Markus Gardill

A smart jamming system for UMTS/WCDMA cellular phone networks for search and rescue applications

Recent statistics show an increase in environmental disasters, a fact which is also perceivable to the public as reports of avalanches, earthquakes and landslides mount in media coverage. This paper introduces one part of the I-LOV project, endorsed by the German Federal Ministry of Education and Research. In this project partners from relief organizations, universities and industry investigate enhancements to disaster handling and victim rescue. One possible option is to take advantage of the fact, that a lot of people own a mobile phone today. To locate a person by his or her mobile phone requires to take over the phone by an own Base Transceiver Station (BTS). Jamming all other networks is one option to achieve that. This paper will introduce a new Field Programmable Gate Array (FPGA) based jamming system which disturbs only the absolute necessary parts of the WCDMA spectrum but reliably cuts all connections between mobile stations (MS) and existing BTS. The whole system including the signal generator and the front end will be discussed. Also measurement results will be shown.

Low latency evaluation of an adaptive industrial wireless communications system for ISM bands

Low latency and highest transmission reliability are the key challenges for enabling time-critical industrial wireless applications, e.g. in factory automation. Both are significantly determined by the rough and dynamic environmental conditions as well as regulatory limitation of spectrum access in unlicensed frequency bands, especially in the 2.4 GHz industrial, scientific and medical (ISM) band. In order to get these influences under control, a novel concept for an adaptive and low latency (≤ 1 ms) industrial wireless communications (IWC) system that adopts a robust IEEE 802.11p physical layer (PHY) is proposed and evaluated. Based on representative coexistence measurements in a real environment, the results of extensive simulations and analysis are shown in order to evaluate achievable latencies.

Ultra-wideband small antenna subarray module with narrow elevation pattern

We propose a small ultra-wideband antenna subarray module with narrow elevation pattern for future use in antenna arrays providing spatial processing capabilities such as Direction-Of-Arrival estimation in the azimuth plane, for the frequency range from 5 GHz to 8 GHz. The proposed subarray design is based on four mutually coupled Vivaldi antennas stacked on a common substrate in the E-Plane, with an element distance of delem ≤ λ0, high/2. We optimize the antenna element in an infinite E-plane array configuration and show that the truncation effects when reducing the infinite array to only four elements do even improve the total scan element reflection for broadside excitation. In addition our design does not utilize a parallel-plate to microstrip balun at the feed point of each antenna element. Instead we use a novel ultra-wideband and geometrically small hybrid ring coupler to realize an ultra-wideband corporate feed network directly in parallel plate technology.

Design of a robust and low-cost monocone antenna element for use in vehicle roof-mounted antenna arrays

We present the design of a wideband monocone antenna element having more than one octave impedance as well as pattern bandwidth. It is optimized for use in vehicle roof-mounted antenna arrays for spatial processing in an ultra-wideband local positioning secondary radar system, operating in the frequency range from 5 GHz to 8 GHz. We focus on a low-cost design, offering mechanical robustness, being ruggedized towards environmental influence, and achieving small physical dimensions using a protective dielectric-encapsulated design. In addition, we suggest a solderless and robust interconnection between coaxial connector and antenna element. The antenna element allows for arbitrary planar array geometries with grid spacing at the order of the lowest frequency of operation and a simple integration in any vehicle with a metallic roof.

Smart communication and relative localization system for firefighters and rescuers

This paper presents a smart communication system for simultaneous data reception and direction of arrival estimation for firefighters, rescuers, and other emergency personnel. The system consists of a passive six-port microwave interferometer which transforms the challenge of an accurate phase measurement for direction estimation to a relative power measurement. This can be easily realized by the readout of the received signal strength indicator of low-cost commercial off-the-shelf transceivers which are simultaneously used for communication. Due to the differential IQ structure the robustness of the system is enhanced, even for severe disturbance and interference, where it still can provide a relative angle of emergency team members to each other.

Ultra-wideband compressed sensing radar based on pseudo random binary sequences

In this paper, the application of compressed sensing (CS) to pseudo random binary sequence (PRBS) radar is analyzed. We show that under the principles of CS theory, the sampling rate of the signal can be reduced without loss of resolution. CS theory is used to reconstruct the signal of an UWB PRBS radar system with a bandwidth of 20 GHz, when the radar signal is undersampled with a sample frequency lower than the Nyquist frequency. Finally, the performance of the reconstruction is evaluated under the presence of static and moving targets.

A Clock Synchronization for M-Sequence-Based Ultra-Wideband Systems

This paper presents a cross-correlation-based synchronization architecture between the clock of the receiver and the transmitter of ultra-wideband systems. The proposed architecture is based on M-sequence signals instead of the conventional impulse signals. The M-sequence generator and the analog correlation circuit are fabricated on-chip using a low-cost 0.25 μm 95 GHz fmax SiGe-HBT-BiCMOS process technology. The chip is mounted on a printed circuit board (PCB) with a commercial voltage-controlled oscillator (VCO). The synchronization scheme obtains the clock information with a received signal as low as 2 mV peak to peak and minimum input power of -52 dBm at 10 GHz. The power spectrum measurement of the locking VCO shows a low phase noise of -69 dBc/Hz at 1 kHz offset and an rms jitter of 0.93 ps for a 10 GHz frequency and a bit rate of 20 Gb/s. The achieved mismatch between the received and the reference signals is a maximum of 25 ps at signal bandwidth of 10 GHz. The proposed clock recovery system acquires the clock information correctly with different materials placed in the transmission channel.

A wideband unidirectional antenna array element with stable radiation pattern

A modification of the famous Bow Tie antenna element for wideband Direction-Of-Arrival estimation antenna arrays is designed. A broadband impedance match from 5 GHz to 14.5 GHz corresponding to a 97% bandwidth, as well as a very stable radiation pattern over a 37% bandwidth from 5.5 GHz to 8 GHz is achieved. A method for pattern stabilization using parasitic edge currents is shown. In addition the proposed design uses a double layer substrate and hence aims at direct integration of the feed network and analog RF circuitry directly into the antenna array. The particular design is suited for low-cost integration and optimized for a wireless high-precision localization system.