Continuous-wave doppler radar

Top PDF Continuous-wave doppler radar:

Feasibility of Heartbeat Detection Behind a Wall Using CW Doppler Radar

Feasibility of Heartbeat Detection Behind a Wall Using CW Doppler Radar

Keywords—heartbeat detection; continuous wave Doppler radar; electrocardiogram; heart rate; behind wall I. I NTRODUCTION Contactless monitoring of vital signs is needed in medical surveillance applications and in healthcare [1], especially for burn patients and newly born. In addition, it can be very useful for detecting signs of life of people buried under rubble after an earthquake or tornado.

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Microwave Doppler Radar for Heart Beat Detection Versus Electrocardiogram: A Validation Approach

Microwave Doppler Radar for Heart Beat Detection Versus Electrocardiogram: A Validation Approach

the number of points for a specific trace; thus the sampling rate can be pre-determined. The operational frequency used in these measurements is 16 GHz. The choice of this frequency is made according to two reasons. The first one is to obtain higher phase variation as it is directly proportional to the frequency, and the second reason is due to the equipment’s limits (2 – 16 GHz for the antennas). An extension of the system operating at 60 GHz is described in [16, 17]. The measurements procedure starts by sending a continuous wave signal at the desired frequency. The signal is generated by the VNA and driven to the transmitting antenna, which is directed toward the person’s chest. The transmitted signal is reflected off the person chest and received by an antenna similar to the transmitter. The received signal is driven to the VNA where the phase variation of S 21 is computed. This phase corresponds to the
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Measurements of Cardiac and Cardiopulmonary Activities Using Contactless Doppler Radar

Measurements of Cardiac and Cardiopulmonary Activities Using Contactless Doppler Radar

2 IETR - UMR CNRS 6164, INSA Rennes, France Abstract-This paper presents a wireless measurement system for cardiopulmonary activity. This system generates a continuous wave signal at 2.4 GHz toward the target and then measures the reflected signal. The target is the person’s chest set at a distance of 1 m. The radar system contains a vector network analyzer, which measures the phase of S 21 . The phase variation of S 21

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Coded continuous wave meteor radar

Coded continuous wave meteor radar

Received: 29 June 2015 – Published in Atmos. Meas. Tech. Discuss.: 30 July 2015 Revised: 18 January 2016 – Accepted: 27 January 2016 – Published: 3 March 2016 Abstract. The concept of a coded continuous wave specu- lar meteor radar (SMR) is described. The radar uses a con- tinuously transmitted pseudorandom phase-modulated wave- form, which has several advantages compared to conven- tional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compres- sion gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit wave- form and they can be fairly flexibly changed after per- forming a measurement. The low signal-to-noise ratio be- fore pulse compression, combined with independent pseu- dorandom transmit waveforms, allows multiple geographi- cally separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are dis- cussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect me- teor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of me- teor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.
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KuROS: A new airborne Ku-band Doppler radar for observation of the ocean surface

KuROS: A new airborne Ku-band Doppler radar for observation of the ocean surface

(related to surface slopes) and surface velocity modulations (related to orbital modulations of the waves): for each spectral component, a positive (negative) correlation between these modulations denote waves going away from (approaching), the radar, so that the sign of the real part of this cross-spectrum gives the direction of propagation. Directional spectra of ocean waves contain information from different components related to different sources of generation (wind-waves generated locally, swell propagating from remote sites). Therefore it is essential to be able to distinguish different components in the 2D spectra. To do so, we have adapted a method based on a watershed partitioning algorithm [11] to take into account the noisy nature of the 2D spectra: while using the “watershed” method, we have applied noise reduction (averaging in wave number), discretization of energy levels, and an iterative scheme. In summary the processing of ocean wave spectra includes 4 steps:
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X-Band Polarimetric & Doppler radar observations of heavy precipitation events over the Mediterranean region (France).

X-Band Polarimetric & Doppler radar observations of heavy precipitation events over the Mediterranean region (France).

In this section the spatial variability of extreme events is investigated statistically. As previously the pdf is computed on 5 km² area in the radar domain and the value for which rain rate is exceeded for 0.01% of the whole time series is got. Figure 6 Rain rate (mm/h) exceeded for 0.01% of a year Results are given Figure 6 for all the year. They highlight regions statistically prone to extreme rainfall events. It reveals that foothills and concave regions have a higher probability to be subjected to heavy precipitation than high mountain or sea. Summer months are also (not shown) prone to heavy events because of deep convection. Such results highlight the high impact of local forcing on rainfall in this region. They could be used to choose regions were mobile stations can be deployed (area were the probability of extreme events is higher).
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Toward Continuous-Wave Regime Teleportation for Light Matter Quantum Relay Stations

Toward Continuous-Wave Regime Teleportation for Light Matter Quantum Relay Stations

F. Kaiser 1 , ∗ A. Issautier 1 , L. A. Ngah 1 , D. Aktas 1 , T. Delord 2,1 , and S. Tanzilli 1 † 1. Universit´e Nice Sophia Antipolis, Laboratoire de Physique de la Mati`ere Condens´ee, CNRS UMR 7336, Parc Valrose, 06108 Nice, France. 2. ´ Ecole Normale Sup´erieure de Lyon, 46 All´ee d’Italie, F-69364 Lyon Cedex 07, France. We report a teleportation experiment involving narrowband entangled photons at 1560 nm and qubit photons at 795 nm emulated by faint laser pulses. A nonlinear difference frequency generation stage converts the 795 nm photons to 1560 nm in order to enable interference with one photon out of the pairs, i.e., at the same wavelength. The spectral bandwidth of all involved photons is of about 25 MHz, which is close to the emission bandwidth of emissive quantum memory devices, notably those based on ensembles of cold atoms and rare earth ions. This opens the route towards the realization of hybrid quantum nodes, i.e., combining quantum memories and entanglement-based quantum relays exploiting either a synchronized (pulsed) or asynchronous (continuous- wave) scenario.
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Performance comparison of pulse-pair and wavelets methods for the pulse Doppler weather radar spectrum

Performance comparison of pulse-pair and wavelets methods for the pulse Doppler weather radar spectrum

Several methods of signal processing are worked out, others offered, to complete successfully the extraction of useful information to be transmitted to the user. The pulse-pair method acts on the Doppler radar signal in the temporal domain by autocorrelation. As for the wavelets method, it spreads out in the spectral domain while having references to time.

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Room-temperature continuous-wave opertation of GaInNAsSb laser diodes at 1.55μm

Room-temperature continuous-wave opertation of GaInNAsSb laser diodes at 1.55μm

Introduction: Recently, several reports have illustrated the promise of dilute nitride, GaAs-based lasers with continuous-wave (CW) opera- tion near 1.5 mm [1–3] . However, to adequately address the needs of long-haul fibre transmission, the output wavelength of such devices must be further red-shifted, and we recently reported pulsed operation of GaInNAsSb laser diodes at 1532 nm [4] . In this Letter we present results of GaInNAsSb=GaNAs double quantum well lasers with record CW lasing wavelength of 1553 nm at room temperature. This encouraging result suggests that further optimisation may soon lead to devices suitable for C-band operation.
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KuROS: A new airborne Ku-band Doppler radar for observation of the ocean surface

KuROS: A new airborne Ku-band Doppler radar for observation of the ocean surface

4. CONCLUSION The first results obtained with the new airborne Doppler Ku-Band radar KuROS on ocean wave spectra and normalized radar cross-section at low to medium incidence have been shown to be very consistent. The fall-off of the normalized radar cross-section with incidence agrees with results from the literature. We have shown that the speckle- free wave directional spectra obtained by using the modulation transfer function according to [2] combined with profiles of σ° with incidence angles, are consistent with directional buoy observations, both in terms of significant wave height and principal parameters of the wavenumber spectrum (mean or peak frequency and direction). As concerns the issue of the 180° ambiguity removal, the method based on the correlation between modulations of σ° and modulation of Doppler velocity within the footprint is more efficient than the one based on the analysis of cross-spectra between successive modulations of σ° separated by some time lag. Partitioning of the 2D wave spectrum has been obtained using an improved “watershed” method. With these first results, we show that KuROS is a very useful tool for the preparation of the CFOSAT mission allowing tests of various algorithms and performance evaluation. Ongoing work concerns the analysis of speckle properties as a function of surface conditions (wind, waves) and geometry of observations, as well as analysis of the Doppler measurements. The very interesting data set of these first campaigns will also be used to study wind/wave and wave/ current coupling at with a high spatial sampling (3 to 6 km). Finally, mean profiles of radar cross-section will be used to assess electromagnetic model and/or study statistical properties of short waves.
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A Continuous Millimeter-Wave Imaging Scanner for Art Conservation Science

A Continuous Millimeter-Wave Imaging Scanner for Art Conservation Science

jar with an estimated volume of 125 cm 3 . Moreover, the 3D reconstruction makes it possible to reveal a trough in the central part of this content, which was not visible from the 2D THz images in Figure 9 . Finally, Figure 10(c) presents the 3D THz image of the deformable mobile content with an esti- mated volume of 25 cm 3 . As explained previously, from the tilted series and the 3D reconstructions, we can now measure the dimensions of the fixed and mobile contents of the jar and the global thickness of the pottery wall. Assuming that the thickness of the pottery wall varies from 5 to 8 mm, we first can estimate the 110 GHz absorption coefficient α of the jar wall according to the expression Abs = α · l where l is the distance the THz wave travels through the materials. For the pottery wall, taking into account measurement uncertainties, we found α = 1 .3 ± 0 .3 cm − 1 , the large uncertainty coming from the difficult evaluation of the wall thickness owing to the limited transverse spatial resolution. Taking into account this wall absorbance, we can finally deduce the 110 GHz absorption coe fficients of the internal contents. For the fixed and the mobile contents, taking into account measurement uncertainties, we found the same absorption coe fficient α =
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Continuous-wave optical parametric oscillator tuned by a diffraction grating

Continuous-wave optical parametric oscillator tuned by a diffraction grating

1. Introduction The operation of continuous-wave optical parametric oscillators (cw OPOs) is based on a non- linear optical effect called parametric amplification [1]. An intense pump beam (angular fre- quency ω 1 ) and a signal beam (angular frequency ω 2 , such that ω 1 > ω 2 ) are focused into a nonlinear medium where some of the pump beam photons are converted to the frequency of the signal beam, which is thereby amplified. In addition, for every photon created at the signal frequency ω 2 , another photon is created at the idler frequency ω 3 = ω 1 − ω 2 , thus generating the idler beam. The idler frequency can be tuned by adjusting either the pump beam frequency (pump tuning) or the signal beam frequency (signal tuning). It is often easier to tune the fre- quency of the signal beam because pump tuning is limited by the properties of the pump laser. Ultimately, the tuning range is limited by the nonlinear medium, which must support suffi- ciently strong parametric amplification for the frequencies involved. This amplification must exceed the threshold determined by the losses in the OPO in order for it to operate.
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A continuous-wave second harmonic gyrotron oscillator at 460 GHz

A continuous-wave second harmonic gyrotron oscillator at 460 GHz

The quantum cascade laser (QCL), on the other hand, does not suffer from this drawback; its operating wavelength is determined by the layer thickness rather than [r]

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Repeatability, variability and reference values of pulsed wave Doppler echocardiographic measurements in healthy Saanen goats.

Repeatability, variability and reference values of pulsed wave Doppler echocardiographic measurements in healthy Saanen goats.

Keywords Goat, Pulsed wave, Doppler echocardiography, Reference intervals, Repeatability, Variability Background During the last thirty years, pulsed wave (PW) Doppler echocardiography has been developed first in humans [1,2], and then in several domestic animals species including dogs [3,4], cats [5], horses [6,7], cattle [8] and sheep [9]. This technique has become a routine for the diagnosis and evaluation of heart disease in veterinary medicine [10]. It allows detecting the returning signal during a time interval specified by a sample depth ignoring all other signals. Blood cells flow moving around the chosen specific location is analysed and gives information about direction, velocity, character and timing of the blood flow which cannot be assess without Doppler imaging [2,10]. So it provides a non-invasive tool to evaluate intracardiac blood flow, to diagnose regurgitant flow through the cardiac valves and intracardiac shunts and to assess systolic and diastolic function of the heart [10,11]. Accurate interpretation of Doppler echocardiographic variables requires reference values following standardised measurement guidelines in the studied species to interpret indices of cardiac function [10].
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A single bunch selector for the next low $\beta$ continuous wave ion beam

A single bunch selector for the next low $\beta$ continuous wave ion beam

The MEBT line of EURISOL heavy ion post- accelerator and the SPIRAL2 deuton/ion accelerator should transport a continuous wave (cw) beam from a 88.05 MHz RFQ (β respectively 0.035 and 0.04) to a drift-tube linac. A high frequency chopper is being studied to select only 1 bunch over N, respectively 10 < N and 100 < N as asked by the physicists. It requires pulse voltages up to 2.5k kV, rising in less than 6 ns at a repetition rate up to 8.8 MHz. These figures are at the border of what can be provided by the travelling wave fast choppers and the capacitive-type chopping technologies [1,2,3,4]. We have reviewed the current fast and slow chopping structures and their associated pulse generator [5]. Some preliminary RF simulations to adapt the present chopping devices to our requirements are presented. The main limitations of these technologies when applied to select one bunch in cw ion accelerators are also shown. Our first studies and results to solve the arising problems are discussed.
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Millimetre-wave Scanning Radar for the Detection and Remote Reading of Passive Electromagnetic Sensors

Millimetre-wave Scanning Radar for the Detection and Remote Reading of Passive Electromagnetic Sensors

1 CNRS;LAAS;7 av. du colonel Roche, 31077 Toulouse, France (dhenry@laas.fr,arifai@laas.fr,ppons@laas.fr,aubert@laas.fr) 2 University of Toulouse; UPS, INSA, INP, ISAE; LAAS; F-31077 Toulouse, France Abstract— This communication reports the latest developments in Frequency-Modulated Continuous-Wave (FMCW) radar interrogation technique for chipless and wireless sensors. For the first time a millimetre-wave scanning radar is used for detecting and reading passive and chipless electromagnetic sensors. Measurement results show that, with a 24 cm depth resolution and a 2 degrees angular resolution, it is possible to localize and distinguish two passive sensors separated by 5 cm at a distance of 3 meters from a FMCW radar operating at 30GHz. Sensing modes visualization derived from the millimetre-wave radar scanning of a scene makes possible the separation length measurement with an accuracy of 1cm.
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Continuous-wave and femtosecond laser operation of Yb:CaGdAlO4 under high-power diode pumping

Continuous-wave and femtosecond laser operation of Yb:CaGdAlO4 under high-power diode pumping

substitution is strongly predominant because of the same valence of the Yb 3+ and Gd 3+ ions. This leads to the large inhomogeneous broadening observed in the emission spectrum [Fig. 1(a) ]. The presence of a pla- teau in the gain cross section between 1000 and 1050 nm can be explained by the complementarity of two different sites in the host. A selective excitation experiment at low temperature was carried out to check this assumption. At 10 K, for pump wave- lengths of 978 and 983 nm, two complementary emis-

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Source mechanisms and dynamics of volcanic pyroclastic emissions : a perspective from Doppler radar (VOLDORAD) and other geophysical data

Source mechanisms and dynamics of volcanic pyroclastic emissions : a perspective from Doppler radar (VOLDORAD) and other geophysical data

III.3.2. Introduction Small-scale volcanic eruptions commonly expel a wide range of pyroclast sizes, ranging from coarse blocks with ballistic trajectories, to fine ash driven away within ash plumes. As both the plume and the ballistics are emitted simultaneously, it is often difficult to discriminate and to collect quantitative data on both phenomena. Thermal ( Patrick, 2007 ; Marchetti et al., 2009 ) and ultraviolet imagery ( Yamamoto et al., 2008 ) have provided powerful insights into the dynamics of mild strombolian and vulcanian eruptions, shedding light onto the plume rise dynamics and the relative ash / ballistics distribution of the ejecta. In this paper, we describe similar small-scale transient eruptions at Arenal (Costa Rica), monitored with a ground-based Doppler radar (VOLDORAD) ( Dubosclard et al., 2004 ; Donnadieu et al., 2005 ). The radar provides quantitative information on exit velocities and mass loading of the ejecta. We show that the time-velocity distribution of the mass load (i.e. Doppler radargram) reveals two distinct dynamics, which discriminates the ballistics and the ash plume transiting through the radar beam. We compute synthetic Doppler radargrams by numerical modeling of the ballistics, and constrain the dynamics and mass loadings of both the ballistics and the ash plume. Such characterization of the near-vent eruptive dynamics has strong potential applications, as the degree of fragmentation and the mass proportion injected into the atmosphere are of interest for hazard mitigation issues.
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Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

Lasing experiments were performed using a µ-PL setup, where the cw pump laser beam at 1550 nm wavelength was fo- cused on the sample surface into a 12 µm spot diameter by a x40 reflective objective with NA of 0.5 and working distance of 4 mm. The same objective was used for pumping and for collection of light emitted from the microdisk. A CaF 2 beamsplitter was used to separate the excitation and emission beam paths. The outgoing emission, collected from the objective, was coupled to a Fourier Transform Infrared (FTIR) spectrometer equipped with a CaF 2 beam splitter. The emission was detected by a nitrogen-cooled InSb photodetector, which has a cut-off wavelength 4.8 µm. The telecom wavelength pump laser was out-coupled from a single-mode fiber to free space using a hyperbolic mirror, the output fiber being clamped at the focal point of the mirror. The pump can be taken through a Mach-Zehnder modulator, controlled by an rf-pulse generator so that the pump beam power can be switched from cw to quasi-continuous and to pulsed mode. The same output from a single-mode fiber was used in both cases, cw or pulsed, so that switching from one pump mode to another did not induce any change of the beam waist or its alignment to the disk. The pulse shape under modulated excitation had 3.5 ns width and a repetition rate of 25 MHz. As discussed below, the pulse duration was longer than the non-radiative lifetime, so the optical excitation can be considered quasi-cw in this respect. The FTIR spectrometer resolution was set to 0.25 cm −1 for line-width narrowing analysis of lasing mode around threshold otherwise it was set to 4 cm −1 .
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Continuous-wave electrically pumped 1.55-mu m edge-emitting platelet ridge laser diodes on silicon

Continuous-wave electrically pumped 1.55-mu m edge-emitting platelet ridge laser diodes on silicon

Approaches to achieve electrically pumped lasers on silicon have typically involved the hybrid integration of III–V semi- conductor lasers onto silicon substrates. Most often these ef- forts have involved bonding epitaxial III–V active structures directly on silicon [13], [14]. Pollentier et al. and Seo et al. reported pulsed lasing of GaAs-AlGaAs single quantum-well (QW) lasers on silicon and InP-InGaAsP multiple QW ridge lasers on silicon, respectively; however, continuous-wave (CW) lasing was not achieved [13], [14]. Rojo Romeo et al. reported ultralow threshold pulsed lasing of microdisk lasers consisting of InP membranes molecularly bonded on Si [15]. Researchers at the University of California at Santa Barbara and Intel have recently demonstrated an electrically pumped CW diode laser [16] made by oxide-bonding a III–V semiconductor QW active gain region and upper cladding layers to silicon waveguides on SiO on Si. This novel evanescently coupled, hybrid cavity laser structure has several attractive features, but it uses epitaxial ma- terial inefficiently and can only integrate devices fabricated from the same heterostructure layer sequence.
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