Richard J. Bullock

Designing input signals to disrupt commercial systems in band - a nonlinear dynamics approach

Describes a method for disrupting a standard, commercially available, nonlinear electronic system. In particular, we show how, with relatively little knowledge of the commercial system design, an in-band signal can be determined which will disrupt the operation of the circuit. Our approach is based on a nonlinear analysis of the most susceptible subsystem in the circuit. Analytical, numerical, and experimental results are reported to demonstrate the efficacy of our approach.

THE EFFECT OF THE FORCING FUNCTION ON DISRUPTION OF A PHASE-LOCKED LOOP (PLL)

In this paper we compare the disruption of a second-order type II phase-locked loop (PLL) by two different waveforms: a sinusoid and a sawtooth. The choice of these two waveforms results from a novel approach to the problem of determining an appropriate forcing function for studying the disruption of such systems. It is shown that the sawtooth is the better disruptor for low frequencies of modulation, i.e. in the regime of physical interest. Analytical, numerical and experimental results are reported which support this conclusion. The paper presents the first results of a sawtooth modulated PLL, which viewed as a nonsmooth dynamical system with a nonsmooth forcing function is a problem of considerable theoretical interest. This paper demonstrates that forcing functions can be designed for nonlinear dynamical systems which are well suited to the study of certain aspects of the system dynamics, and significantly better than the conventional choice of a simple sinusoid.

Optimal Input Signals for Driving Nonlinear Electronic Systems into Chaos

In this paper we have described a novel approach to the problem of disrupting nonlinear electronic circuits; this approach is applicable to a wide range of nonlinear electronic systems. It allows us to calculate input signals of smallest amplitude and power which will induce homoclinic chaos and, hence, disruption in the circuit. Further-more, as is clearly demonstrated by the results described above, this approach allows us to develop in-band signals with which to disrupt such circuits.

An RF-ID Reader Using SAW Dispersive Delay Lines For Wideband Synchronisation

RF-ID systems are susceptible to frequency interference from other communcation systems particularly when the RF-ID tags transmit on a fixed carrier frequency. The RF-ID systems are less vunerable to frequency interference when frequency diversity is used by the RF-ID system. This paper proposes an architecture for an RF-ID receiver which allows a number of active RF-ID tags with oscillators of low frequency stability to be accommodated within the same RF-ID cell. The synchronisation technique used by the receiver contains a carrier frequency estimator which has been designed using SAW dispersive delay lines. The carrier frequency estimator uses the spectral properties of the received signal to estimate the carrier frequency. The analytic and simulated performance of the carrier frequency estimator has been examined for two peak search algorithms.

An RF-ID Receiver Using SAW Filters For Wideband Synchronisation

This paper proposes an architecture for an RFID receiver which allows a number of RFID tags with oscillators of low frequency stability to be accommodated within the same RFID cell. The RFID tags can transmit at carrier frequencies anywhere within a wide band of 30 MHz centred on 5.8 GHz. The synchronisation technique uses a carrier frequency estimator which is implemented using SAW dispersive delay filters. The carrier frequency estimator uses the spectral properties of the received signal to estimate the carrier frequency. The performance of the synchronisation technique on a BPSK modulated carrier signal has been examined for two peak search algorithms.

IN-BAND CHAOS IN COMMERCIAL ELECTRONIC SYSTEMS

In this paper we have presented an approach to the problem of disrupting effectively a commercial nonlinear electronic system. Our approach is based on a minimal understanding of the circuit concerned, the basic design and operational specifications, rather than a detailed knowledge of the design implementation itself.