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Histogram equalisation (HE) is widely used to enhance the image contrast but it tends to over-enhance the image background brightness. Improvement schemes have been introduced to reduce this defect of the conventional HE, but the over-enhancement of the background brightness is still obvious. A novel approach of nonlinear HE is presented, which is able to enhance the image contrast while preserving the background brightness for images with well-defined background brightness. [ABSTRACT FROM AUTHOR]

The probability model of multipath delays is proposed for scattering centres above the ocean surface. The surface is endowed with the Kirchhoff approximation, as well as a probability density function of the elevations and slopes. The model faithfully reflects the stochastic character of the multipath delays in imaging radar echoes. Moreover, it explores a way to simulate the synthetic aperture radar images without the time-consuming process of electromagnetic computation. [ABSTRACT FROM AUTHOR]

A new Unitary ESPRIT algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation in bistatic MIMO radar is proposed. The properties of centro-Hermitian matrices are utilised to transform the complex-valued data matrix into a real-valued data matrix. Then the real-valued rotational invariance equations for signal subsapce are figured out to estimate DOAs and DODs which are paired automatically in a new way. The proposed algorithm provides increased estimation accuracy with reduced computational complexity owing to real-valued processing and double the number of data samples inherently in unitary ESPRIT. Simulation results are presented to verify the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A digital pre-coding based serial compressed sensing (CS) ultra-wideband (UWB) communication system is proposed. By establishing a mathematical model, signal detection is studied based on the CS theory. Simulation results in the IEEE 802.15.3a channel model show that with a low sampling rate, the proposed system can operate in a regime of heavy intersymbol interference. [ABSTRACT FROM AUTHOR]

Dual-band filtiers are common in dual-band transceivers, to attenuate interfering signals, and transmit the main signal in the desired passband. Reported is a compact low-temperature co-fired ceramic (LTCC) dual-band filter, constructed with a vertically folded structure and stepped-impedance stubs. The novel vertical interconnection scheme with its multilayered structure reduces the area of the filter by half. A 2.4/5.8 GHz dual-band experimental filter has been designed and assembled to verify the proposed design concept. S-parameter test results demonstrated good agreement between simulation and measurement. [ABSTRACT FROM AUTHOR]

Presented is a novel method that can detect pedestrians in images based on the combination of AdaBoost learning with a local histogram's features. Instead of using the raw image for further processing, introduced is a layer enhanced by orientation filters which are superimposed to the original image. Experimental results obtained using the INRIA dataset show the superior performance of the presented method and thus demonstrate its robustness with the novel enhanced layer embedded pedestrian detector. [ABSTRACT FROM AUTHOR]

An SPDT transmit/receive (T/R) switch for X-band on-chip radar applications is proposed with the combination of new techniques. These methodologies include optimisation of the transistor widths for lower insertion loss (IL) while preserving high isolation and using a parallel resonance technique to improve isolation. Also, techniques such as applying DC bias to source and drain, using on-chip impedance transformation networks (ITN) and body-floating are used to improve power handling capability (P1dB) of the switch. All these techniques result in the switch with insertion loss less than 1.3 dB, isolation between transmit and receive ports better than 29.2 dB, 29 dBm input P1dB and return loss of better than 22 dB from 8 to 12 GHz in 0.44 mm2 chip area. [ABSTRACT FROM AUTHOR]

The wavefront curvature error in one stationary bistatic synthetic aperture radar (SAR) image focused via the polar format algorithm (PFA) is analysed and a space-variant filtering method for wavefront curvature correction is proposed. The correction method presented, extends the focused scene size when using the bistatic PFA effectively. Point target simulation validates the filtering method. [ABSTRACT FROM AUTHOR]

The novelty of multiple-input multiple-output (MIMO) radar is to improve the performance of radar utilising spatial diversity and waveform diversity. Proposed is the optimisation design of complete complementary sequence (CC-S) for MIMO radar based on channel capacity with the clutter statistical properties known. The method obtains the optimised CC-S through maximising the channel capacity of MIMO radar. The result shows that the optimised CC-S is a function of the clutter covariance matrix. Finally, the method from the information theoretical point of view is verified. [ABSTRACT FROM AUTHOR]

A high-gain dual-polarised planar etched slot array for use in wireless local area networks (WLAN) is presented. Two sets of four collinear slots are used as radiators for each polarisation. Each set of four collinear slots is constructed as a centre-fed long slotline, with etched crossovers to split the slotline into four resonant and in-phase half-wavelength slots. A reflector etched on a separate substrate spaced a quarter-wavelength away from the slot array ensures unidirectional radiation. The final antenna achieved a gain of 14.5 dBi, a return loss better than 10 dB, and port isolation in excess of 30 dB over the 2.4–2.484 GHz WLAN frequency band. [ABSTRACT FROM AUTHOR]

A substrate integrated waveguide (SIW) cavity backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor. The cavity backed structure permits overcoming potential problems such as heat dissipation and unwanted surface wave modes in large array implementations, and may provide better phase noise performance. The use of SIW technology permits a cost-effective fabrication process and simple implementation at millimetre-wave frequency, for radar and communication applications. Full-wave FEM-based analysis is used for the design of the radiating structure, while harmonic balance and transient simulations are employed in the design of the active antenna oscillator and in the study of the stability of its steady-state solutions. Tunable active antenna prototypes have been implemented and measured. [ABSTRACT FROM AUTHOR]

A new method for joint direction of arrival (DOA)-direction of departure (DOD) estimation in bistatic MIMO radar is proposed. This method, based on the decomposition of the 2D direction finding into double 1D direction finding, uses the ESPRIT method to estimate the DOD and the Root-MUSIC for the DOA estimation. Some simulation results are presented to verify the efficiency of this approach. [ABSTRACT FROM AUTHOR]

An analytical model to compute the minimum delay of Bluetooth 2.0 transmissions is presented. The model, particularised for connections using serial port profile, characterises the effects of the enhanced date rates introduced by Bluetooth 2.0, which is massively implemented in commercial Bluetooth interfaces. The model has been empirically evaluated in a real piconet. [ABSTRACT FROM AUTHOR]

An analogue nonvolatile memory is presented, which is not only CMOS-compatible but also capable of storing analogue currents with a resolution of more than eight bits. The programming process is controlled by a hysteretic comparator on-chip, which stops the injection current automatically by negative feedback, regardless of the programming nonlinearity and device mismatches. With the simple, on-chip programming circuit, the proposed analogue memory is capable of storing currents ranging from 1 to 18 µA accurately with negligible variations across different memory cells. [ABSTRACT FROM AUTHOR]

For synthetic aperture radar (SAR), imaging based on compressed sensing (CS) can reconstruct the target scene with a reduced number of collected samples. But for a multi-channel along-track interferometric (ATI) SAR, the number of samples required could also be huge even though the CS processing is adopted. In this reported work, distributed compressed sensing (DCS) is introduced into ATI SAR. The ATI SAR based on DCS can achieve good performance and requires even fewer samples than that based on CS. [ABSTRACT FROM AUTHOR]

Several compact, low-profile and planar ultra-wideband (UWB) antennas with band-notch characteristics of size 20×25 mm are proposed. These antennas are designed to cover the bandwidth for UWB applications (3.4–12 GHz), and are obtained with promising performance, including broadband matched impedance, stable radiation patterns over the whole frequency band of interest. By introducing a resonant I-shaped strip, H-shaped strip and U-shaped strip on the radiator at this frequency, a bandstop of 1 GHz (from 5 to 6 GHz) for band rejection of the wireless local network (WLAN) can be achieved. [ABSTRACT FROM AUTHOR]

A technique is presented that uses a single composite right/left-handed transmission line (CRLH TL) unit cell to design n-bit digital phase shifters with small sizes, high power-handling capacities, low insertion losses, and arbitrary phase-shift ranges and step sizes. A 3-bit phase shifter with an operating frequency band of 9–10 GHz has been designed and fabricated for study. [ABSTRACT FROM AUTHOR]

Edge detection plays a critical role in image reconstruction of remote imaging systems. To gain better quality detection, a novel method is proposed that combines the curvelet transform and Duda operator in a special fashion for processing synthetic aperture radar (SAR) images. To extract the coarse regions in the image, the curvelet transform is first applied to the image and then, after some processing, the Duda operator locates the edges precisely inside the regions. The superiority of the proposed method is demonstrated for Pi-SAR image data. [ABSTRACT FROM AUTHOR]

A method of joint estimation of angle and frequency for bistatic multiple-input multiple-output (MIMO) radar based on ESPRIT using the rotational factor produced by time delay sampling is discussed. In this algorithm, transmit angles, receive angles and Doppler frequencies can be obtained simultaneously and automatically paired without array aperture loss. Simulation results confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A novel scheme for an adjustable low-voltage CMOS current mirror is introduced. The proposed current mirror provides continuous gain adjustment, while it simultaneously features the attractive characteristic of low-voltage operation. The behaviour of the proposed topology has been experimentally verified through a first-order lowpass filter fabricated in AMS 0.35 µm CMOS technology. [ABSTRACT FROM AUTHOR]

The ratio of the arithmetic to the geometric mean, a general index to test synthetic aperture radar (SAR) image homogeneity, is applied to the speckle reducing algorithm. A novel filter, based on improved speckle reducing anisotropic diffusion, is designed to denoise the SAR image. Experiments validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A serial iterative co-channel interference cancellation scheme is proposed for the MFSK/FH-SSMA system. First, a soft-limiter is employed to formulate the received time-frequency matrix with multilevel entry to suppress the residual interference due to the co-channel interference cancellation. Secondly, a serial detection scheme is utilised to solve the ambiguity problem. Both the detection performance and the computation complexity are simulated to validate the applicability of the proposed scheme. It is unveiled that the proposed scheme could be utilised to improve the iterative interference cancellation scheme significantly with negligible increase in computation complexity. Moreover, the proposed scheme is able to achieve the maximum likelihood detection performance with much lower computation complexity. [ABSTRACT FROM AUTHOR]

A vision-based system is described for adaptive cruise control to track road signs from within a moving vehicle. The proposed system has the standard architecture with a particle filter due to its robust tracking performance in a complex environment. In the case of tracking road signs in a real environment, it has great difficulty in predicting time series data by reason of its nonlinear characteristics. To overcome this problem, proposed is a state transition model to which the differences of affine parameters and a fuzzy-autoregressive model are applied. Also, to make an observation model, the Parzen window is used at a measurement step in the particle filter. [ABSTRACT FROM AUTHOR]

A quasi-circulator, composed of two branch-line couplers and an asymmetric power combiner, is proposed to effectively cancel the transmitter leakage signals in a monostatic six-port radar. The effective isolation is improved by 12.2 dB at 24 GHz. With the proposed quasi-circulator, the maximum detectable range of the six-port radar is improved by 167%, compared with that of the six-port radar with a conventional branch-line coupler. [ABSTRACT FROM AUTHOR]

A novel method employing an ESPRIT and Kalman filter is proposed for the one-dimensional direction finding problem of MIMO radar. The rotational invariance among the multiple equivalent virtual subarrays of MIMO radar is exploited to derive multiple estimates of the direction of each target through ESPRIT. The multiple estimates of each target are fused through a Kalman filter to refine the accuracy of estimation. Numerical examples demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Bilateral filtering (BF) can realise both smoothing images and preserving edges, whereas its filtering results are always influenced since its two parameters are difficult to configure to the optimum. In this reported work, the application of BF is extended to synthetic aperture radar (SAR) image despeckling, and the despeckling evaluation indexes, including the equivalent number of looks and the edge save index, are used to estimate the parameters. After BF with estimated parameters imposed on a normalised SAR image, further processing can achieve both despeckling and edge preservation simultaneously. Experimental results show that the visual quality and evaluation indexes of the proposed algorithm outperform the classical Lee filtering. [ABSTRACT FROM AUTHOR]

A simple microwave sensor for the detection of the dynamic characteristics of large structure vibration is proposed. It consists of a continuous-wave radar capable of detecting the structure movement by measuring the phase of the back-reflected wave. The system performances have been demonstrated in a case study monitoring a pedestrian bridge. [ABSTRACT FROM AUTHOR]

A successive Fourier transform technique is applied to efficiently generate an interrupted sparse waveform for a monostatic high-frequency surface wave radar. With few iterations a good stop to passband ratio is reached, and it is show that, when using an optimised envelope, a better average and a lower standard deviation are obtained in terms of minimal contrast ratio than in the case of a simple train of pulses. [ABSTRACT FROM AUTHOR]

A novel wideband and broad-beam microstrip antenna loaded with gaps and stubs is proposed. The antenna is based on a two-layer stacked electromagnetic coupling microstrip patch antenna (ECMSA). The upper patch of the antenna is loaded with two arc gaps and three stubs. The ECMSA is used to achieve wide impedance bandwidth, while the gaps and stubs-loaded patch is used to obtain broad-beam. The impedance bandwidth is up to 34.6%. In this impedance bandwidth, the pattern bandwidth is 13%. In this pattern bandwidth, the 3 dB beamwidth of E-plane and H-plane remain stable and are about ±60°. Simulation results agree well with measured results. [ABSTRACT FROM AUTHOR]

Hardware architecture of a tessellator based on a vertex shader is proposed to save memory bandwidth for a mobile 3D graphics engine. According to the appropriate separation of the tessellation process, the powerful performance of a vertex shader, 120 Mvertices/s, is utilised for floating point computations. The remaining part of the process is handled by a dedicated control unit, implementation of which requires 6.2% additional logic gates. The proposed tessellator reduces the bandwidth consumed to transfer 3D geometry data up to 1/250. [ABSTRACT FROM AUTHOR]

A novel photovoltaic dipole antenna employing a solar concentrator as a reflector is proposed. Four identical emitter-wrap-through rear contact solar cells connected in series as a folded dipole are simultaneously used for power generation and as the antenna radiating element, which is located in the focal line of a parabolic solar concentrator. The parabolic structure acts as a solar concentrator for the photovoltaic cells as well as a reflector for the folded dipole antenna. Full-wave electromagnetic simulation with supportive experimental work validates this design. The measured fractional impedance bandwidth and gain were 21% and 11.1 dBi, respectively. The antenna/solar arrangement provide a power output of 73.7 mW for an irradiance of 1000 Wm-2. [ABSTRACT FROM AUTHOR]

The GPS antenna on mobile terminals suffers from multipath effects owing to reflection, diffraction and scattering of the incident wave in a radio environment. A traditional approach to evaluate the GPS antenna performance in a real multipath environment is therefore insufficient. Presented is a new technique to characterise these environmental effects and the system performance of GPS antennas on mobile terminals. [ABSTRACT FROM AUTHOR]

Presented are novel theoretical probability density functions (PDF) for the magnitude and phase of electromagnetic fields inside reverberation chambers (RC) operating in a ‘good-but-imperfect regime’. The derivation is based on considering two Gaussian random variables with mean values, variances and correlation between them that depart from the ideal assumptions. A multivariate approach using a complete joint Gaussian distribution of these variables is defined. Marginal distributions obtained by integration of this two-dimensional joint PDF are compared with theoretical PDFs for ideal situations, and significantly lower rejection rates are experienced for field data measured in real RCs. Additionally, these novel marginal PDFs are highly general since they are able to describe both ideal and non-ideal stirred fields. [ABSTRACT FROM AUTHOR]

The emerging trend for handset antenna design puts strong constraints on their volume occupation and user's proximity resilience. Several PIFA antenna configurations are investigated, studying the influence of substrate/superstrate dielectric loading on both absorption and mismatch loss at 900 MHz. By using high-permittivity materials and by leaving a small clearance area between the PIFA top plate and the back of the handset, both absorption and mismatch loss can be reduced at the expense of a narrower bandwidth. [ABSTRACT FROM AUTHOR]

A novel architecture of a hybrid continuous-time/discrete-time cascade ΣΔ modulator that takes advantage of both circuit techniques, by including implicit anti-aliasing filtering and reduced sampling requirements, while presenting high robustness to circuit non-idealities, is presented. These circuital features are combined with programmable resonation to optimally distribute the zeros of the noise transfer function. In addition, the unity signal transfer function is implemented in all the modulator stages in order to reduce the integrator's output swing. All these characteristics make the proposed architecture well suited to the implementation of reconfigurable A/D conversion in future generations of wireless telecom systems. [ABSTRACT FROM AUTHOR]

A framework for human aggressive motion detection in image sequences captured from a single stationary camera is described. Background subtraction, connected chips linking and mean-shift estimation are used to extract target contour information. The binary rectangle containing contour points of the blob-set is transformed into a normalised Radon matrix. With labelled (normal or aggressive motion) Radon matrix as feature pools an online AdaBoost feature selection is implemented. Using the selected classifiers the human aggressive motion in a frame can be recognised. Experimental results show that the system performs well. [ABSTRACT FROM AUTHOR]

Electrically-pumped GaSb-based vertical-cavity surface-emitting lasers emitting up to 2.63 µm at room temperature are reported. The whole structure was grown monolithically in one run by solid-source molecular beam epitaxy. This heterostructure is composed of two n-doped AlAsSb/GaSb DBRs, a type-I GaInAsSb/AlGaAsSb multi-quantum-well active region and an InAsSb/GaSb tunnel junction. A quasi-CW (1 µs, 5 %) operation was obtained at room temperature for 35 µm-diameter devices with threshold current of 85 mA. [ABSTRACT FROM AUTHOR]

Grating couplers for efficient coupling between silicon sandwiched slot waveguides and standard singlemode fibres are demonstrated. Coupling efficiency up to 20% is experimentally measured for TM polarisation and a wavelength of 1550 nm. A 20 nm 1 dB bandwidth is also obtained. Higher coupling efficiency is expected for particular designs according to simulation results. [ABSTRACT FROM AUTHOR]

Non-uniform coupled lines, which corrugate periodically not only on the inner edges but also on the inner and outer edges of the conductors, are proposed on longitudinally-magnetised ferrite for the first time. Compared with the conventional parallel ferrite-coupled-line (FCL) section, the corrugated structure can modify the operating frequency for non-reciprocity without changing the physical length of the conventional one. In addition, the simulated performance of a periodically non-uniform FCL section indicates a significant performance improvement of broader bandwidth. [ABSTRACT FROM AUTHOR]

The outage performance of a multiple-input multiple-output (MIMO) relay system over slow frequency-nonselective fading channels, where maximal ratio transmission is adopted at both the source and relay transmitters whereas maximal ratio combining is used at relay and destination receivers, is investigated. A closed-form expression for the outage probability is presented. Numerical results are presented to verify the analysis. [ABSTRACT FROM AUTHOR]

Two recent carrier recovery loops for high-order quadrature amplitude modulation (QAM) and optimisation of their parameters for minimum frequency acquisition times are analysed. All variations on the parameters were analysed and optimised to obtain optimal loop bandwidths and damping factors, for given signal-to-noise ratios. Simulation results show that after optimisation, the average acquisition time for 64-QAM is kept below 1000 symbols over the entire range of initial frequency offsets from 0 to 1/8 the symbol rate. This number increases to 3200 symbols for 256-QAM. [ABSTRACT FROM AUTHOR]

A reduced-complexity modified decoding algorithm for turbo trellis-coded modulation (TTCM) is proposed and evaluated in terms of complexity and bit error rate (BER) performance in an additive white Gaussian noise channel. The algorithm uses an optimal approximation of the Jacobian logarithm, used in the so-called Log-MAP decoding, by means of the max operation and three piecewise-linear terms. Further computational complexity savings are obtained by applying this approximation only to the two largest values within the decoding step. To improve performance, the algorithms are also investigated using a scaling factor for the extrinsic information. Computer-simulated BER performance evaluation results and complexity comparisons are reported showing the near-optimal performance as well as noticeable implementation advantages of the proposed algorithms with respect to the Log-MAP decoding. [ABSTRACT FROM AUTHOR]

Resonance splitting has been demonstrated for two coupled micro-cavities with control of the free spectral range between the resonance peaks, together with a normalised transmission level of approximately 60%. Coupled micro-cavity-based structures that were separated by two closely spaced in-line coupler sections between the two micro-cavities have also been successfully fabricated and measured. The coupling strength of the two cavities was controlled via the use of hole tapering in the middle section between the two cavities. 2D finite-difference time-domain simulation shows close agreement with the results of measurements. [ABSTRACT FROM AUTHOR]

Two 40 Gbit/s WDM signals to one 80 Gbit/s signal multiplexing based on cross-phase modulation in a 0.8 metre bismuth oxide highly nonlinear fibre, is experimentally demonstrated. Error-free operation was achieved after demultiplexing the 80 Gbit/s signal to 10 Gbit/s and less than 2.5 dB penalty was observed. [ABSTRACT FROM AUTHOR]

A novel subspace-based detection scheme for space–time block-coded co-operative diversity is presented. By applying singular value decomposition to the received signal matrix, noise subspace orthogonal to a transmitted codeword is obtained. Detection without channel state information is achieved by searching for the codeword, including columns with the best orthogonal relationships to noise subspace. Such detection requires only the number of decoding relays and is robust to the fading channels varying from block to block, as verified by Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

Adaptive pulse compression (APC) is an effective method for mitigating the mutual interference of the multiple waveforms transmitted in multiple-input multiple-output (MIMO) radar. But APC based on minimum mean-square error (MMSE) is computationally inefficient. Therefore, APC of MIMO radar based on a generalised sidelobe canceller (GSC) is proposed, which can effectively reduce the complexity. Numerical experiments show that the proposed method is superior to the matched filter (MF), and performs similarly as APC based on MMSE. [ABSTRACT FROM AUTHOR]

A novel algorithm for estimating the ranges and velocities of multiple moving targets in randomised stepped-frequency pulse-train radar is presented. By using the iterative alternating projection technique, this algorithm can achieve high range-velocity resolution and estimation accuracy close to the Cramer-Rao bounds. The sidelobe pedestal problem of randomised stepped-frequency waveforms can also be mitigated. The effectiveness of the algorithm is illustrated with simulation results. [ABSTRACT FROM AUTHOR]

The design of simple feed networks is of great interest in synthesising monopulse radar array antennas in order to reduce the complexity of the antenna architecture, the costs as well as the occupied physical space (e.g. on aircraft). Sub-arraying techniques have been proposed to properly address such a task. Starting from the formulation of the sub-arraying problem in terms of a combinatorial one, the final compromise solution is obtained by looking for the minimum cost path inside a binary tree graph through an ant colony optimiser. [ABSTRACT FROM AUTHOR]

A study of quasi-continuous waveform and its performance in detection is presented, taking into consideration eclipsing loss and free-space decay. A genetic algorithm is then used to optimise the waveform and lower the dynamic range of the matched filtering output. The resulting waveform with high duty cycle and minimal loss at maximal range maintains good detection performance along the whole operating range of the radar. [ABSTRACT FROM AUTHOR]

An electromagnetic bandgap (EBG) surface that can be independently tuned over two separate frequency bands is demonstrated. The EBG consists of a dual layer of square element based designs with varactor diodes. The EBG tuning ranges for each band were from 600 to 1200 and 1700 to 2600 MHz. [ABSTRACT FROM AUTHOR]