Transmission of digital signals is today more frequently used than transmission of analog signals. One reason for this is that a digital signal is less sensitive to noise than an analog, another reason is that almost all signals today are handled in a digital format. This thesis describes the development of a system that receives digital video signals through FireWire. The standard for FireWire, which is a high performance serial bus, is under development. Today the standard of the bus supports transmission of data with a speed of up to 400 Mbit/s.

This report is an outcome of a master degree project at Linköpings University in co-operation with Micronic Laser Systems AB. The purpose with this master degree project was to investigate how to implement a receiver in a data transfer system. The system consists of several data channels, where every channel consists of three parts: driver, transmission lines and receiver. The driver send low amplitude differential signals via the transmission lines to the receiver that amplifies and converts it to a single-ended signal. The receiver has to be fast and be able to feed an output signal with high voltage swing.

I det här examensarbetet har jag tittat närmare på hur man med hjälp av en transformator kan höja signal/brus-förhållandet för en mikrofonsignal som förstärks av en förstärkarkrets. Arbetet baseras sig på en psykoakustisk brusmätning enligt standarden ITU-468-4.Ett bra förhållande mellan signal och brus är alltid eftersträvat i en krets. När signalen i kretsen är svag kan signalen i värsta fall försvinna i bruset. Arbetet kommer att titta på hur man definierar och mäter signal/brus-förhållanden på en förstärkare samt vad som påverkar signal/brus-förhållandet. Arbetet kommer visa att med hjälp av en spänningstransformering av en in-signal så kan ett bättre signal/brus- förhållande ut från en serie förstärkare erhållas..

In this thesis some different modulation schemes for xDSL-techniques are compared. The investigated techniques are ADSL, G.lite, ADSL2, HDSL, SHDSL and VDSL. The modulation methods used are DMT, CAP and different versions of PAM. Several broadband techniques also use Trellis Coded Modulation (TCM) to increase the coding gain of the transmission. For each one of the different modulation methods the signal-to-noise ratio is calculated for generating a bit error rate probability of 10-7.

Sweden's drinking water quality is considered to be high partly due to a high quality of the raw water and a well developed sewage infrastructure. Despite this, there is water contamination that could be prevented by installation of a sophisticated early warning system. Some of the major players in the production of drinking water have already invested in different types of early warning systems to ensure drinking water of high quality. There are various forms of early warning systems where automatic monitoring of E. Coli is an interesting alternative.

We have different kinds of signal processing everywhere around us in our everyday life, in our cellphones, when we are listening to music, watching TV etc. This makes signal processing a very interesting and important technical area, where the demand of skilled engineers sets the limit of what is possible.Working with signal processing requires in-depth knowledge in areas such as mathematics, physics, electronics, and other related areas. For this, it has traditionally been demanded by a talented developer to also master the advanced programming languages such as C / C + + and Assembler.This has begun to change; today there are several companies that offer graphical development environments for signal processing, environments where programming skills are not needed anymore, and the focus can be on signal processing instead.The goal with this project is to build a corresponding graphical development environment to reach an understanding of what is required of these systems, and also to grasp what opportunities that are available within graphic programming. Inspiration for the work has partly arise from some of the tools available on the market, and partly from previous theses that have been written about graphic programming.The challenge lies in creating a program that can execute signal diagrams in real time from given signal blocks, and be able to handle feedback loops in an efficient way and to do so at the lowest "cost" in terms of clock cycles as possible. This should also be compared against to code, compile and run a complete signal diagram directly.To increase the usability it should also be possibility to externally manage in real time the parameters of the signal diagram during execution.The interface is a separate program, which is to some extent similar to Matlab Simulink, where a signal diagram is drawn up graphically by connecting wires between different signal blocks.

The data acquisition system COMET developed by Saab AB contains a unit for signal conditioning and A/D conversion, called KSM. The varieties in signal conditioning constitutes of a number of specific PBAs and maintenance as well as reconfiguration of these are complicated not to mention costly. This thesis has aimed to investigating whether the signal conditioning circuits can be replaced by a general purpose, programmable solution. If so, how can this be done? The development has been carried out by evaluating ideas through the use of a laboratory environment and has resulted in an analog design for laboratory purpose.

The purpose with the report is to show that it is possible to design a class-D amplifier, using a programmable FPGA mounted on a developing card from Xess and a H-bridge. The FPGA was programmed in VHDL which is the language the software from Xilinx use to implement a logical function into the FPGA The logical function corresponds to a modeling of the music signal and the modeling can be described as a comparator which compare the music signal with a triangle wave and as a out signal produce a pulse width modulated (PWM) signal. The report is also a review and evaluating of two different modulating technologies, AD- modeling and BD-modeling. A detailed part about how the H-bridge was designed and how it works. The result of this project is a working audio amplifier to a significant lower price than the products in todays market..

To be able to evaluate different radio waveforms in a laboratory environment FOI in Linköping has developed an experimental system for radio communication called Rasmus. The system consists of a transmitter, a channel emulator and a receiver. The transmitter modulates a digital signal to a desired analogue waveform. The channel emulator is used to simulate a real radio channel. The channel emulator distorts the signal by splitting it up in several propagation paths.

This report is introduced with a presentation of fundamental electromagnetic theories, which have helped a lot in the achievement of methods for calculation and design of microstrip transmission lines and circulators. The used software for the work is also based on these theories. General considerations when designing microstrip solutions, such as different types of transmission lines and circulators, are then presented. Especially the design steps for microstrip lines, which have been used in this project, are described. Discontinuities, like bends of microstrip lines, are treated and simulated.

This thesis has the overall objective to develop the optimum sealing system between the retarder and transmission. Today, there is a pressure-relief and two radial seals separation between the retarder and transmission. It has been found that carbon residue formation may occur between retarder axle and seal lips with, in some cases, leakage as a result.We have in this thesis tried to explain the phenomenon of carbon residue, how it is formed and why it can be seen just on the seals? A rig test was conducted where we show how friction, speed, transmission temperature and mitigation phases of the retarder affects temperatures in the sealing environment. Factors affecting the coke structure are reported, together with proposals for measures that provide a mitigating seal environment.

The majority of all power cuts that affects individuals and communities are caused by earth faults on the power transmission lines at 10kV and 20kV level [1]. If these power cuts could be eliminated, less disturbances and interrupts would lead to large amounts of money savings.Swedish Neutral has developed such a protection system. When an earth fault occurs power is injected into the neutral point of the transformer. The RCC (Residual Current Compensation) protection calculates a compensation current exactly 180 degrees out of phase to the fault current. Doing this, the voltage at the fault location becomes very close to zero, without affecting the power transmission.The protection system can only compensate automatically for the fundamental frequency (50Hz), and manually for the 3rd, 5th, 7th and 9th harmonics.

In modern industrial robots the components in the transmission contain nonlinearities. These nonlinearities need to be to estimated either for better control or to use the parameters for diagnosis of the system. There is a lot of work done within system identification and mainly within the field of iterative parameter estimation.This thesis considers recursive grey-box identification for a nonlinear model of the transmission in an industrial robot. The nonlinearities that are identified are friction, spring stiffnes, hysteresis and backlash. These nonlinearities are a part of the models that are presented in this thesis.

The purpose of this project was to produce signal relay stations that could receive information via 2.4 GHz radio and relay the information to a designated target station. If a relay station was located outside of signal range for the target station it was supposed to utilize other relay stations to transfer the information to the target station, so called multi-hop.The would-be application of the relay stations was orienteering. When an orienteer punches a checkpoint the signal stations would relay information of who punched the control, when it was punched and the checkpoint that was punched to the speaker tower in the goal area.The work resulted in prototypes which fulfilled the statement of purpose and was tested at an orienteering competition with satisfactory results. The performance of the prototypes was tested and found adequate for the would-be application..

This thesis studies the negative impact that control signal saturation may have on a controlled system. Different methods that are used to compensate for this problem are also studied and evaluated. Both sensitivity to disturbances and the effect the method has on the systems'ability to follow a reference signal will be examined. Stability will be discussed, but no conclusions whether the systems are stabilized or not can be drawn. Control signal saturation will lead to a slower behavior in general.