Showing 7 results for Range
A. Saberkari, S. B. Shokouhi,
Volume 1, Issue 4 (10-2005)
Abstract
In this paper, an imaging chip for acquiring range information using by
0.35 μm CMOS technology and 5V power supply has been described. The system can
extract range information without any mechanical movement and all the signal processing
is done on the chip. All of the image sensors and mixed-signal processors are integrated in
the chip. The design range is 1.5m-10m with 18 scales.
A. Moharampour, J. Poshtan, A. Khaki-Sedigh,
Volume 4, Issue 3 (10-2008)
Abstract
In this paper, after defining pure proportional navigation guidance in the 3-
dimensional state from a new point of view, range estimation for passive homing missiles is
explained. Modeling has been performed by using line of sight coordinates with a particular
definition. To obtain convergent estimates of those state variables involved particularly in
range channel and unavailable from IR trackers, nonlinear filters such as sequential U-D
extended Kalman filter and Unscented Kalman filter in modified spherical coordinate
combined with a modified proportional navigation guidance law are proposed. Simulation
results indicate that the proposed tracking filters in conjunction with the dual guidance law
are able to provide the convergence of the range estimate for both maneuvering and nonmaneuvering
targets.
Shahram Mohammad Nejad, Saeed Olyaee,
Volume 5, Issue 2 (6-2009)
Abstract
In this paper, we present a high accuracy laser range finder and velocimeter using ultra-fast time-to-digital converter (TDC). The system operation is based on the measuring the round-trip time of a narrow laser pulse. A low-dark current high-speed PIN photodiode is used to detect the triggered laser beam and to produce start signal. The pulsed laser diode generates 45W optical power at 30ns duration time and 905nm wavelength. A high-responsivity avalanche photodiode (APD) detects the reflected beam from the target. An optical head including beam splitter, lenses and optical filters is also designed and implemented. The signal conditioner of the system includes pre- and post-amplifiers, comparator, opto-isolators and monostable. By using a 3MV/W reach-through structure avalanche photodiode and a wideband pre-amplifier, the pre-amplifier output reaches 15.9mV, resulting from the minimum detectable optical power. The APD temperature and as a result its responsivity is controlled by a thermoelectric controller unit. The start and stop signals from PIN and APD are led to the time-to-digital converter to count the round-trip time of the laser beam. The system is tested by a retro-reflector as a target for 30-1200m distances. The resolutions of the distance and velocity measurement are limited to 18.75mm and 1.2m/s, respectively. In the worst condition, the minimum reflected optical power is limited to about 5.3nW in 1.2km distance.
M H Refan, A Dameshghi, M Kamarzarrin,
Volume 9, Issue 4 (12-2013)
Abstract
Differential base station sometimes is not capable of sending correction information for minutes, due to radio interference or loss of signals. To overcome the degradation caused by the loss of Differential Global Positioning System (DGPS) Pseudo-Range Correction (PRC), predictions of PRC is possible. In this paper, the Support Vector Machine (SVM) and Genetic Algorithms (GAs) will be incorporated for predicting DGPS PRC information. The Genetic Algorithm is employed to feature subset selection. Online training for real-time prediction of the PRC enhances the continuity of service on the differential correction signals and therefore improves the positioning accuracy in Real Time DGPS. Given a set of data received from low cost GPS module, the GASVM can predict the PRC precisely when the PRC signal is lost for a short period of time. This method which is introduced for the first time for prediction of PRC is compared to other recently published methods. The experiments show that the total RMS prediction error of GASVM is less than 0.06m for on step and 0.16m for 10 second ahead cases
M. R. Mosavi, S. Azarshahi, I. Emamgholipour , A. A. Abedi,
Volume 10, Issue 1 (3-2014)
Abstract
In present study, using Least Squares (LS) method, we determine the position smoothing in GPS single-frequency receiver by means of pseudo-range and carrier phase measurements. The application of pseudo-range or carrier phase measurements in GPS receiver positioning separately can lead to defects. By means of pseudo-range data, we have position with less precision and more distortion. By use of carrier phase data, we do not have absolute position and just dislocation is available, but the accuracy is high. In present research, we have combined pseudo-range and carrier phase data using LS method in order to determine GPS receiver's position smoothing. The results of comparison by LS method show less RMS error, less calculation volume and more smoother in using carrier phase-pseudo-range data together relative to pseudo-range data in isolation.
P. Teymouri, M. R. Mosavi, M. Moazedi,
Volume 14, Issue 3 (9-2018)
Abstract
Due to widespread use of Global Positioning System (GPS) in different applications, the issue of GPS signal interference cancelation is becoming an increasing concern. One of the most important intentional interferences is spoofing signals. An effective interference (delay spoof) reduction method based on adaptive filtering is developed in this paper. The principle of method is using adaptive filters to eliminate interference, obtain an estimate of interfering signal and subtract that from the corrupted signal. So, what remains in the output is the desired signal. Here, for updating the filter coefficients adaptive algorithms in both time (statistical and deterministic) and transform domain will be studied. The proposed adaptive filter is applied to a batch of spoofing GPS data in pseudo-range level. The results indicate that all investigated algorithms are able to reduce positioning steady-state miss-adjustment up to 70 percent. In this context, the variable step-size least mean square algorithm performs better than others do.
A. Zakipour, K. Aminzare, M. Salimi,
Volume 18, Issue 3 (9-2022)
Abstract
Considering the presence of different model parameters and controlling variables, as well as the nonlinear nature of DC to AC inverters; stabilizing the closed-loop system for grid current balancing is a challenging task. To cope with these issues, a novel sliding mode controller is proposed for the current balancing of local loads using grid-connected inverters in this paper. The closed-loop system includes two different controlling loops: a current controller which regulates the output current of grid-connected inverter and a voltage controller which is responsible for DC link voltage regulation. The main features of the proposed nonlinear controller are reactive power compensation, harmonic filtering and three-phase balancing of local nonlinear loads. The developed controller is designed based on the state-space averaged modelling its stability and robustness are proved analytically using the Lyapunov stability theorem. The accuracy and effectiveness of proposed controlled approach are investigated through the PC-based simulations in MATLAB/Simulink.
