<p>More to come</p>

<p>Au catalyst ZnO nanostructures have been grown on the a- and c-plane sapphire substrate by PLD. Influence of substrate lattice orientation, substrate surface and different substrate annealing temperature have been characterized by AFM, SEM and XRD. This report shows that a-plane sapphire substrate annealed at 1000 degree C and 1200 degree C improves the growth condition of Au catalyst ZnO nanostructures. For c-plane sapphire; annealing at 1200 degree C and 1400 degree C enhances the nanostructure growth. The better growth condition is a result of the terrace-and-step morphology seen on the substrate surface prior to growth. This report also indicates a correlation between the azimuthal in-plane alignment of the grown nanostructures and the sapphire substrate lattice orientation.</p>

<p>The main goal of this thesis is to present two good alternatives for the HDL+ protocol proposed for ratification in STANAG 4538, as this partially is restricted by a patent claims. The HDL+ protocol is used as a starting point, and in order to accommodate for the patented parts, the adaptive process is altered, and the code combining process is removed for the highest rate. For simplifying the comparison between the performance of the proposed protocols, and the HDL+, both proposed protocols is simulated in a MATLAB environment, over the same channels as Harris has presented the throughput capabilities of the HDL+. These channels include the AWGN, single tap channel with flat fading, the ITU-MLD channel, and the ITU-MLD channel with Long- and Intermediate- Time SNR variations. By analyzing the results, it is clear that the current implementation of the proposed protocols does not achieve as high throughput as the HDL+, but there are indications that there is potential for better results if further development is performed.</p>

<p>This report presents a method for fabrication of ridge-type waveguide electro-optic modulators in 500 nm thick, c-oriented, epitaxial, (Pb0.92,La0.08)(Zr0.4,Ti0.6)O3 thin films on a MgO substrate. The method is based on ordinary photolitography and wet etching techniques with lift-off metallisation of gold electrodes. To achieve good input coupling of light the device end faces were polished using diamond lapping film swith grain sizes as small as 0.5 um. Several devices with both Mach-Zehnder electro-optic modulators and phase modulators with co-planar gold electrodes and an interaction length of L = 3 mm were fabricated using this method. These modulators were used to examine the electro-optic efect in the thin films at the wavelength 1.55 um. Coherent, linearly polarised light was coupled into the waveguide end face using tapered fibres while a modulation voltage was applied to the electrodes. The phase modulators were used as intensity modulators by exciting them with light polarised 45 degrees on the optical axis and placing a linear polariser at the output. Practical modulation was achieved using voltages as low as 46 V with the phase modulators and 80 V with the Mach-Zehnder modulators. Using a numerical curve fitting technique, the measured data was fitted to a proposed theoretical model for the modulators. The model was based on Jones matrix formalism and the assumption that the electro-optic effect in the thin films corresponds with the Pockels effect. Good fits were achieved indicating that the effect is indeed a Pockels effect and estimates of the Pockels coecient r51 ranged from 4.4 pm/V to 11 pm/V depending on the device. These values were obtained under the uncertain assumption that the birefringence of (Pb,La)(Zr,Ti)O3 is 0.005. It is found that if the actual value of the birefringence is lower, then r51 will also be lower than estimated. Based on previous works the Pockels coeficient was expected to be on the order or ~102 pm/V. The low measured values of r51 and the variation between films is believed to be due to the thin films being multi domain with a domain structure created by a stochastic process.</p>

<p>Atmospheric impairments are a major obstacle in satellite communications at Ka-band in high latitude regions. This report gives a short summary of the existing models that can be used to model the impairments. Further a simple measurement system based on satellite beacon reception is designed using locally available and off-the-shelf components as well as locally manufactured ones. Performance of the components as well as of the whole system is examined and found to be in agreement with the expected values with overall system figure of merit (G/T) of 21 dB/K. Data from 25 days of measurements are presented and compared with model predictions. The comparison points to possible deficiencies in some of the system components that should be assessed for further use. Most notably low amplitude accuracy of the spectrum analyzer and a low sampling rate of the data acquisition system.</p>

<p>The major issue with solar cells today, is the price per watt. To tackle this challenge several approaches are being made. One possible approach is to reduce the amount of silicon raw material used in todays wafer-based solar cells by making the wafers thinner. This approach does however bring with it another problem; much of the incident light will escape the cell before being absorbed. One possible way to solve this problem is to use a photonic crystal (PC) as a rear reflector. PCs is a periodic dielectric structure that can reflect light in a non-specular manner, which can substantially increase the optical pathlength for the light within the cell, and hence increase the probability of absorption- One such PC is the inverted opal. To make an inverted opal, one first fabricates a synthetic opal, consisting of microspheres of some kind, that can be used as a template. The gaps between the spheres of such an opal can then be filled with a suitable dielectric, e.g. silicon, and the spheres can be removed by a selective process, leaving the inverted opal structure. In this master project, opals were attempted made with Ugelstad spheres and polysterene (PS) spheres. With the Ugelstad spheres, wafer sized monolayers were made, but opals were not achieved. The PS spheres however, proved very suitable, and opals with a grain size of 150x300$mu m$ were successfully made. These opals were then partially inverted, by first filling in the gaps between the spheres with silicon, using a low temperature low pressure PECVD process, and then heating the samples to 600 degrees Celsius for 2.5 hours.</p>

<p>This thesis will seek to design a capacitive touch sensor that uses as little power as possible while still having decent performance. The study will start by discussing oscillators and find that relaxation oscillators with a frequency dependent on an RC-circuit is of greatest interest. Thorough simulations and theory will show that it is power efficient for the RC-circuit to oscillate between two voltage levels close to the supply voltage. It will also show that it is only the resistance that affect the power dissipation in the RC-circuit. A Finite State Machine that monitors changes in the period of the oscillator is described and designed. It uses two IIR filters to reject noise from the oscillator and provide an average over time the input can be compared to. A prototype is built and tests establish that both the oscillator and FSM behave as expected. It is found that the response time of the FSM can be stated in sampling periods and that lower bit lengths give faster response time. Power estimations are done and it is found that the FSM uses two orders of magnitude less power than the oscillator. The full design is compared to a low power capacitive touch system currently on the market. Power estimations indicate that the design proposed uses an order of magnitude less power than the commercial implementation it is compared with. The results also indicate that the proposed design has a potential for even more power optimization.</p>

<p>This work contains a study of underwater acoustic networks. The concept of underwater acoustic networks has been presented with its benefits and drawbacks. An overview of the marine research areas oceanography, seismology, waterside security, marine pollution and marine biology has been made and a review of conventional methods and instrumentation committed. The research methods used today have been compared with the potential of underwater acoustic networks as a platform for maritime applications. Underwater acoustic networks were reviewed as feasible within all areas with some restrictions. The fact that respectable data rate is best achieved for nodes deployed in a high density grid give limitations on the coverage area. Battery as an energy source limits the life span of an underwater acoustic network and makes it best suited for missions for short term monitoring, if not a recharging technology is applied. The energy restrictions also put constraint on the amount of sensing done and the temporal solution in measurements. Underwater acoustic networks were found applicable for intrusion detection in waterside security to increase the range of current ultrasonic surveillance systems or realize distributed systems for passive diver detection. In oceanography and pollution monitoring current in situ sensors may enable underwater acoustic networks to do autonomous synoptic sampling of limited areas to measure a number of parameters, e.g. oxygen, turbidity, temperature and salinity. For seismic exploration this technology might save costs for permanent seismic installations in constant monitoring of producing oil fields. It might also aid marine biologists in habitat monitoring.</p>

<p>Due to increase in ship traffic and activities related to oil and gas there is currently grate interest in the northern regions of Norway. Satellite communications to these areas i.e. north of the polar circle is however challenging due to low elevation angles and restricted visibility of geostationary satellites. Limited work has been done to study the propagation effects at theses latitudes and low elevation angles, especially at millimeter frequencies and for maritime communications. Some measurements have been conducted at Svalbard [5] and in Canada [5.1]. The studies from Svalbard were conducted at Ku-band frequencies whilst the Canadian measurements were conducted at 38 GHz. Non of the two did however include maritime measurements. Further measurements are therefore needed to characterize the propagation effects under these conditions. A beacon receiver is radio which is used to detect and measure the signal strength of a transmitted radio beacon signal. Beacon signals transmitted by satellites are often low power continuous wave signals intended for antenna steering and power control purposes. These signals are well suited for propagation measurement due to their constant transmits power and frequency. Propagation research often relies on beacon measurements along with other information such as weather data and radiometer readings. This thesis discusses the design and implementation of a low cost beacon receiver based on digital signal processing techniques and software defined radio. The intention was originally to design a Ka-band (20 GHz) receiver. This was however extended to a general purpose beacon receiver intended to operate at an L-band intermediate frequency. Different architectures and realizations are discussed with emphasis on costs and performance. It is shown that a 1.2 m antenna, receiving a Ka-band beacon with, 9 dBW EIRP would produce a signal level of about -130 dBm at its output. This would in turn yield a C/N0 ratio of about 46 dBHz at 76°North, assuming a receiver with overall noise figure of 1.5 dB and clear air conditions. Based on the link budget calculations two different beacon receiver designs are proposed. One based on the superheterodyne receiver architecture realized with standard RF-components such as mixers and amplifiers with coaxial connectors. The second design is based on the universal software radio peripheral, (USRP), which is a software radio, intended to allow personal computers function as radio transceivers. It was found that building a complete beacon receiver from standard RF-components would require about 100.000 NOK to achieve the wanted performance. This includes a complete system with antenna, front-end and baseband receiver. Due to the relatively inexpensive hardware (4900 NOK) of the USRP and the availability of front-end plug inn boards in the required intermediate frequency range the USRP was chosen as the hardware portion of the receiver. Linearity measurments and observations of the USRP output spectrum shows a linear dynamic range of about 60 dB which is found sufficient for beacon measurements. A Ku-band antenna intended for television reception has been used to receive a 12.2 GHz beacon transmitted by Eutelsat W3A Software code was developed based on the GNU radio framework in order to use the USRP as a beacon receiver. A number of issues were discovered during this work: • GNU radio does not contain filters for spectral averaging • Attempts to implement additional functionality in software proved challenging due to limitations in computational speed Both of the two issues affected the performance of the beacon receiver. Modifications and additions to the GNU radio software is therefore suggested for future work</p>

<p>This Thesis covers a part of the study comprised in the ULTRASPONDER (In vivo Ultrasonic Transponder System for Biomedical Applications) Project. The main area of interest is to study how to combine different signals which can imply an improvement onto the diagnostic information carried by the ECG records. It is believed that monitoring blood pressure inside the heart may give vital information to correctly diagnose and provide treatment for chronic heart failure patients. Moreover, heart rate variability analysis has proved to be one of the most important risk predictors in detecting ventricular tachycardias and fluttering. With this focus, the Thesis provides a solid background on cardiac anatomy and physiology, uncommon in many engineering texts, in order to understand the biological changes that affect the waveforms, for then moving to the performance of a theoretical and statistical study in order to find correlations, redundancies, or new information content in the signals intended to cohabit in the ULTRASPONDER control unit, namely, signals from the intra-cavity pressure sensors, ECG electrodes and other type of sensors, as well as heart rate time-series. Because this control unit, implanted underneath the patient's skin, must handle several different signals and transmit clinically relevant information in a power constraint manner to an external device, which may have much larger amount of resources, all signal processing performed in the context of the control unit must be kept under a reasonable limit that permits to efficiently extract information about the patient's health without decreasing the device's lifetime. We have implemented two time-domain QRS complexes detection systems, two simple beat classification algorithms based on beat-to-beat segmentation and template correlation, and some HRV measures as fundamental elements of ECG signal processing. Detection performance is analyzed from a critical point of view, considering several not so common parameters, such as Qalpha and MCC, which collect much more information than the usual sensitivity and predictivity assessments. A closed-loop DPCM system was chosen for the encoding and compression tasks, experiments showing its validity for ECG and blood pressure signals, although advising against its usage for HR time series. Compression performance is analyzed in terms of compression ratio attained and distorsion introduced. A novel measure called "compressibility quotient" (CQ) is presented as an indicator of the balance between theoretical compression limits marked by the sample entropy and actual compression obtained with a concrete scheme, in terms of the tradeoff CR-distorsion. A strong correlation between signal-to-noise ratio and CQ was found, implying that this measure might have some relevance for analyzing real compression possibilities under some quality criteria. The approaches followed in this Thesis, particularly regarding the theoretical study and data fusion comments, are valid for the ECG, blood pressure and heart rate signals considered, without detriment to be likewise applied to new signals that might become of interest in the future years. When new sensors are implemented to provide distinct signals, a theoretical study can include them to find out their usefulness and relation to the ones already considered. Data fusion should then be reviewed to assess the validity and convenience of the communication system for the new set of significant signals.</p>