Pavel Puricer

Technical Limitations of GNSS Receivers in Indoor Positioning

This paper presents an overview of aspects that have to be taken into account in use of GNSS receivers for positioning in the difficult environment, for example indoors. The performing position determination and navigation tasks in such environments come nowadays more and more in the focus of the GNSS community. The GNSS signal indoor reception is affected by strong attenuation and due to the nature of the environment by strong multipath. The paper discusses both of them and their possible impact to the navigation tasks. The effect of the user movement is discussed and the experimental measurements are presented. The measurements were realized with use of experimental GNSS software receiver, described in the paper as well.

Telemetry system for research stratospheric balloon

The paper presents telemetry system for stratospheric balloon mission based on the UHF transceivers designed for Internet of Things. The system operates in 869.5 MHz frequency band. The system uses very short packet without channel coding that can be successfully received and decoded under low signal to noise ratio. The modem sensitivity −124 dBm and the transmission power 25 dBm can ensure reliable communication for distances longer than 100 km with omnidirectional antennas and 200 km with 10 dBi ground station directional antenna. The telemetry system uses GFSK modulation of bit rate 1200 Bd and is designed for a transmission of the balloon position and status.

Experimental SDR receiver for monitoring and processing of solar radio bursts

The paper introduces a design of radio spectrography receiver that shall serve as equipment for reception, monitoring, and processing of solar radio bursts. These burst can affect operation of many radio communication and navigation services as is presented on example of GPS satellites signal degradation. The concept and design of the spectrography receiver is presented together with discussion of hardware requirements and proposed solution.

A new assessment method of pHEMT models by comparing relative errors of drain current and its derivatives up to the third order

At present, there are relatively more precise pHEMT models available for computer-aided design, and they are frequently compared to each other. However, such comparisons are mostly based on absolute errors of drain-current equations and their derivatives. In the paper, a novel method is suggested based on relative root-mean-square errors of both drain current and its derivatives up to the third order. Moreover, the relative errors are then relativized to the best model in each category to further clarify obtained accuracies of the drain current and its derivatives. Furthermore, one our older and two newly suggested models are also included in the comparison with the traditionally accurate Ahmed, TOM2 and Materka ones. The assessment is performed using measured characteristics of a 110 GHz pHEMT. Finally, a usability of the models of the higher-order derivatives is illustrated using an IP3 computation/measurement of a multi-constellation receiver for a satellite navigation with ATF-54143.

A new assessment of pHEMT models by comparing relative errors of drain current and its derivatives up to the third order

At present, there are relatively more precise pHEMT models available for computer-aided design, and they are frequently compared to each other. However, such comparisons are mostly based on absolute errors of drain-current equations and their derivatives. In the paper, a novel method is suggested based on relative root-mean-square errors of both drain current and its derivatives up to the third order. Moreover, the relative errors are then relativized to the best model in each category to further clarify obtained accuracies of the drain current and its derivatives. Furthermore, one our older and two newly suggested models are also included in the comparison with the traditionally accurate Ahmed, TOM2 and Materka ones. The assessment is performed using measured characteristics of a 110 GHz pHEMT. Finally, a usability of the models of the higher-order derivatives is illustrated using an IP3 computation/measurement of a multi-constellation receiver for a satellite navigation with ATF-54143.

Empirical model of the ADS-B channel for airport area

The paper describes approach to processing of the ADS-B extended squitter signals and data provided by targets on the ground area of the airport. These signals are affected by radio channel environment which causes distortion and interference. The paper presents a method for estimation of the channel TDL model based on empirical data processing. This method is applied on measurement and processing campaign with the real signals from MLAT transmitters at the Prague Vaclav Havel airport. The results of channel model parameters are presented here as well.

GNSS software receiver - a versatile platform for navigation systems signals processing

The paper presents concept of software receiver for me as a development, implementation, and testing platform for GNSS signal processing. There are discussed approaches to design of the receiver, then the concept of FPGA and CPU combination is presented. The design of experimented GNSS software receiver developed at the Czech Technical University in Prague is described and methods of receiver design are discussed. The verification of the design as an integral part of the design process is shown. Implementation of signal processing algorithms is shown on the example of implementation of fast algorithm of the EGNOS signal detection