Benjamin Waldmann

Method for high precision local positioning radar using an ultra wideband technique

In this paper a novel approach for a high precision local positioning radar using an ultra wideband technique is presented. The concept is based on the standard FMCW (frequency modulated continuous wave) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. With this concept, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D, and 3D localization. A prototype was built which operates around the center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a low standard deviation.

Pulsed frequency modulation techniques for high-precision ultra wideband ranging and positioning

In this paper a novel approach for a high precision local positioning radar using an ultra wideband technique is presented. The concept is based on the standard FMCW (frequency modulated continuous wave) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. The system combines the advantages of FMCW radar systems and the advantages of the use of a wide bandwidth. With this concept, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D, and 3D localization. A prototype was fabricated which operates around the center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a low standard deviation.

An ultra-wideband local positioning system for highly complex indoor environments

In this paper a novel approach for a high precision local positioning radar using an ultra-wideband (UWB) technique is presented. The concept is based on the standard frequency modulated continuous wave (FMCW) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. Besides the well known advantages of a FMCW radar, the proposed system implies a wide frequency bandwidth. With this concept, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D, and 3D localization applications for complex industrial environments. Investigations on the achievable performance of such an UWB system show very promising results and are presented within this paper. A prototype system was fabricated which operates at the center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a standard deviation and absolute accuracy in the low centimeter range, even in challenging multipath environments.

On the performance of pulsed frequency modulated UWB local positioning systems

Recently, a novel ultra-wideband (UWB) local positioning concept based on pulsed frequency modulated (PFM) signals was introduced by the research groups of the authors of this paper. The current paper presents a detailed analysis of the performance - i.e. range and accuracy - of the proposed PFM-UWB approach. It is shown that with PFM-UWB an excellent coverage / range can be achieved. It is also shown that for high precision ranging a VCO with good phase-noise performance is needed. Based on simulations and measurement results the theoretical findings are verified. The results confirm that PFM-UWB allows for accuracy in the mm-range and a maximum range of more than 100 m with a measuring time of only 1 ms.

An ultra-wideband coupled-line balun using patterned ground shielding structures

In this paper a new planar balun for UWB- applications has been developed using a two-stage Wilkinson divider for power splitting followed by two coupled line sections for plusmn90 phase shifting. Patterned ground shielding (PGS) is used to increase the even-mode and decrease the odd mode impedances. The compact balun structure covers an area of less than 5 mm2 and has been fabricated on a conventional double-layer printed circuit board to validate simulation results by measurement. The measured input and output return loss is below -10 dB from 3.5 to 10.5 GHz, so that a relative bandwidth of 100% is achieved. The measured insertion loss is about 0.5 dB by an acceptable phase imbalance over the operating frequency range. Measurements show a good agreement with the corresponding simulations.

An ultra wideband positioning system enhanced by a short multipath mitigation technique

In this paper an approach for high precision local positioning radar using an ultra wideband technique is presented. The concept is based on the standard FMCW (frequency modulated continuous wave) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. In this way, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D and 3D localization. A prototype was built which operates at a center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a standard deviation down to 6 mm. Additionally, we studied the effects of short multipath propagation and present simulation results for an applicable mitigation technique.

Short Multipath Mitigation Technique Using Feedforward Neural Networks

In this paper a novel approach for mitigation of short multi-path distortions is presented. The technique is applicable to FMCW-based distance measurement systems assuming distinctly separated targets. The effects of spectral distortion caused by short multipath propagation in conjunction with Fourier-based frequency analysis methods are mitigated. For this purpose the distorted spectrum is first analyzed and specific characteristics are calculated. A Feedforward Neural Network processes these characteristics and provides a correction frequency relative to the erroneously shifted maximum in order to estimate the true line-of-sight frequency. A comprehensive analysis was performed by means of a two tone test. Applicability to real world environments was investigated by means of a multi tone test using an IEEE 802.15.4a channel model.

A comparison of channel access concepts for high-precision local positioning

In this paper, we review channel access concepts for two competitive radiolocation systems, High-Precision Location System (HPLS) and Local Positioning Radar (LPR), which share similar physical layers, but operate with different bandwidths. After a short review of the advantages of ultra-wideband signaling as employed by LPR, we spotlight tradeoffs in the servicing of multiple terminals. While HPLS supports both dynamic and static channel access, LPR is limited to static frequency multiplexing. The characteristics of these approaches are highlighted with theoretical analysis and simulation results.

A Pulsed Frequency Modulated Ultra Wideband Technique for Indoor Positioning Systems

In this paper a novel approach for a high precision local positioning radar using an ultra wideband technique is presented. The concept is based on the standard FMCW (frequency modulated continuous wave) radar principle combined with short pulses to fulfill the emission limits given by the official regulatory authorities. Besides the well knowen advantages ifa FMCW radar the proposed system implies a wide frequency bandwidth. With this concept, a high accuracy in dense multipath indoor environments can be achieved, ideally suited for 1D, 2D, and 3D localization. A prototype was fabricated which operates at the center frequency of 7.5 GHz utilizing a bandwidth of 1 GHz. With the setup presented in this paper the distance between two wireless units can be measured achieving a low standard deviation. Index Terms – Ultra wideband, FMCW, radar position measurement, indoor navigation