Signal Processing Series Research Articles

Real-Time Odor Discrimination Using Single Antenna of Insect

In this letter, a system that discriminates between two odorants in real-time with a single antenna of an insect was constructed. In previous studies, odorants were discriminated through arraying multiple types of sensors. However, the use of a sensor array enlarges the entire system and requires complex signal processing, which makes it difficult to mount the system on a quadcopter with limited payloads or an autonomous robot with low computational power. On the other hand, the antenna of an insect is composed of several olfactory receptors; thus, a single antenna responds to multiple odorants. Therefore, a system for discriminating between multiple odorants from the electroantennogram (EAG) signal of a single antenna of an insect is proposed. An antenna of an adult male silkmoth is employed; the silkmoth antenna exhibits an electric potential change when detecting an odor, but the difference in the EAG amplitude and recovery time depends on the type of odorant. Since EAG is a type of neural signal, it is difficult to perform odor discrimination by simply setting the threshold, because it drifts due to noise. Therefore, the Hodgkin-Huxley model (HH model) was applied to the raw EAG signal as a dynamic filter, and the spike firing rate of the output value was calculated using the HH model. Then, the odorants were discriminated against based on the magnitude of the spike firing rate. A series of signal processing was implemented in a microcontroller, and the experiments indicated that all antennae demonstrated a discrimination performance of 90$\%$ or more.

Displacement measurement method based on laser self-mixing interference in the presence of speckle

In order to achieve the accurate measurement of displacement, this Letter presents a self-mixing interference displacement measurement method suitable for the speckle effect. Because of the speckle effect, the amplitude of the self-mixing interference signal fluctuates greatly, which will affect the measurement accuracy of displacement. The ensemble empirical mode decomposition is used to process the interference signal, which can filter out high-frequency noise and low-frequency noise at the same time. The envelope of the self-mixing interference signal is extracted by Hilbert transform, and it is used to realize the normalization of the signal. Through a series of signal processing, the influence of speckle can be effectively reduced, and the self-mixing interference signal can be transformed into standard form. The displacement can be reconstructed by fringe counting and the interpolation method. The experimental results show that the method is successfully applied to the displacement measurement in the presence of speckle, which verifies the effectiveness and feasibility of the method.

Time division control optical pulse width method of distributed optical vibration sensing system in smart power plant

To improve the performance of distributed fiber vibration sensing system used in smart power plant, time division control optical pulse width method is proposed. It used periodic optical pulses during transmitting and a series of signal processing after received the backscattered signal. By using this method, system positioning accuracy is better than the single pulse width case. It can also compensate for the defects of low sensitivity and weak signal strength at long distance.

Uplink Interference Suppression by Semi-Blind Adaptive Array With Decision Feedback Channel Estimation on Multicell Massive MIMO Systems

This paper proposes a novel semi-blind uplink interference suppression scheme for multicell multiuser massive multiple-input multiple-output (MIMO) systems. The inter-cell interference (ICI) becomes intenser when a number of users are spatially multiplexed via massive MIMO. Here arises a pilot contamination problem due to the limitation of orthogonal sequence set and thus inter-user interference (IUI) also remains unsuppressed. Our proposal employs a constant modulus algorithm (CMA) known as a blind interference suppression scheme and exploits channel state information (CSI)-aided minimum mean square error (MMSE) postcoding weight as an initial weight of CMA. Although MMSE weight cannot suppress ICI and IUI due to the pilot contamination, it can help subsequent CMA to capture the desired signals which is required for CMA to effectively work. Since CMA can fully exploit degree of freedom of massive arrays by using uncorrelated data signal part, derived weight successfully suppresses ICI/IUI while resolving the pilot contamination problem. A decision feedback channel estimation (DFCE) is then introduced to further improve CSI estimation accuracy and subsequent interference suppression performance. A series of signal processing, MMSE–CMA–DFCE, can be iteratively performed. The computer simulation reveals that our proposal can improve outage probability and it satisfies below the fifth percentile of cumulative distribution with saved symbol amount.

Signal and Power Synchronous Transmission in WPT System Based on Capacitance Modulation

In inductive coupled power transmission system, at the same time of power transmission, signal transmission is necessary in order to realize the closed-loop control. Synchronous transmission of power and signal has advantages of high speed and stability. By using the method of capacitance modulation via changing capacitance, the working state of the resonator changes. The voltage across the coil appears certain changes. After step-down divider, demodulation, filtering, comparison and a series of signal processing, the transmitting signal will reproduce. The simulation and experiments show that the scheme is correct, the signal can be sent and extracted correctly, and the effect of power transmission is small. The synchronous transmission of signal in wireless power transmission system is realized

Research on Communication Reconnaissance Information Processing and Fusion

In complex electromagnetic signal environment, the reconnaissance equipments in tactical communication system can uninterruptedly reconnoiter a variety of enemy’s communication signals as well as access a number of characteristic parameters of time, frequency and space domain by searching analysis, feature extraction, direction finding and comprehensive identification. After a series of signal processing, data mining and information fusion, we can get the characteristic parameters of the electromagnetic spectrum of the enemy’s reconnaissance equipments, which provide the basis for analysis and estimation of electromagnetic situation in battlefield. In this paper a multi-hierarchical blackboard model is proposed for multi-sources communication reconnaissance information mining and fusion and the effectiveness of the method is validated in simulation environment.

A downhole forward-looking ultrasonic imaging system

Inspection and evaluation of casing damages is important in oil fields. Compared to normal casing damage detecting equipments which can only measure the radius of casing around the equipment, the downhole forward-looking ultrasonic imaging system can detect casing damage in front of the equipment. A phased-array transducer was used in this imaging system, the FPGA and DSP were introduced to reduce the size of downhole equipment significantly, and the image of the casing is generated via a series of signal processing, which correctly reflects the real shape of the casing. In addition, we analyzes the factors influencing ultrasonic image quality. It shows that the influences of the three kinds of inconsistency among channels on ultrasonic imaging are trivial. The possible ranges of these inconsistencies are given. Several experiments were completed on damaged casing models by using the downhole forward-looking ultrasonic imaging system. The results show that the methods introduced in this article are valid ...

Automatic Two Axes Sun-Tracking System Applied to Photovoltaic System for LED Street Light

This paper presents an electromechanical, two axes sun tracking system based on single chip microcomputer (MCU). According to the path of the sun in the space, the earth coordinate system is chosen to design the tracking device. The whole device consists of one worm-drive and one gear-drive, which is operated by two step motors. The photodiodes are used as photoelectric sensors to detect the pointing of the sun. Eight photodiodes are installed in the diameter hole of the hemispherical surface. The comparative signals produced by the diodes array are performed to judge the orientation of the solar panel. The circuit of the control system based on MCU is demonstrated. The comparative signals may be amplified, A/D converted. After a series of signal processing, the signals are sent to the MCU which will produce the pulse to control the speed and steering of step motors. The sun tracking system is an efficient system for solar energy collection. It has been proved that the sun tracking systems can collect up to 50% more energy than what a fixed panel system collects.

유비쿼터스 지향의 16채널 스트레인 게이지 계측 시스템 개발

A strain gauge weight measuring instrumentation system was designed with RF sensor network facilities. In the sensor module system data conversion and a series of signal processing were totally equipped. 16 strain gauges are incoming sensors and each output of the strain gauge was amplified and filtered for proper analog signal processing. Several measuring instrumentation OP amps and general purposed OP amps were used. 12 bits A/D converters converted analog signals to digital bits and a PIC microprocessor controlled the 16 channels of strain gauges. RF RS232 modules were used for wireless communication between the PIC microprocessor and an Ethernet host far a remote sensor monitoring system development.