ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The paper describes the development of a robotic platform which can autonomously map terrain using a COTS infrared imaging and ranging system. The robotic system is based on an omnidirectional platform, and can navigate typical commercial indoor environments. An on-board processor performs surface reconstruction, and condenses the point clouds generated by the ranging system to mesh models which can be more easily stored and transmitted. The processor then correlates new frames with the existing world model by using sensor odomerty. The robot will autonomously determine the best areas of the environment to map, and gather complete three dimensional color models of arbitrary environments.

The Western Cape population of Blue Cranes (Anthropoides paradiseus) is the largest and most stable population for the species. The population is primarily threatened by high mortality due to collisions with power-lines and the development of wind farms. Yet, little is known about how this population uses the agricultural landscape and their movements. Thirteen Blue Cranes were fitted with trackers to collect Global Position System data and tracked for 3 – 18 months in the Overberg region of the Western Cape. With the provided spatial-temporal information, I estimated the home range size, daily flight distances, and distance travelled throughout the day of breeding and non-breeding cranes to determine whether the breeding status/season influences their ranging behaviour. There was no significant difference of the home range size between breeding cranes and non-breeding cranes (p > 0.05). There was also no significant difference of the home range size of breeding cranes between their seasons (p > 0.05). Breeding cranes travelled significantly shorter daily flight distances than non-breeding cranes (p < 0.05). Breeding cranes also travelled significantly shorter daily distances during the breeding season than the non-breeding season (p < 0.01). All cranes, regardless of breeding status or season, travelled further distances in the morning, decreasing distance during the midday and early afternoon with an increase in the late afternoon. Breeding cranes travelled shorter distances throughout the day than non-breeding cranes during the breeding season (p < 0.001). Lastly, breeding cranes travelled significantly shorter distances throughout the day in the breeding season than the non-breeding season (p < 0.001). From this study the results suggest that factors other than breeding status influence the ranging behaviour of these cranes. Factors such as the availability of roost and forage sites, the agricultural landscape of the Overberg and the presence of other Blue Cranes could also affect ranging behaviour. Although this study does not give clear guidelines on the movement of the population, it establishes a baseline for further studies into factors that affect their ranging behaviour and can still be used to aid in conservation strategies for the species. Future studies should focus on recording their time budgets, including overnight GPS fixes and assessing ranging behaviour over multiple years.

No / Initial ranging is the primary and important process in wireless networks for the customer premise equipments (CPEs) to access the network and establish their connections with the base station. Contention may occur during the initial ranging process. To avoid contention, the mandatory solution defined in the standards is based on a truncated binary exponential random backoff (TBERB) algorithm with a fixed initial contention window size. However, the TBERB algorithm does not take into account the possibility that the number of contended CPEs may change dynamically over time, leading to a dynamically changing collision probability. To the best of our knowledge, this is the first attempt to address this issue. There are three major contributions presented in this paper. First, a comprehensive analysis of initial ranging mechanisms in wireless networks is provided and initial ranging request success probability is derived based on number of contending CPEs and the initial contention window size. Second, the average ranging success delay is derived for the maximum backoff stages. It is found that the collision probability is highly dependent on the size of the initial contention window and the number of contending CPEs. To achieve the higher success probability or to reduce the collision probability among CPEs, the BS needs to adjust the initial contention window size. To keep the collision probability at a specific value for the particular number of contending CPEs, it is necessary for the BS to schedule the required size of the initial contention window to facilitate the maximum number of CPEs to establish their connections with reasonable delay. In our third contribution, the initial window size is optimized to provide the least upper bound that meets the collision probability constraint for a particular number of contending CPEs. The numerical results validate our analysis.

<p> The literature on relevant parameters used in the model is reviewed. </p> <p> A Rigid Mathematical Model and a Stochastic Model are developed to describe acoustic propagation in the medium. </p> <p> The two models are used to determine bounds on the design parameters for a hypothetical shipborne SONAR System. </p> <p> The System so designed is evaluated on the basis of measurements made at sea. </p> / Thesis / Master of Engineering (MEngr)

No description available.

No description available.

In spite of major research initiatives by DARPA and other research organizations, precise indoor geolocation still remains as a challenge facing the research community. The core of this challenge is to understand the cause of large ranging errors in estimating the time of arrival (TOA) of the direct path between the transmitter and the receiver. Results of wideband measurement in variety of indoor areas reveal that large ranging errors are caused by severe multipath conditions and frequent occurrence of undetected direct path (UDP) situations. Empirical models for the behavior of the ranging error, which we refer to as the distance measurement error (DME), its relation to the distance between the transmitter and the receiver and the bandwidth of the system is needed for development of localization algorithms for precise indoor geolocation. The main objective of this dissertation is to design a direct empirical model for the behavior of the DME. In order to achieve this objective we provide a framework for modeling of DME, which relates the error to the distance between the transmitter and the receiver and bandwidth of the system. Using this framework we first designed a set of preliminary models for the behavior of the DME based on the CWINS proprietary measurement calibrated ray-tracing simulation tool. Then, we collected a database of 2934 UWB channel impulse response measurements at 3-8GHz in four different buildings to incorporate a variety of building materials and architectures. This database was used for the design of more in depth and realistic models for the behavior of the DME. The DME is divided into two components, Multipath-DME (MDME) and UDP-DME (UDME). Based on the empirical data, models for the behavior of each of these components are developed. These models reflect the sensitivity to bandwidth and show that by increasing the bandwidth MDME decreases. However in UDME the behavior is complicated. At first it reduces as we increase the bandwidth but after a certain bandwidth it starts to increase. In addition to these models through an analysis on direct path power versus the total power the average probability of having a UDP was calculated.

I Sverige utförs dagligen observationer av snöns djup och utbredning under snösäsongen.Observationerna används till exempel för att årsvis avgöra maximalt snödjup, snötäckets första ochsista dag samt antal dygn med snötäcke på olika platser. Traditionellt utförs snödjupsmätningarmanuellt med en enkel mätpinne, men med ny teknik kommer nya möjligheter. Med enultraljudssnömätare kan automatiserade snödjupsmätningar utföras med bättre upplösning i bådetiden och rummet vilket därmed ger bättre uppfattning av snöns tillväxt, hopsjunkning samtsmältning och innebär att alla signifikanta förändringar i snötäcket garanterat kommer observeras. I denna utvärdering har en jämförelse gjorts av manuella och automatiska snödjupsmätningarutförda parallellt på samma plats men med olika frekvens. Instrumentet som utvärderats är enSR50A Sonic Ranging Sensor uppmonterad vid Institutionen för geovetenskapers mätstation vidUppsala universitet. Vid mätstationen görs även manuella snödjupsmätningar en gång per dag. Deautomatiska snödjupsmätningarna genomförs varje minut och medelvärdesbildas över ett 10minuters intervall. Utvärderingen visar att de båda metodernas mätresultat stämmer mycket väl överrens förutomen mer eller mindre systematisk skillnad. I medeltal ger Sonic Ranging Sensorn 1,6 cm större snödjup,något som till största del kommer av en osäkerhet vid kalibreringen av instrumentet. Resultaten visartydligt på en bättre upplösning hos de automatiska mätningarna men att de manuella mätningarnaändå fått med de stora förändringarna av snötäcket vad gäller tillväxt, minskning samt max‐ ochmindjup. Rådata från Sonic Ranging Sensorn visade på större och mindre fluktuationer som berodde påosäkra mätningar. Kvaliteten på mätningarna har avgjorts antingen med instrumentets inbyggdakvalitetsnummer eller utifrån max‐ och minvärden på snödjupet tagna under varje 10 minutersintervall. De faktorer som försämrade kvaliteten i mätningarna var först och främst snöfall, men ävenregndroppar eller snö som drev på grund av vinden gav försämrad kvalitet. Instrumentets känslighetför temperaturdifferensen i skiktet precis ovanför snöytan har också utvärderats vilket visade att detemperaturmätningar som görs i nuläget på 1,5 m höjd ger tillräckligt bra mätresultat. Det skildeendast 0,14 cm i medeltal om temperaturdifferensen togs med i beräkningarna av snödjupet. Förutom en systematisk skillnad visade sig drivbildning inom mätområdet vara den faktor som gavstörst skillnad mellan manuella och automatiska snödjupsmätningar. För att avgöra hurrepresentativa snödjupsmätningarna vid mätstationen är i jämförelse med närområdet och därmedockså eliminera påverkan av drivbildning genomfördes ytterligare manuella mätningar av snödjupetpå ett homogent fält i närheten. Resultaten visar att de manuella mätningarna vid mätstationen gerett för området representativt snödjup. / During the snow season, daily observations of snow depth and distribution are performed all aroundSweden. The observations are for example used to yearly determine maximum snow depth, first andlast day of snow coverage and number of days with snow coverage in different areas. Manual snowdepth measurements are traditionally performed with a simple measurement stick but with newtechnology new possibilities arise. With an ultrasonic snow depth sensor, automatic snow depthmeasurements can be performed with much better resolution in both time and space, thus give amore detailed picture of the growth, compaction and melting of the snow coverage. There is also norisk to miss out on any important changes in the snow coverage. In this evaluation, a comparison has been made between manual and automatic snow depthmeasurements performed parallel on the same place but with different frequency. The instrumentthat has been evaluated is a SR50A Sonic Ranging Sensor mounted at a measuring station near theDepartment of Earth Sciences, Uppsala University. At the measuring station manual snow depthmeasurements are made once a day. The automatic snow depth measurements are made everyminute and an average is taken over a 10 minute interval. The evaluation shows that the measuring results of both techniques follow each other very wellexcept for a more or less systematic difference. The Sonic Ranging Sensor gives in average 1.6 cmlarger snow depth which mostly is due to in uncertainty in the calibration of the instrument. Theresults clearly show a better resolution in the automatic snow depth measurements, although themanual measurements still show all significant changes of the snow coverage when it comes togrowth, compaction, maximum and minimum depth. Raw data from the Sonic Ranging Sensor showed some large amplitude and small amplitudefluctuations that were implemented by uncertainty in the measurements. The quality of themeasurements have been determined either with the built in quality number of the instrument orfrom maximum and minimum snow depth measurements during each 10 minute interval. The factorsthat reduced the quality of the measurements was mainly snow fall, but also rain drops or driftingsnow reduced the quality. The sensitivity of the instrument due to the temperature difference in thelayer just above the snow surface was also evaluated, showing that the temperature measurementsthat currently are performed at 1.5 m height give good enough measuring results. The difference wasonly 0.14 cm in average if the temperature difference was taken into account when calculating thesnow depth. Except for a systematic difference, drifting snow inside the measuring area was the factor givinglargest difference between manual and automatic snow depth measurements. To determine howrepresentative the snow coverage at the measuring station is compared to the local area, extramanual measurements were performed at a field near the station. The result shows that themeasuring station has a representative snow depth.

Global navigation satellite systems (GNSS) have radically changed business, industry, and society, shaping the way we transport, navigate, and generally live every day. After all these years, however, GNSS location information remains only valuable outdoors, leaving indoor environments where people dwell most of the time without proper localization support. Many technologies and systems have approached this problem including optical, inertial, ultrasonic, and radio-frequency (RF), to name a few; yet the problem remains. In this thesis, inspired by the indisputable success of GNSS and the re-emergence of ultra-wideband (UWB) radios to the forefront of technology, we aim to change the state of affairs in RF localization by proposing novel clean-slate UWB ranging and localization schemes based on concurrent transmissions. These are generally considered harmful for communication but become a rich source of localization information when combined with knowledge of the channel impulse response (CIR). Our first novel contribution lies in the concept of concurrent ranging, which allows mobile nodes to simultaneously measure the distance to multiple devices—hereafter, called responders—removing the need for the wasteful long packet exchanges traditionally used for ranging and localization. Different from conventional schemes, which spread responder transmissions over time, we force responders to transmit concurrently and let their signals “fuse” in the wireless channel; the resulting impulse response, as measured by commercial UWB radios, contains all the necessary timing information to extract the desired distance to all responders. This first contribution, however, also serves us to realize the many challenges ahead to unlock the real power of concurrent transmissions for localization. We address these challenges along the way, starting with Chorus, our second contribution. Chorus exploits an anchor infrastructure that transmits packets concurrently. Mobile nodes listen for these transmissions and measure from the CIR the time difference of arrival (TDoA) of the concurrent signals, privately computing their own position at a high rate using hyperbolic localization. This reverse TDoA scheme, although simple in concept, is extremely powerful in that it enables passive self-localization of infinitely many targets at once, a feature largely missing in the RF literature. In Chorus, we address the difficult challenges to reliably detect and identify the signal from the different responders. Yet, the limited transmission precision of commercial UWB transceivers constrains the many benefits of Chorus. In this context, we i) contribute a model to ascertain the impact of the transmission uncertainty on concurrent transmissions, and ii) address the issue with a compensation mechanism that fine-tunes the local oscillator frequency of responders while they prepare to transmit, allowing us to simultaneously tackle the impact of clock drift on distance estimation. We demonstrate in our evaluation that with this compensation mechanism we can schedule transmissions with &lt; 1 ns error, removing the need to share timestamps to precisely measure distance. We rebuild concurrent ranging around this mechanism, obtaining decimeter-level ranging and localization at a fraction of the cost of conventional schemes. These results turn concurrent ranging into an immediately applicable technique that new systems can now exploit, benefiting from a different set of trade-offs hitherto unavailable. Further, the TX compensation mechanism can be directly applied to Chorus, similarly making fast and accurate passive self-localization a tangible reality. We continue our endeavor with a systematic characterization of the conditions under which UWB concurrent transmissions succeed to provide reliable ranging and communication across different complex channels. The results we put forth empower developers to fully exploit concurrent transmissions in their designs, potentially inspiring a new wave of ranging, and also communication, primitives that can bring to UWB the same striking benefits found in low-power narrowband radios. The thesis is completed by looking at other challenges preventing the wide adoption of UWB localization systems, namely, large-scale operation, energy efficiency, and the complexity to install anchor deployments. We tackle these aspects in the last part of the thesis with three additional contributions. First, we propose Talla, a TDoA system that provides seamless large-scale localization for many tags across cells of time-synchronized anchors. Secondly, we fuse UWB ranging with odometry information and build an uncertainty model that only triggers new UWB estimates if and when needed, reducing consumption and channel utilization while satisfying the application-specific demands in terms of accuracy. And thirdly, we build state-of-the-art mechanisms to automatically compute the positions of all anchors deployed across large areas based on ranging information, facilitating anchor network deployment for the many UWB-based real-time location systems (RTLS) to come. Overall, this thesis changes the landscape of UWB localization with a new set of potentially disruptive schemes and systems that exploit the peculiar benefits of concurrent transmissions and that consequently redefine the trade-offs of the technology.

Yes / The only available solution in the IEEE 802.22 standard for avoiding collision amongst various contending customer premises equipment (CPEs) attempting to associate with a base station (BS) is binary exponential random backoff process in which the contending CPEs retransmit their association requests. The number of attempts the CPEs send their requests to the BS are fixed in an IEEE 802.22 network. This paper presents a mathematical framework that helps the BS in determining at which attempt the majority of the CPEs become part of the wireless regional area network from a particular number of contending CPEs. Based on a particular attempt, the ranging request collision probability for any number of contending CPEs with respect to contention window size is approximated. The numerical results validate the effectiveness of the approximation. Moreover, the average ranging success delay experienced by the majority of the CPEs is also determined.