59 research outputs found
Impact of Road Vehicle Accelerations on SAR-GMTI Motion Parameter Estimation
In recent years many powerful techniques and algorithms have been developed to detect moving targets and estimate their motion parameters from single- or multi-channel SAR data. In case of single- and two-channel systems, most of the developed algorithms rely on analysis of the Doppler history.
Nowadays it is known, that even small unconsidered across-track accelerations can bias the along-track velocity estimation. Since we want to monitor real and more complex traffic scenarios with a future traffic monitoring system like TRAMRAD, we must know which target accelerations we have to handle in reality. For this reason a common passenger car was equipped with an inertial measurement system and differential GPS to measure accelerations in all three dimensions during rush-hour traffic.
In this paper the results of the acceleration measurements are presented and discussed. The standard deviations of the measured accelerations are in the order of 0.5 m/s2 for accelerations in driving direction and 0.6 m/s2 for radial accelerations. A theoretical analysis (which is verified by detailed simulations) of the Doppler slope shows also that at such high across-track accelerations a reliable estimation of the along-track velocity by means of a Doppler slope analysis without further information is unemployable in practice.
Also oscillations of the car body along the vertical axis are investigated in this paper. From the field of vehicle dynamics it is known that the eigen frequencies of the car body are in the range from 0.7 to 2.0 Hz. Deflections in the order of one wavelength (X-band) or higher are possible at such frequencies. The simulation results for spaceborne SAR systems with integration times in the order of one second show that the shape and azimuth shift of the impulse response depend beside the oscillation frequency and the deflection also on the initial phase of the oscillation. However, at practical applications the main part of the energy could also be reflected by double bounce from the road surface. Thus, further investigations in the topic of vehicle oscillations by using real radar data are necessary.
Finally, some basic ideas are presented which enable a reliable separation between along-track velocity and across-track acceleration. For example, the easiest way to separate both just mentioned motion parameters is the use of a road database, from which the information about the motion direction of the assigned vehicle can be extracted. Hence, the accuracy of along-track velocity estimation is mainly given by the accuracy of the estimated across-track velocity and the angle of the road section in relation to the flight path of the SAR platform
An imaging algorithm for spaceborne high-squint L-band SAR based on time-domain rotation
For spaceborne high-squint L-band synthetic aperture radar (SAR), the long wavelength and high-squint angle result in strong coupling between the range and azimuth directions. In conventional imaging algorithms, linear range walk correction (LRWC) is commonly used to correct linear range cell migration which dominates the coupling. However, LRWC introduces spatial variation in the azimuth direction, limits the depth-of-azimuth-focus (DOAF) and affects the imaging quality. This article constructs a polynomial range model and develops a modified omega-k algorithm to achieve spaceborne high-squint L-band SAR imaging. The key to this algorithm is to rotate the two-dimensional (2-D) data after LRWC in the time domain by a proposed time-rotation (TR) operation that eliminates the DOAF degradation caused by LRWC. The proposed algorithm, which is composed of LRWC, bulk compression, TR, and modified Stolt interpolation, achieves well-focused results at a 1-m resolution and a swath of 4 km Γ 4 km at a squint angle of 45Β°
Sleeping Beauties Cited in Patents: Is there also a Dormitory of Inventions?
A Sleeping Beauty in Science is a publication that goes unnoticed (sleeps)
for a long time and then, almost suddenly, attracts a lot of attention (is
awakened by a prince). In our foregoing study we found that roughly half of the
Sleeping Beauties are application-oriented and thus are potential Sleeping
Innovations. In this paper we investigate a new topic: Sleeping Beauties that
are cited in patents. In this way we explore the existence of a dormitory of
inventions. We find that patent citation may occur before or after the
awakening and that the depth of the sleep, i.e., citation rate during the
sleeping period, is no predictor for later scientific or technological impact
of the Sleeping Beauty. Inventor-author self-citations occur only in a small
minority of the Sleeping Beauties that are cited in patents, but other types of
inventor-author links occur more frequently. We analyze whether they deal with
new topics by measuring the time-dependent evolution in the entire scientific
literature of the number of papers related to both the precisely defined topics
as well as the broader research theme of the Sleeping Beauty during and after
the sleeping time. We focus on the awakening by analyzing the first group of
papers that cites the Sleeping Beauty. Next, we create concept maps of the
topic-related and the citing papers for a time period immediately following the
awakening and for the most recent period. Finally, we make an extensive
assessment of the cited and citing relations of the Sleeping Beauty. We find
that tunable co-citation analysis is a powerful tool to discover the prince and
other important application-oriented work directly related to the Sleeping
Beauty, for instance papers written by authors who cite Sleeping Beauties in
both the patents of which they are the inventors, as well as in their
scientific papers.Comment: 30 pages, 17 figure
ΠΡΠΎΡΡΠΎΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΠΊΠΎΠΌΠΏΠ΅Π½ΡΠ°ΡΠΈΠΈ ΠΌΠΈΠ³ΡΠ°ΡΠΈΠΉ ΡΠ²Π΅ΡΡΡΠΈΡ ΡΡ ΡΠΎΡΠ΅ΠΊ ΠΏΠΎ Π΄Π°Π»ΡΠ½ΠΎΡΡΠΈ Π΄Π»Ρ ΡΠ΅ΠΆΠΈΠΌΠ° Π±ΠΎΠΊΠΎΠ²ΠΎΠ³ΠΎ ΠΎΠ±Π·ΠΎΡΠ° Π Π‘Π (Π°Π½Π³Π».)
Introduction.Β Range Cell Migration (RCM) is a source of image blurring in synthetic aperture radars (SAR). There are two groups of signal processing algorithms used to compensate for migration effects. The first group includes algorithms that recalculate the SAR signal from the "alongβtrack range β slant range" coordinate system into the "along-track rangeΒ βΒ cross-track range"Β coordinates using the method of interpolation. The disadvantage of these algorithms is their considerable computational cost. Algorithms of the second group do not rely on interpolation thus being more attractive in terms of practical application.Aim. To synthesize a simple algorithm for compensating for RCM without using interpolation.Materials and methods. The synthesis was performed using a simplified version of the Chirp Scaling algorithm.Results.Β A simple algorithm, which presents a modification of the Keystone Transform algorithm, was synthesized. The synthesized algorithm based on Fast Fourier Transforms and the Hadamard matrix products does not require interpolation.Conclusion. A verification of the algorithm quality via mathematical simulation confirmed its high efficiency. Implementation of the algorithm permits the number of computational operations to be reduced. The final radar imageΒ produced using the proposed algorithm is built in the true Cartesian coordinates. The algorithm can be applied for SAR imaging of moving targets. The conducted analysis showed that the algorithm yields Β theΒ image of a moving target provided that the coherent processing interval is sufficiently large. The image lies along a line, which angle of inclination is proportional to the projection of the target relative velocity on the line-of-sight. Estimation of the image parameters permits the target movement parameters to be determined.ΠΠ²Π΅Π΄Π΅Π½ΠΈΠ΅. ΠΠΈΠ³ΡΠ°ΡΠΈΠΈ ΡΠ²Π΅ΡΡΡΠΈΡ
ΡΡ ΡΠΎΡΠ΅ΠΊ ΠΏΠΎ Π΄Π°Π»ΡΠ½ΠΎΡΡΠΈ ΡΠ²Π»ΡΡΡΡΡ ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΎΠΌ ΡΠ°ΡΡΠΎΠΊΡΡΠΈΡΠΎΠ²ΠΊΠΈ ΡΠ°Π΄ΠΈΠΎΠ»ΠΎΠΊΠ°ΡΠΈΠΎΠ½Π½ΡΡ
ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ Π² ΡΠ°Π΄ΠΈΠΎΠ»ΠΎΠΊΠ°ΡΠΎΡΠ°Ρ
Ρ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΉ Π°ΠΏΠ΅ΡΡΡΡΠΎΠΉ (Π Π‘Π). Π‘ΡΡΠ΅ΡΡΠ²ΡΠ΅Ρ Π΄Π²Π΅ Π³ΡΡΠΏΠΏΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π΄Π»Ρ ΠΊΠΎΠΌΠΏΠ΅Π½ΡΠ°ΡΠΈΠΈ ΠΌΠΈΠ³ΡΠ°ΡΠΈΠΉ. ΠΠ΅ΡΠ²Π°Ρ Π³ΡΡΠΏΠΏΠ° Π²ΠΊΠ»ΡΡΠ°Π΅Ρ Π°Π»Π³ΠΎΡΠΈΡΠΌΡ, Π² ΠΊΠΎΡΠΎΡΡΡ
Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΡΡΠ½ΠΊΡΠΈΠΎΠ½Π°Π»ΡΠ½ΠΎΠΉ ΠΈΠ½ΡΠ΅ΡΠΏΠΎΠ»ΡΡΠΈΠΈ ΠΎΡΡΡΠ΅ΡΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΠ΅ΡΠ΅ΡΡΠ΅Ρ ΠΏΡΠΈΠ½ΡΡΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ² ΠΈΠ· ΡΠΈΡΡΠ΅ΠΌΡ ΠΊΠΎΠΎΡΠ΄ΠΈΠ½Π°Ρ "ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½Π°Ρ Π΄Π°Π»ΡΠ½ΠΎΡΡΡ β Π½Π°ΠΊΠ»ΠΎΠ½Π½Π°Ρ Π΄Π°Π»ΡΠ½ΠΎΡΡΡ"Β Π² ΡΠΈΡΡΠ΅ΠΌΡ "ΠΏΡΠΎΠ΄ΠΎΠ»ΡΠ½Π°Ρ Π΄Π°Π»ΡΠ½ΠΎΡΡΡ β ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½Π°Ρ Π΄Π°Π»ΡΠ½ΠΎΡΡΡ". ΠΠ΅Π΄ΠΎΡΡΠ°ΡΠΊΠΎΠΌ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² Π΄Π°Π½Π½ΠΎΠΉ Π³ΡΡΠΏΠΏΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΈΡ
Π²ΡΡΠΎΠΊΠ°Ρ Π²ΡΡΠΈΡΠ»ΠΈΡΠ΅Π»ΡΠ½Π°Ρ ΡΠ»ΠΎΠΆΠ½ΠΎΡΡΡ. ΠΠ»Π³ΠΎΡΠΈΡΠΌΡ Π²ΡΠΎΡΠΎΠΉ Π³ΡΡΠΏΠΏΡ Π½Π΅ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡ ΠΈΠ½ΡΠ΅ΡΠΏΠΎΠ»ΡΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈ ΡΠ²Π»ΡΡΡΡΡ ΠΏΠΎΡΡΠΎΠΌΡ Π±ΠΎΠ»Π΅Π΅ ΠΏΡΠΈΠ²Π»Π΅ΠΊΠ°ΡΠ΅Π»ΡΠ½ΡΠΌΠΈ Π΄Π»Ρ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ.Π¦Π΅Π»Ρ.Β Π‘ΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°ΡΡ ΠΏΡΠΎΡΡΠΎΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΠΊΠΎΠΌΠΏΠ΅Π½ΡΠ°ΡΠΈΠΈ ΠΌΠΈΠ³ΡΠ°ΡΠΈΠΉ Π±Π΅Π· ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΡΡΠ½ΠΊΡΠΈΠΎΠ½Π°Π»ΡΠ½ΠΎΠΉ ΠΈΠ½ΡΠ΅ΡΠΏΠΎΠ»ΡΡΠΈΠΈ.ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. Π‘ΠΈΠ½ΡΠ΅Π· Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΎΡΡΡΠ΅ΡΡΠ²Π»Π΅Π½ Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠΏΡΠΎΡΠ΅Π½Π½ΠΎΠΉ Π²Π΅ΡΡΠΈΠΈ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΠ§Π-ΡΠΈΠ»ΡΡΡΠ°ΡΠΈΠΈ (Chirp Scaling Algorithm).Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. Π‘ΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½ ΠΏΡΠΎΡΡΠΎΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌ, ΡΠ²Π»ΡΡΡΠΈΠΉΡΡ ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΠ΅ΠΉ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° "Π·Π°ΠΌΠΊΠΎΠ²ΠΎΠ³ΠΎ ΠΊΠ°ΠΌΠ½Ρ".ΠΠ»Π³ΠΎΡΠΈΡΠΌ ΠΎΡΠ½ΠΎΠ²Π°Π½ Π½Π° ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠΈ Π±ΡΡΡΡΡΡ
ΠΏΡΠ΅ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠΉ Π€ΡΡΡΠ΅ ΠΈ ΠΏΠΎΡΠ»Π΅ΠΌΠ΅Π½ΡΠ½ΡΡ
ΠΌΠ°ΡΡΠΈΡΠ½ΡΡ
ΡΠΌΠ½ΠΎΠΆΠ΅Π½ΠΈΠΉ. Π Π°Π»Π³ΠΎΡΠΈΡΠΌΠ΅ Π½Π΅ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡΡΡ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΠ½ΡΠ΅ΡΠΏΠΎΠ»ΡΡΠΈΠΈ.ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅. ΠΡΠΎΠ²Π΅ΡΠΊΠ° ΠΊΠ°ΡΠ΅ΡΡΠ²Π° Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΏΠΎΠ΄ΡΠ²Π΅ΡΠ΄ΠΈΠ»Π° Π΅Π³ΠΎ Π²ΡΡΠΎΠΊΡΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ. ΠΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠΌΠ΅Π½ΡΡΠΈΡΡ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²ΠΎ Π²ΡΡΠΈΡΠ»ΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΠΎΠΏΠ΅ΡΠ°ΡΠΈΠΉ.Π€ΠΈΠ½Π°Π»ΡΠ½ΠΎΠ΅ ΡΠ°Π΄ΠΈΠΎΠ»ΠΎΠΊΠ°ΡΠΈΠΎΠ½Π½ΠΎΠ΅ ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠ΅, ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΠΎΠ΅ Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ°, ΡΡΡΠΎΠΈΡΡΡ Π²Β ΠΈΡΡΠΈΠ½Π½ΠΎΠΉ Π΄Π΅ΠΊΠ°ΡΡΠΎΠ²ΠΎΠΉ ΡΠΈΡΡΠ΅ΠΌΠ΅ ΠΊΠΎΠΎΡΠ΄ΠΈΠ½Π°Ρ. ΠΠ»Π³ΠΎΡΠΈΡΠΌ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ Π΄Π»Ρ ΠΏΠΎΡΡΡΠΎΠ΅Π½ΠΈΡ Π Π‘Π ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠΉ Π΄Π²ΠΈΠΆΡΡΠΈΡ
ΡΡ ΡΠ΅Π»Π΅ΠΉ. ΠΠ°Π½Π½ΡΠΉ Π² ΡΡΠ°ΡΡΠ΅ Π°Π½Π°Π»ΠΈΠ· ΠΏΠΎΠΊΠ°Π·Π°Π», ΡΡΠΎ Π°Π»Π³ΠΎΡΠΈΡΠΌ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΏΠΎΡΡΡΠΎΠΈΡΡ Ρ
ΠΎΡΠΎΡΠΎ ΡΡΠΎΠΊΡΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ΅ ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ Π΄Π²ΠΈΠΆΡΡΠ΅ΠΉΡΡ ΡΠ΅Π»ΠΈ, ΠΊΠΎΠ³Π΄Π° ΠΈΠ½ΡΠ΅ΡΠ²Π°Π» ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄ΠΎΡΡΠ°ΡΠΎΡΠ½ΠΎ Π²Π΅Π»ΠΈΠΊ. ΠΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΠ΅ Π΄Π²ΠΈΠΆΡΡΠ΅ΠΉΡΡ ΡΠ΅Π»ΠΈ Π²ΡΡΡΡΠ°ΠΈΠ²Π°Π΅ΡΡΡ Π²Π΄ΠΎΠ»Ρ ΠΎΡΡΠ΅Π·ΠΊΠ° ΠΏΡΡΠΌΠΎΠΉ, ΡΠ³ΠΎΠ» Π½Π°ΠΊΠ»ΠΎΠ½Π° ΠΊΠΎΡΠΎΡΠΎΠΉ ΠΏΡΠΎΠΏΠΎΡΡΠΈΠΎΠ½Π°Π»Π΅Π½ ΠΏΡΠΎΠ΅ΠΊΡΠΈΠΈ ΠΎΡΠ½ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΡΠΊΠΎΡΠΎΡΡΠΈ ΡΠ΅Π»ΠΈ Π½Π° Π»ΠΈΠ½ΠΈΡ Π²ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½ΠΈΡ. ΠΡΠ΅Π½ΠΊΠ° ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΡ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΠΈΡΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠ΅Π»ΠΈ
A 94-GHz Frequency Modulation Continuous Wave Radar Imaging and Motion Compensation
A compact and lightweight synthetic aperture radar (SAR) that can be loaded on a miniature unmanned aerial vehicle (UAV) was recently developed. The higher the frequency is, the smaller is the antenna size and the microwave characteristics are improved. Thus, a high frequency is favorable for miniaturization and weight reduction. In this chapter, a method of obtaining a radar image through a 94-GHz frequency modulation continuous wave (FMCW) radar is proposed. In addition, a method of motion compensation is described, and the W-band SAR image after motion compensation is confirmed. This kind of SAR imaging can provide geographic information and characteristics of extreme environments, disaster scenes, and information on sites where human access is difficult
- β¦