Reception Bandwidth Research Articles

High-frequency inlaid cylindrical piezoelectric transducer for high-sensitivity acoustics

This work develops a high-frequency high-sensitivity inlaid cylindrical hydroacoustic transducer by enhancing the electromechanical coupling coefficient, amplifying stress, and adopting circumferential inlaid techniques. Equivalent circuit and finite element simulation methods were used to determine the optimum parameters of the unit, then the transducer was fabricated. Tests show that the resonant frequency of every array unit was 220 kHz. The maximum emission voltage response and reception sensitivity were respectively about 172 dB and −177 dB, with emission and reception bandwidths both about 40 kHz at 3 dB loss. The horizontal and vertical beamwidths were 15° and 4° for each unit respectively.

Deep learning for signal clock and exposure estimation in rolling shutter optical camera communication.

In rolling shutter (RS)-based optical camera communication (OCC) links, selecting the appropriate camera's exposure time is critical, as it limits the reception bandwidth. In long exposures, the pixels accumulate over time the incoming irradiance of several consecutive symbols. As a result, a harmful intersymbol interference corrupts the received signal. Consequently, reducing the exposure time is required to increase the reception bandwidth at the cost of producing dark images with impracticable light conditions for human or machine-supervised applications. Alternatively, deep learning (DL) equalizers can be trained to mitigate the exposure-related ISI. These equalizers must be trained considering the transmitter clock and the camera's exposure, which can be exceptionally challenging if those parameters are unknown in advance (e.g., if the camera does not reveal its internal settings). In those cases, the receiver must estimate those parameters directly from the images, which are severely distorted by the exposure time. This work proposes a DL estimator for this purpose, which is trained using synthetic images generated for thousands of representative cases. This estimator enables the receiver operation under multiple possible configurations, regardless of the camera used. The results obtained during the validation, using more than 7000 real images, registered relative errors lower than 1% and 2% when estimating the transmitter clock and the exposure time, respectively. The obtained errors guarantee the optimal performance of the following equalization and decoding receiver stages, keeping bit error rates below the forward error correction limit. This estimator is a central component of any OCC receiver that operates over moderate exposure conditions. It decouples the reception routines from the cameras used, ultimately enabling cloud-based receiver architectures.

An RX AFE With Programmable BP Filter and Digitization for Ultrasound Harmonic Imaging.

This paper presents a front-end integrated circuit for ultrasound (US) harmonic imaging, interfacing to a one-dimensional capacitive micromachined ultrasonic transducer (CMUT). It contains a complete ultrasound receiving chain, from analog front-end (AFE) to gigabit/s data link. A two-stage self-biased inverter-based transimpedance amplifier (TIA) is proposed in this work to improve tradeoffs between power, noise, and linearity at the first stage. To improve harmonic imaging performance, the design is further equipped with a 4[Formula: see text]-order highly programmable bandpass filter, which has a tunable bandwidth from 2 MHz to 15 MHz. An 8 b 80 MS/s SAR ADC digitizes the signal, which is further encoded and serialized into an LVDS data link, enabling a reduction in the number of output cables for future systems with multiple ADCs. The design is realized in a 40 nm CMOS technology. Electrical measurements show it consumes 2.9 mW for the AFE and 2.1 mW for the ADC and digital blocks. Its overall dynamic range varies from 61 dB to 69 dB, depending on the reception bandwidth. The imaging capability of this design is further demonstrated in a US transmission and reception imaging system. The acoustic measurements prove successful ultrasound harmonic acquisition, where the on-chip bandpass filter can improve the lateral resolution by more than 30%.

Noise factor and reception bandwidth in optoacoustical GW antenna

An expression has extracted from the OGRAN project theory, which provides connection between numerical values of noise factor F and achieved displacement resolution and antenna’s threshold signal in metric variations. Noise factor and “reception bandwidth” connects across displacement resolution. There is defined analytical expression and numerical value for design displacement resolution (sensitivity) on the base intention F = 1. It has appeared that the extracted analytical expression for readout resolution does not correspond to applied Pound-Drever-Hall technique and AURIGA circuitry. This requires an improvement in theoretical design. The achieved resolution value 2·10−15 cm/Hz1/2 is matched to the value for metric sensitivity in pulse hmin ≃ 10−18, which is 15 dB higher than the thermal sensitivity limit.

Convolutional autoencoder for exposure effects equalization and noise mitigation in optical camera communication.

In rolling shutter-based optical camera communication (OCC), the camera's exposure time limits the achievable reception bandwidth. In long-exposure settings, the image sensor pixels average the incident received power, producing inter-symbol interference (ISI), which is perceived in the images as a spatial mixture of the symbol bands. Hence, the shortest possible exposure configuration should be selected to alleviate ISI. However, in these conditions, the camera produces dark images with impracticable light conditions for human or machine-supervised applications. In this paper, a novel convolutional autoencoder-based equalizer is proposed to alleviate exposure-related ISI and noise. Furthermore, unlike other systems that use artificial neural networks for equalization and decoding, the training procedure is conducted offline using synthetic images for which no prior information about the deployment scenario is used. Hence the training can be performed for a wide range of cameras and signal-to-noise ratio (SNR) conditions, using a vast number of samples, improving the network fitting and the system decoding robustness. The results obtained in the experimental validation record the highest ISI mitigation potential for Manchester encoded on-off keying signals. The system can mitigate the ISI produced by exposure time windows that are up to seven times longer than the transmission symbol duration, with bit error rates (BER) lower than 10-5 under optimal SNR conditions. Consequently, the reception bandwidth improves up to 14 times compared to non-equalized systems. In addition, under harsh SNRs conditions, the system achieves BERs below the forward error correction limit for 1dB and 5 dB while operating with exposure times that are 2 and 4 times greater than the symbol time, respectively.

Photoacoustic and ultrasound (PAUS) dermoscope with high sensitivity and penetration depth by using a bimorph transducer.

A bimorph transducer was proposed to improve the detection sensitivity and imaging depth of photoacoustic and ultrasound (PAUS) dermoscope. By applying the bimorph transducer, the imaging depth and sensitivity of PAUS dermoscope were enhanced by simultaneously improving excitation efficiency and reception bandwidth. The integrated design of the imaging head of the dermoscope makes it highly convenient for detecting human skin. The PAUS imaging performance was demonstrated via visualizing subcutaneous tumor and depicting full structures of different skin layers from epidermis to subcutaneous tissue. The results confirm that the dermoscope with the bimorph transducer is well suited for PA and US dual-modality imaging, which can provide multi-information for skin disease.

An Energy-Efficient Wirelessly Powered Millimeter-Scale Neurostimulator Implant Based on Systematic Codesign of an Inductive Loop Antenna and a Custom Rectifier.

In this work, a switched-capacitor-based stimulator circuit that enables efficient energy harvesting for neurostimulation applications is presented, followed by the discussion on the optimization of the inductive coupling front-end through a codesign approach. The stimulator salvages input energy and stores it in a storage capacitor, and, when the voltage reaches a threshold, releases the energy as an output stimulus. The dynamics of the circuit are automatically enabled by a positive feedback, eliminating any stimulation control circuit blocks. The IC is fabricated in a 180nm CMOS process and achieves a quiescent current consumption of 1.8 μA. The inductive coupling front-end is optimized as a loaded resonator, in which the input impedance of the custom rectifier directly loads the inductive loop antenna. The loaded quality factor and the rectifier's efficiency determine the reception sensitivity of the stimulator, while a balance should be achieved for the robustness of the system against dielectric medium variations by increasing the reception bandwidth. The finalized stimulator adopts a 4.9mm × 4.9mm inductive loop antenna and achieves an overall assembly dimension of 5mm × 7.5mm. Operating at the resonant frequency of 198MHz, the stimulator works at a 14cm distance from the transmitter in the air. An animal experiment was performed, in which a fully implanted stimulator excited the sciatic nerve of a rat that consequently triggered the movement of the limb.

Performance Comparison of Cognitive Radio Sensor Networks for Industrial IoT With Different Deployment Patterns

Square lattice (SL), triangle lattice (TL), and hexagon lattice (HL) are widely used regular deployment patterns for industrial Internet of Things (IoT). However, the performance of cognitive-radio-based access with these three deployment patterns has not been explored yet. This paper first designs a transmission scheduling method named cognitive access for regular topology (CART) in cognitive radio sensor networks (CRSNs) with minimal occupation of channels and high transmission efficiency. CART consists of a timeslot-and-channel allocation scheme, a cooperative spectrum-sensing scheme, and a scheme for reporting spectrum-sensing results (SSRs) in SL, TL, and HL. This paper also analyzes CART’s cooperative spectrum-sensing performance, reception bandwidth, and transmission delay for different transmission interference range and coverage patterns. Based on numerical analysis and simulation, this paper makes comparison between CART and optimal transmission scheduling method for single channel, and that among these three deployment patterns. Results show the following insights for efficient deployment of CRSN: 1) TL yields the optimal cooperative spectrum-sensing performance among three patterns by data fusion rule of 3-out-of-7; 2) under the same conditions and area for deployment, SL provides the optimal reception bandwidth; 3) SL and TL lead to low transmission delay for critical complete coverage; 4) SL leads to the lowest transmission delay for critical multiple coverage; 5) the false alarm (FA) probability of individual node has little influence on transmission delay, while the probability of primary user’s (PU) occurrence has noticeably influence on it; and 6) increasing the ratio of transmission timeslot to spectrum-sensing timeslot may decrease transmission delay

A C-band broadband ortho-mode transducer for radioastronomy polarimetry.

BackgroundWe describe the design, the construction and performance of a narrow band ortho-mode transducer, currently used in the 5 GHz polarimetric receiver of the Galactic Emission Mapping project.ResultsThe ortho-mode transducer was designed to achieve a high degree of transmission within the 400 MHz of the GEM band around the 5 GHz (4.8–5.2 GHz). It is composed of a circular-to-square waveguide transition, a septum polarizer, a thin waveguide coupler and a smooth square-to-rectangular waveguide transition with custom waveguide bends to the output ports.ConclusionOur simulations and measurements show a very low level of cross-polarization of about −60 dB and a good impedance match for all three ports (S11; S22; S33 < −30 dB) with only 0:25 dB of insertion loss offset across the 400 MHz (4.8–5.2 GHz) of the reception bandwidth.

DeRe: A Buffer Saving and Controllable Video-on-Demand Broadcasting Scheme for Heterogeneous Receivers

One way to reduce bandwidth requirement in video-on-demand system is using periodic broadcasting for popular videos. It periodically broadcasts video segments on several channels and clients need to wait some time to access the video. Many periodic broadcasting schemes have been proposed to reduce server’s bandwidth and client’s waiting time. However, most of these schemes assume all clients have enough reception bandwidth which is, in fact, different in various network environment. To solve this problem, two types of broadcasting schemes have been proposed: 1) reception bandwidth adaptable (RBA) and 2) reception bandwidth limited (RBL) approaches. RBA includes HeRO, BroadCatch, CAR, FBR, and MBC. RBL contains CCA, CCA+, CCA++, and GDB. In this paper, we propose a novel RBL approach called delay receiving (DeRe) to accomodate the heterogeneous receiving problem. By limiting client’s reception bandwidth to two or three channels, we achieve relatively low service latency for all users compared to other schemes. Also, DeRe scheme is allowed to adjust buffer requirement directly, which is a unique property among all broadcasting schemes. The performance evaluation results of DeRe scheme with buffer requirement of 15% and 20% of video size are presented in this paper.

ChemInform Abstract: Radiofrequency Microcoils for Magnetic Resonance Imaging and Spectroscopy

AbstractReview: 61 refs.

Measurement and modeling of electromagnetic noise from LED light bulbs

The characteristics of broadband noise radiated by LED light bulbs were investigated. According to the measurement results of the noise waveform in the time domain, LED noise can be categorized as intermittent type or non-intermittent type, in accordance with the operation of the switching power supply installed in the LED bulb. Intermittent-type noise is emitted by some LEDs supporting dimmer operation, and its repetitive bursts are synchronized with the AC mains frequency. For both types, the noise is a sequence of short pulses, each of which is generated at the instant that the power-supply circuit of the LED bulb is switched on or off. Hence, an "on pulse" and an "off pulse" are alternatively emitted. The interval of the pulses varies with time in general. A time-domain noise model representing the time-varying pulse interval and amplitude was developed by applying amplitude and frequency modulations to a regularly repetitive pulse train. As a statistical property of LED noise, amplitude probability distribution (APD) was also measured with various resolution bandwidths of the receiver. When the bandwidth was larger than the switching frequency of the power supply, Middleton's class-A model gave a good approximation of the APD. For narrower reception bandwidths down to 1 kHz, the noise can be regarded as Gaussian for non-intermittent type or intermittent Gaussian for intermittent type, respectively.

Radiofrequency microcoils for magnetic resonance imaging and spectroscopy

Small radiofrequency coils, often termed “microcoils”, have found extensive use in many areas of magnetic resonance. Their advantageous properties include a very high intrinsic sensitivity, a high (several MHz) excitation and reception bandwidth, the fact that large arrays can fit within the homogeneous volume of the static magnetic field, and the very high resonance frequencies (several GHz) that can be achieved. This review concentrates on recent developments in the construction of single and multiple RF microcoil systems, and new types of experiments that can be performed using such assemblies.

Adaptive Overlay Network for High-Bandwidth Streaming

In this paper, we investigate the limitation caused by reception bandwidth in current overlay streaming, and propose a novel overlay network architecture for high-quality, real-time streaming. The proposed architecture consists of two components: 1) join and retransmission control (JRC), and 2) redundant node selection (RNS). The JRC dynamically adjusts the number of join and data retransmission requests based on the network condition and reception packet fluctuation of the receiver. The RNS selects retransmission nodes based on the retention probability of lost packets requested by the receivers. We have designed and implemented the algorithm of the proposed architecture. According to our evaluation, our approach results in an additional 1-2Mbps reception bandwidth from existing overlay streaming applications.

Proxy-assisted scalable periodic broadcasting of videos for heterogeneous clients

Periodic broadcasting (PB) is a scalable technique for providing video-on-demand services. It significantly reduces server input and output (I/O) and backbone network bandwidth requirements, but increases the clients' need for storage space and network bandwidth. Traditional protocols assume homogeneous clients with identical resources. In practice, however, clients have very different bandwidths, which are usually not sufficient for video-on-demand service from a PB server. Existing work on heterogeneous clients has focused on devising broadcast schedules that cater to low-bandwidth clients; these schedules inevitably require additional backbone network bandwidth between the server and the clients. In this paper, we propose a scheme to significantly reduce the waiting time of all heterogeneous clients, without the need for any additional backbone bandwidth. This scheme uses a proxy buffer within video-on-demand systems using PB. In the proposed system, the server broadcasts a video using one of the traditional PB protocols. Simultaneously, the proxy receives the stream from the server and stores it in its local buffer, then broadcasts the stored data to the clients in its local network. Because the proxy provides extra, transparent channels to the server, clients are likely to reduce their reception bandwidth requirements through the use of efficient reception schedules using the extra channels.

Scalable on-demand media streaming for heterogeneous clients

Periodic broadcast protocols enable efficient streaming of highly popular media files to large numbers of concurrent clients. Most previous periodic broadcast protocols, however, assume that all clients can receive at the same rate, and also assume that reception bandwidth is not time-varying. In this article, we first develop a new periodic broadcast protocol, Optimized Heterogeneous Periodic Broadcast (OHPB), that can be optimized for a given population of clients with heterogeneous reception bandwidths and quality-of-service requirements. The OHPB protocol utilizes an optimized segment size progression determined by solving a linear optimization model that takes as input the client population characteristics and an objective function such as mean client startup delay. We then develop a generalization of the OHPB linear optimization model that allows optimal server bandwidth allocation among multiple concurrent OHPB broadcasts, wherein each media file and its clients may have different characteristics. Finally, we propose complementary client protocols employing work-ahead buffering of data during playback, so as to enable more uniform playback quality when the reception bandwidth is time-varying.

New superregenerative architectures for direct-sequence spread-spectrum communications

The superregenerative receiver has been used for many decades as a low-cost and low-power receiver in short-range narrow-band communications. In this paper, we present two new architectures that make use of the superregeneration principle to achieve noncoherent detection of direct-sequence spread-spectrum signals. The local pseudorandom code generator is clocked by the quench oscillator, making the quench frequency equal to the chip rate. Under this condition, it is possible to take advantage of the characteristic broad reception bandwidth and the pulsating nature of the receiver to filter and despread the signal. The two superregenerative architectures, operating under periodic and pseudorandom quench, respectively, are analyzed and compared. Theoretical predictions are confirmed by experimental results in the ISM band of 2.4 GHz.

Bandwidth and Noise of Submillimeter Wave Cuprate Bicrystal Josephson Junction Detectors

Detectors made from superconducting cuprate YBa/sub 2/Cu/sub 3/O/sub x/ bicrystal Josephson junctions (BJJs) on sapphire and NdGaO/sub 3/ substrates have been fabricated and characterized in the frequency band 200-900 GHz. Junctions on sapphire substrates had a normal state resistance R/sub N//spl ap/15-60 /spl Omega/, and I/sub C/R/sub N/ product up to 2.5 mV at T=4.2 K. Junctions on NdGaO/sub 3/ substrates had lower R/sub N/=1-5 /spl Omega/ and I/sub C/R/sub N/=0.4-0.9 mV at T=77 K. Three types of detecting devices have been investigated in both the broadband and the frequency-selective detection modes. One type was patterned with log-periodic antenna, and two others with Pt-metal double-slot antenna designed for a central frequency f=300 GHz and f=400 GHz, respectively. Measurements at f=320 GHz of the reception bandwidth /spl Delta/f for a device with double-slot antenna gave a quality factor Q=f//spl Delta/f/spl ap/10. A low-noise cooled 1-2 GHz bandwidth amplifier enables a better sensitivity in the self-pumping frequency mixing mode, avoiding the 1/f noise. The dependence of the spectral density of noise on voltage was compared to the data for the Josephson emission linewidth obtained by the selective detector response method. Also discussed are measurements at 500 GHz of the NEP values carried out at different experimental conditions.

Fourth-order blind identification of underdetermined mixtures of sources (FOBIUM)

For about two decades, numerous methods have been developed to blindly identify overdetermined (P/spl les/N) mixtures of P statistically independent narrowband (NB) sources received by an array of N sensors. These methods exploit the information contained in the second-order (SO), the fourth-order (FO) or both the SO and FO statistics of the data. However, in practical situations, the probability of receiving more sources than sensors increases with the reception bandwidth and the use of blind identification (BI) methods able to process underdetermined mixtures of sources, for which P>N may be required. Although such methods have been developed over the past few years, they all present serious limitations in practical situations related to the radiocommunications context. For this reason, the purpose of this paper is to propose a new attractive BI method, exploiting the information contained in the FO data statistics only, that is able to process underdetermined mixtures of sources without the main limitations of the existing methods, provided that the sources have different trispectrum and nonzero kurtosis with the same sign. A new performance criterion that is able to quantify the identification quality of a given source and allowing the quantitative comparison of two BI methods for each source, is also proposed in the paper. Finally, an application of the proposed method is presented through the introduction of a powerful direction-finding method built from the blindly identified mixture matrix.

NMR microscopy with a high-resolution liquid-state spectroscopy probe

NMR microscopy is usually achieved at ultra-high-static magnetic field (9.4 Tesla) with the use of home-built coils adapted to the size of the sample. In that way, well-resolved images can be obtained with voxel size smaller than 50 m. The purpose of this article is to show that high-resolution imaging can be realized at lower field strength (4.7 Tesla) using 5- and 10-mm probes initially dedicated to vertical magnets. These coils are easily adaptable to horizontal imaging systems. Excellent quality and filling factors permitted isotro- pic resolutions (50 m) on a biomaterial and on mouse femoris. This study also demonstrates that spoiled-gradient echo sequence (FLASH) with low reception bandwidth or with the use of gadolinium are particularly effective for 3D MR microscopy. © 2005 Wiley Periodicals, Inc.