Искажение спектра сигнала протяженной цели в радаре с непрерывным частотно-модулированным сигналом

The problem of spectrum distortion in radar with a continuous frequency modulated signal (FMCW radar) is considered in the case of locating extended targets containing a large number of closely spaced reflection points. An extended target model is introduced for which a beat signal is analyzed based on its representation in the form of an amplitude-modulated oscillation. It is shown that the distortion of the spectrum occurs due to a certain relationship between the distances of the target points, the values of the carrier frequency and the deviation of the probe signal frequency. The results of numerical calculations for various values of the signal parameters and the long target model are given.En el presente artículo se aborda el problema de la distorsión del espectro en radares con señal continua de frecuencia modulada (radar FMCW) al producir objetivos prolongados que contienen un gran número de puntos de reflexión cercanos. El documento introduce un modelo de objetivo extendido para el cual se realiza un análisis de la señal de los latidos en función de su presentación en forma de oscilación de amplitud modulada. Este estudio muestra que la distorsión del espectro se produce como resultado de ciertas relaciones entre las distancias de los puntos de destino, los valores de frecuencia portadora y la frecuencia de desviación de la señal de sondeo. El artículo presenta los resultados de los cálculos numéricos para los diferentes valores de los parámetros de la señal y el modelo de objetivo extendido.No presente artigo, o problema da distorção do espectro em radares com sinal de frequência modulada contínua (radar FMCW) é abordado ao produzir objetivos prolongados que contêm um grande número de pontos de reflexão próximos. O documento introduz um modelo objetivo estendido para o qual uma análise do sinal de batimentos cardíacos é realizada de acordo com sua apresentação na forma de uma oscilação de amplitude modulada. Este estudo mostra que a distorção do espectro ocorre como resultado de certas relações entre as distâncias dos pontos de destino, os valores da freqüência da portadora e a freqüência do desvio do sinal sonoro. O artigo apresenta os resultados dos cálculos numéricos para os diferentes valores dos parâmetros do sinal e do modelo objetivo estendido.Рассмотрена проблема искажения спектра в радаре с непрерывным частотно-модулированным сигналом (FMCW радаре) при лоцировании протяженных целей, содержащих большое число близкорасположенных точек отражения. Введена модель протяженной цели, для которой проведен анализ сигнала биений на основе представления его в виде амплитудно-модулированного колебания. Показано, что искажение спектра возникает в результате определенных соотношений между расстояниями точек цели, значениями несущей частоты и частоты девиации зондирующего сигнала. Приведены результаты численных расчетов для различных значений параметров сигнала и модели протяженной цели

THE INFLUENCE OF CHANGING CLIMATE AND GEOCRYOLOGICAL CONDITIONS ON THE REGIME OF REGIONAL DISCHARGE AND ICING IN THE UPPER PART OF LENA RIVER’S BASIN

Using the balance method authors showed for the case of 1990 that the reaction of the river discharge on the climate change is different in the regions with continuous and sporadic permafrost extent. In mountain with continuous permafrost extent the climate warming has no strong influence on the river discharge but affects on the ice-mounds’ volume. In case of sporadic permafrost extent the decreasing of permafrost area to 30% leads to decreasing of snow-melting overflow up to 38%. Also the period of the flood became longer because the underground storage increasing that takes away the precipitation, snow-melting and condensation water from surface discharge

32-Channel Single Photon Counting Module For Ultra-sensitive Detection of DNA Sequences

ABSTRACT We continue our work on the design and implementation of multi-channel single photon detection systems for highly sensitive detection of ultra-weak fluorescence signals, for high-performance, multi-lane DNA sequencing instruments. A fiberized, 32-channel single photon detection (SPD) module based on single photon avalanche diode (SPAD), model C30902S-DTC, from Perkin Elmer Optoelectronics (PKI) has been designed and implemented. Unavailability of high performance, large area SPAD arrays and our desire to design high performance photon counting systems drives us to use individual diodes. Slight modifications in our quenching circuit has doubled the linear range of our system from 1MHz to 2MHz, which is the upper limit for these devices and the maximum saturation count rate has increased to 14 MHz. The detector module comprises of a single board computer PC-104 that enables data visualization, recording, processing, and transfer. Very low dark count (300-1000 counts/s), robust, efficient, simple data collection and processing, ease of connectivity to any other application demanding similar requirements and similar performance results to the best commercially available single photon counting module (SPCM from PKI) are some of the features of this system

Publisher Correction:Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird (Nature Communications, (2018), 9, 1, (4263), 10.1038/s41467-018-06673-5)

In the original HTML version of this Article, the order of authors within the author list was incorrect. The consortium VRS Castricum was incorrectly listed after Theunis Piersma and should have been listed after Cornelis J. Camphuysen. This error has been corrected in the HTML version of the Article; the PDF version was correct at the time of publication

Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Under climate warming, migratory birds should align reproduction dates with advancing plant and arthropod phenology. To arrive on the breeding grounds earlier, migrants may speed up spring migration by curtailing the time spent en route, possibly at the cost of decreased survival rates. Based on a decades-long series of observations along an entire flyway, we show that when refuelling time is limited, variation in food abundance in the spring staging area affects fitness. Bar-tailed godwits migrating from West Africa to the Siberian Arctic reduce refuelling time at their European staging site and thus maintain a close match between breeding and tundra phenology. Annual survival probability decreases with shorter refuelling times, but correlates positively with refuelling rate, which in turn is correlated with food abundance in the staging area. This chain of effects implies that conditions in the temperate zone determine the ability of godwits to cope with climate-related changes in the Arctic

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4

The response of the CMS combined electromagnetic and hadron calorimeter to beams of pions with momenta in the range 5-300 GeV/c has been measured in the H2 test beam at CERN. The raw response with the electromagnetic compartment calibrated to electrons and the hadron compartment calibrated to 300 GeV pions may be represented by sigma = (1.2) sqrt{E} oplus (0.095) E. The fraction of energy visible in the calorimeter ranges from 0.72 at 5 GeV to 0.95 at 300 GeV, indicating a substantial nonlinearity. The intrinsic electron to hadron ratios are fit as a function of energy and found to be in the range 1.3-2.7 for the electromagnetic compartment and 1.4-1.8 for the hadronic compartment. The fits are used to correct the non-linearity of the e pi response to 5% over the entire measured range resulting in a substantially improved resolution at low energy. Longitudinal shower profile have been measured in detail and compared to Geant4 models, LHEP-3.7 and QGSP-2.8. At energies below 30 GeV, the data, LHEP and QGSP are in agreement. Above 30 GeV, LHEP gives a more accurate simulation of the longitudinal shower profile

Synchronization and Timing in CMS HCAL

The synchronization and timing of the hadron calorimeter (HCAL) for the Compact Muon Solenoid has been extensively studied with test beams at CERN during the period 2003-4, including runs with 40 MHz structured beam. The relative phases of the signals from different calorimeter segments are timed to 1 ns accuracy using a laser and equalized using programmable delay settings in the front-end electronics. The beam was used to verify the timing and to map out the entire range of pulse shapes over the 25 ns interval between beam crossings. These data were used to make detailed measurements of energy-dependent time slewing effects and to tune the electronics for optimal performance

Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Design, Performance, and Calibration of CMS Hadron Endcap Calorimeters

Detailed measurements have been made with the CMS hadron calorimeter endcaps (HE) in response to beams of muons, electrons, and pions. Readout of HE with custom electronics and hybrid photodiodes (HPDs) shows no change of performance compared to readout with commercial electronics and photomultipliers. When combined with lead-tungstenate crystals, an energy resolution of 8\% is achieved with 300 GeV/c pions. A laser calibration system is used to set the timing and monitor operation of the complete electronics chain. Data taken with radioactive sources in comparison with test beam pions provides an absolute initial calibration of HE to approximately 4\% to 5\%