Some Notes on the Performance of Regression-based Time Synchronization Algorithms in Low Cost WSNs

2015 ◽  
pp. 439-443
Author(s):  
Giovanni Betta ◽  
Deborah Casinelli ◽  
Luigi Ferrigno
Keyword(s):  
Time Synchronization ◽  
Low Cost

scholarly journals Design of Orbit Controls for a Multiple CubeSat Mission Using Drift Rate Modulation

Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 323
Author(s):  
Youngbum Song ◽  
Sang-Young Park ◽  
Geuk-Nam Kim ◽  
Dong-Gu Kim
Keyword(s):  
Drift Rate ◽  
Time Synchronization ◽  
Control Method ◽  
Low Cost ◽  
Relative Distance ◽  
Laser Communication ◽  
Surveillance Systems ◽  
Rate Modulation ◽  
Orbit Control ◽  
Orbital Drift

For the low-cost improvement of laser communication, which is critical for various applications such as surveillance systems, a study was conducted on relative distance control based on orbital drift rate modulations for multiple CubeSats during formation flying. The VISION mission covered in this paper comprises two CubeSats to demonstrate laser communication technology in space. During the mission, the deputy CubeSat changes the relative distance to execute mission objectives within various scenarios. Impulsive controls decrease, maintain, and increase the relative distance between the CubeSats by changing the orbital drift rates. The simulation results indicated that the desired orbital operation can be conducted within a given ΔV budget. In addition, the errors in the orbit determination, thrust maneuvers, and time synchronization were analyzed to satisfy the mission requirements. The mass-to-area ratio should be matched to adjust the relative distance between satellites with different properties by drift rate modulation. The proposed orbit control method appropriately operated the VISION mission by adjusting the drift rate modulation. The results of this study serve as a basis for the development of complex orbit control simulations and detailed designs that reflect the characteristics of the thrust module and operational aspects.

scholarly journals Energy Efficiency Due to a Common Global Timebase—Synchronizing FlexRay to 802.1AS Networks as a Foundation

2018 ◽  
Vol 8 (3) ◽  
pp. 26
Author(s):  
Paul Milbredt ◽  
Efim Schick ◽  
Michael Hübner
Keyword(s):  
Time Synchronization ◽  
Fault Tolerant ◽  
Low Cost ◽  
Autonomous Driving ◽  
Consumer Electronics ◽  
Area Network ◽  
Control Applications ◽  
Synchronization Mechanism ◽  
Global Clock ◽  
Time And Energy

Modern automotive control applications require a holistic time-sensitive development. Nowadays, this is achieved by technologies specifically designed for the automotive domain, like FlexRay, which offer a fault-tolerant time synchronization mechanism built into the protocol. Currently, the automotive industry adopts the Ethernet within the car, not only for embedding consumer electronics, but also as a fast and reliable backbone for control applications. Still, low-cost but highly reliable sensors connected over the traditional Controller Area Network (CAN) deliver data needed for autonomous driving. To fusion the data efficiently among all, a common timebase is required. The alternative would be oversampling, which uses more time and energy, e.g., at least double the perception rates of sensors. Ethernet and CAN do require the latter by default. Hence, a global synchronization mechanism eases tremendously the design of a low power automotive network and is the foundation of a transparent global clock. In this article, we present the first step: Synchronizing legacy FlexRay networks to the upcoming Ethernet backbone, which will contain a precise clock over the generalized Precision Time Protocol (gPTP) defined in IEEE 802.1AS. FlexRay then could still drive its strengths with deterministic transmission behavior and possibly also serve as a redundant technology for fail-operational system design.

scholarly journals Greenhouse gas flux studies: An automated online system for gas emission measurements in aquatic environments

2019 ◽  
Author(s):  
Nguyen Thanh Duc ◽  
Samuel Silverstein ◽  
Martin Wik ◽  
Patrick Crill ◽  
David Bastviken ◽  
...  
Keyword(s):  
Climate Models ◽  
Time Synchronization ◽  
Low Cost ◽  
Ghg Emissions ◽  
Raspberry Pi ◽  
Radio Communication ◽  
Flux Chamber ◽  
Robust Measurements ◽  
Carbon Dioxide Co2 ◽  
Ghg Fluxes

Abstract. Aquatic ecosystems are major sources of greenhouse gases (GHG). Robust measurements of natural GHG emissions are vital for evaluating regional to global carbon budgets and for assessing climate feedbacks on natural emissions to improve climate models. Diffusive and ebullitive (bubble) transport are two major pathways of gas release from surface waters. To capture the high temporal variability of these fluxes in a well-defined footprint, we designed and built an inexpensive device that includes an easily mobile diffusive flux chamber and a bubble counter, all in one. In addition to automatically collecting gas samples for subsequent various analyses in the laboratory, this device also utilizes a low cost carbon dioxide (CO2) sensor (SenseAir, Sweden) and methane (CH4) sensor (Figaro, Japan) to measure GHG fluxes. Each of the devices were equipped with an XBee module to enable a local radio communication (DigiMesh network) for time synchronization, and data readout at a server-controller station on the lakeshore. Software of this server-controller is operated on a low-cost computer (Raspberry Pi) which has a 3G connection for remote control and monitor functions from anywhere in the world. This study shows the potential of a low cost automatic sensor network system to study GHG fluxes on lakes in remote locations.

scholarly journals DEVELOPMENT AND EVALUATION OF A UAV BASED MAPPING SYSTEM FOR REMOTE SENSING AND SURVEYING APPLICATIONS

2015 ◽  
Vol XL-1/W4 ◽  
pp. 233-239 ◽  
Author(s):  
C. Eling ◽  
M. Wieland ◽  
C. Hess ◽  
L. Klingbeil ◽  
H. Kuhlmann
Keyword(s):  
Remote Sensing ◽  
Reference Point ◽  
Time Synchronization ◽  
Low Cost ◽  
Single Point ◽  
Single Frequency ◽  
Dual Frequency ◽  
Lever Arm ◽  
Rtk Gps ◽  
Camera Synchronization

In recent years, unmanned aerial vehicles (UAVs) have increasingly been used in various application areas, such as in the remote sensing or surveying. For these applications the UAV has to be equipped with a mapping sensor, which is mostly a camera. Furthermore, a georeferencing of the UAV platform and/or the acquired mapping data is required. The most efficient way to realize this georeferencing is the direct georeferencing, which is based on an onboard multi-sensor system. In recent decades, direct georeferencing systems have been researched and used extensively in airborne, ship and land vehicle applications. However, these systems cannot easily be adapted to UAV platforms, which is mainly due to weight and size limitations. <br><br> In this paper a direct georeferencing system for micro- and mini-sized UAVs is presented, which consists of a dual-frequency geodetic grade OEM GPS board, a low-cost single-frequency GPS chip, a tactical grade IMU and a magnetometer. To allow for cm-level position and sub-degree attitude accuracies, RTK GPS (real-time kinematic) and GPS attitude (GPS compass) determination algorithms are running on this system, as well as a GPS/IMU integration. <br><br> Beside the direct georeferencing, also the precise time synchronization of the camera, which acts as the main sensor for mobile mapping applications, and the calibration of the lever arm between the camera reference point and the direct georeferencing reference point are explained in this paper. Especially the high accurate time synchronization of the camera is very important, to still allow for high surveying accuracies, when the images are taken during the motion of the UAV. <br><br> Results of flight tests demonstrate that the developed system, the camera synchronization and the lever arm calibration make directly georeferenced UAV based single point measurements possible, which have cm-level accuracies on the ground.

scholarly journals Low cost GNSS receivers in time synchronization systems

2018 ◽  
Vol 67 (1) ◽  
pp. 65-72
Author(s):  
Grzegorz Czopik ◽  
Tomasz Kraszewski
Keyword(s):  
Time Synchronization ◽  
Low Cost ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Time Frequency ◽  
Delay Times ◽  
Gnss Receivers ◽  
Frequency Counter ◽  
The One ◽  
Global Navigation Satellite

The GNSS (GNSS — Global Navigation Satellite Systems) receivers can be utilized to obtain accurate time markers. The preliminary results of the cheap GNSS receivers’ tests are presented in the paper. The one receiver’s price (including antenna) does not exceed 30 $. The studies on the use of receivers in the time synchronization systems were executed. Three identical models of receiver modules were used. The 1PPS (1PPS — 1 Pulse Per Second) signals available on the receiver’s output were used. The 1PPS’s main time characteristics were described. Delay times between different receivers 1PPS signals were measured. Measurements were taken using 1 GHz oscilloscope and precise time/frequency counter T3200U. Keywords: time synchronization, 1PPS, GNSS, GPS time

scholarly journals The Testing of MLAT Method Application by means of Usage low-cost ADS-B Receivers

2014 ◽  
Vol 2 (7) ◽  
pp. 8
Author(s):  
Stanislav Pleninger
Keyword(s):  
Time Synchronization ◽  
Low Cost ◽  
Specific Time ◽  
Font Size ◽  
Synchronization Method ◽  
Synchronization Module

<span style="font-family: 'Times New Roman','serif'; font-size: 10pt; mso-fareast-font-family: 'MS Mincho'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">The paper describes the process and results achieved during the measurement which was realized with the aim of identify an applicability of MLAT (Multilateration) method by means of using so-called “low-cost” ADS-B receivers. In terms of measurement, ADS-B receivers without GPS time synchronization module was utilized thus specific time synchronization method was required to implement.</span>

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