Space-Time Adaptive Processing (STAP)

The GA-ASI/Sandia Lynx SAR/GMTI radar (AN/APY-8) established the template for lightweight, high-resolution UAV-based all-weather ISR when it first flew in 1998. Operating at Ku band (15.2-18.2 GHz) with a 320-W TWTA, mechanically gimbaled dish antenna, and 16-node PowerPC signal processor, the system achieved 0.1-m spotlight and 0.3-m stripmap SAR resolution at 25-30 km slant range within a 57-kg package. This paper describes the original system architecture, quantifies its key performance parameters, traces its operational evolution through Block 20A and Block 30 configurations, and assesses the combat record including MQ-9 losses to Houthi air defenses. A detailed subsystem-bysubsystem modernization analysis demonstrates that current GaN AESA, navigation-grade IMU, multiantenna GNSS, GPU signal processing, and deeplearning exploitation technologies could yield 10-15 dB improvement in system sensitivity, 4-6× increase in standoff range, simultaneous SAR/GMTI operation, and sub-3-knot minimum detectable velocity-while maintaining or reducing the original SWaP envelope.

The traditional moving target indicator (MTI) radars perform range-doppler processing using MTI filters or FFT filter bank for ground clutter rejection and identifying and estimating velocities of the moving targets. These radars may use physical antennas with tracking capability or phased array antennas to electronically scan the beam. The radar may also employ Space Time Processing (STP)with an electronically scanned antenna beam to spatially filter out the clutter and to identify the target directions. The stand-alone narrow band DOA techniques are highly matured, space time processing of wideband (e.g., multi frequency) radars, especially the adaptive version of space time adaptive processing (STAP) continues to be an interesting task. The scenario of multiple targets, multiple pulse repetition frequencies (PRFs), diverse clutter types and jamming make the radar receiver processing even more complex. A radar simulator is very useful to test the target detection and estimation algorithms. In this work, a staggered pulse repetition frequency (PRF) radar simulator is proposed. MTI radar scenarios such as multiple targets, multiple clutters and jamming sources are also simulated. The synthetic echo signal data is validated using a basic STP algorithm. The Range-Angle, the Doppler-Angle and the Velocity-Angle maps are produced by spatial time processing. The spatial beam patterns to capture the direction of arrival (DOA) of the targets are plotted and beamwidths are computed. Results confirmed the accuracy and usefulness of the simulated data.

The second edition of Principles of Modern Radar Volume 1: Basic Principles is a comprehensive textbook for courses on radar systems and technology at the college senior and graduate student level. It is also a professional training and self-study textbook for engineers switching to a career in radar as well as a professional reference for current radar engineers. It is unique in its breadth of coverage, its emphasis on current methods and its careful balance of qualitative explanation and quantitative rigor appropriate to its intended audience.

Airborne radar tracking in moving ground vehicle scenarios is impacted by sensor, target, and environmental dynamics. Moving targets can be assessed with 1-D High Range Resolution (HRR) Radar profiles with sufficient signal-to-noise (SNR) present which contain enough feature information to discern one target from another to help maintain track or to identify the vehicle. Typical radar clutter suppression algorithms developed for processing moving ground target data not only remove the surrounding clutter but also a portion of the target signature. Enhanced clutter suppression can be achieved using a multi-channel signal subspace (MSS) algorithm which preserves target features. In this paper, we (1) exploit extra information from enhanced clutter suppression for automatic target recognition (ATR), (2) present a gain comparison using displaced phase center antenna (DPCA) and MSS clutter suppressed HRR data; and (3) develop a confusion-matrix identity result for simultaneous tracking a...

Design issues for the multistage Generalized Cube network are discussed in this paper. An analysis of the merits of 2-input/2-output interchange boxes versus 4-input/4-output crossbars for interconnection network implementation is made. The cost and performance of each network for the two switching node alternatives are examined. Discussion of the s u i t a b i l i t y of each approach for VLSI implementation is included. I t is shown that in a packet switching environment, 4x4 crossbars outperform, and are less expensive to implement than the four interchange boxes they replace.

Na jaren van groei staat het stadmaken in Rotterdam voor een nieuwe uitdaging. De aantrekkende markt en hernieuwde professionele drukte in de stad dreigen particulier initiatief en gedeelde stadsontwikkeling minder vanzelfsprekend te maken -ondanks de waarde die veel partijen er aan hechten. De vraag is hoe het stadmaken in Rotterdam zich in deze nieuwe context kan verstevigen en consolideren. Dit essay is het verslag van een zoektocht naar die vraag onder Rotterdamse stadmakers in de periode zomer 2017 -voorjaar 2018. Rotterdamse stadmakers bespraken de kenmerken en kernwaarden van het stadmaken, en dachten na over manieren om het stadmaken sterker te maken. Vijf concrete suggesties kwamen naar voren: zorgen voor (i) meer uitwisseling en regelmatige meetups, (ii) meer politieke verbinding, (iii) meer kennis over waardeontwikkeling en ondernemingsmodellen, (iv) verduidelijking van afspraken in stadmaak-omgevingen en (v) grotere toegankelijkheid en inclusiviteit van het stadmaken. Deze suggesties kunnen het stadmaken verder consolideren terwijl ze tegelijkertijd de dynamiek, het onverwachte, het gedeelde en de openheid van het stadmaken in stand houden. De Rotterdamse stadmaker. Bevlogen, betrokken, ondernemend. Met hart en ziel verbonden aan de stad en haar plekken, gedreven om deze plekken nog levendiger, meer gedeeld en toegankelijker te maken. De stadmaker en het stadmaken werd de afgelopen jaren een steeds breder gedragen begrip in Rotterdam. Er ontstond een levendige praktijk van kleinschalige particuliere stadsontwikkeling, initiatieven van bewoners, ondernemers en zelfstandigen, ondersteund door professionele partijen zoals woningbouwcorporaties, ontwikkelaars en de gemeentelijke diensten. De Rotterdamse stadmakers-praktijk is geworteld in een lange lokale traditie van ondernemerschap, privaat-particuliere-publieke stadsontwikkeling en bewonersbetrokkenheid, maar kwam vooral aan het licht toen de financiële crisis in al haar hevigheid losbarstte. Burgers en lokale ondernemers sprongen in het gat dat de terugtrekkende overheid en markt achterlieten. Zij begonnen vanuit hun eigen belang, interesse en kennis en met eigen middelen initiatieven te ontwikkelen die, ondanks hun kleinschaligheid en relatieve autonomie, een belangrijke bijdrage leverden aan de stedelijke kwaliteit. Het speelveld van stedelijke ontwikkeling veranderde daardoor in rap tempo. Niet langer was dit het exclusieve domein van professionele partijen zoals gemeenten, Rijk, woningcorporaties, ontwerpbureaus en ontwikkelaars, maar in toenemende mate ook van de stadmakers. De werkwijze van het stadmaken verschilde sterk van voorheen gangbare (markt-en overheid gestuurde) stadsontwikkeling. In het stadmaken deelt men initiatief, is er ruimte voor lokale, actuele oplossingen en kansen, en draait het om het leggen van creatieve verbindingen tussen mensen, plekken en innovatieve ideeën. De Rotterdamse stadsontwikkeling ging daarmee steeds meer lijken op de maatschappij die de filosoof Gilles Deleuze al in 1993 beschreef: een maatschappij van nooit geheel te doorgronden individuen, die

Na jaren van groei staat het stadmaken in Rotterdam voor een nieuwe uitdaging. De aantrekkende markt en hernieuwde professionele drukte in de stad dreigen particulier initiatief en gedeelde stadsontwikkeling minder vanzelfsprekend te maken -ondanks de waarde die veel partijen er aan hechten. De vraag is hoe het stadmaken in Rotterdam zich in deze nieuwe context kan verstevigen en consolideren. Dit essay is het verslag van een zoektocht naar die vraag onder Rotterdamse stadmakers in de periode zomer 2017 -voorjaar 2018. Rotterdamse stadmakers bespraken de kenmerken en kernwaarden van het stadmaken, en dachten na over manieren om het stadmaken sterker te maken. Vijf concrete suggesties kwamen naar voren: zorgen voor (i) meer uitwisseling en regelmatige meetups, (ii) meer politieke verbinding, (iii) meer kennis over waardeontwikkeling en ondernemingsmodellen, (iv) verduidelijking van afspraken in stadmaak-omgevingen en (v) grotere toegankelijkheid en inclusiviteit van het stadmaken. Deze suggesties kunnen het stadmaken verder consolideren terwijl ze tegelijkertijd de dynamiek, het onverwachte, het gedeelde en de openheid van het stadmaken in stand houden. De Rotterdamse stadmaker. Bevlogen, betrokken, ondernemend. Met hart en ziel verbonden aan de stad en haar plekken, gedreven om deze plekken nog levendiger, meer gedeeld en toegankelijker te maken. De stadmaker en het stadmaken werd de afgelopen jaren een steeds breder gedragen begrip in Rotterdam. Er ontstond een levendige praktijk van kleinschalige particuliere stadsontwikkeling, initiatieven van bewoners, ondernemers en zelfstandigen, ondersteund door professionele partijen zoals woningbouwcorporaties, ontwikkelaars en de gemeentelijke diensten. De Rotterdamse stadmakers-praktijk is geworteld in een lange lokale traditie van ondernemerschap, privaat-particuliere-publieke stadsontwikkeling en bewonersbetrokkenheid, maar kwam vooral aan het licht toen de financiële crisis in al haar hevigheid losbarstte. Burgers en lokale ondernemers sprongen in het gat dat de terugtrekkende overheid en markt achterlieten. Zij begonnen vanuit hun eigen belang, interesse en kennis en met eigen middelen initiatieven te ontwikkelen die, ondanks hun kleinschaligheid en relatieve autonomie, een belangrijke bijdrage leverden aan de stedelijke kwaliteit. Het speelveld van stedelijke ontwikkeling veranderde daardoor in rap tempo. Niet langer was dit het exclusieve domein van professionele partijen zoals gemeenten, Rijk, woningcorporaties, ontwerpbureaus en ontwikkelaars, maar in toenemende mate ook van de stadmakers. De werkwijze van het stadmaken verschilde sterk van voorheen gangbare (markt-en overheid gestuurde) stadsontwikkeling. In het stadmaken deelt men initiatief, is er ruimte voor lokale, actuele oplossingen en kansen, en draait het om het leggen van creatieve verbindingen tussen mensen, plekken en innovatieve ideeën. De Rotterdamse stadsontwikkeling ging daarmee steeds meer lijken op de maatschappij die de filosoof Gilles Deleuze al in 1993 beschreef: een maatschappij van nooit geheel te doorgronden individuen, die brought to you by CORE View metadata, citation and similar papers at core.ac.uk

Na jaren van groei staat het stadmaken in Rotterdam voor een nieuwe uitdaging. De aantrekkende markt en hernieuwde professionele drukte in de stad dreigen particulier initiatief en gedeelde stadsontwikkeling minder vanzelfsprekend te maken -ondanks de waarde die veel partijen er aan hechten. De vraag is hoe het stadmaken in Rotterdam zich in deze nieuwe context kan verstevigen en consolideren. Dit essay is het verslag van een zoektocht naar die vraag onder Rotterdamse stadmakers in de periode zomer 2017 -voorjaar 2018. Rotterdamse stadmakers bespraken de kenmerken en kernwaarden van het stadmaken, en dachten na over manieren om het stadmaken sterker te maken. Vijf concrete suggesties kwamen naar voren: zorgen voor (i) meer uitwisseling en regelmatige meetups, (ii) meer politieke verbinding, (iii) meer kennis over waardeontwikkeling en ondernemingsmodellen, (iv) verduidelijking van afspraken in stadmaak-omgevingen en (v) grotere toegankelijkheid en inclusiviteit van het stadmaken. Deze suggesties kunnen het stadmaken verder consolideren terwijl ze tegelijkertijd de dynamiek, het onverwachte, het gedeelde en de openheid van het stadmaken in stand houden. De Rotterdamse stadmaker. Bevlogen, betrokken, ondernemend. Met hart en ziel verbonden aan de stad en haar plekken, gedreven om deze plekken nog levendiger, meer gedeeld en toegankelijker te maken. De stadmaker en het stadmaken werd de afgelopen jaren een steeds breder gedragen begrip in Rotterdam. Er ontstond een levendige praktijk van kleinschalige particuliere stadsontwikkeling, initiatieven van bewoners, ondernemers en zelfstandigen, ondersteund door professionele partijen zoals woningbouwcorporaties, ontwikkelaars en de gemeentelijke diensten. De Rotterdamse stadmakers-praktijk is geworteld in een lange lokale traditie van ondernemerschap, privaat-particuliere-publieke stadsontwikkeling en bewonersbetrokkenheid, maar kwam vooral aan het licht toen de financiële crisis in al haar hevigheid losbarstte. Burgers en lokale ondernemers sprongen in het gat dat de terugtrekkende overheid en markt achterlieten. Zij begonnen vanuit hun eigen belang, interesse en kennis en met eigen middelen initiatieven te ontwikkelen die, ondanks hun kleinschaligheid en relatieve autonomie, een belangrijke bijdrage leverden aan de stedelijke kwaliteit. Het speelveld van stedelijke ontwikkeling veranderde daardoor in rap tempo. Niet langer was dit het exclusieve domein van professionele partijen zoals gemeenten, Rijk, woningcorporaties, ontwerpbureaus en ontwikkelaars, maar in toenemende mate ook van de stadmakers. De werkwijze van het stadmaken verschilde sterk van voorheen gangbare (markt-en overheid gestuurde) stadsontwikkeling. In het stadmaken deelt men initiatief, is er ruimte voor lokale, actuele oplossingen en kansen, en draait het om het leggen van creatieve verbindingen tussen mensen, plekken en innovatieve ideeën. De Rotterdamse stadsontwikkeling ging daarmee steeds meer lijken op de maatschappij die de filosoof Gilles Deleuze al in 1993 beschreef: een maatschappij van nooit geheel te doorgronden individuen, die

In this paper, we exploit the spiked covariance structure of the clutter plus noise covariance matrix for radar signal processing. Using state-of-the-art techniques high dimensional statistics, we propose a nonlinear shrinkage-based rotation invariant spiked covariance matrix estimator. We state the convergence of the estimated spiked eigenvalues. We use a dataset generated from the high-fidelity, site-specific physics-based radar simulation software RFView to compare the proposed algorithm against the existing Rank Constrained Maximum Likelihood (RCML)-Expected Likelihood (EL) covariance estimation algorithm. We demonstrate that the computation time for the estimation by the proposed algorithm is less than the RCML-EL algorithm with identical Signal to Clutter plus Noise (SCNR) performance. We show that the proposed algorithm and the RCML-EL-based algorithm share the same optimization problem in high dimensions. We use Low-Rank Adaptive Normalized Matched Filter (LR-ANMF) detector to compute the detection probabilities for different false alarm probabilities over a range of target SNR. We present preliminary results which demonstrate the robustness of the detector against contaminating clutter discretes using the Challenge Dataset from RFView. Finally, we empirically show that the minimum variance distortionless beamformer (MVDR) error variance for the proposed algorithm is identical to the error variance resulting from the true covariance matrix.

We propose an alternative waveform scheme built on mutually-orthogonal complementary sets for a distributed multistatic radar. Our analysis and simulation show a reduced frequency band requirement for signal separation between antennas with centralized signal processing using the same carrier frequency. While the scheme can tolerate fluctuations of carrier frequencies and phases, range sidelobes arise when carrier frequencies between antennas are significantly different.

A novel Decision-Feedback (DF) aided reduced complexity Maximum Likelihood (ML) Space-Time Equalizer (STE) designed for a single-carrier system is introduced. Two different methods of incorporating DF into the recursive tree search based receiver structure are proposed for allowing detection at a moderate computational cost. Additionally, a further complexity reduction scheme is proposed, which exploits the specific characteristics of both the wide-band channel and the proposed DF-STE. In comparison to the DF-STE not benefiting from this complexity reduction, the proposed detector is capable of reducing the complexity by several orders of magnitude. More quantatively, for the specific rank-deficient system considered, which detected the signal transmitted from four transmit antennas with the aid of two receive antennas, the complexity might be reduced by a factor of 100 at low Signal-to-Noise Ratios (SNRs) without noticeable performance degradation. By contrast, at higher SNRs a complexity reduction of a factor of 10 might be achieved, depending on the tolerable performance degradation.

The spacc charge bcliavior of snnie pnlyvinylchloride (PVC) samplcs with different iniolecular microstructures, obtained through chcniical inodiiicalion of i'vc has been analyzcd by iiieans of tlie thermal stcp (TS) and the thermally stimulated discharge current (TSIIC) techniques. The tnagnitude of the spicc cliargc distribution has been shown to be lower as thc dcgrcc of chemical modification increases. Combiniiig the 'IS and the TSIK tiicthods allowed its tu study niinority carriers, which could not be observed by a singlc TS nieasorement,

Space-time adaptive processing (STAP) refers to a class of methods for detecting targets using an array of sensors. The output of the array is weighted using data collected from the sensors over a given period of time. An optimal method of calculating weights exists: however, this method is usually computationally impractical. Therefore, various heuristic methods are used that approximate the optimal method. These heuristics use many of the same operations and are computationally demanding. We are in the process of constructing a portable, parallel library of subroutines useful for constructing STAP heuristics. As a first step in this process, we implemented one STAP heuristic, higher-order post-Doppler processing, using three different parallel methods on the IBM SP2 and the Intel Paragon: these methods characterize different parallel approaches to the STAP problem. From implementing these algorithms, we have been able to identify components for our parallel library. We pro...

In long-term evolution (LTE) systems, there is an option to extend the size of the cyclic-prefix (CP) when the propagation environment is characterized by severe time dispersion. Such a peculiar feature makes the system more resilient against multipath distortions, but inevitably complicates the downlink synchronization task, which cannot be accomplished through conventional techniques devised for a specified CP size. In this work, we study the problem of CP length detection in the LTE downlink in the presence of a timing uncertainty and frequency offset. In contrast to previous investigations based on heuristic arguments, our approach relies on the maximum likelihood (ML) estimation criterion. Furthermore, it accounts for the irregular LTE symbol (characterized by a different CP size), which is present in the normal CP operation mode. The resulting scheme operates in the time-domain and computes a different metric for each possible position of the irregular symbol within the observation window. Due to its flexibility, the proposed ML approach can be applied to any future multicarrier standard for the design of a CP length detection algorithm, either in the presence or in the absence of irregular symbols.

In long-term evolution (LTE) systems, there is an option to extend the size of the cyclic-prefix (CP) when the propagation environment is characterized by severe time dispersion. Such a peculiar feature makes the system more resilient against multipath distortions, but inevitably complicates the downlink synchronization task, which cannot be accomplished through conventional techniques devised for a specified CP size. In this work, we study the problem of CP length detection in the LTE downlink in the presence of a timing uncertainty and frequency offset. In contrast to previous investigations based on heuristic arguments, our approach relies on the maximum likelihood (ML) estimation criterion. Furthermore, it accounts for the irregular LTE symbol (characterized by a different CP size), which is present in the normal CP operation mode. The resulting scheme operates in the time-domain and computes a different metric for each possible position of the irregular symbol within the observation window. Due to its flexibility, the proposed ML approach can be applied to any future multicarrier standard for the design of a CP length detection algorithm, either in the presence or in the absence of irregular symbols.

Displaced Phase Center Antenna (DPCA) and Space-Time Adaptive Processing (STAP) are two general methods to
cancel clutter in order to detect small, slowly moving targets that may be obscured by clutter. To detect these targets, the
radar detection threshold needs to be as low as possible to ensure some minimum probability of detection (Pd).
Unfortunately, lowering the radar threshold naturally results in a higher false alarm rate. Although there are standard
methods such as M of N to reduce the false alarms, new techniques can potentially drive the false alarm rate down even
further.
Many “theoretical” papers have shown that STAP can be designed to outperform DPCA because of its potential
additional “degrees-of-freedom”. However, in “practice,” this isn’t always the case. For example, it is well known that
STAP can have training issues in heterogeneous clutter. Typically, a radar signal processor will implement one method
or the other to detect these small endoclutter targets.
The technique being explored here is a two-fold approach in which the existing STAP code first processes the data in
order to find a list of candidate targets. Next, a DPCA technique is also used to find a separate list of candidate detections
from the same data. Although the algorithms are working on the same data, the processing is “independent” between
them so the target lists are different. After both techniques have finished processing, the modified radar signal processing
code “intelligently” combines the two detection lists into a single detection list. It will be shown that the combined list of
detections from the two methods results in better detection performance than either method used separately.

A reconfigurable space-time coding technique is investigated, for a high-speed downlink packet access multiple-antenna network, which combats the effects of antenna correlation. Reconfigurability is achieved at the link level by introducing a linear precoder in a space-time block coded system. The technique assumes knowledge of the long-term characteristics of the channel, namely the channel correlation matrix at the transmitter. The benefits of the proposed reconfigurable technique as compared to the conventional non-reconfigurable versions are evaluated via system-level simulations. In order to characterize the system-level performance accurately and, at the same time, use a feasible approach in terms of computational complexity, a suitable linkto-system interface has been developed. The average system throughput and the number of satisfied users are the performance metrics of interest. Simulation results demonstrate the performance enhancements achieved by the application of reconfigurable techniques as compared to their conventional counterparts.

A reconfigurable space-time coding technique is investigated, for a high-speed downlink packet access multiple-antenna network, which combats the effects of antenna correlation. Reconfigurability is achieved at the link level by introducing a linear precoder in a space-time block coded system. The technique assumes knowledge of the long-term characteristics of the channel, namely the channel correlation matrix at the transmitter. The benefits of the proposed reconfigurable technique as compared to the conventional non-reconfigurable versions are evaluated via system-level simulations. In order to characterize the system-level performance accurately and, at the same time, use a feasible approach in terms of computational complexity, a suitable linkto-system interface has been developed. The average system throughput and the number of satisfied users are the performance metrics of interest. Simulation results demonstrate the performance enhancements achieved by the application of reconfigurable techniques as compared to their conventional counterparts.

This article addresses the problem of clutter cancelation for slowly moving target detection and localization in multichannel passive radar onboard mobile platforms. A post-Doppler space-time adaptive processing (STAP) approach is exploited in the case of an angle-dependent imbalance affecting the receiving channels. While the clutter suppression capability is ensured by the adaptivity of space-time filtering, different solutions are compared, aimed at recovering the detection performance losses associated with channel calibration errors. A space-time generalized-likelihood ratio test (GLRT) scheme is considered, where the steering vector is not specified in the spatial domain, resulting in a noncoherent integration of target echoes across the receiving channels. This is compared with a fully coherent GLRT scheme where echoes from the stationary scene are exploited for the proper calibration of spatial steering vector mismatch. The first scheme proves to be a simple solution for target detection in the passive radar case, offering comparable clutter cancelation capability. The

This research presents mitigating the effect of multi terrain on quality of multipath signal using adaptive equalization technique. This was achieved using neural network to improve the performance of an equalizer and then integrated on a wireless network system to improve quality of service at the receiver end during downlink. The system was implemented with simulation and the result when tested showed that the adaptive equalizer was able to improve received signal from-93.5125dBm in the characterized to-73.3875dBm. The percentage improvement achieved is 21.52%. The results achieved were analyzed by the Nigerian Communications Commission (NCC) standard for quality of service and the result showed that the new system achieve good signal indicator which showed that the impact of fading from the environment was not able to affect quality of receiver service. The result achieved as the average signal strength is good, but future work can improve it to very good by training the neural network with more data which has only optimal signal strength.