dB Peak Research Articles

Design considerations for low-margin elastic optical networks in the nonlinear regime [Invited

We demonstrate from a system design perspective that nonlinearity can be exploited to minimize the impact of system margins on system performance for both point-to-point links and elastic optical networks. A nonlinear interaction causes a 2 dB reduction in launch power to be reduced to $ \lt\!{0.25}\,\,{\rm{dB}}$ signal-to-noise ratio (SNR) penalty, and likewise, a 2 dB peak–peak (pk-pk) perturbation to the output power of an optical amplifier is reduced to $ \lt\!{0.25}\,\,{\rm{dB}}$ SNR penalty (for 5, 10, and 20 spans). Extending this to a gain ripple of 1 dB pk-pk with an internode spacing of ${5} \times {80}\,\,{\rm{km}}$, ${10} \times {80}\,\,{\rm{km}}$, and ${20} \times {80}\,\,{\rm{km}}$, the penalty is 0.4 dB, 1.5 dB, and 5.1 dB, respectively, with pre-emphasis reducing this to 0.01 dB, 0.3 dB, and 1.2 dB, respectively. In elastic optical networks, we consider the nonlinear relationship among SNR, margin, and the fraction of capacity available. We consider scaling internode distances of a 9-node German scale network (DT9), such that the initial network diameter increases from 1120 km to 6720 km (six-fold scaling). We generate 1000 different topologies based on the scaled DT9 node locations to quantify the impact of margin. For the unscaled DT9 network, a 3 dB margin results in, on average, a 21% reduction in network throughput; however, when the internode spacing is increased six-fold to a continental scale network, the network throughput is reduced by 40%, on average, for the same 3 dB margin.

Measurement and characterization of infrasound from a tornado producing storm.

A hail-producing supercell on 11 May 2017 produced a small tornado near Perkins, Oklahoma (35.97, -97.04) at 2013 UTC. Two infrasound microphones with a 59-m separation and a regional Doppler radar station were located 18.7 and 70 km from the tornado, respectively. Elevated infrasound levels were observed starting 7 min before the verified tornado. Infrasound data below ∼5 Hz was contaminated with wind noise, but in the 5-50 Hz band the infrasound was independent of wind speed with a bearing angle that was consistent with the movement of the storm core that produced the tornado. During the tornado, a 75 dB peak formed at ∼8.3 Hz, which was 18 dB above pre-tornado levels. This fundamental frequency had overtones (18, 29, 36, and 44 Hz) that were linearly related to mode number. Analysis of a larger period of time associated with two infrasound bursts (the tornado occurred during the first event) shows that the spectral peaks from the tornado were present from 4 min before to 40 min after tornadogenesis. This suggests that the same geophysical process(es) was active during this entire window.

Microcavity-based narrowband parametric amplifier for carrier recovery in optical coherent self-homodyne detection.

We demonstrate all-optical carrier recovery exploring optical parametric amplification (OPA) in a monolithic high-finesse silicon nitride microring cavity. Compared to a nonresonant OPA process in nonlinear waveguides, cavity-based OPA allows a much narrower gain bandwidth by manipulating the intracavity light interactions with a controllable parametric gain, thus facilitating high-resolution carrier extraction without needing a large guard band between the carrier tone and data spectrum. Here, we achieve narrowband OPA with a 22.0dB peak gain and a bandwidth as low as 15.2MHz in a 100μm radius microring cavity, which is applied to implement carrier recovery of a 16QAM optical orthogonal-frequency-division-multiplexing data signal. A highly coherent phase is conserved between the recovered carrier tone and the original data, enabling self-homodyne detection with high data quality and minimized electrical compensation. Our study holds potential to constitute energy-friendly coherent receivers.

Constant envelope FrFT OFDM: Spectral and energy efficiency analysis

Constant envelope with a fractional Fourier transformorthogonal frequency division multiplexing (CE-FrFT-OFDM) is a special case of a constant envelope OFDM (CE-OFDM), both being energy efficient wireless communication techniques with a 0 dB peak to average power ratio (PAPR). However, with the proper selection of fractional order, the first technique has a high bit error rate (BER) performance in the frequency-time selective channels. This paper performs further analysis of CE-FrFT-OFDM by examining its spectral efficiency (SE) and energy efficiency (EE) and compare to the famous OFDM and FrFT-OFDM techniques. Analytical and comprehensive simulations conducted show that, the CE-FrFT-OFDM has five times the EE of OFDM and FrFT-OFDM systems with a slightly less SE. Increasing CE-FrFT-OFDM's transmission power by increasing its amplitude to 1.7 increases its SE to match that of the OFDM and FrFT-OFDM systems while slightly reducing its EE by 20% to be four times that of OFDM and FrFTOFDM systems. OFDM and FrFT-OFDM's amplitude fluctuations cause rapid changing output back-off (OBO) power requirements and further reduce power amplifier (PA) efficiency while CE-FrFTOFDM stable operational linear range makes it a better candidate and outperforms the other techniques when their OBO exceeds 1.7. Higher EE and low BER in time-frequency selective channel are attracting features for CE-FrFT-OFDM deployment in mobile devices.

An Ultra-Low-Power, 16 Bits CT Delta-Sigma Modulator Using 4-Bit Asynchronous SAR Quantizer for Medical Applications

In this paper, a low-power second-order feed-forward capacitor-structure continuous-time [Formula: see text] modulator with a 4-bit asynchronous successive approximation register (SAR) quantizer is presented. Through the utilization capacitor structure in the proposed modulator, first, the summation node of the integrators’ outputs and the feed-forward signals is implemented within the second integrator to reduce power consumption by eliminating an active summing amplifier. Second, the proposed architecture can compensate for the quantizer delay without using any excess inner digital to analog converter (DAC). In this design, the modulator applies two different low-power operational amplifiers. These advantages cause the modulator to consume very low power and achieve a favorable figure of merit (FOM) value. In fact, in this paper, the combination of the previously reported methods and designs and doing required reforms has led to a new design with better performance, especially in power reduction. The designed modulator which is simulated using 0.18[Formula: see text][Formula: see text]m CMOS technology achieves 95.98[Formula: see text]dB peak signal-to-noise and distortion (SNDR) for 10[Formula: see text]KHz signal bandwidth and dissipates 44[Formula: see text][Formula: see text]w while its FOM is obtained about 43 fJ/conv.-step.

Photoconductive terahertz detectors with 105 dB peak dynamic range made of rhodium doped InGaAs

Rhodium (Rh)-doped In0.53Ga0.47As grown by gas-source molecular beam epitaxy is investigated as a terahertz (THz) detector antenna for optical excitation at 1550 nm. The 4d transition metal rhodium acts as a deep level and ultrafast trapping center. At a doping concentration around 8 × 1019 cm−3, InGaAs:Rh exhibits ideal properties for application as a THz antenna: an ultrashort carrier lifetime below 200 fs in combination with a mobility of 1010 cm2/Vs. The THz detectors fabricated from this sample show a record peak dynamic range of 105 dB and a bandwidth of up to 6.5 THz.

Hearing Dysfunction in a Large Family Affected by Dominant Optic Atrophy (OPA8-Related DOA): A Human Model of Hidden Auditory Neuropathy.

Hidden auditory neuropathy is characterized by reduced performances in challenging auditory tasks with the preservation of hearing thresholds, resulting from diffuse loss of cochlear inner hair cell (IHC) synapses following primary degeneration of unmyelinated terminals of auditory fibers. We report the audiological and electrophysiological findings collected from 10 members (4 males, 6 females) of a large Italian family affected by dominant optic atrophy, associated with the OPA8 locus, who complained of difficulties in understanding speech in the presence of noise. The patients were pooled into two groups, one consisting of 4 young adults (19–50 years) with normal hearing thresholds, and the other made up of 6 patients of an older age (55–72 years) showing mild hearing loss. Speech perception scores were normal in the first group and decreased in the second. Otoacoustic emissions (OAEs) and cochlear microphonics (CMs) recordings were consistent with preservation of outer hair cell (OHC) function in all patients, whereas auditory brainstem responses (ABRs) showed attenuated amplitudes in the first group and severe abnormalities in the second. Middle ear acoustic reflexes had delayed peak latencies in all patients in comparison with normally hearing individuals. Transtympanic electrocochleography (ECochG) recordings in response to 0.1 ms clicks at intensities from 120 to 60 dB peak equivalent SPL showed a reduction in amplitude of both summating potential (SP) and compound action potential (CAP) together with delayed CAP peak latencies and prolonged CAP duration in all patients in comparison with a control group of 20 normally hearing individuals. These findings indicate that underlying the hearing impairment in OPA8 patients is hidden AN resulting from diffuse loss of IHCs synapses. At an early stage the functional alterations only consist of abnormalities of ABR and ECochG potentials with increased latencies of acoustic reflexes, whereas reduction in speech perception scores become apparent with progression of the disease. Central mechanisms increasing the cortical gain are likely to compensate for the reduction of cochlear input.

Design and analysis of a millimetre‐wave high gain antenna

A broadband and high gain transmit array (TA) antenna, operating at 60 GHz, is proposed. To meet the design requirements of a TA antenna with polarisation-insensitive radiation performance, an optimal multi-layer unit cell (UC) is introduced. The dimensions of the UC are parametrically expressed to realise a linear transmission phase response with a variation range of 270° and insertion loss <;-3 dB over the desired frequency band ranging from 58 to 64 GHz. A new planar array composed of 2 × 4 aperture-coupled-patches interleaved with a soft-surface is also designed as a feed for the proposed TA. Furthermore, a hybrid method based on full-wave simulations and analytical formulations is developed to calculate the radiation characteristics of the TA antenna and the results are compared to the ones achieved with full-wave simulations. The designed TA antenna is fabricated and the measurement results are presented. The obtained results show peak aperture efficiencies of 38.48% (30.85 dB peak gain) and 32.37% (30.1 dB peak gain), and -1 dB gain bandwidths of 7.7 and 8.2% from the full-wave simulations and measurements, respectively. Such a broadband and high gain antenna is deemed to be suitable for mm-wave backhaul links in 5G cellular systems.

A Reconfigurable 28-/37-GHz MMSE-Adaptive Hybrid-Beamforming Receiver for Carrier Aggregation and Multi-Standard MIMO Communication

This paper presents a multi-standard fully connected hybrid beamforming (FC-HBF) receiver that can be reconfigured between two fully connected two-stream multi-input-multi-output (MIMO) modes at 28- or 37-GHz band, and an inter-band carrier-aggregation (CA) mode enabling concurrent single-stream operation at 28 and 37 GHz. A new image-reject (IR) heterodyne beamforming architecture is introduced that facilitates easy reconfiguration. Concurrent dual-band operation of the beamformer front end is achieved by using an inherently wideband Cartesian-combining-based RF-domain complex-weighting architecture, which is implemented using coupled-resonator-based dual-band gain stages, and current-mode dual-band active combiners. The downconversion stage comprises a cascade of complex-quadrature mixing stages that combines Cartesian complex-weighting operation with image rejection. A new quadrature error detection and calibration scheme is also introduced to improve the image rejection of the proposed architecture. A minimum mean-square error (MMSE) beam adaptation technique, introduced for the first time in an RF or hybrid beamformer, breaks the need for individual access to the beamformer inputs needed in a traditional least-mean-square (LMS) scheme and allows both main lobe and null adaptation. A 28-/37-GHz hybrid beamforming receiver with four antenna inputs and two baseband output streams is designed in 65-nm CMOS that demonstrates the above features. In each antenna path, the receiver achieves 33-dB (26.5 dB) peak conversion gain, 2.75-GHz (3.75 GHz) RF bandwidth, and 5.7-dB (8.5 dB) NF at 28 GHz (37 GHz). The entire receiver consumes 310 mW and occupies 2.2 mm2 core area. Extensive characterization results for single-element and several multi-element scenarios are presented including concurrent dual-band receiving (>35-dB image rejection), null-steering (>25-dB peak to null for two elements), and multi-element CA (~50-dB inter-carrier interference rejection).

Is There a Safe Level for Recording Vestibular Evoked Myogenic Potential? Evidence From Cochlear and Hearing Function Tests.

There is a growing concern among the scientific community about the possible detrimental effects of signal levels used for eliciting vestibular evoked myogenic potentials (VEMPs) on hearing. A few recent studies showed temporary reduction in amplitude of otoacoustic emissions (OAE) after VEMP administration. Nonetheless, these studies used higher stimulus levels (133 and 130 dB peak equivalent sound pressure level [pe SPL]) than the ones often used (120 to 125 dB pe SPL) for clinical recording of VEMP. Therefore, it is not known whether these lower levels also have similar detrimental impact on hearing function. Hence, the present study aimed at investigating the effect of 500 Hz tone burst presented at 125 dB pe SPL on hearing functions. True experimental design, with an experimental and a control group, was used in this study. The study included 60 individuals with normal auditory and vestibular system. Of them, 30 underwent unilateral VEMP recording (group I) while the remaining 30 did not undergo VEMP testing (group II). Selection of participants to the groups was random. Pre- and post-VEMP assessments included pure-tone audiometry (250 to 16,000 Hz), distortion product OAE, and subjective symptoms. To simulate the time taken for VEMP testing in group I, participants in group II underwent these tests twice with a gap of 15 minutes. No participant experienced any subjective symptom after VEMP testing. There was no significant interear and intergroup difference in pure-tone thresholds and distortion product OAE amplitude before and after VEMP recording (p > 0.05). Furthermore, the response rate of cervical VEMP was 100% at stimulus intensity of 125 dB pe SPL. Use of 500 Hz tone burst at 125 dB pe SPL does not cause any temporary or permanent changes in cochlear function and hearing, yet produces 100% response rate of cervical VEMP in normal-hearing young adults. Therefore, 125 dB pe SPL of 500 Hz tone burst is recommended as safe level for obtaining cervical VEMP without significantly losing out on its response rate, at least in normal-hearing young adults.

Highly compact GaN-based all-digital transmitter chain including SPDT T/Rx switch for massive MIMO applications

AbstractThis paper presents a fully digital transmitter chain from baseband to antenna, including a modulator, two truly digital (i.e. fully switched) microwave power amplifiers and a transmit/receive switch. Both, amplifier and switch monolithic microwave integrated circuits were implemented in a GaN HEMT process. The novel amplifier design provides greatly reduced complexity, needing only three voltage sources. Measurements were conducted using 5, 20, and 100 MHz wide baseband signals. Carrier frequencies cover the 900 and 2000 MHz bands. For the 5 MHz BB signal an ACLR of over 52 dB is reached, fulfilling the 3GPP specs for base station use while still maintaining a final-stage drain efficiency of 46% at 6.5 dB peak to average power ratio. Full-scale output power at 30 V supply voltage was measured to exceed 3 W at 80% drain efficiency. Further features of this digital amplifier approach include small form factor and frequency agility, making it an ideal candidate for software defined radio.

2.4 GHz dual polarised monostatic antenna with simple two‐tap RF self‐interference cancellation (RF‐SIC) circuitry

This Letter presents a dual polarised monostatic patch antenna with a simple two-tap RF/analogue domain-based self-interference cancellation (SIC) (RF-SIC) circuitry to achieve high interport isolation in a comparatively wider bandwidth for a 2.4 GHz in-band full duplex wireless transceiver. A brief mathematical description for the deployed two-tap RF-SIC is also presented to provide insight into self-interference (SI) suppression in a comparatively wider bandwidth. The implemented antenna with a two-tap RF-SIC circuitry achieves around 80 dB T-x-R-x isolation for a 20 MHz bandwidth in addition to more than 90 dB peak isolation for measurements performed in a lab environment where SI may result from the nearby placed objects. The deployed two-tap RF-SIC circuit can be tuned to effectively cancel out SI caused by reflections of the radio signal from the surroundings. Moreover, an 80 dB isolation bandwidth can be tuned within a 10 dB return loss bandwidth of the implemented dual polarised antenna.

Impulsive exposures from ceremonial and signal cannons

Cannons, small firearms, and starter pistols are sometimes used with blank charges during sporting events, ceremonies, and historical re-enactments. The sound levels produced by such devices are not widely known, and it is possible that the personnel discharging them could underestimate the potential risk to hearing. Depending upon the proximity to participants and spectators, the sound levels produced by such devices can be potentially hazardous. The exposures have not been widely examined because they fall outside of regulations and standards that cover typical occupational or military exposures. This presentation describes the acoustic characteristics and exposure limits for two large-caliber ceremonial cannons and a signal cannon. The cannons produced impulses between 150 and 174 dB peak sound pressure level (SPL) and 8-h equivalent A-weighted levels ranging between 60 and 108 dBA, respectively. In addition, measurements from small firearms and starter pistols are presented, which produced sound levels between 145 and 165 dB SPL. Such sound levels exceed the various occupational recommended and permissible exposure limits. This paper provides recommendations for noise and administrative controls for all personnel within 15 m of the ceremonial cannons and 10 m of the signal cannon. Double hearing protection should be required during all activities.Cannons, small firearms, and starter pistols are sometimes used with blank charges during sporting events, ceremonies, and historical re-enactments. The sound levels produced by such devices are not widely known, and it is possible that the personnel discharging them could underestimate the potential risk to hearing. Depending upon the proximity to participants and spectators, the sound levels produced by such devices can be potentially hazardous. The exposures have not been widely examined because they fall outside of regulations and standards that cover typical occupational or military exposures. This presentation describes the acoustic characteristics and exposure limits for two large-caliber ceremonial cannons and a signal cannon. The cannons produced impulses between 150 and 174 dB peak sound pressure level (SPL) and 8-h equivalent A-weighted levels ranging between 60 and 108 dBA, respectively. In addition, measurements from small firearms and starter pistols are presented, which produced sound level...

A 0.58 mm2 CMOS reconfigurable sigma delta ADC for mobile WiMAX receiver

Objective: In this work the design of a fourth-order Reconfigurable Sigma Delta analog-to-digital converter (ΣΔ ADC) for 5MHz, 7MHz or 10MHz channel bandwidths are presented. Materials and methods: Our design technique aims to keep the same ADC architecture in response to multi-band and multi-mode aspects of Mobile WiMAX standard. To this end, we set each sampling frequency corresponding to each channel bandwidth, in order that the same OSR value would be kept for the different channel bandwidths. This technique is intended to optimize the power and area of the ADC that efficiently covers varying channel bandwidths. Moreover, we use the pole placement method to calculate the optimized filter coefficients of Continuous-Time Sigma-Delta (CT ΣΔ) ADC. Results and discussion: Over 5MHz, 7MHz and 10MHz channel bandwidths, the ADC achieved 72.89dB, 67.26dB and 66.47dB peak SNR values, respectively and a dynamic range of 73.5dB, 69.47dB and 66.5dB respectively with only 28mW, 28.2mW and 28.6mW power consumption respectively. Conclusions: The design of the proposed reconfigurable ADC intended for use in the mobile WiMAX standard were achieved. Moreover, the results obtained are satisfactory and are in accordance with theoretical expectations.

ICast: Fine-Grained Wireless Video Streaming Over Internet of Intelligent Vehicles

Recent years have witnessed a steep grow in the multimedia-oriented Internet of Things (IoT) over vehicular networks. Huge volume of multimedia traffic generated from the in-built IoT devices should be delivered among vehicles and immediate surroundings in real time. However, as network nodes with higher mobility, vehicles often experience more unpredictable wireless channels. Such time-frequency diversity poses substantial challenges to achieve pervasive and real-time multimedia connectivity. The hurdle lies in the inability of automatically approaching the subcarrier level channel variations in the existing video codecs. With coarse-grained traffic delivery rate, video decoding fails, and intermittent connection occurs. To break this stalemate, we propose a fine-grained wireless video streaming strategy, namely iCast, that intelligently achieves the most appropriate data rate and frame protection for multimedia traffic in highly mobile vehicular environments. The insight of iCast is a simple joint source-channel rateless code. It reaps the benefits of the frequency diversity to provide fine-grained data rate for the channel in conjunction with suitable protection for the source. Our experiments show that, by harnessing frequency diversity in mobile environments, iCast outperforms the existing competitive wireless video delivery schemes by up to 5 dB peak signal-to-noise ratio.

Robust watermarking in curvelet domain for preserving cleanness of high-quality images

Watermarking inserts invisible data into content to protect copyright. The embedded information provides proof of authorship and facilitates the tracking of illegal distribution, etc. Current robust watermarking techniques have been proposed to preserve inserted copyright information from various attacks, such as content modification and watermark removal attacks. However, since the watermark is inserted in the form of noise, there is an inevitable effect of reducing content visual quality. In general, most robust watermarking techniques tend to have a greater effect on quality, and content creators and users are often reluctant to insert watermarks. Thus, there is a demand for a watermark that maintains maximum image quality, even if the watermark performance is slightly inferior. Therefore, we propose a watermarking technique that maximizes invisibility while maintaining sufficient robustness and data capacity to be applied in real situations. The proposed method minimizes watermarking energy by adopting curvelet domain multi-directional decomposition to maximize invisibility and maximizes robustness against signal processing attacks with a watermarking pattern suitable for curvelet transformation. The method is also robust against geometric attacks by employing the watermark detection method utilizing curvelet characteristics. The proposed method showed very good results of a 57.65 dB peak signal-to-noise ratio in fidelity tests, and the mean opinion score showed that images treated with the proposed method were hardly distinguishable from the originals. The proposed technique also showed good robustness against signal processing and geometric attacks compared with existing techniques.

Continuously spacing-tunable dual-wavelength erbium-doped fiber laser based on polarization-dependent in-line multimode-single-mode-multimode fiber filter

A continuously spacing-tunable dual-wavelength erbium-doped all-fiber laser is proposed and experimentally demonstrated in this paper. The key component of the laser is a novel polarization-maintained multimode-single-mode-multimode fiber interference filter, which is composed of two single-mode-multimode-single-mode fiber mode converters with a polarization-maintaining fiber sandwiched between them. As the polarization-maintaining fiber gives rise to a polarization-dependent phase difference, the fiber filter shows good polarization-dependent characteristics in interference filtering. Based on the mode interference and polarization control, the good wavelength tuning results are obtained in experiment. An optimized length of 1.3 mm for multimode fiber and 1.5 mm for polarization-maintaining fiber are adopted based on the theoretical and experimental analysis. When the phase difference between the lasing in the fast axial direction and that in the slow axial direction is &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ {\text{π}}$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20190297_M1.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="15-20190297_M1.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, the peaks and valleys in the transmission spectrum of the fiber filter correspond exactly to the two orthogonal polarization states. In the test, when the pump power is 50 mW, a high-quality dual-wavelength lasing output (at 1544.82 nm and 1545.61 nm) is observed to have side-mode suppression ratio better than 45 dB, the wavelength spacing of 0.8 nm, the peak power difference of less than 1 dB, and the output keeps stable with a small power fluctuation less than 0.7 dB. By adjusting the polarization controller in the ring cavity, two different dual-wavelength outputs can be obtained, which are corresponding to tuning Ⅰ and tuning Ⅱ. In tuning Ⅰ, a dual-wavelength lasing output in a wavelength spacing tuning range of 0−1.2 nm can be obtained within 1 dB peak power difference, correspondingly, 0−1.6 nm tuning range within 10 dB peak power difference. In tuning Ⅱ, with continuously adjusting the polarization controller, the short wavelength signal of the dual-wavelength output stops resonating, and simultaneously another wavelength signal near 1547.8 nm is excited, the switching is continuous and the system remains dual-wavelength output. In tuning Ⅱ, a maximum tuning range of 1.6−3 nm is obtained. In both of tuning Ⅰ and tuning Ⅱ, a 0−3 nm continuously spacing-tunable dual-wavelength output is obtained, all of which keep stable single-polarization operation. The test results show that the polarization state of the dual-wavelength lasing varies with tuning; a maximum polarization extinction ratio of 35 dB is obtained as the two wavelengths are orthogonally polarized.

Co‐polarized monostatic antenna with high Tx–Rx isolation for 2.4 GHz single channel full duplex applications

AbstractThis article presents a linear co‐polarized (same polarization for transmit and receive modes), proximity coupled monostatic patch antenna with high port to port RF isolation for 2.4 GHz single channel full duplex (SCFD) wireless applications. The presented proximity coupled monostatic patch antenna deploys differential feeding for receive (Rx) mode to significantly suppress RF leakage from transmit (Tx) port and external single‐tap self‐interference cancellation (SIC) circuit provides additional interport isolation. The measurements for implemented prototype of antenna in lab environment provide around 50 dB Tx–Rx isolation for 50 MHz bandwidth in addition to better than 75 dB peak isolation. Moreover, the deployed single‐tap RF SIC circuit can be used to suppress SI resulted from environmental reflections and 50 MHz SIC bandwidth with 50 dB isolation can be tuned within antenna's 10 dB return loss impedance bandwidth of 150 MHz.

ROI-based reversible watermarking scheme for ensuring the integrity and authenticity of DICOM MR images

Reversible and imperceptible watermarking is recognized as a robust approach to confirm the integrity and authenticity of medical images and to verify that alterations can be detected and tracked back. In this paper, a novel blind reversible watermarking approach is presented to detect intentional and unintentional changes within brain Magnetic Resonance (MR) images. The scheme segments images into two parts; the Region of Interest (ROI) and the Region of Non Interest (RONI). Watermark data is encoded into the ROI using reversible watermarking based on the Difference Expansion (DE) technique. Experimental results show that the proposed method, whilst fully reversible, can also realize a watermarked image with low degradation for reasonable and controllable embedding capacity. This is fulfilled by concealing the data into ‘smooth’ regions inside the ROI and through the elimination of the large location map required for extracting the watermark and retrieving the original image. Our scheme delivers highly imperceptible watermarked images, at 92.18–99.94 dB Peak Signal to Noise Ratio (PSNR) evaluated through implementing a clinical trial based on relative Visual Grading Analysis (relative VGA). This trial defines the level of modification that can be applied to medical images without perceptual distortion. This compares favorably to outcomes reported under current state-of-art techniques. Integrity and authenticity of medical images are also ensured through detecting subsequent changes enacted on the watermarked images. This enhanced security measure, therefore, enables the detection of image manipulations, by an imperceptible approach, that may establish increased trust in the digital medical workflow.

High isolation slot coupled antenna with integrated tunable self‐interference cancellation circuitry

This letter presents a high interport isolation, compact dual polarized slot coupled monostatic patch antenna with integrated tunable analog/RF self interference cancellation (SIC) circuitry for 2.4/2.5 GHz In Band Full Duplex (IBFD) wireless applications. The presented antenna deploys hybrid feeding for improved interport isolation through polarization diversity and integrated single-tap RF SIC circuitry provides additional isolation on top of antenna isolation. Brief mathematical description for deployed single-tap RF SIC is also presented. The implemented prototype of proposed antenna module provides around 80 dB interport isolation for 20 MHz bandwidth and better than 97 dB peak isolation when measured in lab in the presence of environmental reflections. Moreover, 20 MHz SIC bandwidth with 80 dB interport isolation can be tuned within antenna’s 10 dB return loss impedance bandwidth of 60 MHz.