Descending staircase detection for service robots based on M-sequence UWB radar. - In: 2021 18th European Radar Conference, (2022), S. 29-32
Service robotics is expected to be one of the central growth industries of this century. The technological key to this lies in the sufficient perception of the environment, even under difficult conditions, because mobile robots have to orientate themselves and navigate without collision under all circumstances. However, the safe detection of especially descending stairs is a big challenge so far. In this paper, the results of descending staircase detection using UWB radar are shown. The individual steps of the signal processing from signal preparation to multi-target tracking are briefly explained and an outlook is given on how to classify a staircase based on the results. For all investigated stairs the edge of the first step could be detected reliably from a distance of 1.5 m and multiple steps are distinguishable as well.
https://doi.org/10.23919/EuRAD50154.2022.9784493
Localization and navigation of service robots by means of M-sequence UWB radars. - In: 2021 18th European Radar Conference, (2022), S. 189-192
The use of service robots has become much more relevant in industry and retail in recent years. To be of best possible benefit to humans, an autonomous motion ability of the service robots is of central importance. This requires that the robot can perceive its surroundings as precisely as possible by using different sensors and their fusion. In contrast to optical sensors, an UWB sensor can, for example, detect small and almost invisible objects such as glass panes with high range resolution. In this paper, a signal processing chain for detection of the environment with M-sequence UWB sensors is proposed. The proposed chain includes pulse reconstruction based on calibration measurements, background subtraction, object detection based on CFAR techniques, and multi-target tracking based on the Kalman filter and the nearest-neighbor approach.
https://doi.org/10.23919/EuRAD50154.2022.9784511
RF performance of USRP TwinRX daughterboard under influence of strong interferers. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
In this paper, we investigate the sensitivity of the software-defined radio (SDR) universal software radio peripheral (USRP) X310 with a TwinRX daughterboard to strong interferers. In a conducted test setup, the signal-to-interference-plus-noise ratio (SINR) is measured under the influence of a mock-up Long-Term Evolution (LTE) base station. The frequency of the interferer is varied to analyze the effects over a wide frequency band, whereby a distinction is made between signals inside and outside the intermediate frequency (IF) band. The former can cause clipping at the analog-to-digital converter (ADC), while the latter are to be suppressed in the analog part of the software-defined radio. Here, leakage and higher-order mixing products make the receiver sensitive to spurious frequencies, whereby the performance degradation is particularly noticeable near the first intermediate frequency (IF1) of 1.25 GHz. At this point, even an interference signal with −28 dBm peak envelope power (PEP) causes an SINR loss of 3 dB.
https://doi.org/10.23919/EuCAP53622.2022.9769615
A frequency domain approach for estimating the angular dependent delay of an UWB antenna. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
The procedure of estimating the angular dependent delay of an Ultra Wideband (UWB) antenna, directly in frequency domain, is presented. It is shown that in this approach any occurrences that can lead to inaccurate results, such as the windowing effect, can be entirely avoided. It alleviates the need to design a specific pulse, since the transfer function can be obtained by a frequency sweep. Moreover, polarization mismatch is accounted in the analysis. To this end, an UWB monopole antenna is designed and it is simulated with time and frequency domain solvers. The simulation results demonstrate that only frequency domain analysis is sufficient for the delay estimation. The outcome of this work provides a clear procedure for obtaining the angular dependent delay of an antenna in an accurate way.
https://ieeexplore.ieee.org/document/9769534
From sub-6 GHz to mm-wave: simultaneous multi-band characterization of propagation from measurements in industry scenarios. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
In the present paper we introduce simultaneous multi-band measurements at sub-6 GHz and two mm-wave bands with the objective of characterizing propagation for multi-band channel modelling purposes in industry scenarios. The marginal power profiles show that the dominant scatterers are common in the different frequencies. In addition, a relation of decreasing average delay and angular spreads with increasing frequency is observed. The different measured parameters are contrasted with the 3GPP model for indoor factories.
https://ieeexplore.ieee.org/document/9768944
Level measurement of low-permittivity material using an M-sequence UWB radar. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
Due to increasingly complex and automated manufacturing processes, the demands on the control parameters of these processes are also increasing. One parameter is the fill quantity of e.g. liquids in production plants, whose precise determination is of ever growing importance. Up to now, the exact level determination under difficult conditions, such as high ambient temperatures, has been a particular challenge. This paper demonstrates a novel method by which an M-sequence UWB radar can determine levels of low-permittivity materials in small metal containers. For this purpose, hot melt is used as an example. Thus, the influence of large temperature differences on the long-term stability of level measurement can also be investigated. The measurements show that the level of hot melt can be measured long-term stable with an accuracy of better than 3 mm.
https://ieeexplore.ieee.org/document/9769405
Verification of THz channel sounder and delay estimation with over-the-air multipath artifact. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
In the present paper we introduce the empirical results of measurements with an over-the-air based propagation artifact for verification and validation of sub-THz and THz channel sounders and parameter estimation algorithms. This experiment produces a fixed number of multipath components with traceable propagation properties in the different domains that can be used to test resolution and performance. Because of the inherent characteristics of the measurement hardware, we have introduced an adaptation on a parametric high resolution estimation algorithm to account the imperfections of the channel sounder. The results have shown to account for a relative good performance of the sounder and the tested parametric and non-parametric estimation algorithms.
https://ieeexplore.ieee.org/document/9769269
Fast gain switching on TwinRX USRPs. - In: 16th European Conference on Antennas and Propagation, (2022), insges. 5 S.
In this paper, we investigate the gain switching performance of the software-defined radio (SDR) universal software radio peripheral (USRP) X310 with the TwinRX daughterboard and propose a method to optimize it for fast transitions. This receiver uses a complex structure of two switchable amplifiers and two digital step attenuators to realize the wide gain setting range of up to 92 dB. Our measurements of the settling time show that the bulk of transitions between two gain settings take below 1.5 µs, but some require more than 50 µs, caused by the power-up of the switchable amplifiers. Based on this knowledge, we propose a modified switching regime, in which the amplifiers are not toggled in time-critical phases, e.g., during a running measurement, so that a transition time of 1.5 µs can be reliably realized. Thus, a gain switching range of 62 dB is achieved, within which, for example, a fast automatic gain control can be realized.
https://doi.org/10.23919/EuCAP53622.2022.9769488
Improving medium frequency R-Mode ranging with GMSK modulation. - In: Proceedings of the 34th International Technical Meeting of the Satellite Division of the Institute of Navigation, (2021), S. 3227-3233
The R-Mode terrestrial navigation system evaluates the phase of two carriers next to a modulated signal, from which a range can be derived to allow positioning using different stations. To improve the accuracy of ranging, we propose in this paper to replace the currently used Minimum Shift Keying (MSK) modulation with Gaussian Minimum Shift Keying (GMSK). By applying a Gaussian pulse shape for the bit transition to that of the MSK a higher spectral efficiency is achieved. If the data rate is kept constant, this reduces the energy of the modulated signal within the bandwidth of the phase estimator. This increases the accuracy of the added carrier estimate and achieves our goal of improved distance-estimation accuracy. In this paper, we compare the estimates for an R-Mode signal with MSK and two different GMSK modulations. The increased accuracy is verified using software and hardware in-the-loop simulations.
Make some noise: energy-efficient 38 Gbit/s wide-range fully-configurable linear feedback shift register. - In: SMACD / PRIME 2021, (2021), S. 384-387
https://ieeexplore.ieee.org/document/9547997