High frequency oscillators for chaotic radar

Beal, Aubrey N.; Blakely, Jonathan N.; Corron, Ned J.; Dean, Robert N.

doi:10.1117/12.2223818

Cited by 11 publications

(12 citation statements)

References 14 publications

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“…Recently, switching compensation has been developed to mitigate some of these effects [17]. This compensation corrects imperfections in the circuit's finite switching times, though issues can still arise from the analog amplification mechanisms [58,59].…”

Section: Hardware Designmentioning

confidence: 99%

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Generating and Detecting Solvable Chaos at Radio Frequencies with Consideration to Multi-User Ranging

Beal

Cohen

Syed

2020

Sensors

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High entropy waveforms exhibit desirable correlation properties in radar and sonar applications when multiple systems are used in close proximity. Unfortunately, the information content of these signals can impose high sampling requirements for digital detection techniques. Solvable chaotic oscillators have been proposed to address such issues due to their simple, matched filters, where hardware has been demonstrated with a bandwidth of 10–20 kHz. To extend applications of these systems, we present theory, design, and experimental verification of solvable chaos at 1 MHz using simple off-the-shelf components. The waveforms produced by this system were propagated over a 2.45 GHz RF link and detected with an RLC-based, purely analog matched filter. Further, we show that properties of this special class of chaotic systems can be exploited to yield RF noise sources that are generally advantageous for multi-user ranging applications when compared to conventional techniques. The result is a simple, low-cost, and potentially low-power RF ranging system that requires very little digital signal processing.

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Section: Hardware Designmentioning

confidence: 99%

“…The folding mechanism keeps these oscillations stable about the two fixed points and contributes to the system's mixing properties. Details and issues relating the frequency increase of op-amp based NICs used for negative resistances in the −RLC have been addressed [58][59][60].…”

Section: Generating Solvable Chaos At Radio Frequenciesmentioning

confidence: 99%

Generating and Detecting Solvable Chaos at Radio Frequencies with Consideration to Multi-User Ranging

Beal

Cohen

Syed

2020

Sensors

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“…Then, with time normalization, the normalized frequency ω norm can be gradually shifted from 100 kHz to the tens of MHz and above, allowing us to progressively observe the multipath effect on chaos synchronization. In the analog domain, the chaotic Colpitts time constant can be manipulated using the different discrete components to achieve higher frequencies (e.g., [30] for chaotic radar applications). Finally, since the model described in (1) and (2) is in continuous time; for numerical simulation purposes we employed a fixed step solver (Runge-Kutta, ode4) with a step size of ∆t = 10 −7 s, which is scaled with T. This is effectively a discretization procedure from the analog to the digital domain.…”

Section: Parametersmentioning

confidence: 99%

Chaos Synchronization in Visible Light Communications with Variable Delays Induced by Multipath Fading

Canyelles-Pericas

Haigh

Ghassemlooy³

et al. 2018

ASI

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Visible Light Communication (VLC) uses light-emitting diodes to provide wireless connectivity in public environments. Transmission security in this emerging channel is not trivial. Chaotic modulation techniques can provide encryption directly in the physical layer based on the random-alike evolution and strong synchronization prospect given by deterministic chaos. In secure chaotic inclusion or embedding methods, continuous-time chaos oscillator models need to be synchronized via a coupling carrier. Here we present a first numerical simulation study for the impact of the variable delays induced by line-of-sight and non-line-of-sight multipath fading in complete chaotic synchronization. More precisely, we analyze a chaotic Colpitts oscillator that is simultaneously transmitting the carrier to several mobile receivers via nine spotlights. Such induced delays depend on both the receiver position and the carrier frequency, influencing the complete synchronization required in modulation via chaotic inclusion. Correlation values for several receiver positions and carrier frequencies are presented, examining the progressive emergence of the multipath effect and its impact on chaotic synchronization. We show that, for the chaotic oscillator and coupling applied in the defined room settings, complete chaotic synchronization can be achieved and that it is robust up to the tens of MHz region.Despite the sensitivity towards the starting point, chaotic oscillators can be set to synchronize in several modes, provided that adequate coupling mechanisms are implemented [2,3]. This pseudorandomevolution and synchrony prospects associate very well with both the standard cryptographic and data transmission requirements [4], thus paving the way for secure, chaos-based, communications. There are broadly two main categories of chaos synchronization schemes: one is based in continuous time models (e.g., dynamical systems), such as ordinary differential equations. The other group corresponds to discrete models such as chaotic maps. To synchronize the first group, one needs to transmit a chaotic signal carrier continuously over time, which is affected by channel effects such as multipath. The discrete group can be set to synchronize with the transmission of a secret key only, but with less cryptographic potential [1].Visible light communication (VLC) is an emerging free space optical communication method built upon intensity modulation of light-emitting diodes (LEDs). LEDs, fabricated with p-n junction technology, produce light based on the principle of electroluminescence, where photonic emission takes place in response to an electric field. Their fundamental operation allows LEDs to be switched on and off beyond millions of times per second, far too fast for the human eye to realize flickering, enabling binary transmission of information in combination with adequate photodetectors. Accordingly, VLC allows high data rates in the Gb/s region [5,6]. In fact, most related research has focused on increasing the data rates or implementation o...

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“…Limitations of hybrid chaotic systems in [28,34] force them to operate at low-throughput levels and operating frequencies that are lower than the acoustic frequency boundary [35,[37][38][39] because they are based on forward time and symbolic dynamics. Although hybrid chaotic systems based on reverse time have solved the problem of low-operating frequencies, presented a simpler circuit, and provided low-cost and low-power consumption compared with hybrid chaotic systems based on forward time [24,[40][41][42], they have not been evaluated with multilevel discrete states under AWGN.…”

Section: Introductionmentioning

confidence: 99%

A generalized multilevel-hybrid chaotic oscillator for low-cost and power-efficient short-range chaotic communication systems

Dukhan

Jayalath

Heijster

et al. 2020

J Wireless Com Network

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In this paper, we present and evaluate a novel multilevel hybrid-chaotic oscillator. The proposed generalized multilevel-hybrid chaotic oscillator (GM-HCO) was created by combining a multilevel discrete function generated from user data with a continuous function having a damping factor greater than ln(2) to achieve variable rates and adaptive carrier frequencies. Improved spectral efficiency and lower complexity of the transceiver compared with differentially coherent systems were achieved by multilevel signals at the transmitter and a matched filter at the receiver. An exact analytical solution for the generalized fixed basis function and the impulse response of the matched filter were also derived. The bit error rate (BER) expression of the GM-HCO was derived for two levels. It was found that the noise performance of the proposed system was better than a hybrid chaotic system based on forward time and differential chaos shift keying (DCSK). A comprehensive set of simulations were carried out to evaluate the performance of the proposed system with chaotic communication systems in the presence of additive white Gaussian noise (AWGN). The performance of the proposed system was comparable with that of conventional communication systems. The results demonstrate that the proposed system can offer better noise performance than existing chaotic communication systems, and it also offers variable transmitter frequencies and improved spectral efficiency. Noise-like behavior of the chaotic signals provides an additional layer of security at the physical layer compared with conventional (sinusoidal) communication systems.

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High frequency oscillators for chaotic radar

Cited by 11 publications

References 14 publications

Generating and Detecting Solvable Chaos at Radio Frequencies with Consideration to Multi-User Ranging

Generating and Detecting Solvable Chaos at Radio Frequencies with Consideration to Multi-User Ranging

Chaos Synchronization in Visible Light Communications with Variable Delays Induced by Multipath Fading

A generalized multilevel-hybrid chaotic oscillator for low-cost and power-efficient short-range chaotic communication systems

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