<p>Conventional airborne laser scanner systems output the three-dimensional coordinates of the surface location hit by the laser pulse. Data storage capacity and processing speeds available today has made it possible to digitally sample and store the entire reflected waveform, instead of only extracting the coordinates. Research has shown that return waveforms can give even more detailed insights into the vertical structure of surface objects, surface slope, roughness and reflectivity than the conventional systems. One of the most important advantages with registering the waveforms is that it gives the user the possibility to himself define the way range is calculated in post-processing. </p><p>In this thesis different techniques have been tested to visualize a waveform data set in order to get a better understanding of the waveforms and how they can be used to improve methods for classification of ground objects.</p><p>A pulse detection algorithm, using the EM algorithm, has been implemented and tested. The algorithm output position and width of the echo pulses. One of the results of this thesis is that echo pulses reflected by vegetation tend to be wider than those reflected by for example a road. Another result is that up till five echo pulses can be detected compared to two echo pulses that the conventional system detects.</p>

<p>This thesis is focused on the improvement of an existing implementation of a waveform visualizer. The problem area handled in this work has its focus on how to reduce the number of points to be plotted. The given waveform visualizer was extended by the use of two additional algorithms. First, a Level Of Detail (LOD) algorithm that gives the subset of points that are necessary to plot the waveform in the current zoom level. Second, a straight line identification algorithm to find a series of points aligned in a straight line, only leaving the end points and then drawing a line between them. These two optimizations are the main focus of this work.Additionally, an exporting functionality was implemented to export the plot data into several different data formats. Also some improvements of zooming, panning, some GUI design, and a new drag and drop functionality was constructed.</p>

<p>For a long time radio devices have been constructed in hardware with a fixed functionality. This way of constructing radio devices is starting to change with the concept of Software Defined Radio (SDR) evolving. The SDR concept leads to more flexible and long lasting radio devices. In order to make the radio software more standardized and portable, the U.S. military has defined the Software Communication Architecture (SCA). Internal communication within the SCA is done by CORBA, which limit waveforms to be only distributed over CORBA-capable hardware. The U.S. military has defined the Modem Hardware Abstraction Layer(MHAL) to enable distribution over devices not supporting CORBA. This thesis presents an implementation of MHAL and an underlying transport mechanism based on Ethernet. The implementation is done for the OSSIE package. The implementation is evaluated both in terms of real-time and throughput performance. The results show that MHAL achieves good performance, in comparison to CORBA, and can greatly be used to distribute waveforms over both CORBA and non-CORBA capable devices.</p>

For a long time radio devices have been constructed in hardware with a fixed functionality. This way of constructing radio devices is starting to change with the concept of Software Defined Radio (SDR) evolving. The SDR concept leads to more flexible and long lasting radio devices. In order to make the radio software more standardized and portable, the U.S. military has defined the Software Communication Architecture (SCA). Internal communication within the SCA is done by CORBA, which limit waveforms to be only distributed over CORBA-capable hardware. The U.S. military has defined the Modem Hardware Abstraction Layer(MHAL) to enable distribution over devices not supporting CORBA. This thesis presents an implementation of MHAL and an underlying transport mechanism based on Ethernet. The implementation is done for the OSSIE package. The implementation is evaluated both in terms of real-time and throughput performance. The results show that MHAL achieves good performance, in comparison to CORBA, and can greatly be used to distribute waveforms over both CORBA and non-CORBA capable devices.

Conventional airborne laser scanner systems output the three-dimensional coordinates of the surface location hit by the laser pulse. Data storage capacity and processing speeds available today has made it possible to digitally sample and store the entire reflected waveform, instead of only extracting the coordinates. Research has shown that return waveforms can give even more detailed insights into the vertical structure of surface objects, surface slope, roughness and reflectivity than the conventional systems. One of the most important advantages with registering the waveforms is that it gives the user the possibility to himself define the way range is calculated in post-processing. In this thesis different techniques have been tested to visualize a waveform data set in order to get a better understanding of the waveforms and how they can be used to improve methods for classification of ground objects. A pulse detection algorithm, using the EM algorithm, has been implemented and tested. The algorithm output position and width of the echo pulses. One of the results of this thesis is that echo pulses reflected by vegetation tend to be wider than those reflected by for example a road. Another result is that up till five echo pulses can be detected compared to two echo pulses that the conventional system detects.

Equipped with advanced field instruments in the past few decades, oceanographers have been able to comprehend some characteristics of the internal waves(IWs), such as the generation, propagation and energy dissipation, as well as to promote understanding in oceanography and marine ecology affected by IWs in the world ocean. Although surface gravity wave and internal wave are two of the most common natural phenomena in the ocean, the interaction between them has not been fully investigated, despite limited theoretical derivations in the literature, nor using laboratory experiments to verify the theory. A series of laboratory experiments were conducted at the National Sun Yen-sen University to study the waveform evolution of continuous IWs propagation on the flat bottom and across a trapezoidal obstacle. Surface waves were generated on a density stratified fluid system in a wave flume, from which IWs were induced indirectly to investigate their wave properties associated with their propagation . The experimental results are then used to determine the maximum depth which could be affected by surface waves in different wave conditions(wave height and period), as well as the amplitude of the IWs induced. The relationship between them are then presented in graphic form. Experiments were also conducted in uniform density and stratified fluid system with a trapezoidal obstacle. The results reveal that (1)long-period surface waves were susceptible to the interaction with the IWs in a stratified system, thus rendering wave height reduction, and (2)short-period surface waves interactions with their IWs counterparts was insignificant, hence yielded wave height similar to that in uniform density fluid system. Moreover, experiments were also conducted to study for long and short period IW propagated over pseudo slope-shelf(using trapezoidal obstacle). The results show that the variation in the IWs significantly affected the strength of internal hydraulic jump and vortices on the front slope and subsequent waveform inversion on the horizontal plateau. For IWs with short period, the horizontal distance on the plateau affected by the IWs was shirter and the total time of wave-topography interaction decreased.

The disadvantage of FDTD method is that it needs a long simulation time, and it is difficult to simulate a complex circuit. The methods to improve the efficiency in FDTD simulation are increase in width of time step, enlargement in space grid and extrapolation of late time records. In this paper, we predict the late time record in FDTD simulation by applying Prony¡¦s method, and save the computation time of FDTD simulation. The cost of computation time of Prony¡¦s method is low, and it has a good result that applying Prony¡¦s method at predicting a waveform which resonates with period. In this paper, we try to make a rule for finding training start point and width of training period in Prony¡¦s method. The result of prediction with a short period of time records under the rule is accurate and reliable

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / Massive amounts of data are typically acquired in third generation full-waveform (FW) LIDAR systems to generate image-like depthmaps of a scene of acceptable quality. The sampling systems acquiring this data, however, seldom take into account the low information rate generally present in the FW signals and, consequently, they sample very inefficiently. Our main goal here is to compare two efficient sampling models and processes for the individual time-resolved FW signals collected by a LIDAR system. Specifically, we compare two approaches of sub-Nyquist sampling of the continuous-time LIDAR FW return pulses: (i) modeling FW signals as short-duration pulses with multiple bandlimited echoes, and (ii) modeling them as signals with finite rates of innovation (FRI).

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Third generation LIDAR full-waveform (FW) based systems collect 1D FW signals of the echoes generated by laser pulses of wide bandwidth reflected at the intercepted objects to construct depth profiles along each pulse path. By emitting a series of pulses towards a scene using a predefined scanning patter, a 3D image containing spatial-depth information can be constructed. Unfortunately, acquisition of a high number of wide bandwidth pulses is necessary to achieve high depth and spatial resolutions of the scene. This implies the collection of massive amounts of data which generate problems for the storage, processing and transmission of the FW signal set. In this research, we explore the recovery of individual continuous-time FW signals at sub-Nyquist rates. The key step to achieve this is to exploit the sparsity in FW signals. Doing this allows one to sub-sample and recover FW signals at rates much lower than that implied by Shannon's theorem. Here, we describe the theoretical framework supporting recovery and present the reader with examples using real LIDAR data.

Third generation full-waveform (FW) LIDAR systems image an entire scene by emitting laser pulses in particular directions and measuring the echoes. Each of these echoes provides range measurements about the objects intercepted by the laser pulse along a specified direction. By scanning through a specified region using a series of emitted pulses and observing their echoes, connected 1D profiles of 3D scenes can be readily obtained. This extra information has proven helpful in providing additional insight into the scene structure which can be used to construct effective characterizations and classifications. Unfortunately, massive amounts of data are typically collected which impose storage, processing and transmission limitations. To address these problems, a number of compression approaches have been developed in the literature. These, however, generally require the initial acquisition of large amounts of data only to later discard most of it by exploiting redundancies, thus sampling inefficiently. Based on this, our main goal is to apply efficient and effective LIDAR sampling schemes that achieve acceptable reconstruction quality of the 3D scenes. To achieve this goal, we propose on using compressive sampling by emitting pulses only into random locations within the scene and collecting only the corresponding returned FW signals. Under this framework, the number of emissions would typically be much smaller than what traditional LIDAR systems require. Application of this requires, however, that scenes contain many degrees of freedom. Fortunately, such a requirement is satisfied in most natural and man-made scenes. Here, we propose to use a measure of rank as the measure of degrees of freedom. To recover the connected 1D profiles of the 3D scene, matrix completion is applied to the tensor slices. In this paper, we test our approach by showing that recovery of compressively sampled 1D profiles of actual 3D scenes is possible using only a subset of measurements.