Signal Transmission Distance Research Articles

A New Method for Compaction Quality Evaluation of Asphalt Mixtures with the Intelligent Aggregate (IA).

To provide a new method for the evaluation of the compaction quality of asphalt mixture, a real-time data acquisition and processing system (RDAPS) for the motion state of aggregate with a small volume and high precision is developed. The system consists of an intelligent aggregate (IA), analysis software and hardware equipment. The performance of the IA was tested by regarding data sensitivity, high-temperature resistance, and mechanical properties. A new evaluation method was proposed for evaluating the compaction quality of AC-25 and SMA-25 asphalt mixtures based on an IA. The results show that the best transmission baud rate for the IA was 9600 bps, and the corresponding signal transmission distance was 380 m. Only one IA was needed to complete the state data collection for the aggregate within the asphalt mixture in a circular area, with the IA layout point as the center of the circle and a radius of 5 m. The IA conducted reliable data transmission up to 200 °C; however, its compressive strength decreased with increasing temperature until reaching stability. Traditional aggregate could be replaced by an IA to withstand external forces and internal load transfer. Embedding an IA into AC-25 or SMA-25 asphalt mixtures did not have a significant impact on the original mechanical properties of the mixture. The effect of the gradation type of the asphalt mixture on the IA motion state was not significant. When the compaction degree met the specification requirements, the motion data of the IA did not reach a stable state, and the interlocking effect between aggregates in the asphalt mixture could be further optimized. An evaluation method is proposed based on the IA for the compaction quality of AC-25 and SMA-25 asphalt mixtures with the compaction degree as the main index and the spatial attitude angle and spatial acceleration of the IA as the auxiliary indexes.

A GPS signal acquisition algorithm for the high orbit space

In the high orbit space, the visibility of GPS main lobe signal is poor due to the earth's occlusion and the increase in signal transmission distance. Therefore, the side lobe signals are essential for navigation mission, which puts forward higher requirements for the sensitivity of the receiver. In addition, the cross-correlation interference (CCI) caused by the large power difference between the main and side lobe signals is serious and results in the false acquisition of the side lobe signals. To improve the acquisition sensitivity and stability of the receiver, we designed a GPS signal acquisition algorithm for the high orbit space. The characteristics of high orbit GPS signal are analyzed according to the propagation process of GPS signal link. The influence of CCI on the acquisition performance of the side lobe signals is explored. Based on the parallel code phase search method, the coherent accumulation and incoherent accumulation are combined to improve the acquisition sensitivity. At the same time, according to the different probability distribution characteristics of autocorrelation peak and cross-correlation peaks in the correlator output, CCI is detected by means of hypothesis testing. The strong signals are reconstructed by using the amplitudes, code phases and Doppler shifts provided by the tracking loop. The CCIs are estimated by correlating the reconstructed strong signals with the local duplicated signals and eliminated from the correlation results of the side lobe signals to obtain the correct acquisition results. Simulation results show that the proposed algorithm can eliminate the CCIs in the high orbit space and improve the acquisition sensitivity of the receiver. Moreover, the CCIs under different Doppler shift differences of the main and side lobe signals can be effectively eliminated.

Optimal choice of signal compensation in coaxial cable: Modified non-negative Tikhonov regularization method within Bayesian frame

As a key medium for signal transmission, coaxial cable is widely used in various fields such as television broadcast, communication and radar system. With the increase of signal frequency, bandwidth and transmission distance, the distortion problem brought by the coaxial cable becomes serious and cannot be ignored. Specifically, the coaxial cable often encounters accidental extrusion, stretching or folding, and becomes deformed during use, which will cause more serious distortion to the transmitted signal. Inspired by the inverse analysis approach, we propose a modified signal compensation method on the basis of the non-negative Tikhonov regularization method with Bayesian inference. The modified method doesn’t have non-negative constraint to the input signal. The modified method is firstly employed for the compensation of double exponential pulse, whose waveform is identical to that of high-altitude nuclear electromagnetic pulse signal, transmitted in a 10-m coaxial cable. The compensated signal is almost the same to the input signal, the relative error (RE) in between the compensated signal and input signal is only 0.6%, which is much smaller than that of output signal and input signal (10.1%). Moreover, the modified method is utilized to compensate other three types of signals, and the compensated signals match well with the input signals. Furthermore, the compensation results for these four types of signals of the modified method are compared with those by using one of the most commonly used de-convolution method, i.e., inverse filtering method, which considers both the amplitude and phase response. The REs vary from 5.0% to 8.4% for the inverse filtering method. In contrast, the maximum RE for the modified method is below 1.1%, demonstrating a significantly improved performance in the signal compensation.

Designs of Q-switching Laser Power Supply with High Voltage Narrow Pulse

Based on the pulse generation principle of Q-switching and cavity-dumping technologies, this paper designs a power supply with high voltage and narrow pulse for switching avalanche transistor with rising edge of ns level. In the power supply, an avalanche transistor and VOMS transistor are matched to design a driving circuit, which outputs 4.6ns narrow pulse signal. The circuit replaces the traditional cable transmission signal drive mode, reduces the whole signal transmission distance, and improves the signal transmission stability. It makes the two ends of the laser Q-switched crystal KD*P be pushed off instantaneously, which shortened the output laser pulse width from 18ns to 5.6ns. The power supply with high voltage and narrow pulse can be well used in many laser fields including communication, medical treatment, ocean exploration, etc.

Communication Control System of UAV Based On 5G Network

Remote control is the traditional control mode of unmanned aerial vehicle (UAV), which limits the signal transmission distance. To accomplish ultra-long-distance UAV control, we propose a communication control system which based on 5G network to transmit UAV control signals. We develop a backstage service platform based on 5G network to connect with the communication module installed on the remote UAV. In this paper, we describe the detail of this system which realizes the normal communication control of the remote UAV and the service platform. Our experiment results show that our system has the characteristics of stability and scalability.

Channel Coding Scheme for Relay Edge Computing Wireless Networks via Homomorphic Encryption and NOMA

Edge computing extends the service resources of cloud computing to the edge of the network, providing less latency and higher bandwidth utilization. The relay edge computing wireless network (RECWN) with intelligent edge device can effectively solve the problem of wireless signal transmission distance and attenuation. However, the relay node’s forwarding brings greater risks to the leakage of private information. In this article, we propose a homomorphic encryption and non-orthogonal multiple access (NOMA) based channel coding scheme to address the problem of stealing private information from users by incompletely trusted relay node or potential malicious nodes. Specifically, the homomorphic encryption algorithm is adopted to protect the privacy of users’ private information. Furthermore, the code domain NOMA and LDPC algorithm are introduced to compensate for the problem of drastic drop in communication performance caused by poor sub-channel conditions, thereby improving the efficiency of data transmission, and guaranteeing the users’ QoS requirements and fairness. The simulation results demonstrate that the proposed channel coding scheme has better performance than the existing approaches in terms of privacy preservation and data transmission efficiency.

Acoustic frequency spectrum characteristics in periodic drill string under tension

AbstractIt is a promising measure to transmit downhole information by acoustic wave through drill string. However, the transmission distance and quality of acoustic signals in field conditions are still not satisfied because the acoustic frequency spectrum in drill string is vulnerable to interference. This paper studied acoustic frequency spectrum characteristics in periodic drill string by experiments under different axial tensile forces. The multilevel method is established to evaluate frequency spectrum through drill string based on improved radar chart. The impact of axial tensile force on spectrum characteristics is analyzed by the proposed method. The results indicate that the axial tensile force has remarkable impact on the acoustic frequency spectrum and passband characteristics. The spectrum characteristics change with axial tensile force. These changes are reflected in the position, width, and attenuation of different passbands. And the extent of changes is distinct to different passbands. Both the evaluation indicators of each passband and spectrum are change with increasing axial tensile force. The spectrum quality is excellent in the range of 17‐134 MPa for axial tensile force in drill string. And when the force exceeds 152 MPa, methods such as adjusting the carrier frequency and relay installation location are necessary to improve the transmission quality of acoustic signals.

STIR: A Smart and Trustworthy IoT System Interconnecting Legacy IR Devices

Legacy-infrared (IR) devices are pervasively used. They are often controlled by IR remotes and cannot be controlled over the Internet. A trustworthy and cost-effective smart IR system that is able to change an IR controllable device into a smart Internet of Things (IoT) device and interconnect them for smart city/home applications is offered in this article. First, a printed circuit board (PCB) consisting of an IR receiver and multiple IR transmitters side by side which are capable of transmitting about 20 m indoors is designed and implemented. This IR transceiver board is the first of its kind. Second, the IR transceiver can be linked up with a Raspberry Pi, for which we develop two software tools, recording and replaying any IR signals so as to put the corresponding IR device in control. Third, a smartphone can be connected to the Pi by means of a message queuing telemetry transport (MQTT) cloud server so that the commands can be sent by the smartphone to the legacy IR device over the Internet. We have also identified the deficiency of TLS mutual authentication implemented by the popular MQTT open-source package Mosquitto for a trustworthy IoT system and patched the system. We analyze the factors that affect the IR signal transmission distance, discuss the security concerns of our IR transceiver, and illustrate the scenarios for attacks. For instance, TV can be turned off remotely by a drone equipped with the transceiver.

On-chip implementation of the probabilistic quantum optical state comparison amplifier.

Propagation losses in transmission media limit the transmission distance of optical signals. In the case where the signal is made up of quantum optical states, conventional deterministic optical amplification schemes cannot be used to increase the transmission distance as the copying of an arbitrary and unknown quantum state is forbidden. One strategy that can offset propagation loss is the use of probabilistic, or non-deterministic, amplification schemes - an example of which is the state comparison amplifier. Here we report a state comparison amplifier implemented in a compact, fiber-coupled femtosecond laser-written waveguide chip as opposed to the large, bulk-optical components of previous designs. This pathfinder on-chip implementation of the quantum amplifier has resulted in several performance improvements: the polarization integrity of the written waveguides has resulted in improved visibility of the amplifier interferometers; the potential of substantially-reduced losses throughout the amplifier configuration; and a more compact and environmentally-stable amplifier which is scalable to more complex networks.

Dense Wavelength Division Multiplexing using Dispersion Fibre with Erbium Doped Fiber Amplifier

Dense wavelength division multiplexing is used in various broadband communications. It combines information from distinct sources on an optical fiber, each signal being transmitted simultaneously on its own distinct light wavelength. Radio over fibre is a hybrid system that has both fibre optic link and free space radio path. This paper aims to evaluate the performance of the system using Erbium Doped Fibre Amplifier, Single Mode Fibre and Dispersion compensating Fibre. Single beam of light is passed by the SMF and is used for long distance signal transmission. DCF is used to reduce the dispersion in the optical signal. EDFA reduces the degradation of the signal by cancelling the effect of attenuation. It is an optical repeater used to raise the intensity of the optical signal. Mach – Zehnder modulator is used for the modulation. The simulation is carried out by using optisystem software version 15.0. Various parameters like Q-factor, BER pattern, threshold, minimum BER are compared and estimated.

Photonics-Aided Millimeter-Wave Technologies for Extreme Mobile Broadband Communications in 5G

To meet the enhanced-mobile-broadband (eMBB) challenges in 5G, we have systematically explored the potential of the photonics-aided millimeter-wave (mm-wave) communication in terms of the wireless transmission capacity and distance it can accommodate. Enabled by various kinds of advanced multiplexing and digital-signal-processing (DSP) techniques, we have successfully achieved the significant enhancement of the wireless mm-wave signal transmission capacity from 100 Gb/s to 400 Gb/s, even to 1 Tb/s. Since our large-capacity (>100-Gb/s) experimental demonstrations typically have a very short wireless transmission distance of several meters, we have further explored the techniques for the extension of the wireless mm-wave signal transmission distance, and successfully achieved a series of field-trial demonstrations on photonics-aided long-distance (>100-m) wireless mm-wave signal transmission. We have realized the record-breaking product of wireless transmission capacity and distance, i.e., 54 Gb/s × 2.5 km.

Combating the Distance Problem in the Millimeter Wave and Terahertz Frequency Bands

In the millimeter wave (30-300 GHz) and Terahertz (0.1-10 THz) frequency bands, high spreading loss and molecular absorption often limit the signal transmission distance and coverage range. In this paper, four directions to tackle the crucial problem of distance limitation are investigated, namely, a physical layer distance-aware design, ultra-massive MIMO communication, reflectarrays, and intelligent surfaces. Additionally, the potential joint design of these technologies is proposed to combine the benefits and possibly further extend the communication distance. Qualitative analyses and quantitative simulations are provided to illustrate the benefits of the proposed techniques and demonstrate the feasibility of mm-wave and THz band communications up to 100 meters in both line-of-sight and non-line-of-sight areas.

Analysis of the carrier suppressed single sideband modulation for long distance optical communication systems

In this research paper, we report on a simulation study of the Radio over Fibre (RoF) Carrier Suppressed Single Sideband (CS-SSB) modulation scheme. This scheme is based on a Dual Parallel Dual Drive Mach-Zehnder modulator (DP-DDMZM), for a long-distance transmission. The proposed system consists of the combination of a carrier and a message signal at two parallel modulators, where the laser and link power is varied for the two different dispersion compensation techniques. We found that by suppressing the optical carrier and cancelling one sideband, we can limit the nonlinear effects that are caused by power fading and interference. We demonstrate that by varying the launched laser and link power up to optimised threshold levels, the signal to noise ratio (SNR) increases and the Q-Factor improves significantly. Our proposed RoF optic communication architecture can support an extended reach transmission of up to 200 km without dispersion compensation. Moreover, for the bitrate of 10 Gbit/s and span length of 25 km, we achieved a span ratio of 520, alternatively viewed as the system link signal transmission distance of 13,000 km. Therefore, this method is cost-effective and less complex.

Analysis of Signal Reception Mechanism of Sky Wave Long-distance Maritime Communication

Based on the principle of high frequency radio propagation, the signal reception mechanism of sky wave communication over oceans is investigated. Due to long distance signal transmission, the energy loss is inevitable, especially in the space and on the sea surface. Firstly, we establish the space propagation loss model by the ionospheric absorption, the free space propagation characteristics and other extra loss. Referring to the reflection principle of smooth ground and the Kirchhoff approximation, the energy loss models of the calm sea surface and the turbulent sea surface are obtained respectively. Then, through combining the space propagation loss model and the sea surface propagation loss models, we give out a formula of receiving point field strength. According to the signal to noise ratio, we summarize a complete and concise sky wave maritime communication calculation process, through which multi hops number of the receivable sky wave signal can be calculated accurately. The experimental results show the effectiveness.

On compensation of four wave mixing effect in dispersion managed hybrid WDM-OTDM multicast overlay system with optical phase conjugation modules

Abstract This paper investigated the effect of FWM and its suppression using optical phase conjugation modules in dispersion managed hybrid WDM-OTDM multicast overlay system. Interaction between propagating wavelength signals at higher power level causes new FWM component generation that can significant limit the system performance. OPC module consists of the pump signal and 0.6 km HNLF implemented in midway of optical link to generate destructive phase FWM components. Investigation revealed that by use of even OPC module in optical link reduces the FWM power and mitigate the interaction between wavelength signals at variable signal input power, dispersion parameter ( β 2 ) and transmission distance. System performance comparison is also made between without DM-OPC module, with DM and with DM-OPC module in scenario of FWM tolerance. The BER performance of hybrid WDM-OTDM multicast system using OPC module is improved by multiplication factor of 2 as comparable to dispersion managed and coverage distance is increased by factor of 2 as in Singh and Singh (2016).

Rock wrens preferentially use song types that improve long distance signal transmission during natural singing bouts

When animals are capable of producing variable signals they may preferentially use some signal types over others. Among songbirds, individuals are known to alter song type form and usage patterns in contest and mating situations, but studies have not examined how song choice improves signal efficacy during broadcast song. For this study we investigated rock wren Salpinctes obsoletus song type use rates during natural singing bouts. We tested three hypotheses for adaptive song use during broadcast song: 1) birds improve signal content by increasing the use of high quality songs, 2) birds optimize for signal propagation by preferentially using songs that transmit well, and 3) birds maintain energy by reducing the use of costly songs. The study included 19 058 songs sung by 12 individuals, each of which had a measured song repertoire of between 52 and 117 song types which were produced at highly variable rates. Results indicated that rock wrens did not preferentially sing song types with shorter durations or fewer frequency switches, as would be expected if they selected song types to minimize delivery costs. They also did not favor songs with more rapid trills or more frequency switches, as would be expected if they adjusted song use primarily to indicate quality. Focal birds did preferentially sing significantly longer songs with lower bandwidths, lower frequencies, and slower trill rates. Results suggest that natural broadcast singing patterns are shaped more by the benefits of long distance transmission than by the benefits of advertising performance ability or the costs of song production.

A high-efficiency self-powered wireless sensor node for monitoring concerning vibratory events

This paper presents a self-powered wireless alarming sensor node (SWASN), which was designed to monitor the occurrence of concerning vibratory events. The major components of the sensor node include a vibration-threshold-triggered energy harvester (VTTEH) that powers the sensor node, a dual threshold voltage control circuit (DTVCC) for power management and a radio frequency (RF) signal transmitting module. The VTTEH generates significant electric energy only when the input vibration reaches certain amplitude. Thus, the VTTEH serves as both the power source and the vibration-event-sensing element for the sensor node. The DTVCC was specifically designed to utilize the limited power supply from the VTTEH to operate the sensor node. Constructed with only voltage detectors and MOSFETs, the DTVCC achieved low power consumption, which was 65% lower compared with the power management circuit designed in our previous work. Meanwhile, a RF transmit circuit was constructed based on the commercially available CC1110-F32 wireless transceiver chip and a compact planar antenna was designed to improve the signal transmission distance. The sensor node was fabricated and was characterized both in the laboratory and in the field. Experimental results showed that the SWASN could automatically send out alarming signals when the simulated concerning event occurred. The waiting time between two consecutive transmission periods is less than 125 s and the transmission distance can reach 1.31 km. The SWASN will have broad applications in field surveillances.

Research on mud pulse signal detection based on adaptive stochastic resonance

The original data signals have small amplitude with a long distance signal transmission from the underground to the ground. And thousands of meters of drilling mud channel in the drilling process will contain a lot of noise sources. Therefore, the original mud pulse signals are submerged by the complex noise environment. Detecting the original signal after receiving the signal on the ground is still a serious issue. In connection with mud pulse signal detection under complex background in measurement while drilling (MWD), nonlinear bistable stochastic resonance theory and the production condition was analyzed. On the basis of this, a method of using genetic simulated annealing algorithm to adaptive optimize the parameters of stochastic resonance was proposed to realize the detection of mud pulse signal in the background of complex noise. Finally, through the simulation experiment and the field verification, this method realizes the signal detection even under the low signal-to-noise ratio (SNR). And the proposed method can overcome the shortcomings of existing detection method of signal detection performance in low SNR. It proves the proposed method's effectiveness and feasibility.

Dispersion characteristics and compensation in the POLMUX coherent optical communication system

The trend of high-speed optical communication is to realize large capacity, fast speed and long haul transmission. However, the dispersion in an optical fiber link can cause signals distortion or even inter symbol interference (ISI). With increasing signal rate and transmission distance in the optical communication system, the development of high-speed optical fiber communication is restricted seriously. This paper is focusing on the dispersion characteristics and compensation of the polarization multiplexing (POLMUX) coherent optical communication system: (i) to study on dispersion theoretically, e.g., chromatic dispersion (CD), polarization mode dispersion (PMD) and dispersion tolerance; (ii) to analyze and compare the performance of dispersion with various 16-ary modulation formats; (iii) to compensate dispersion by the classical dispersion compensation methods.

The Research on the Establishment and Simulation of Intelligent Drill String Cables Based on Nonuniform Transmission Line Theory

The cable transmission line has more obvious advantages in long-distance information transmission, and is suitable for the transmission of various MWD signals during drilling. The research on the information transmission pattern of the cable transmission line will be the focus of intelligent drill string. According to the characters of the intelligent drill string, combing with the nonuniform transmission line theory, and considering the effect of temperature variation on the impedance of the smart drill string, the distribution parameters of the cable transmission line has been analyzed. On the basis of the two port network system, the transfer function and the transport matrix of the nonuniform transmission line have been obtained, and the model of nonuniform transmission line impedance of the intelligent drill string cable has been established. In order to verify the feasibility of the established model, the communication channel model has been built utilizing the MATLAB/Simulink software. Through experiment simulation and result analysis, the error rate curves under different parameters have been obtained, the transmission rate and transmission distance of different signals have been explored, and the influence of modulation and demodulation on data transmission quality has been studied, which provides a certain reference for the information transmission pattern of the intelligent drill string.