Microwave frequency detectors enable immediate determination of an unknown microwave signal frequency. Measurement is possible if the output characteristic of a frequency detector is unequivocal in a selected band of operation. The paper presents a method for obtaining unequivocal output characteristics for a given band of frequency detector operation.
Sensors designed by Polish engineers help detect traces of life beyond Earth. Adam Piotrowski of Vigo System tells us what else these devices can do.
The paper reports on the photoelectrical performance of the long wavelength infrared (LWIR) HgCdTe high operating temperature (HOT) detector. The detector structure was simulated with commercially available software APSYS by Crosslight Inc. taking into account SRH, Auger and tunnelling currents. A detailed analysis of the detector performance such as dark current, detectivity, time response as a function of device architecture and applied bias is performed, pointing out optimal working conditions.
Beamforming is an advanced signal processing technique used in sensor arrays for directional signal transmission
or reception. The paper deals with a system based on an ultrasound transmitter and an array of
receivers, to determine the distance to an obstacle by measuring the time of flight and – using the phase
beamforming technique to process the output signals of receivers for finding the direction from which the
reflected signal is received – locates the obstacle. The embedded beam-former interacts with a PID-based
line follower robot to improve performance of the line follower navigation algorithm by detecting and
avoiding obstacles. The PID (proportional-integral-derivative) algorithm is also typically used to control
industrial processes. It calculates the difference between a measured value and a desired set of points, then
attempts to minimize the error by adjusting the output. The overall navigation system combines a PID-based
trajectory follower with a spatial-temporal filter (beamformer) that uses the output of an array of sensors to
extract signals received from an obstacle in a particular direction in order to guide an autonomous vehicle
or a robot along a safe path.
The work proposes a new method for vehicle classification, which allows treating vehicles uniformly at the stage of defining the vehicle classes, as well as during the classification itself and the assessment of its correctness. The sole source of information about a vehicle is its magnetic signature normalised with respect to the amplitude and duration. The proposed method allows defining a large number (even several thousand) of classes comprising vehicles whose magnetic signatures are similar according to the assumed criterion with precisely determined degree of similarity. The decision about the degree of similarity and, consequently, about the number of classes, is taken by a user depending on the classification purpose. An additional advantage of the proposed solution is the automated defining of vehicle classes for the given degree of similarity between signatures determined by a user. Thus the human factor, which plays a significant role in currently used methods, has been removed from the classification process at the stage of defining vehicle classes. The efficiency of the proposed approach to the vehicle classification problem was demonstrated on the basis of a large set of experimental data.
Prof. Ewa Rondio from the National Center for Nuclear Research (NCBJ) explains the nature of neutrinos, the measurements taken by the Super-Kamiokande detector, and the involvement of Polish scientists in the project.
The Long March-2F rocket was launched on 15 September 2016 from the Jiuquan Satellite Launch Centre in China, carrying the Tiangong-2 space laboratory. The laboratory is fitted with the detector of the POLAR experiment, which was prepared jointly with Polish scientists.
This article presents the results of the research of noiseimmunity of wireless communication systems using signals that are formed on the basis of eight-position quadrature-amplitude modulation (8-QAM) and eight-position amplitude modulation of many components (8-AMMC). The research was conducted using simulation of a wireless communication system, built using a detector, implemented on the basis of a phase locked loop. The influence of phase locked loop parameters on the detection quality of these signals in the condition of the interference in the communication channel was researched, and a comparative analysis of the noise immunity of wireless communication systems using these signals was carried out.
Non-intentionally doped GaSb epilayers were grown by molecular beam epitaxy (MBE) on highly mismatched semi-insulating GaAs substrate (001) with 2 offcut towards (110). The effects of substrate temperature and the Sb/Ga flux ratio on the crystalline quality, surface morphology and electrical properties were investigated by Nomarski optical microscopy, X-ray diffraction (XRD) and Hall measurements, respectively. Besides, differential Hall was used to investigate the hole concentration behaviour along the GaSb epilayer. It is found that the crystal quality, electrical properties and surface morphology are markedly dependent on the growth temperature and the group V/III flux ratio. Under the optimized parameters, we demonstrate a low hole concentration at very low growth temperature. Unfortunately, the layers grown at low temperature are characterized by wide FWHM and low Hall mobility.
This article describes a novel approach to measure responsivity of a FET-based sub-THz detector using on-wafer probes to directly feed a bare antenna-less detecting device. Thus, the approach eliminates the need to know beforehand the detector’s effective aperture, which can be a source of large variation between responsivity measurements of various FET-based detectors often cited in the literature. It seems that the presented method can be useful at making direct comparisons between responsivity of various devices (e.g., MOSFETs, HEMTs etc.). As a demonstration, the sub-THz responsivity of a pHEMT device fabricated using a commercial GaAs process has been measured in a WR-3 frequency band. Additionally, the results have been compared against data obtained using an alternative approach. The verification method consisted in integrating exactly the same device with a broad-band antenna and a carefully selected high-resistivity silicon lens and comparing its performance with that of a commercial calibrated detector based on Schottky diodes.
Based on the publications regarding new or recent measurement systems for the tokamak plasma experiments, it can be found that the monitoring and quality validation of input signals for the computation stage is done in different, often simple, ways. In the paper is described the unique approach to implement the novel evaluation and data quality monitoring (EDQM) model for use in various measurement systems. The adaptation of the model is made for the GEM-based soft X-ray measurement system FPGA-based. The EDQM elements has been connected to the base firmware using PCI-E DMA real-time data streaming with minimal modification. As additional storage, on-board DDR3 memory has been used. Description of implemented elements is provided, along with designed data processing tools and advanced simulation environment based on Questa software.
Graphene applications in electronic and optoelectronic devices have been thoroughly and intensively studied since graphene discovery. Thanks to the exceptional electronic and optical properties of graphene and other two-dimensional (2D) materials, they can become promising candidates for infrared and terahertz photodetectors.
Quantity of the published papers devoted to 2D materials as sensors is huge. However, authors of these papers address them mainly to researches involved in investigations of 2D materials. In the present paper this topic is treated comprehensively with including both theoretical estimations and many experimental data.
At the beginning fundamental properties and performance of graphene-based, as well as alternative 2D materials have been shortly described. Next, the position of 2D material detectors is considered in confrontation with the present stage of infrared and terahertz detectors offered on global market. A new benchmark, so-called “Law 19”, used for prediction of background limited HgCdTe photodiodes operated at near room temperature, is introduced. This law is next treated as the reference for alternative 2D material technologies. The performance comparison concerns the detector responsivity, detectivity and response time. Place of 2D material-based detectors in the near future in a wide infrared detector family is predicted in the final conclusions.
Recent advances in THz detection with the use of CMOS technology have shown that this option has the potential to be a leading method of producing low-cost THz sensors with integrated readout systems. This review paper, based on authors’ years of experience, presents strengths and weaknesses of this solution. The article gives examples of some hints, regarding radiation coupling and readout systems. It shows that silicon CMOS technology is well adapted to the production of inexpensive imaging systems for sub-THz frequencies. As an example paper presents the demonstrator of a multipixel Si-CMOS THz spectroscopic system allowing for chemical identification of lactose. The THz detectors embedded in this system were manufactured using the CMOS process.
HPM meters are required for the assessment of fields generated by sources of high-power microwaves. Finding the inverse calibration curves for such instruments is important for ensuring accuracy. The procedure is relatively simple for meters consisting of linear devices but there can also be hardware solutions implementing nonlinear ones. The objective of the present work was to develop a convenient procedure to allow finding such a curve when the meter uses a D-dot probe and a power detector. For that purpose, the results of low voltage measurements describing the properties of the detector were first analysed. Then a software code was developed to estimate the RMS value of an incident field based on measured output and frequency response. The response was estimated with very low electric field. And finally, the performance of the proposed procedure was verified by tests conducted with high electric field in a TEM cell. High conformity of the output of the meter with fields of known values was demonstrated. The maximum error related to the meter range did not exceed 4%.