PLL Tracking Performance in the Presence of Oscillator Phase Noise   总被引：3，自引：3，他引：3  

Markus Irsigler  Bernd Eissfeller 《GPS Solutions》2002,5(4):45-57

The tracking performance of a Phase Lock Loop (PLL) is affected by the influence of several error sources. In addition to thermal noise and dynamic stress error, oscillator phase noise can cause significant phase jitter which degrades the tracking performance. Oscillator phase noise is usually caused by two different effects: Allan deviation phase noise is caused by frequency instabilities of the receiver's reference oscillator and the satellite's frequency standard. It can be termed as system-inherent phase noise and is relevant for both static and dynamic applications. “External” phase noise, however, is caused by vibration and is a major problem for dynamic applications. In the context of this paper, both types of phase noise will be modeled and the resulting integrals will be evaluated for PLLs up to the third order. Besides, phase jitter induced by thermal noise and signal dynamics will also be discussed, thus providing all necessary formulas for analyzing the performance of a phase lock loop in case of different forms of stress. Since the main focus is centered on the effects of oscillator phase noise, the overall PLL performance is graphically illustrated with and without consideration of oscillator phase noise. © 2002 Wiley Periodicals, Inc.  相似文献   

Flood Events in the Rhine Basin: Genesis,Influences and Mitigation   总被引：4，自引：1，他引：4  

Disse  Markus  Engel  Heinz 《Natural Hazards》2001,23(2-3):271-290

The paper analyses the hydrological regime of the Rhine catchment,the genesis of recent floods,and recommends some research and practical activities to mitigate flood damage. The catchment of the Rhine River can be divided into four main subcatchments: the alpine region with the Aare River as its main tributary and downstream the lower mountain regions of the tributaries Neckar, Main and Moselle. These four basins generate very different hydrographs. Due to the geographical conditions, the average discharge maximums shift from summer to winter downstream the Rhine. Moreover, the spatial and temporalprecipitation patterns of each river have a strong influence on the individual flood events. Some recent extraordinary floods are used to illustrate the parameters that have influenced these events.A strong relationship between recent climate change observationsand the occurrence of flood levels cannot be proven. However, the consequences of human interventions and the resulting changes to the river system (the Rhine and its tributaries) for the hydrograph can be quantified precisely.The influences of different land-use and climatic scenarios on flood conditions in the Rhine basin have not yet been separately identified. Thus, the Dutch-German project LAHoR was established. The primary aim of this project is to giveadvice for the ``Action Plan on Flood Defence' of the International Commission for the Protection of the Rhine (IKSR). In this plan a multidisciplinary approach to mitigating floods is suggested.It is anticipated that the plan willgenerate synergistic effects between flood prevention, water management, regional planning, agriculture, forestry and ecological demands.  相似文献   

Deep seismic reflection experiments at Kiruna     

Dr. Markus Båth  Cand. Eysteinn Tryggvason 《Pure and Applied Geophysics》1962,51(1):79-90

Summary In August 1955 a series of specially arranged quarry blasts in the Kiruna iron ore mines was recorded with a refraction apparatus at approx. 10 km distance. The experiments are the first seismic investigations of the deeper crustal structure in Fennoscandia and were mainly undertaken in order to study near-vertical reflections from crustal discontinuities. The records show clear directP waves with sharp onsets and a velocity of 5.65±0.13 km/sec (in porphyry), furthermoreS waves of less definite onsets and sound waves through the atmosphere.P waves reflected from crustal discontinuities are weak and of erratic occurrence, in agreement with theoretical expectation for near-vertical reflections. Approx. depths to the Conrad and the Mohorovii'c discontinuities are calculated as 19 km and 33–34 km. There is general agreement with the explosion records written by the Grenet seismograph at Kiruna, and the differences which exist can be explained by the different frequency response of the two instruments.

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Zusammenfassung Im August 1955 wurde eine Reihe speziell angeordneten Steinbruchsprengungen in den Eisenerzgruben bei Kiruna mittels einer Refraktionsapparatur in rund 10 km Entfernung registriert. Diese Versuche sind die ersten seismischen Untersuchungen der tieferen Krustenstruktur in Fennoskandien und wurden hauptsächlich wegen eines Studiums von Reflexionen an krustalen Diskontinuitäten bei nahe vertikalem Einfall der Wellen vorgenommen. Deutliche, direkteP-Wellen mit scharfen Einsätzen und einer Geschwindigkeit von 5.65±0.13 km/sec (Porphyr) wurden registriert, ausserdemS-Wellen mit weniger scharfen Einsätzen und Schallwellen durch die Atmosphäre. An krustalen Diskontinuitäten reflektierteP-Wellen sind schwach und unregelmässig, im Einklang mit theoretischen Erwartungen für Reflexionen bei nahe vertikalem Einfall. Die Tiefen der Conrad- und der Mohorovii-Diskontinuitäten wurden annähernd zu 19 km bzw. 33–34 km berechnet. Es besteht allgemeine Übereinstimmung mit den Explosionsregistrierungen des Grenet-Seismographen in Kiruna, und die Unterschiede können lediglich durch die unterschiedliche Frequenzempfindlichkeit der Instrumente erklärt werden.

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A method for determination of epicenters of near earthquakes     

Mr. Ari Ben-Menahem M. Sc.  Dr. Markus Båth 《Pure and Applied Geophysics》1960,46(1):37-46

Summary A method is developed, which permits a rapid and reliable determination of the location of near epicenters (within about 10^o) using the differences of arrival times of a common phase (usually Sg) to a net of three stations. The resulting equation for computation of epicentral distances is solved numerically once for all by an electronic computer for every station triangle and for all possible time differences for every wave used. The calculated epicentral distances and coordinates are arranged in tables with the two travel-time differences for each triangle as entries. Such tables permit an immediate solution of the problem in every special case. The accuracy of the method is investigated, and necessary precautions in its use are emphasized. Application is made to a few cases of Sg recorded at the Swedish stations.

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Zusammenfassung Eine Methode wird entwickelt, die eine schnelle und zuverlässige Bestimmung der Lage von nahegelegenen Epizentren (innerhalb rund 10^o) mittels der Laufzeitdifferenzen einer gegebenen Welle (gewöhnlichSg) in einem Netz von drei Stationen ermöglicht. Die erhaltene Gleichung für die Berechnung der Herdentfernungen wird mittels einer elektronischen Rechenmaschine für jedes Stations-dreieck und für alle möglichen Zeitdifferenzen für jede verwendete Welle ein für allemal numerisch gelöst. Die berechneten Herdentfernungen und-Koordinaten werden in Tabellenform dargestellt mit den beiden Laufzeitdifferenzen für jedes Dreieck als Eingangswerte. Solche Tabellen ermöglichen eine unmittelbare Lösung des Problems in jedem einzelnen Fall. Die Genauigkeit der Methode wird untersucht, und die notwendigen Vorsichtsmassregeln bei ihrer Verwendung werden hervorgehoben. Die Methode wird auf einige Registrierungen vonSg an den schwedischen Stationen angewendet.

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Seismic surface-wave dispersion: A world-wide survey     

Markus Båth 《Pure and Applied Geophysics》1959,43(1):131-147

Summary By means of the long-period records at Uppsala and Kiruna of thirteen specially selected earthquakes, the Love and Rayleigh wave dispersion is determined for all oceans and all continents except for South America. The observations have given information on crustal structure along several paths, not investigated earlier; in other cases, they have confirmed earlier results. The methods are discussed. The results for oceanic areas are summarized in the following table: The observations demonstrate the oceanic structure of the central Arctic area as well as the complete similarity of the Atlantic and Pacific bottom structure. Continental dispersion curves are determined for very long paths over Euro-Asia and for the hitherto longest path over North America as well as for a path crossing Africa. These observations indicate an average crust about 10–15 km thicker along the Euro-Asiatic path than along the North American path, whereas there is perfect agreement between the North American and the African continent. A shear-wave velocity of 4.3–4.4 km/sec is obtained for the upper part of the mantle under the continents. Further conclusions must await the computation of a greater number of theoretical dispersion curves.

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Zusammenfassung Mittels der langperiodischen Registrierungen in Uppsala und Kiruna von dreizehn speziell ausgewählten Erdbeben ist die Dispersion der Love-und Rayleigh-Wellen für alle Ozeane und alle Kontinente mit Ausnahme von Süd-Amerika bestimmt worden. Die Beobachtungen haben in mehreren Fällen Auskunft über die Krusten-Struktur längs Wellenwege gegeben, die nie früher untersucht worden sind; in anderen Fällen haben sie frühere Resultate bestätigt. Die Methoden werden diskutiert. Die Resultate für ozeanische Gebiete sind in der folgenden Tabelle zusammengefasst: Die Beobachtungen beweisen sowohl die ozeanische Struktur des zentralen Teiles des arktischen Gebietes als auch die vollständige Gleichheit der atlantischen und pazifischen Krusten-Struktur. Kontinentale Dispersionskurven sind für sehr lange Wellenwege über Euro-Asien und für den bisher längsten Wellenweg über Nord-Amerika bestimmt worden. Diese Beobachtungen zeigen, dass die mittlere Krusten-Dicke 10–15 km grösser längs des euro-asiatischen Weges ist als längs des nordamerikanischen Weges; dagegen zeigen die Beobachtungen für Nord-Amerika und Afrika sehr gute Übereinstimmung. Eine Transversalwellen-Geschwindigkeit von 4.3–4.4 km/sek wird für den oberen Teil des Erdmantels unter den Kontinenten gefunden. Weitere Schlussfolgerungen müssen die Berechnung einer grösseren Anzahl theoretischer Dispersionskurven erwarten.

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A continental channel wave,guided by the intermediate layer in the crust     

Dr. Markus Bath 《Pure and Applied Geophysics》1957,38(1):19-31

Summary A study has been made of a new channel wave, denotedLi, using a total of 83 observations from the seismic records of Swedish stations, mainly from earthquakes at normal depth.Li resembles theLg waves in several respects: it propagates only through continental structures, it has a similar particle motion, i.e. mainly transverse horizontal, and only slightly larger period. ButLi has a higher velocity, 3.79±0.07 km/sec, and it is believed to propagate in the intermediate layer in the crust in a way similar to the propagation of theLg waves in the granitic layer.Li is identical withS ^* in records of near-by earthquakes in the same way asLg2 is identical withSg. Li usually exhibits no clear dispersion.

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Zusammenfassung Es wurden Untersuchungen angestellt über eine neue Kanalwelle, welcher die BezeichnungLi gegeben wurde, wobei insgesamt 83 Erdbebenregistrierungen von schwedischen Stationen Verwendung fanden. Hauptsächlich waren es Erdbeben mit normaler Herdtiefe. DieLi-Wellen haben in verschiedener Hinsicht Ähnlichkeit mit denLg-Wellen: Sie pflanzen sich nur im Bereich kontinentaler Struktur fort und sie haben eine ähnliche Partikelbewegung, d.h. hauptsächlich horizontaltransversal.Li hat eine nur unwesentlich höhere Periode als dieLg-Wellen. AberLi hat eine wesentlich höhere Geschwindigkeit, 3.79±0.07 km/sec, und es ist anzunehmen, dass sie sich in der Basaltschicht der Kruste in ähnlicher Weise fortpflanzt wieLg in der Granitschicht.Li ist identisch mitS ^* in Aufzeichnungen von Nahbeben, so wieLg2 identisch mitSg ist.Li weist gewöhnlich keine deutliche Dispersion auf.

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Strike and dip of crustal boundaries — A method and its application     

R. James Brown  Harry Borg  Markus Båth 《Pure and Applied Geophysics》1971,88(1):60-74

Summary If for a point on the earth's surface, the apparent (moveout) seismic velocities have been determined for a number of profiles in different directions, a possibility is offered to calculate true strike and dip of crustal boundaries. In the present paper the theory is developed, partly for a sloping Mohorovii discontinuity only, partly for sloping Conrad and Mohorovii discontinuities with parallel strikes. The theory for the sloping Mohorovii discontinuity is applied to field measurements at a place about 30 km west of Uppsala performed in June 1969. With a crustalP-wave velocity of 6.3 km/sec, a good fit to the observations is obtained for aPn-velocity of 8.55 km/sec and a downdip of Moho of 7.2° in the direction S 3.8° E. These numerical values are not the most important output of this paper. On the other hand, the testing of the method appears far more important, and also that improvements can be suggested in the experimental procedure in future applications of this method.  相似文献   

Incentives for field hydrology and data sharing: collaboration and compensation: reply to “A need for incentivizing field hydrology,especially in an era of open data”*     

Theresa Blume  Ilja van Meerveld  Markus Weiler 《水文科学杂志》2020,65(Z2):1266-1268

ABSTRACT

We thank Allen and Berghuijs for continuing the discussion on field hydrology and data sharing and discuss two incentives to promote data collection and sharing in hydrological sciences: a collaborative attitude and additional funding to make data publicly available.  相似文献   

Comparative hydrogeology – reference analysis of groundwater dynamics from neighbouring observation wells     

Markus Giese  Ezra Haaf  Benedikt Heudorfer  Roland Barthel 《水文科学杂志》2020,65(10):1685-1706

ABSTRACT

Groundwater level fluctuations are caused by spatial and temporal superposition of processes within and outside the aquifer system. Most of the subsurface processes are usually observed on a small scale. Upscaling to the regional scale, as required for future climate change scenarios, is difficult due to data scarcity and increasing complexity. In contrast to the limited availability of system characteristics, high-resolution data records of groundwater hydrographs are more generally available. Exploiting the information contained in these records should thus be a priority for analysis of the chronical lack of data describing groundwater system characteristics. This study analyses the applicability of 63 indices derived from daily hydrographs to quantify different dynamics of groundwater levels in unconfined gravel aquifers from three groundwater regions (Bavaria, Germany). Based on the results of two different skill tests, the study aids index selection for different dynamic components of groundwater hydrographs.  相似文献   

Collected papers of Sir Harold Jeffreys on geophysics and other sciences. 1. Theoretical and observational seismology : Sir Harold Jeffreys (editor). Gordon and Breach, London, 1971, 537 pp., £11,45     

Markus Bth 《Tectonophysics》1974,22(1-2)

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