xi, Lingyu Ge, Zhong Yang, Yizhi Wang, Weina Chen, and Zhenzhong Yu. "Compressed Sensing for THz FMCW Radar 3D Imaging." Complexity 2021 (August 26, 2021): 1–10. http://dx.doi.org/10.1155/2021/5576782.
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A terahertz (THz) frequency-modulated continuous wave (FMCW) imaging radar system is developed for high-resolution 3D imaging recently. Aiming at the problems of long data acquisition periods and large sample sizes for the developed imaging system, an algorithm based on compressed sensing is proposed for THz FMCW radar 3D imaging in this paper. Firstly, the FMCW radar signal model is built, and the conventional range migration algorithm is introduced for THz FMCW radar imaging. Then, compressed sensing is extended for THz FMCW radar 3D imaging, and the Newton smooth L0-norm (NSL0) algorithm is presented for sparse measurement data reconstruction. Both simulation and measurement experiments demonstrate the feasibility of reconstructing THz images from measurements even at the sparsity rate of 20%.
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Wang, Rongrong, Bingnan Wang, Maosheng Xiang, Chuang Li, Shuai Wang, and Chong Song. "Simultaneous Time-Varying Vibration and Nonlinearity Compensation for One-Period Triangular-FMCW Lidar Signal." Remote Sensing 13, no. 9 (April 29, 2021): 1731. http://dx.doi.org/10.3390/rs13091731.
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Frequency modulation continuous wave (FMCW) Lidar inevitably suffers from vibration and nonlinear frequency modulation, which influences the ranging and imaging results. In this paper, we analyze the impact of vibration error coupled with nonlinearity error on ranging for FMCW Lidar, and propose a purely theoretical approach that simultaneously compensates for time-varying vibration and nonlinearity in one-period triangular FMCW (T-FMCW) signals. We first extract the localized characteristics of dechirp signals in time-frequency domain by using a second-order synchro-squeezing transform (second-order SST), and establish an instantaneous ranging model based on second-order SST which can characterize the local distributions of time-varying errors. Second, we estimate the nonlinearity error by using time-frequency information of an auxiliary channel and then preliminarily eliminate the error from the instantaneous measurement range. Finally, we construct a particle filtering (PF) model for T-FMCW using the instantaneous ranging model to compensate for the time-varying vibration error and the residual nonlinearity error, and calculate the range of target by using triangular symmetry relations of T-FMCW. Experimental tests prove that the proposed method can accurately estimate the range of target by compensating for the time-varying vibration and the nonlinearity errors simultaneously in one-period T-FMCW signal.
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Xiao, Zhenzhen, Zhengmao Wu, and Guangqiong Xia. "Broadband dual-chirp FMCW laser source based on DSB-SC modulation and cascaded FWM." Optics Express 31, no. 18 (August 24, 2023): 29925. http://dx.doi.org/10.1364/oe.498896.
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Based on dual-sideband suppressed-carrier (DSB-SC) modulation and two-stage cascaded four-wave-mixing (FWM), a scheme of broadband dual-chirp frequency-modulated continuous-wave (FMCW) laser source is proposed and experimentally demonstrated. First, via a Mach-Zehnder modulator biased at its null point, an original DSB-SC FMCW signal with 4.0 GHz swept-frequency range and 0.2 GHz/μs sweep rate is generated. Next, the original DSB-SC FMCW signal is sent to a 1 km dispersion compensation fiber for implementing first-stage FWM, a dual-chirp FMCW signal with 12.0 GHz swept-frequency range and 0.6 GHz/μs sweep rate is acquired and used as the pump for second-stage FWM. Finally, via second-stage FWM in a 200 m highly nonlinear fiber, a dual-chirp FMCW signal with a swept-frequency range of 36.0 GHz and sweep rate of 1.8 GHz/μs is generated. Taking the FMCW signal generated at different stages as the emitted signal, we evaluate the ranging resolution through fiber-based distance measurement, and the results demonstrate that the achieved ranging resolutions are 5.31 cm, 2.04 cm, and 1.18 cm, respectively. Through equalizing the optical power of generated FMCW signal over the swept-frequency range, the ranging resolution can be further improved.
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Wu, Zibo, Yue Song, Jishun Liu, Yongyi Chen, Hongbo Sha, Mengjie Shi, Hao Zhang, et al. "Advancements in Key Parameters of Frequency-Modulated Continuous-Wave Light Detection and Ranging: A Research Review." Applied Sciences 14, no. 17 (September 3, 2024): 7810. http://dx.doi.org/10.3390/app14177810.
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As LiDAR technology progressively advances, the capability of radar in detecting targets has become increasingly vital across diverse domains, including industrial, military, and automotive sectors. Frequency-modulated continuous-wave (FMCW) LiDAR in particular has garnered substantial interest due to its efficient direct velocity measurement and excellent anti-interference characteristics. It is widely recognized for its significant potential within radar technology. This study begins by elucidating the operational mechanism of FMCW LiDAR and delves into its basic principles. It discuss, in depth, the influence of various parameters on FMCW LiDAR’s performance and reviews the latest progress in the field. This paper proposes that future studies should focus on the synergistic optimization of key parameters to promote the miniaturization, weight reduction, cost-effectiveness, and longevity of FMCW LiDAR systems. This approach aims at the comprehensive development of FMCW LiDAR, striving for significant improvements in system performance. By optimizing these key parameters, the goal is to promote FMCW LiDAR technology, ensuring more reliable and accurate applications in automated driving and environmental sensing.
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Park, Kyungeun, Jeongpyo Lee, and Youngok Kim. "Deep Learning-Based Indoor Two-Dimensional Localization Scheme Using a Frequency-Modulated Continuous Wave Radar." Electronics 10, no. 17 (September 5, 2021): 2166. http://dx.doi.org/10.3390/electronics10172166.
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In this paper, we propose a deep learning-based indoor two-dimensional (2D) localization scheme using a 24 GHz frequency-modulated continuous wave (FMCW) radar. In the proposed scheme, deep neural network and convolutional neural network (CNN) models that use different numbers of FMCW radars were employed to overcome the limitations of the conventional 2D localization scheme that is based on multilateration methods. The performance of the proposed scheme was evaluated experimentally and compared with the conventional scheme under the same conditions. According to the results, the 2D location of the target could be estimated with a proposed single radar scheme, whereas two FMCW radars were required by the conventional scheme. Furthermore, the proposed CNN scheme with two FMCW radars produced an average localization error of 0.23 m, while the error of the conventional scheme with two FMCW radars was 0.53 m.
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Abdul Rahman, I., M. I. Mohd Lazim, Mohammad S., Soo Peng K., and Mohd Asri M.A. "Storage stability assessment and quality performance of fermented mature coconut water beverage." Food Research 6, Supplementary 2 (December 8, 2022): 43–48. http://dx.doi.org/10.26656/fr.2017.6(s2).002.
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Nutritional enhancement of mature coconut water was developed using mixed culture fermentation of Lactobacillus acidophilus and Lactobacillus brevis. The fermented mature coconut water (FMCW) was subsequently formulated to produce a palatable fermented beverage. For the FMCW to be considered safe for consumption, a storage study with a duration of 12 months was done. Prior to storage, the formulated FMCW was pasteurized at 90°C for 30 mins and allowed to cool to room temperature. The formulated FMCW was then stored at two different storage conditions of 4°C and approximately 24°C (refrigerator and room temperatures, respectively). Samplings for microbial growth by counting colony-forming unit (CFU/mL), Brix and pH values, and nutritional contents were done every three months by removing individual bottles of the formulated FMCW products for specific months to monitor the product quality quarterly. The results showed that the physical analyses and nutritional contents were maintained for the whole 12 months duration without any significant changes. In addition, samples at both storage temperatures did not show any microbial growth. The potential spoilage of the FMCW product by the common microbial spoilers was prevented probably by the presence of biopreservatives in the form of high lactic acid or other antimicrobial compounds produced from the mixed culture fermentation. Therefore, the storage study concluded that the FMCW beverage was stable and remained safe for consumption for at least 12 months when kept at refrigerator and room temperatures.
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Bhutani, Akanksha, Sören Marahrens, Michael Gehringer, Benjamin Göttel, Mario Pauli, and Thomas Zwick. "The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor." Sensors 19, no. 18 (September 12, 2019): 3938. http://dx.doi.org/10.3390/s19183938.
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High-accuracy, short-range distance measurement is required in a variety of industrial applications e.g., positioning of robots in a fully automated production process, level measurement of liquids in small containers. An FMCW radar sensor is suitable for this purpose, since many of these applications involve harsh environments. Due to the progress in the field of semiconductor technology, FMCW radar sensors operating in different millimeter-wave frequency bands are available today. An important question in this context, which has not been investigated so far is how does a millimeter-wave frequency band influence the sensor accuracy, when thousands of distance measurements are performed with a sensor. This topic has been dealt with for the first time in this paper. The method used for analyzing the FMCW radar signal combines a frequency- and phase-estimation algorithm. The frequency-estimation algorithm based on the fast Fourier transform and the chirp-z transform provides a coarse estimate of the target distance. Subsequently, the phase-estimation algorithm based on a cross-correlation function provides a fine estimate of the target distance. The novel aspects of this paper are as follows. First, the estimation theory concept of Cramér-Rao lower bound (CRLB) has been used to compare the accuracy of two millimeter-wave FMCW radars operating at 60 GHz and 122 GHz. In this comparison, the measurement parameters (e.g., bandwidth, signal-to-noise ratio) as well as the signal-processing algorithm used for both the radars are the same, thus ensuring an unbiased comparison of the FMCW radars, solely based on the choice of millimeter-wave frequency band. Second, the improvement in distance measurement accuracy obtained after each step of the combined frequency- and phase-estimation algorithm has been experimentally demonstrated for both the radars. A total of 5100 short-range distance measurements are made using the 60 GHz and 122 GHz FMCW radar. The measurement results are analyzed at various stages of the frequency- and phase-estimation algorithm and the measurement error is calculated using a nanometer-precision linear motor. At every stage, the mean error values measured with the 60 GHz and 122 GHz FMCW radars are compared. The final accuracy achieved using both radars is of the order of a few micrometers. The measured standard deviation values of the 60 GHz and 122 GHz FMCW radar have been compared against the CRLB. As predicted by the CRLB, this paper experimentally validates for the first time that the 122 GHz FMCW radar provides a higher repeatability of micrometer-accuracy distance measurements than the 60 GHz FMCW radar.
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Stove, A. G. "Linear FMCW radar techniques." IEE Proceedings F Radar and Signal Processing 139, no. 5 (1992): 343. http://dx.doi.org/10.1049/ip-f-2.1992.0048.
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Chen, Zhe, Debin Hou, Ji-Xin Chen, Pinpin Yan, Lei Bao, Zheying Hong, and Yuanye Zheng. "A K-Band FMCW Frequency Synthesizer Using Q-Boosted Switched Inductor VCO in SiGe BiCMOS for 77 GHz Radar Applications." Electronics 9, no. 11 (November 17, 2020): 1933. http://dx.doi.org/10.3390/electronics9111933.
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In this article, a fractional-N phase-locked loop (PLL) with integrated chirp generation circuit block for a 76~81 GHz frequency-modulated continuous-wave (FMCW) radar system is presented. Thanks to the switched inductor voltage-controlled oscillator (VCO) topology, the linearity, phase noise, chirp bandwidth, and chirp rate of the FMCW synthesizer can be optimized for the short-range radar (SRR) and long-range radar (LRR) applications, with switch at ON/OFF states, respectively, according to different requirements and concerns. In this way, the proposed FMCW synthesizer shows improved phase noise for switch OFF-state, good for LRR applications, compared to the conventional single-varactor VCOs or cap-bank VCOs. The switch loss at ON-state is further decreased with the Q-boosting technique, which helps the FMCW synthesizer to simultaneously obtain a wide chirp bandwidth, steep modulation rates and good phase noise for SRR applications. The FMCW synthesizer is fabricated in 0.13 µm SiGe BiCMOS technology, occupies an area of 1.7 × 1.9 mm2, and consumes 330 mW from a 3.3 V voltage supply. Measured results show that the FMCW synthesizer can cover 25.3~27 GHz (with a frequency tripler to fully cover 76~81 GHz band), showing optimized phase noise, chirp bandwidth, linearity, and modulation rates performance. The measured K-band phase noise is −110.5 dBc/Hz for switch OFF-state, and −106 dBc/Hz for switch ON-state at 1 MHz offset. The normalized root mean square (RMS) frequency error is 518 kHz for chirp rate of ±14.6 MHz/μs and 1.44 MHz for chirp rate of ±39 MHz/μs for the 77 GHz band. Moreover, the integrated waveform generator offers fully programmability in chirp rate, duration and bandwidth, which supports multi-slope chirp generations. With a frequency tripler, the chip is well suited for the 76~81 GHz FMCW radar system.
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Wang, Dingyang, Sungwon Yoo, and Sung Ho Cho. "Experimental Comparison of IR-UWB Radar and FMCW Radar for Vital Signs." Sensors 20, no. 22 (November 23, 2020): 6695. http://dx.doi.org/10.3390/s20226695.
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In this paper, we compare the performances of impulse radio ultra-wideband (IR-UWB) and frequency modulation continuous wave (FMCW) radars in measuring noncontact vital signs such as respiration rate and heart rate. These two type radars have been widely used in various fields and have shown their applicability to extract vital signs in noncontact ways. IR-UWB radar can extract vital signs using distance information. On the other hand, FMCW radar requires phase information to estimate vital signs, and the result can be enhanced with Multi-input Multi-output (MIMO) antenna topologies. By using commercial radar chipsets, the operation of radars under different conditions and frequency bands will also affect the performance of vital sign detection capabilities. We compared the accuracy and signal-to-noise (SNR) ratios of IR-UWB and FMCW radars in various scenarios, such as distance, orientation, carotid pulse, harmonics, and obstacle penetration. In general, the IR-UWB radars offer a slightly better accuracy and higher SNR in comparison to FMCW radar. However, each radar system has its own unique advantages, with IR-UWB exhibiting fewer harmonics and a higher SNR, while FMCW can combine the results from each channel.
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Almeida, Filipe, Andreia Gameiro, Jorge Correia, and Fernando Ferreira. "Histone Deacetylase Inhibitors and Microtubule Inhibitors Induce Apoptosis in Feline Luminal Mammary Carcinoma Cells." Animals 11, no. 2 (February 15, 2021): 502. http://dx.doi.org/10.3390/ani11020502.
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Feline mammary carcinoma (FMC) is the third most common type of neoplasia in cats, sharing similar epidemiological features with human breast cancer. In humans, histone deacetylases (HDACs) play an important role in the regulation of gene expression, with HDAC inhibitors (HDACis) disrupting gene expression and leading to cell death. In parallel, microtubules inhibitors (MTIs) interfere with the polymerization of microtubules, leading to cell cycle arrest and apoptosis. Although HDACis and MTIs are used in human cancer patients, in cats, data is scarce. In this study, we evaluated the antitumor properties of six HDACis (CI-994, panobinostat, SAHA, SBHA, scriptaid, and trichostatin A) and four MTIs (colchicine, nocodazole, paclitaxel, and vinblastine) using three FMC cell lines (CAT-MT, FMCp, and FMCm), and compared with the human breast cancer cell line (SK-BR-3). HDACis and MTIs exhibited dose-dependent antitumor effects in FMC cell lines, and for all inhibitors, the IC50 values were determined, with one feline cell line showing reduced susceptibility (FMCm). Immunoblot analysis confirmed an increase in the acetylation status of core histone protein HDAC3 and flow cytometry showed that HDACis and MTIs lead to cellular apoptosis. Overall, our study uncovers HDACis and MTIs as promising anti-cancer agents to treat FMCs.
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Li, Yingchun, Qi Long, Zhongjie Wu, and Zhiquan Zhou. "Low-Complexity Joint 3D Super-Resolution Estimation of Range Velocity and Angle of Multi-Targets Based on FMCW Radar." Sensors 22, no. 17 (August 28, 2022): 6474. http://dx.doi.org/10.3390/s22176474.
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Multi-dimensional parameters joint estimation of multi-targets is introduced to implement super-resolution sensing in range, velocity, azimuth angle, and elevation angle for frequency-modulated continuous waveform (FMCW) radar systems. In this paper, a low complexity joint 3D super-resolution estimation of range, velocity, and angle of multi-targets is proposed for an FMCW radar with a uniform linear array. The proposed method firstly constructs the size-reduced 3D matrix in the frequency domain for the system model of an FMCW radar system. Secondly, the size-reduced 3D matrix is established, and low complexity three-level cascaded 1D spectrum estimation implemented by applying the Lagrange multiplier method is developed. Finally, the low complexity joint 3D super-resolution algorithms are validated by numerical experiments and with a 77 GHz FMCW radar built by Texas Instruments, with the proposed algorithm achieving significant estimation performance compared to conventional algorithms.
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Pratiwi, Hana, Mujib R. Hidayat, A. A. Pramudita, and Fiky Y. Suratman. "Improved FMCW Radar System for Multi-Target Detection of Human Respiration Vital Sign." Jurnal Elektronika dan Telekomunikasi 19, no. 2 (December 31, 2019): 38. http://dx.doi.org/10.14203/jet.v19.38-44.
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Frequency Modulated Continuous Wave (FMCW) radar system has been developed and applied for various needs. Based on the conventional FMCW radar concept, a large bandwidth is needed to detect small displacements in the chest wall or abdomen related with respiratory activity. To overcome the need for large bandwidths in detecting vital respiratory signs, several improvements to the FMCW system are proposed in this paper. The phase-detection concept has been elaborated in improving the capability of FMCW to detect the small displacement. In developing multi-target detection capability, range detection capability through beat frequency output needs to be combined with the phase-detection method. Theoretical and simulation studies were performed to investigate the concept of combining range detection and phase detection for detecting respiration on multi-target. The results show that the proposed method is well-performed in detecting the multi-target respiration in high noise reflection.
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Sun, Liang, Xinguang Zhou, Haohao Zhao, Shichang Xu, Zihan Wu, Guohui Yuan, and Zhuoran Wang. "Broadband High-Linear FMCW Light Source Based on Spectral Stitching." Photonics 11, no. 5 (May 19, 2024): 477. http://dx.doi.org/10.3390/photonics11050477.
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The key to realizing a high-performance frequency-modulated continuous wave (FMCW) laser frequency-sweeping light source is how to extend the frequency-swept bandwidth and eliminate the effect of nonlinearity. To solve these issues, this paper designs a broadband high-linear FMCW frequency-sweeping light source system based on the combination of fixed temperature control and digital optoelectronic phase-locked loop (PLL), which controls the temperatures of the two lasers separately and attempts to achieve the coarse spectral stitching based on a time-division multiplexing scheme. Furthermore, we uses the PLL to correct the frequency error more specifically after the coarse stitching, which achieves the spectrum fine stitching and, meanwhile, realizes the nonlinearity correction. The experimental results show that our scheme can successfully achieve bandwidth expansion and nonlinearity correction, and the sweeping bandwidth is twice as much as that of the original single laser. The full-width half-maximum (FWHM) of the FMCW output is reduced from 150 kHz to 6.1 kHz, which exhibits excellent nonlinear correction performance. The relative error of the FMCW ranging system based on this frequency-swept light source is also reduced from 1.628% to 0.673%. Therefore, our frequency-swept light source with excellent performance has a promising application in the FMCW laser ranging system.
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Lee, Theng Wei, and Wan Young Chung. "Interrogation Signal Generation for SAW Temperature Sensor." Advanced Materials Research 694-697 (May 2013): 1089–92. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.1089.
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This paper presents the method to generate frequency modulated continuous wave (FMCW) interrogation signal by using a phase lock loop (PLL) transmitter and NI ELVIS development board. The FMCW interrogation signal can be used for measuring temperature from a surface acoustic wave (SAW) sensor. The development of the PLL transmitter is discussed. The Arbitrary Waveform Generator of NI ELVIS is utilized for generating a linear frequency sweep reference signal, which will be used as a stable input signal for the transmitter. A MATLAB simulation using a pulse compression technique is performed to investigate the relationship between the FMCW bandwidth and range resolution.
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Cha, Kyuho, Sooyoung Oh, Hayoung Hong, Hongsoo Park, and Sun K. Hong. "Detection of Electronic Devices Using FMCW Nonlinear Radar." Sensors 22, no. 16 (August 15, 2022): 6086. http://dx.doi.org/10.3390/s22166086.
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Nonlinear radars can be utilized to detect electronic devices, which are difficult to detect with conventional radars due to their small radar cross sections (RCS). Since the receiver in a nonlinear radar is designed to only receive harmonic or intermodulated echoes from electronic devices, it is able to separate electronic devices from non-electronic scatters (clutter) by rejecting their echoes at fundamental frequencies. This paper presents a harmonic-based nonlinear radar scheme utilizing frequency-modulated continuous-wave (FMCW) signals for the detection of various electronic devices at short range. Using a laboratory experiment setup for FMCW radar at S-band for Tx (C-band for Rx), measurements are carried out to detect electronic devices of various sizes. The results show that the detection of small electronic devices is possible with nonlinear FMCW radar when appropriate system parameters are selected. Furthermore, we also discuss the maximum detectable range estimation for electronic targets using the radar range equation for FMCW nonlinear radar.
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Caffa, Mattia, Francesco Biletta, and Riccardo Maggiora. "Binary-Phase vs. Frequency Modulated Radar Measured Performances for Automotive Applications." Sensors 23, no. 11 (June 1, 2023): 5271. http://dx.doi.org/10.3390/s23115271.
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Radars have been widely deployed in cars in recent years, for advanced driving assistance systems. The most popular and studied modulated waveform for automotive radar is the frequency-modulated continuous wave (FMCW), due to FMCW radar technology’s ease of implementation and low power consumption. However, FMCW radars have several limitations, such as low interference resilience, range-Doppler coupling, limited maximum velocity with time-division multiplexing (TDM), and high-range sidelobes that reduce high-contrast resolution (HCR). These issues can be tackled by adopting other modulated waveforms. The most interesting modulated waveform for automotive radar, which has been the focus of research in recent years, is the phase-modulated continuous wave (PMCW): this modulated waveform has a better HCR, allows large maximum velocity, permits interference mitigation, thanks to codes orthogonality, and eases integration of communication and sensing. Despite the growing interest in PMCW technology, and while simulations have been extensively performed to analyze and compare its performance to FMCW, there are still only limited real-world measured data available for automotive applications. In this paper, the realization of a 1 Tx/1 Rx binary PMCW radar, assembled with connectorized modules and an FPGA, is presented. Its captured data were compared to the captured data of an off-the-shelf system-on-chip (SoC) FMCW radar. The radar processing firmware of both radars were fully developed and optimized for the tests. The measured performances in real-world conditions showed that PMCW radars manifest better behavior than FMCW radars, regarding the above-mentioned issues. Our analysis demonstrates that PMCW radars can be successfully adopted by future automotive radars.
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Zhao, Shuang, and Lei Chen. "Research on the Single Target Recognition of Car Collision Avoidance Radar Based on the FMCW Technology." Advanced Materials Research 1046 (October 2014): 293–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1046.293.
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The signal processing algorithm mainly for the FMCW automotive collision avoidance radar is studied in this paper. Through discussing the FMCW signal processing works with two-dimensional FFT algorithm, we use CZT transform to refine the velocity spectrum so as to accurately extract the velocity of the target.
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Wang, Rongrong, Bingnan Wang, Yachao Wang, Wei Li, Zhongbin Wang, and Maosheng Xiang. "Time-Varying Vibration Compensation Based on Segmented Interference for Triangular FMCW LiDAR Signals." Remote Sensing 13, no. 19 (September 23, 2021): 3803. http://dx.doi.org/10.3390/rs13193803.
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Frequency modulation continuous wave (FMCW) light detection and ranging (LiDAR) 3D imaging system may suffer from time-varying vibrations which will affect the accuracy of ranging and imaging of a target. The system uses only a single-period FMCW LiDAR signal to measure the range of each spot; however, traditional methods may not work well to compensate for the time-varying vibrations in a single period because they generally assume the vibration velocity is constant. To solve this problem, we propose a time-varying vibration compensation method based on segmented interference. We first derive the impact of time-varying vibrations on the range measurement of the FMCW LiDAR system, in which we divide the time-varying vibration errors into primary errors caused by the vibrations with a constant velocity and quadratic errors. Second, we estimate the coefficients of quadratic vibration errors by using a segmented interference method and build a quadratic compensation filter to eliminate the quadratic vibration errors from the original signals. Finally, we use the symmetrical relations of signals in a triangular FMCW period to estimate the vibration velocity and establish a primary compensation filter to eliminate the primary vibration errors. Numerical tests verify the applicability of this method in eliminating time-varying vibration errors with only a one-period triangular FMCW signal and its superiority over traditional methods.
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Ma, Yue, Weimin Huang, and Eric W. Gill. "Bistatic High Frequency Radar Ocean Surface Cross Section for an FMCW Source with an Antenna on a Floating Platform." International Journal of Antennas and Propagation 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/8675964.
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The first- and second-order bistatic high frequency radar cross sections of the ocean surface with an antenna on a floating platform are derived for a frequency-modulated continuous wave (FMCW) source. Based on previous work, the derivation begins with the general bistatic electric field in the frequency domain for the case of a floating antenna. Demodulation and range transformation are used to obtain the range information, distinguishing the process from that used for a pulsed radar. After Fourier-transforming the autocorrelation and comparing the result with the radar range equation, the radar cross sections are derived. The new first- and second-order antenna-motion-incorporated bistatic radar cross section models for an FMCW source are simulated and compared with those for a pulsed source. Results show that, for the same radar operating parameters, the first-order radar cross section for the FMCW waveform is a little lower than that for a pulsed source. The second-order radar cross section for the FMCW waveform reduces to that for the pulsed waveform when the scattering patch limit approaches infinity. The effect of platform motion on the radar cross sections for an FMCW waveform is investigated for a variety of sea states and operating frequencies and, in general, is found to be similar to that for a pulsed waveform.
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Yang, Lewei. "Real-time gesture-based control of UAVs using multimodal fusion of FMCW radar and vision." Journal of Physics: Conference Series 2664, no. 1 (December 1, 2023): 012002. http://dx.doi.org/10.1088/1742-6596/2664/1/012002.
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Abstract Gesture-based control has gained prominence as an intuitive and natural means of interaction with unmanned aerial vehicles (UAVs). This paper presents a real-time gesture-based control system for UAVs that leverages the multimodal fusion of Frequency Modulated Continuous Wave (FMCW) radar and vision sensors, aiming to enhance user experience through precise and responsive UAV control via hand gestures. The research focuses on developing an effective fusion framework that combines the complementary advantages of FMCW radar and vision sensors. FMCW radar provides robust range and velocity measurements, while vision sensors capture fine-grained visual information. By integrating data from these modalities, the system achieves a comprehensive understanding of hand gestures, resulting in improved gesture recognition accuracy and robustness. The proposed system comprises three main stages: data acquisition, gesture recognition, and multimodal fusion. In the data acquisition stage, synchronized data streams from FMCW radar and vision sensors are captured. Then, machine learning algorithms are employed in the gesture recognition stage to classify and interpret hand gestures. Finally, the multimodal fusion stage aligns and fuses the data, creating a unified representation that captures the spatial and temporal aspects of hand gestures, enabling real-time control commands for the UAV. Experimental results demonstrate the system‘s effectiveness in accurately recognizing and responding to hand gestures. The multimodal fusion of FMCW radar and vision sensors enables a robust and versatile gesture-based control interface.
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PRATIWI, HANA, MUJIB RAMADAN HIDAYAT, AHMAD FATHAN MAARIF, ALOYSIUS ADYA PRAMUDITA, and FIKY YOSEP SURATMAN. "Radar FMCW dengan IQ Demodulator Jamak untuk Deteksi Pernafasan pada Pengaruh Clutter." ELKOMIKA: Jurnal Teknik Energi Elektrik, Teknik Telekomunikasi, & Teknik Elektronika 8, no. 1 (January 31, 2020): 125. http://dx.doi.org/10.26760/elkomika.v8i1.125.
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ABSTRAK
Pada pendeteksian pernafasan menggunakan sistem radar maka adanya pantulan dari sejumlah objek statis di sekitar target akan memberikan pengaruh pada hasil pendeteksian. Modifikasi pada sistem FMCW telah diusulkan untuk memberikan kemampuan dalam mendeteksi pernafasan multi target. Konsep deteksi fasa dilaborasi pada metode usulan untuk menghadirkan kemampuan deteksi pergeseran kecil. IQ demodulator jamak diusulkan sebagai konsep
modifikasi pada sistem FMCW untuk permasalah tersebut. Pengujian kemampuan sistem usulan pada kondisi clutter dilakukan dengan melakukan kajian teoritis dan simulasi komputer. Pengujian dilakukan pada kawasan waktu dan kawasan frekuensi. Hasil-hasil yang diperoleh menunjukkan bahwa metode IQ demodulator jamak yang diusulkan memiliki kemampuan dalam mendeteksi pernafasan secara multi target dan mampu mempertahankan kemampuan tersebut pada kondisi adanya clutter.
Kata kunci: deteksi pernafasan, multi target, FMCW, IQ demodulator, clutter
ABSTRACT
In the detection of respiration using a radar system, the reflection of static objects around the target will have an effect to the detection results. Modifications to the FMCW system have been proposed to provide the ability to detect multi-target respiration. The concept of phase detection is elaborated on the proposed method to provide small shift detection capabilities. Multiple IQ demodulator is proposed as a modified concept on the FMCW system for this problem. Testing the ability of the proposed system under clutter conditions is carried out by conducting theoretical studies and computer simulations. Tests carried out in the time zone and frequency region. The results obtained indicate that the proposed multiple-method IQ demodulator has the ability to detect multi-target respiration and is able to maintain that ability in the presence of clutter.
Keywords: respiration detection, multi target, FMCW, IQ demodulator, clutter
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Geng, Ziwei, Longfei Yin, Dasheng Qian, Guohua Wu, and Bin Luo. "Noise suppression of FMCW lidar." Journal of Physics: Conference Series 2480, no. 1 (April 1, 2023): 012001. http://dx.doi.org/10.1088/1742-6596/2480/1/012001.
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Abstract Aiming at the problem that the ranging accuracy of the frequency-modulated continuous wave (FMCW) lidar decreases in the strong noise environment, experiments are carried out to verify the feasibility of the Faraday anomalous dispersion filter (FADOF) in the FMCW lidar system. The transmitter of the system uses the potassium atom vapor cell to stabilize the frequency and uses the field programmable gate array (FPGA) as the servo system. K-FADOF is used to suppress the additive noise at the receiving end of the lidar system. The results of this experiment show that the use of FADOF can successfully eliminate the interference of noise at the receiver. This experiment verifies the effectiveness of FADOF in suppressing noise in the field of FMCW lidar.
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Meta, Adriano, Peter Hoogeboom, and Leo P. Ligthart. "Signal Processing for FMCW SAR." IEEE Transactions on Geoscience and Remote Sensing 45, no. 11 (November 2007): 3519–32. http://dx.doi.org/10.1109/tgrs.2007.906140.
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SALOUS, S., and N. NIKANDROU. "Architecture for advanced FMCW sounding." International Journal of Electronics 84, no. 5 (May 1998): 429–36. http://dx.doi.org/10.1080/002072198134535.
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Marshall, Hans-Peter, and Gary Koh. "FMCW radars for snow research." Cold Regions Science and Technology 52, no. 2 (April 2008): 118–31. http://dx.doi.org/10.1016/j.coldregions.2007.04.008.
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Stove, A. G. "Erratum: Linear FMCW radar techniques." IEE Proceedings F Radar and Signal Processing 140, no. 2 (1993): 137. http://dx.doi.org/10.1049/ip-f-2.1993.0019.
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Gao, Jiaqi, Wuping Zhou, and Xiaozhi Wang. "DopplerPTNet: Object Detection Network with Doppler Velocity Information for FMCW LiDAR Point Cloud." Journal of Physics: Conference Series 2809, no. 1 (August 1, 2024): 012006. http://dx.doi.org/10.1088/1742-6596/2809/1/012006.
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Abstract In the field of autonomous driving, LiDAR plays a crucial role in perception and detection. LiDAR based on Time-of-Flight (ToF) mode can only provide three-dimensional spatial coordinate information of point clouds. In point cloud object detection, the limited feature information of spatial coordinates to some extent restricts the further optimization and improvement of algorithm detection performance. However, LiDAR based on Frequency-Modulated Continuous-Wave (FMCW) mode can not only obtain the three-dimensional spatial coordinates of point clouds, but also directly measure the Doppler velocity information of points, effectively compensating for the limitation of relying solely on spatial coordinate information for object recognition. Therefore, based on the CARLA simulator, we construct the first FMCW LiDAR point cloud object detection simulation dataset, FMCWLidDet. What’s more, a novel 4D object detection algorithm, DopplerPTNet, is proposed based on the direct acquisition of point Doppler velocity information by FMCW LiDAR. The algorithm solves the problem of single spatial coordinate information feature in existing 3D object detection algorithms, which makes it difficult to further improve detection accuracy. The dataset is available at https://github.com/xilight123/FMCW-LiDAR-object-detection-dataset.
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Kim, Sangdong, Bongseok Kim, Youngseok Jin, and Jonghun Lee. "Human Identification by Measuring Respiration Patterns Using Vital FMCW Radar." Journal of Electromagnetic Engineering and Science 20, no. 4 (October 31, 2020): 302–6. http://dx.doi.org/10.26866/jees.2020.20.4.302.
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This letter proposes a method of human identification that measures respiration patterns using frequency-modulated continuous wave (FMCW) radar. We exploit the fact that respiration signal patterns are unique to each individual, and FMCW radar is employed to obtain the respiration information. Based on the strengths of FMCW radar, the proposed algorithm compensates for the inability to distinguish the respiration signals of multiple users, which are difficult for continuous wave radar to measure. The proposed algorithm also employs a deep neural network algorithm instead of the K-nearest neighbor algorithm that was used in a previous study. The proposed algorithm further improves the performance by using a least mean square filter in the input signal of the DNN. The experimental results show that the proposed human identification method successfully classified four persons.
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Hinz, J. O., and U. Zölzer. "A MIMO FMCW radar approach to HFSWR." Advances in Radio Science 9 (July 29, 2011): 159–63. http://dx.doi.org/10.5194/ars-9-159-2011.
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Abstract. In this paper we propose one possible approach how to apply the concept of multiple-input multiple-output (MIMO) to monostatic Frequency Modulated Continuous Wave (FMCW) High-Frequency Surface Wave Radar (HFSWR) in a maritime environment. Common tasks for a HFSWR are sea-state monitoring and ship detection, where our focus is on ship detection. A limiting factor in HFSWR is the available bandwidth, which is inversely proportional to the range resolution capability of the radar and typical below 100 kHz. The question is how to extend or combine a conventional single-input multiple-output (SIMO) FMCW phased-array type radar with stretch processing and the colocated MIMO concept to "reuse" the very limited HF radar band resources. Another important question to answer is how MIMO FMCW waveforms can be separated at the receiver.
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Li, Meng, Mengpeng Hu, Hui Zhang, Jianing Wang, Tongyu Tang, Mai Hu, and Qiang Wang. "All-Fiber Photoacoustic Gas Sensing with Interferometric Location." Photonics 9, no. 8 (August 3, 2022): 546. http://dx.doi.org/10.3390/photonics9080546.
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Photoacoustic spectroscopy (PAS) is a promising gas detection technique with high sensitivity, fast response, and good stability. Frequency-modulated continuous-wave (FMCW) interferometry offers precise distance detection with high spatial resolution. The combination of PAS and FMCW may lead to an optical technique for the simultaneous extraction of gas concentration and location information. Herein, we demonstrate this technique in an all-fiber sensing system by blending a fiber-pigtailed PAS sensor with an FMCW interferometer. As an example, we have measured the methane concentration and location by employing time-division multiplexing, showing a minimum detection limit of 28 ppm and a spatial resolution of 3.87 mm over a distance of ~4.9 m. This study enables the realization of a versatile technique for multiparameter gas sensing in gas leakage detection and gas emission monitoring.
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Jahn, Martin, and Andreas Stelzer. "A 120 GHz FMCW radar frontend demonstrator based on a SiGe chipset." International Journal of Microwave and Wireless Technologies 4, no. 3 (April 19, 2012): 309–15. http://dx.doi.org/10.1017/s1759078712000323.
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This paper presents a frequency-modulated continuous-wave (FMCW) radar operating at 120 GHz, which features silicon–germanium (SiGe) chips that employ HBTs with 320 GHz fmax. The chipset comprises a fundamental-wave signal-generation chip with a voltage-controlled oscillator (VCO) that provides frequencies between 114 and 130 GHz and a corresponding dual–transceiver (TRX) chip that supports monostatic and quasi-monostatic radar configurations. The cascode amplifiers used in the TRX chip were characterized in separate test chips and yielded peak small-signal gains of approximately 15 dB. Finally, a quasi-monostatic two-channel FMCW radar frontend with on-board differential microstrip antennas was built on an RF substrate. FMCW radar measurements with frequency chirps from 116 to 123 GHz verified the functionality of the designed radar sensor.
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Sheng, Li Wen, Yan Ling Xiong, Wen Long Yang, Shuo Duo Li, Xue Ming Jin, and Li Wang. "Fiber Bragg Grating Sensor Multiplexing System Based on FMCW." Applied Mechanics and Materials 336-338 (July 2013): 232–38. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.232.
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The addressing principle of distributed optical fiber Bragg grating (FBG) sensor based on frequency modulation continuous wave (FMCW) multiplexing technology was studied. The effect of grating position information, scanning time and scanning frequency range on the spectrum signals was analyzed by simulation. The FMCW multiplexing system, which was composed of the arbitrary waveform generator, light intensity modulator and multiplier etc, was established and the certifications were delivered by the experimental system.
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Zhang, Yongqiang, Xiaopeng Li, Guilei Ma, Jinlong Ma, Menghua Man, and Shanghe Liu. "A New Model for Human Running Micro-Doppler FMCW Radar Features." Applied Sciences 13, no. 12 (June 15, 2023): 7190. http://dx.doi.org/10.3390/app13127190.
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Human body detection is very important in the research of automotive safety technology. The extraction and analysis of human micro-motion based on frequency-modulated continuous wave (FMCW) radar is gradually receiving attention. Aimed at the modulation effect of human micro-motion on FMCW radar, a human running model is proposed to study human radar characteristics. According to the scattering characteristics of rigid bodies, the analytical expression of human running radar echoes is established. By using time–frequency analysis, the micro-Doppler features in the radar echoes are extracted during the running period. Under running conditions, the micro-Doppler characteristics of key components are studied. This model is applied to the real FMCW radar verification platform, and the runners are measured at a distance of 10 m. The fit rate of all parts of the human body can reach above 90%. The overall fit rate of the human model can reach up to 90.6%. The model proposed is a realistic and simple human kinematic model. This model, which can realize the real simulation of a running human body and provide strong support for human target radar echo analysis, can fill the deficiency of FMCW radar technology in the complex motion model.
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Choi, Ho-Ik, Woo-Jin Song, Heemang Song, and Hyun-Chool Shin. "Selecting Target Range with Accurate Vital Sign Using Spatial Phase Coherency of FMCW Radar." Applied Sciences 11, no. 10 (May 15, 2021): 4514. http://dx.doi.org/10.3390/app11104514.
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Respiration and heartbeat are basic indicators of the physiological state of human beings. Frequency-modulated continuous wave (FMCW) radar can sense micro-displacement in the human body surface without contact, and is used for vital-sign (respiration and heartbeat) monitoring. For the extraction of vital-sign, it is essential to select the target range containing vital-sign information. In this paper, we exploit the coherency of phase in different range-bins of FMCW radar to effectively select the range-bins that contain accurate signals for remote monitoring of human respiration and heartbeat. To quantify coherency, the spatial phase coherency (SPC) index is introduced. The experimental results show that the SPC can select a range-bin containing more accurate vital-sign signals than conventional methods. This result demonstrates that the proposed method is accurate for monitoring of vital signs by using FMCW radar.
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Häfner, Stephan, and Reiner Thomä. "Identification of Linear Time Invariant Systems Using FMCW Signals and Stretch Processing Receivers." International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems 8, no. 2 (July 16, 2019): 35. http://dx.doi.org/10.11601/ijates.v8i2.276.
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The paper deals with the identification of linear time invariant (LTI) systems by a special observer. An observer emitting an frequency modulated continuous wave (FMCW) signal and having a stretch processor as receiver will be considered for system identification. A thorough derivation of the gathered baseband signal for arbitrary LTI systems will be given. It is shown, that the received signal is approximately given by the transfer function of the LTI system over the frequency sweep of the FMCW signal. The proof relies on an infinite large time-bandwidth product of the transmit signal, such that errors remain in practical applications with a finite time-bandwidth product. Monte–Carlo simulations are conducted to verify the approximation and to quantify its accuracy and remaining errors. The findings are important for e.g. calibration or derivation of a device model in FMCW radar applications.
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Edwar, E., and Achmad Munir. "Prototype of Dual DDS FMCW Transmitter for L-Band Synthetic Aperture Radar." Journal of Measurements, Electronics, Communications, and Systems 4, no. 1 (June 30, 2018): 8. http://dx.doi.org/10.25124/jmecs.v4i1.1694.
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One of the popular remote sensing technique is remote sensing using radar technology such as Synthetic Aperture Radar (SAR). In this paper, a compact SAR prototype transmitter was designed so it could be installed in small platform. This SAR transmitter was designed to generate a frequency modulated continuous wave (FMCW) using direct digital synthesizer (DDS) integrated with RF front end modules such as analog filter and power amplifier. The bandwidth of the radar spectrum is 10 MHz, and the carrier frequency used is 1.27 GHz. The L-Band has been chosen as the carrier signal in order to detect the target (trees). The payload was designed for aerial vehicle, hence the choice of components should be as small as possible. The FMCW-SAR transmitter was implemented by using DDS module AD9850 and integrated with another RF component. The FMCW-SAR transmitter produces the transmit power about -17.67 dBm.
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Kim, Bong-seok, Sangdong Kim, Youngseok Jin, and Jonghun Lee. "Low-Complexity Joint Range and Doppler FMCW Radar Algorithm Based on Number of Targets." Sensors 20, no. 1 (December 20, 2019): 51. http://dx.doi.org/10.3390/s20010051.
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A low-complexity joint range and Doppler frequency-modulated continuous wave (FMCW) radar algorithm based on the number of targets is proposed in this paper. This paper introduces two low-complexity FMCW radar algorithms, that is, region of interest (ROI)-based and partial discrete Fourier transform (DFT)-based algorithms. We find the low-complexity condition of each algorithm by analyzing the complexity of these algorithms. From this analysis, it is found that the number of targets is an important factor in determining complexity. Based on this result, the proposed algorithm selects a low-complexity algorithm between two algorithms depending the estimated number of targets and thus achieves lower complexity compared two low-complexity algorithms introduced. The experimental results using real FMCW radar systems show that the proposed algorithm works well in a real environment. Moreover, central process unit time and count of float pointing are shown as a measure of complexity.
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Yoo, Young-Keun, Chae-Won Jung, and Hyun-Chool Shin. "Unsupervised Detection of Multiple Sleep Stages Using a Single FMCW Radar." Applied Sciences 13, no. 7 (March 31, 2023): 4468. http://dx.doi.org/10.3390/app13074468.
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The paper proposes a unsupervised method for detecting the three stages of sleep—wake, rapid eye movement (REM) sleep, and non-REM sleep—using biosignals obtained from a 61 GHz single frequency modulated continuous wave (FMCW) radar. To detect the subject’s sleep stages based on non-learning techniques, the breathing and movement information characteristic of each sleep stage was extracted from the radar signals of the subject acquired in the sleep state and used as the feature factor tailored to the research objective. The experimental results derived from the clinical data obtained in the actual polysomnography (PSG) environment using FMCW radar show an average of 68% similarity to the actual three sleep stages observed in PSG. These results indicate the feasibility of using the FMCW radar sensor as an alternative to the conventional PSG-based method that poses multiple limitations to sleep-stage detection.
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Milovanovic, Vladimir. "On fundamental operating principles and range-doppler estimation in monolithic frequency-modulated continuous-wave radar sensors." Facta universitatis - series: Electronics and Energetics 31, no. 4 (2018): 547–70. http://dx.doi.org/10.2298/fuee1804547m.
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The diverse application areas of emerging monolithic noncontact radar sensors that are able to measure object?s distance and velocity is expected to grow in the near future to scales that are now nearly inconceivable. A classical concept of frequency-modulated continuous-wave (FMCW) radar, tailored to operate in the millimeter-wave (mm-wave) band, is well-suited to be implemented in the baseline CMOS or BiCMOS process technologies. High volume production could radically cut the cost and decrease the form factor of such sensing devices thus enabling their omnipresence in virtually every field. This introductory paper explains the key concepts of mm-wave sensing starting from a chirp as an essential signal in linear FMCW radars. It further sketches the fundamental operating principles and block structure of contemporary fully integrated homodyne FMCW radars. Crucial radar parameters like the maximum unambiguously measurable distance and speed, as well as range and velocity resolutions are specified and derived. The importance of both beat tones in the intermediate frequency (IF) signal and the phase in resolving small spatial perturbations and obtaining the 2-D range-Doppler plot is pointed out. Radar system-level trade-offs and chirp/frame design strategies are explained. Finally, the nonideal and second-order effects are commented and the examples of practical FMCW transmitter and receiver implementations are summarized.
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Sun, Bin, Junfang Song, Gang Zheng, and Xiongxing Zhang. "Application Research of Frequency-Modulated Continuous-Wave Displacement Sensor Based on Zero-Crossing Phase Detecting Algorithm." International Journal of Optics 2021 (March 22, 2021): 1–9. http://dx.doi.org/10.1155/2021/6669539.
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Frequency-modulated continuous-wave (FMCW) interference, as a new technology of laser interferometry, has the advantages of length traceability, large range, high accuracy, simple structure, and optical fiber transmission. Based on the formula of FMCW laser interference displacement, a zero-crossing phase detection algorithm is proposed, which can accurately calculate the initial phase of a cosine signal in a modulation period, and it is successfully applied to the contact laser interference displacement sensor. The experimental results show that the FMCW technology based on the zero-crossing phase detection algorithm can achieve the technical specifications of the contact displacement sensor with a measurement range greater than 15 mm and the standard deviation is less than 0.01 μm. The conversion of noncontact measurement to contact measurement can realize the direct measurement of workpieces with complex surface conditions on the production line, breaking through the limitation of optical measurement and expanding the application of optical fiber interferometry.
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Bi, Hui, Hao Li, and Wei Liang. "High-Squint FMCW SAR Imaging via Wavenumber Domain Algorithm." Wireless Communications and Mobile Computing 2021 (April 2, 2021): 1–7. http://dx.doi.org/10.1155/2021/5551674.
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Nowadays, because the frequency modulation continuous-wave (FMCW) synthetic aperture radar (SAR) shows good potential in minimal transmission power and weight reduction of radar systems, it has been widely used and has become a common technique in modern short-range high-resolution earth observation. Different from the conventional pulsed mode, the stop-to-go approximation is not valid in FMCW SAR. Thus, the typical SAR imaging methods need to be modified to adapt the continuous-wave scheme in practical data processing. In this letter, a wavenumber domain algorithm (WDA) is derived and used for the FMCW SAR imaging under squint and high-squint cases. With the help of the exact scene recovery ability of the proposed WDA, we can achieve the accurate recovery of the considered scene even when using the collected high-squint data and hence obtain the well-focused high-resolution image of the considered scene. Experimental results with simulated and airborne data verify the effectiveness of the proposed method.
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Liu, Bing, and Xinhong Hao. "Research on Anti-Frequency Sweeping Jamming Method for Frequency Modulation Continuous Wave Radio Fuze Based on Wavelet Packet Transform Features." Applied Sciences 12, no. 17 (August 30, 2022): 8713. http://dx.doi.org/10.3390/app12178713.
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Frequency modulation continuous wave (FMCW) radio fuze is widely used in military equipment, due to its excellent range and anti-jamming ability. However, the widespread use of radio fuze jammers on modern battlefields poses a serious threat to fuzes. In this study, a classification method of targeting and sweeping frequency jamming signals of FMCW radio fuze based on wavelet packet transform features is proposed, which improves the anti-jamming ability of fuze. The wavelet packet transform of the output signal of the radio fuze detector is used to form a feature vector, which is fed into a support vector machine for targeting and jamming signal classification. The experimental results of the measured data show that the proposed method can achieve a high accuracy rate of classification and identification of FMCW radio fuze targets and frequency sweeping jamming signals. The highest recognition accuracy reached is 98.81% ± 0.0037. The lowest false alarm probability is 0.57% ± 0.0043, which indicates its potential application values in the near future.