Petr Bojda

Bi-directional DC-DC converters for supercapacitor based energy buffer for electrical gen-sets

The real drawback of the concept of electrical generator sets (EGS) with variable speed is the engine-generator dynamics at sudden load change from low to high. The analysis of dynamic behavior presented in this paper proves that the disadvantageous dynamical properties of EGS concepts with variable speed of engine can be improved by using an energy storage element. This paper give results of design of the bi-directional DC-DC converters for energy buffer with supercapacitors and also demonstrates the results of dynamic behavior EGS with energy buffer.

Dc-Dc converters with FPGA control for photovoltaic system

The paper introduces on operating principle of power management of photovoltaic system with maximum power tracker control to achieve the maximum efficiency of such systems. The paper presents different topologies of basic photovoltaic concepts with DC-DC converters including control design of maximum power tracker by Matlab-Simulink. The paper will be present different topologies of converter concepts that improve the total efficiency value. PWM controlling of such sophisticated system can be achieved by field-programmable-gate-array (FPGA) that more details of set up PWM signals due to FPGA technologies is shown in this paper.

Multipurpose Visualization System

This deals with the design and architecture of the low-cost Multipurpose Flight Visualization System (MFVS). The MFVS system was originally developed as a passive IFR approach system for small general aviation planes. A relatively high adaptability is one of the main advantages. It can be easily used with many types of avionics devices. The GPSIINS system is used as the primary data source. The data from the GPSIINS system are pre-processed by proprietary neural network units that feed the 3-D visualization system. The neural network unit is responsible for adaptation of this system and can eliminate problems caused by data delays and data drop-outs. The 3D visualization unit processes data from the neural network unit and eventually from the 6DOF tracker that is placed on the pilots Head Mounted Display (HMD). The unit then generates a 3D view of the surrounding environment that is similar to the 3D environment the pilot knows from flight simulators. The source of environment data is the terrain and object/obstacle database. The image output can be displayed on HIUD, MED, or HMD.

Concept of a complex navigation signal generator

The paper presents a concept and the first experimental results of a complex navigation signal generator (CNSG). The generator forms a signal of a predefined radio-navigation beacon received at a specific aircraft position. Recently the beacon is represented by a GNSS satellite and its movement is incorporated. The CNSG consists of the two main parts. The first is the DSP part which physically generates the resulting signal and is based on the FPGA device followed by a suitable DA converter. The second part of the CNSG is a software simulator of the navigation situation. A numerical model of a fixed wing aircraft which is suitable to simulate relative position of an aircraft with respect to the beacon is continually resolving the vector aircraft-beacon. That vector and its time derivatives are then transformed into the resulting amplitude, Doppler shift and phase shift of the signal. The aircraft model is based on a description of dynamic characteristics in form of the equations of motion with respect of the fundamental control forces. The main idea is to keep the model as simple as possible. Therefore only those relevant influences are incorporated.

Multiple source navigation signal receiver

Recent technology enables us to design sophisticated navigation systems and improve the capability of positioning and guidance of aircraft. This development can satisfy increasing demands on the air space capacity and on the economy of the commercial flights. Finally, the influence on the environment is diminished when the time of flight is decreasing, which can be achieved also due to a better navigation solution. This paper introduces the design of the navigation receiver, which benefits from the advanced FPGA technology. The developed receiver consists of the analog RF frontend followed by the IF conversion, ADC, and the DSP part. It possesses the capability to process up to 10 navigation sources together. Then, the navigation solution can profit from the higher number of independently measured data to achieve precise and reliable estimation of an aircraft position. Secondly, this paper presents the idea and experimental solution for an approach-to-landing navigation system. The designed system is based on the TDOA positioning methods accompanied with an ILS transmitting channel, which distributes lateral and vertical trajectory error corrections. This system is one of the possible navigation data source for the previously described multiple source navigation signal receiver.

Correlation analysis of the faster-than-nyquist signal

The main goal of the paper is to present an analysis of the possibility of using faster-than-nyquist signal processing method to improve performance of navigation system. First the faster-than-nyquist concept is introduced and its pros and cons are described. After that the correlation signal processing in radio-nav systems is explained and one typical examle is presented. Demonstrated is the TDOA system, defined are requirements, signal parameters and signal processing methods and algorithms. Using the TDOA example given is an analysis of the autocorrelation and cross-correlation functions of the signal which is sampled at faster-than-nyquist rate. Exploited is the influance of ISI and other aspects.

Implementation of GPS — C/A tracking loop in FPGA

• Costas loop can track received signal up to 75 KHz of carrier variation • Its able to track GPS signal, where result of Doppler effect is 5 KHz • Correlatoruses method FFT and provides value of chip delay every millisecond • C/A generator successfully generates pattern of PRN code and it can adjust phase delay with precision 62.5 ns • The design can tracks GPS signal with precision 62.5 ns

Implementation of the GPS-C/A tracking loops in FPGA

This paper describes a hardware approach of one part of GPS receiver - the acquisition and tracking of GPS code and the frequency tracking. Method used for acquisition and tracking code is Fast Fourier Transform, which provides fast acquisition at first step. Costas loop is used for frequency tracking and demodulating GPS signal. The design is implemented in FPGA with support of mega-core functions.

The hardware platform for the tests and evaluation of the airborne GNSS receiver algorithms

The main aim of this project is to show a concept of the hardware platform for evaluation of the GNSS receiver algorithms. There was a request for good flexibility of the system for designing elements of multiple GNSS receivers. Designed system is suitable for receiving a signal at chosen frequency from the operating range (915 to 2175 MHz) and its next processing. Front-end device receives the signal and does a QPSK demodulation. Platform is based on the FPGA, so the module structure of the implemented system allows good dealing with designed entities. Suitable is the possibility of simply designing and implementing the digital filters in this platform. Although used RF frontend MAX2120 is not directly intended for GPS signal receiving or processing, with its number of parameters it is convenient to utilize in this issue. Paper describes how the MAX2120 is tuned through I2C bus by I2C Master device implemented in used FPGA. For demonstration, there was implemented and tested the system that receives GPS signal, demodulates it and do the A/D conversion for next processing in the FPGA. There are designed multiple data filters and dealing with them in the end.

Complex navigation signal generator

Working design of the GNSS signal generator Xilinx Spartan 3MB platform — DA 12bit @ 125 MSPS Complex Air Navigation Geometry Simulator Simulated airplane movement Acquired and transformed real flight data GPS satellite movement model Signal parameters provided