Frequency Interval Research Articles

Theoretical analysis and experiment of multi-modal coupled vibration of piezo-driven Π-shaped resonator

Nonlinear modal interactions have recently become the focus of intense research in mechanical resonators for their use to improve oscillator performance and probe the frontiers of fundamental physics. This paper reports for the first time a piezoelectric driven Π-shaped beam with 1:1:2 internal resonance and systematically studies the multi-mode coupling dynamic behavior. Typically, the influence mechanism of driving voltage on the energy transfer path of the multi-modal vibration is experimentally observed. With the increase of the driving voltage, number of frequency intervals of modal coupled vibration increases from 1 to 3, and then decreases to 2, which is unique to multi-mode coupled resonators. To explain the various complex nonlinear phenomena observed experimentally, a theoretical framework for multi-modal coupled vibration analysis of Π-shaped resonator is proposed for the first time. Perturbation and bifurcation analysis are introduced to deduce the discriminant formula of multi-modal coupled vibration theoretically. Both experimental measurements and theoretical predictions show that the multi-modal coupling greatly complicates the dynamic behavior of the resonant system and induces multiple amplitude jumps. In particular, based on the multi-modal coupled vibration behavior of the Π-shaped resonator, a conceptual model of trigger resonance sensor with multiple mass warnings is creatively proposed. The experimental results show that the amplitude of the resonant system has six distinct changes with the increase of the added mass, accompanied by bifurcation phenomenon. The research results of this paper provide a systematic framework for the development of multi-mode coupled resonant devices.

A meta-analysis on the characteristics of placebo effects on urinary function in placebo-controlled clinical trials among Japanese patients.

This study aimed to assess the effect sizes, changes over time, and ethnic differences in placebo effects on urinary function among Japanese patients participating in clinical trials. A meta-analysis of 30 Japanese placebo-controlled clinical trials was conducted to determine the placebo effects on three functions: daily urinary frequency, nocturnal urinary frequency, and average urine volume per void. The I-square heterogeneity values for the basic values of the three functions ranged from 84.5% to 97.9%, with differences among trials. Longitudinal analysis (1 to 12 weeks) indicated an enhanced placebo effect for up to 8 weeks and no consistency among trials on nocturnal urinary frequency (p < 0.01), unlike those on daily urinary frequency and average urine volume per void (p=1.0). Based on the random-effects model, the mean differences in urinary frequency at 4, 8, and 12 weeks were -0.70 (-0.80; -0.60), -1.06 (-1.16; -0.96), and -1.18 (-1.34; -1.01), respectively. Furthermore, the mean difference (95% confidence interval) in nocturnal urinary frequency and volume of urination per void at 12 weeks was -0.63 (-0.94; -0.31) and 9.67 (7.25; 12.1), respectively. My findings suggest an increase in the strength of placebo effects over time (up to 8 weeks). A comparison of my results to those published in previous global reports showed no meaningful differences in placebo effects among ethnic groups. The consistent placebo effect size on urinary function could be an external indicator in clinical trials.

Few-cycle THz wave manipulation with a high degree of freedom via f-t modulation.

THz waves have been intensively applied in many fields, e.g., spectroscopy, imaging, and communications. However, owing to the rarity of available techniques for manipulating circularly polarized few-cycle THz waves on picosecond time scales, most of the current studies are conducted with linearly polarized THz waves. Here we demonstrate circularly polarized (CP) THz (dual) pulses generated by a polarization-twisting pulse/dual pulse (PTP/PTDP). The polarization-twisting optical dual pulses can be generated via a modified Michelson interferometer (MI) system, which provides the ability to control the frequency, helicity, and time interval of the dual pulses arbitrarily and individually. Such a novel, to the best of our knowledge, modulation technique shows huge potential for applications, not only in imaging and spectroscopy but also in next-generation communications.

Non-destructive detection of adulteration of weight-loss drugs in the field of spectral feature fusion

To crack down on criminals using the delivery channel to transport weight-loss drugs doped with toxic and harmful nonfood raw materials, a pattern recognition method of weight-loss drugs based on terahertz time-domain spectroscopy was proposed. Compared with traditional methods, terahertz spectrum had high signal-to-noise ratio in time-domain spectrum, which was fast, time-saving and lossless. In this study, seven kinds of weight-loss drugs were selected as experimental samples. The terahertz time-domain spectra of the samples were collected. Three characteristic frequency intervals of 0–0.19, 1.75–2.14 and 2.23–2.5 (THz) were found by automatic peak finder. The characteristic frequency intervals were processed by Hilbert transform, Butterworth low-pass filter, fast Fourier transform low-pass filter and the first-order derivatives after standard normal transform, the feature data was fused with the original spectra, and the original data and the data fused by the four methods were classified and recognized by particle swarm optimization least squares support vector machine and extreme learning machine model optimized by Cuckoo algorithm. The experimental results showed that the particle swarm optimization least squares support vector machine model had the best recognition effect on the spectral feature fusion data after Hilbert transform, and the accuracy can reach 100 %. It had a certain reference significance for the identification of weight-loss drugs in forensic science.

Multi-Timeslot Wide-Gap Frequency-Hopping RFPA Signal and Its Sidelobe Suppression

Random frequency and pulse repetition interval agile (RFPA) signals have excellent anti-jamming ability and achieve low probability of intercept (LPI), making them promising for applications in radar systems. However, their matched filter (MF) outputs suffer from random range-velocity sidelobes. In the range dimension, these sidelobes can be classified into two categories: the distant sidelobe floor spread out beyond the minimum interval between pulses, and the near sidelobe plateau confined within about one pulsewidth. These sidelobes seriously degrade the target detection capability of RFPA signals. To address this issue, we propose the concept of a multi-timeslot wide-gap frequency-hopping sequence (multi-timeslot WGFHS) and use it in the design of RFPA signals. In doing so, the distant sidelobes are easily suppressed with a simple low-pass filter (LPF) in the receiver if the parameters of the multi-timeslot WGFHS are chosen properly, while the remaining near sidelobes are suppressed by the iterative adaptive approach based on matched filter outputs (MF-IAA). Simulation results show that the proposed method can effectively suppress the sidelobes of RFPA signals, accurately recover the range-velocity images, and successfully detect weak targets in the presence of strong targets or clutter.

Effect of a Strong Local Atmospheric Perturbation on the Propagation of Low-Frequency Electromagnetic Waves in the Earth Ionosphere

Coefficients of reflection and transmission of electromagnetic waves in a frequency interval of 1–10 kHz are numerically calculated for the passage through a flat inhomogeneous layer of the lower ionosphere in the presence of a strong local perturbation of the atmosphere. A point source of energy is used to simulate the perturbation. When the perturbation passes through the layer of the lower ionosphere, the wave transmission coefficient sharply decreases within 1–2 min while the diagonal components of the matrix of reflectioncoefficients increase to almost unity.

Consequences of Real-World Surveillance of Fellow Eyes in Neovascular Age-Related Macular Degeneration.

This study investigated whether the interval of monitoring at-risk, fellow eyes of patients with unilateral neovascular age-related macular degeneration (nAMD) has any bearing on the severity of the disease at the time of diagnosis. The study comprised a retrospective, cross-sectional comparative case series of treatment-naïve eyes in patients who were diagnosed sequentially with nAMD. We compared the visual acuity (VA) and central macular thickness (CMT) of patients who were actively receiving intravitreal injections (IVIs) of anti-vascular endothelial growth factor (anti-VEGF) agents at the time of second eye diagnosis with the VA and CMT of patients who had ceased treatment in their first eye because of reaching end-stages of disease. Intervals of visits and frequency of monitoring the macula of fellow eyes by means of optical coherence tomography (OCT) were abstracted from the medical record. We found that the at-risk fellow eyes of patients who had stopped treatment for nAMD in their first eye prior to fellow eye conversion were monitored significantly less frequently than the fellow eyes of patients who continued to receive treatment at the time of second eye diagnosis. Despite less frequent monitoring, VA and CMT were similar at the time of fellow eye diagnosis for both groups.

Commissioning of the Iseult CEA 11.7 T whole-body MRI: current status, gradient–magnet interaction tests and first imaging experience

ObjectivesThe Iseult MRI is an actively shielded whole-body magnet providing a homogeneous and stable magnetic field of 11.7 T. After nearly 20 years of research and development, the magnet successfully reached its target field strength for the first time in 2019. This article reviews its commissioning status, the gradient–magnet interaction test results and first imaging experience.Materials and methodsVibration, acoustics, power deposition in the He bath, and field monitoring measurements were carried out. Magnet safety system was tested against outer magnetic perturbations, and calibrated to define a safe operation of the gradient coil. First measurements using parallel transmission were also performed on an ex-vivo brain to mitigate the RF field inhomogeneity effect.ResultsAcoustics measurements show promising results with sound pressure levels slightly above the enforced limits only at certain frequency intervals. Vibrations of the gradient coil revealed a linear trend with the B0 field only in the worst case. Field monitoring revealed some resonances at some frequencies that are still under investigation.DiscussionGradient-magnet interaction tests at up to 11.7 T are concluded. The scanner is now kept permanently at field and the final calibrations are on-going to pave the road towards the first acquisitions on volunteers.

Analysis of the Impact of Vibrations on a Micro-Hydraulic Valve Using a Modified Induction Algorithm

This paper addresses the impact of mechanical vibrations of different frequencies on a particular type of valve. It has been shown that a neural network can be used to compress measurement data and determine the frequency range that is most important in describing the impact of mechanical vibrations on a micro-hydraulic overflow valve. Later, induction decision trees were used for the generated areas, determining key measurement points. The most important areas of dependence are determined using inductive decision trees in induction. The entropy measure is used to determine the most significant attribute. A modified induction algorithm was used for the comprehensive analyses. The analysis carried out in the paper identified the intervals in which the flow rate plays a decisive role for the entire amplitude and frequency spectrum. An analysis was performed for the 200…900 [Hz] frequency interval of the external driving force, with a harmonic step of 10 [Hz]. The analysis was performed while considering these main valve parameters: the pressure of the overflow valve opening p = 10 [MPa]; flow rate in the valve: 0.6, 0.8 and 1 [dm3/min]; stiffness of valve spring c = 7.49 [N/mm]. Plots were presented and for each plot, the most important four intervals were determined. They are hierarchically ordered in the interval range of the whole frequency spectrum range: (coefficient IV)—the most important; (coefficient III)—important; (coefficient II)—less important; (coefficient I)—least important. A test rig and the results of a study on the effect of mechanical vibration on changes in the amplitude-frequency spectrum of pressure pulsations of a micro-hydraulic system, in which a micro-hydraulic relief valve was subjected to mechanical vibration, are presented.

Laterality of blood perfusion in the lower extremities after drinking saline at different temperatures

Skin blood flux (SkBF) changes caused by drinking cold water are generally associated with vagal tone and osmotic factors in the digestive system. However, there is still a lack of relevant research on whether there are left and right differences in these SkBF change. In the current study, a total of 60 subjects were recruited. Skin blood perfusion of the bilateral lower extremities was recorded simultaneously before and after drinking saline of different temperatures saline by using Laser Doppler flowmetry (LDF). The electrogastrogram (EGG) was also monitored, and the dominant frequency of the EGG and heart rate variability were analyzed. The results indicated that after drinking saline, the laterality index of SkBF at the lower extremities was different and the laterality index changes of SkBF were mainly reflected in the frequency interval V (0.4–1.6 Hz). There was a weak negative correlation between the laterality index of endothelial NO-dependent component and change rate of root mean square of successive differences (RMSSD) after drinking 4 °C saline. However, after drinking 30 °C saline, there was a weak positive correlation between neurogenic component and RMSSD The distribution and regulation of bilateral blood flow are not symmetrical but exhibit a certain laterality.

Wavelet analysis of laser Doppler microcirculatory signals: Current applications and limitations.

Laser Doppler flowmetry (LDF) has long been considered a gold standard for non-invasive assessment of skin microvascular function. Due to the laser Doppler (LD) microcirculatory signal's complex biological and physiological context, using spectral analysis is advisable to extract as many of the signal's properties as feasible. Spectral analysis can be performed using either a classical Fourier transform (FT) technique, which has the disadvantage of not being able to localize a signal in time, or wavelet analysis (WA), which provides both the time and frequency localization of the inspected signal. So far, WA of LD microcirculatory signals has revealed five characteristic frequency intervals, ranging from 0.005 to 2Hz, each of which being related to a specific physiological influence modulating skin microcirculatory response, providing for a more thorough analysis of the signals measured in healthy and diseased individuals. Even though WA is a valuable tool for analyzing and evaluating LDF-measured microcirculatory signals, limitations remain, resulting in a lack of analytical standardization. As a more accurate assessment of human skin microcirculation may better enhance the prognosis of diseases marked by microvascular dysfunction, searching for improvements to the WA method is crucial from the clinical point of view. Accordingly, we have summarized and discussed WA application and its limitations when evaluating LD microcirculatory signals, and presented insight into possible future improvements. We adopted a novel strategy when presenting the findings of recent studies using WA by focusing on frequency intervals to contrast the findings of the various studies undertaken thus far and highlight their disparities.

SENSIPLUS-LM: A Low-Cost EIS-Enabled Microchip Enhanced with an Open-Source Tiny Machine Learning Toolchain

The technological step towards sensors’ miniaturization, low-cost platforms, and evolved communication paradigms is rapidly moving the monitoring and computation tasks to the edge, causing the joint use of the Internet of Things (IoT) and machine learning (ML) to be massively employed. Edge devices are often composed of sensors and actuators, and their behavior depends on the relative rapid inference of specific conditions. Therefore, the computation and decision-making processes become obsolete and ineffective by communicating raw data and leaving them to a centralized system. This paper responds to this need by proposing an integrated architecture, able to host both the sensing part and the learning and classifying mechanisms, empowered by ML, directly on board and thus able to overcome some of the limitations presented by off-the-shelf solutions. The presented system is based on a proprietary platform named SENSIPLUS, a multi-sensor device especially devoted to performing electrical impedance spectroscopy (EIS) on a wide frequency interval. The measurement acquisition, data processing, and embedded classification techniques are supported by a system capable of generating and compiling code automatically, which uses a toolchain to run inference routines on the edge. As a case study, the system capabilities of such a platform in this work are exploited for water quality assessment. The joint system, composed of the measurement platform and the developed toolchain, is named SENSIPLUS-LM, standing for SENSIPLUS learning machine. The introduction of the toolchain empowers the SENSIPLUS platform moving the inference phase of the machine learning algorithm to the edge, thus limiting the needs of external computing platforms. The software part, i.e., the developed toolchain, is available for free download from GitLab, as reported in this paper.

QUIJOTE scientific results – IX. Radio sources in the QUIJOTE-MFI wide survey maps

ABSTRACT We present the catalogue of Q-U-I JOint TEnerife (QUIJOTE) Wide Survey radio sources extracted from the maps of the Multi-Frequency Instrument compiled between 2012 and 2018. The catalogue contains 786 sources observed in intensity and polarization, and is divided into two separate sub-catalogues: one containing 47 bright sources previously studied by the Planck collaboration and an extended catalogue of 739 sources either selected from the Planck Second Catalogue of Compact Sources or found through a blind search carried out with a Mexican Hat 2 wavelet. A significant fraction of the sources in our catalogue (38.7 per cent) are within the |b| ≤ 20° region of the Galactic plane. We determine statistical properties for those sources that are likely to be extragalactic. We find that these statistical properties are compatible with currently available models, with a ∼1.8 Jy completeness limit at 11 GHz. We provide the polarimetric properties of (38, 33, 31, 23) sources with P detected above the $99.99{{\ \rm per\, cent}}$ significance level at (11, 13, 17, 19) GHz respectively. Median polarization fractions are in the 2.8–4.7 per cent range in the 11–19 GHz frequency interval. We do not distinguish between Galactic and extragalactic sources here. The results presented here are consistent with those reported in the literature for flat- and steep-spectrum radio sources.

Study of multi-frequency heating based on the nonlinear response characteristics of magnetron to improve uniformity

The majority of microwave ovens on the market are powered by magnetrons, which can only produce a narrow-band frequency that has a large peak, resulting in poor uniformity. A method is proposed to improve nonuniform heating based on nonlinear response characteristics of the magnetron to produce multi-frequency. First, a multi-physics model of microwave heating is established to realize the calculation of multi-frequency heating. Second, a multi-frequency heating experimental system based on the characteristics of the magnetron is built and verified with the calculated results. The results show that the calculated results are in good agreement with the experimental results. Finally, based on the multi-physics model, the influences of different parameters, such as frequency intervals, cavity size, location of the object to be heated and material properties, on microwave heating uniformity have also been discussed. The results show that the method adopted in this paper is feasible, and the heating uniformity of microwaves is improved.

Improvement of Output Power and Bandwidth for Terahertz Extended Interaction Klystron With Multiple Resonance Cavities

In this article, an extended interaction klystron (EIK) in a terahertz band with high power, high efficiency, and wide bandwidth based on a mode overlap scheme and multiple resonance cavities is proposed. The high-frequency characteristics and electric field distribution of modes in 17-gap cavity are analyzed. And <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> mode and 15/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\pi $ </tex-math></inline-formula> mode are selected as the two adjacent working modes to realize mode overlap to expand the bandwidth. The number of cavity gaps and the length ratio of long and short slots are carefully optimized to achieve the appropriate frequency interval between modes. Then the sensitivity analysis of key parameters requires that the processing tolerance of the circuit should not exceed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . The stability of the circuit is analyzed by using the normalized electronic conductance to ensure that the circuit will not produce oscillation. Finally, with the conditions of 0.3-A current, 18.5-kV voltage, and 0.02-W input power for the designed G-band six-cavity EIK, the PIC simulation results shows that the mode overlap can be achieved in different cavities, and the circuit can obtain a power of 740 W, a gain of 45.68 dB, a 3-dB bandwidth of 1.92 GHz, and an efficiency of 13.3%. The power, bandwidth, and efficiency have obvious improvement compared with other reported EIKs in the same frequency band. In addition, the consistency of the simulation results trend between AJDISK and CST also proves that the circuit we designed is reliable and feasible for the terahertz band EIKs with high performance in the future.

Генерация ЭДС магнитостатическими волнами в структуре ЖИГ(111)-Pt в слабых полях подмагничивания

In a structure of an epitaxial film of yttrium iron garnet (YIG) with crystallographic orientation (111) 11.8 μm thick and a 5 nm thick platinum (Pt) film deposited on its surface, the effect of EMF generation in a platinum film during the propagation of magnetostatic waves (MSW) in the structure was studied at values of the tangential constant magnetic field H less than the saturation field H_s~65 Oe of the YIG film. The experiments were performed in a geometry where the field H was parallel to the crystallographic direction [1¯21] and to the MSW antennas, and the distances from the input antenna to the output antenna and to the Pt film were ~5 mm and ~0.5 mm, respectively. In the structure under consideration, at |H|&lt;H_s, a stripe domain structure (SDS) was formed, which in fields |H|&lt;H_1~5 – 7 Oe acquired a branching character in the near-surface layer. In the range of fields H_1&lt;|H|&lt;H_2≈40 Oe, MSW propagation was observed in the frequency band ∆F_1~ 300-550 MHz, which was accompanied by EMF generation due to the inverse spin Hall effect. In the interval H_2&lt;|H|≤H_s, MSW propagation was observed in the frequency band ∆F_2≈ 750-1750 MHz, while the frequency interval in which the EMF signal was recorded turned out to be several times smaller due to the development of MSW parametric instability.

МОДЕЛЮВАННЯ БАГАТОПРОМЕНЕВОГО КАНАЛУ ЗВ'ЯЗКУ

In the article, the simulation of a multipath communication channel with two bands or subbands (intervals) of frequencies, the system function of which is expressed in a closed form through elliptic functions. A multipath communication channel is a linear system with time various parameters. Multipath leads to the fact that there is always a certain number of errors. They characterize the lower limit of the probability of errors, regardless of the applied methods of error-correcting coding and an unlimited increase in the energy potential of the radio link. Mathematical simulation of a multipath communication channel provides the joint consideration of time delays and Doppler frequency shift of the received signal. The correlation between the transfer function 퐻 (휔,푡) and the system function 푆 ̃(휏,휔 ̃) is shown. Іn the article at the first time, the mathematical theory of elliptic functions and elliptic integrals is applied to the definition of a system function, which in known literature sources is determined using the mathematical methods of statistical analysis. In article is shown the application an approach to mobile radio systems, which are operating in several frequency bands, such as a combined mobile digital troposcatter-radiorelay station or a digital troposcatter station. Their work is carried out in two frequency bands or two frequency subbands (transmit / receive). Therefore, in this case it becomes very difficult to create a mathematical model of a multipath communication channel with the definition of system functions. This situation is complicated if a frequency adaptation system is used. At the same time, several frequency intervals are used to combat fading and interferences, in the simplest case – two intervals. The article describes the approach to the representation of system functions through elliptic functions. This allows to have close form of the transfer function for the multipath communication channel. For the considered case of two-frequency intervals, the final expression is written in terms of theta-functions and the complete elliptic integral of the first kind.

The role of particle precipitation on plasma structuring at different altitudes by in-situ measurements

The plasma in the cusp ionosphere is subject to particle precipitation, which is important for the development of large-scale irregularities in the plasma density. These irregularities can be broken down into smaller scales which have been linked to strong scintillations in the Global Navigation Satellite System (GNSS) signals. We present power spectra for the plasma density irregularities in the cusp ionosphere for regions with and without auroral particle precipitation based on in-situ measurements from the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) mission, consisting of two sounding rockets flying simultaneously at different altitudes. The electron density measurements taken from the multi-needle Langmuir probe system (m-NLP) were analyzed for the whole flight duration for both rockets. Due to their high sampling rates, the probes allow for a study of plasma irregularities down to kinetic scales. A steepening of the slope in the power spectra may indicate two regimes, a frequency interval with a shallow slope, where fluid-like processes are dominating, and an interval with a steeper slope which can be addressed with kinetic theory. The steepening occurs at frequencies between 20 Hz and 100 Hz with a median similar to the oxygen gyrofrequency. Additionally, the occurrence of double slopes increases where precipitation starts and throughout the rest of the flight. In addition, strong electron density fluctuations were found in regions poleward of the cusp, thus in regions immediately after precipitation. Furthermore, by investigating the integrated power of the fluctuations within different frequency ranges, we show that at low frequencies (10–100 Hz), the power is pronounced more evenly while the rocket encounters particle precipitation, while at high frequencies (100–1000 Hz) fluctuations essentially coincide with the passing through a flow channel.

Новый метод ладового мультифакторного анализа музыкальной формы для систематического музыковедения. Часть 1: Интервальное масштабирование и формообразующая роль градаций дыхания и музыкальной артикуляции

This article introduces a new method to analyze the tonal organization of music. This method uses “indefinite” intervallic typology instead of “definite.” The focus is on sounds with continuous frequency modulation and fluctuating pitch and time values rather than those with discrete time and frequency intervals that remain constant throughout a music work, forming sets of pitch and interval classes and rhythmic divisions. All existing methods of musicological analysis are primarily intended for the latter kind of music and are hardly useful for analyzing timbral rather than frequency characteristics of sounds and their relative registral position rather than “definite” pitch values. Our novel approach elaborates Eduard Alexeev’s theory of musical mode evolution, corroborating it with findings of modern psychoacoustics, biomusicology, ethology, evolutionary anthropology, genetic epistemology, and cognitive sciences. We implement the latest technologies for frequency and spectral analysis of music. Not only does our approach quantify the melodic, harmonic, rhythmic, metrical, thematic, and textural patterns of TO, but it also allows such aspects of musical expression as dynamics, tempo, articulation, breathing pulse, registration, and timbre to be evaluated. This multivariate method is supposed to improve considerably the analysis of music based on both “indefinite” and “definite” pitch forms. Such a comparative multifactorial analysis is essential for establishing the pathways of the global evolution of music and its biologically ingrained universalities and distinguishing music from other types of auditory communication. To summarize, we present the methodology for identifying the intervallic typology, articulatory gradations, and breathing segmentation of the music flow.

Range-Ambiguous Clutter Suppression for Space-Based Early Warning Radar Using Vertical FDA and Horizontal EPC

The range ambiguous clutter in space-based early warning radar is more severe compared with that in airborne radar due to the faster movement velocity. Meanwhile, the clutter angle-Doppler characteristics vary with range owing to Earth’s rotation. As a result, the mainbeam clutter returned from different ambiguous range occupies most of the Doppler spectrum, which leads to the degradation of the traditional space-time adaptive processing (STAP) performance in canceling clutter. Though frequency diverse array (FDA) based on multiple-input multiple-output can provide the ability to identify the range ambiguous clutter, it cannot perform well for space-based early warning radar because of the finite available vertical elements. In this paper, a novel STAP method, which utilizes the element-pulse coding (EPC) and FDA technique to mitigate the range ambiguous clutter, is proposed. Firstly, EPC is used to pre-whiten the most range ambiguous clutter via coding and decoding in horizontal elements and coherent pulses. Then the interval in the vertical frequency of the residual range-ambiguous clutter is expanded by FDA, and thus the targets and clutter from the vertical mainlobe are easily extracted using a spatial filter with a few vertical elements. Finally, the extracted clutter can be effectively suppressed through the traditional STAP method. Simulation results are provided to demonstrate the performance of the proposed method.