Multipath mitigation using LMS adaptive filtering for GPS applications

This study introduces a simple, compact broadband dual‐band circularly polarised slot antenna suitable for the use in the compact universal ultra‐high frequency (UHF) radio‐frequency identification (RFID) reader devices and Global Positioning System (GPS) applications. The proposed antenna is fed using an open‐end coplanar waveguide with an inverted ‘L’ structure. To realise a broadband circular polarisation and good impedance matching, an inverted L‐shaped strip line is inserted adequately into a square slot at the right centre of the slot toward the slot centre. The experimental results demonstrate that the proposed antenna exhibits a 10 dB return loss bandwidth of 552 MHz (716–1268 MHz) and 3‐dB axial ratio (AR) bandwidth of 564 MHz (824–1388 MHz). Additionally, the antenna gains are 3.8 and 4.29 dBi throughout UHF RFID band and GPS band, respectively. The proposed antenna has a wide AR bandwidth, a compact size, and a simple structure. Furthermore, the proposed antenna is printed on one substrate layer with an overall size of 112 × 112 × 1.6 mm3, which makes it more practical for universal UHF RFID handheld readers and GPS applications.

Undergraduate students pursuing a Bachelor of Science in Forestry (BSF) at Stephen F. Austin State University (SFA) attend an intensive 6-week residential hands-on instruction in applied field methods. The intensive 6-week instruction includes learning how to use the Global Positioning System (GPS) with a Garmin eTrex HCx GPS unit to accurately calculate area. Students were instructed how to assess the accuracy of their GPS collected waypoints by calculating the Root Mean Square Error (RMSE) comparing their GPS collected area measurements with instructor on-screen digitized area. Student’s average area RMSE between digitized and GPS derived area was 0.015 hectares, whereas instructor’s average area RMSE between digitized and GPS derived area was 0.015 hectares. Over 76% of students measured GPS area was within 5% of instructor on-screen digitized area. No difference between the students and instructors area RMSE of 0.015 hectares and high level of agreement between student measured GPS area and instructor on-screen digitized area: (1) indicates students receiving hands-on instruction in GPS applications can record accurate area measurements after only a limited 2 hour introduction; (2) the accuracy of the Garmin eTrex HCx GPS unit is not user dependent; and, (3) validates the interactive hands-on instruction methodology employed at SFA.

Ever since the beginning of time, man has searched for better navigational aids. The NAVSTAR Global Positioning System (GPS) represents the culmination of years of research and development. The system utilizes state of the art satellite communication enabling all weather worldwide navigation never before possible. The system provides position accuracies within 9 meters; velocity information within 0.1 m/sec; time data within 100 nanoseconds. With GPS still in the infancy stages, the potential applications remain limitless. Many James Bond type scenarios become very realistic -a display in every car showing exactly where the car is and an electronic map showing possible courses. The application of GPS is limited only by one's own imagination. This thesis explores the three GPS areas: 1) system concept; 2) signal structure; and 3) Digital Signal Processing (DSP) techniques. The GPS information presented allows the reader to become familiar with the NAVSTAR system concept and the application of a DSP technique in a GPS receiver design. By capitalizing on the rapid electronics

The expected limit of accuracy of the Global Positioning System (GPS) is of the order of the dimensions of the antenna in use.which translates into the centimeter range at GPS frequencies of 1.2–1.6 GHz. In these instances, phase-derived position determination is affected by the antenna phase centre movement which in turn is a function of the observation angle. The circularly polarized short quadrifilar helix is compact and lightweight and is one of the antennas presently used with GPS receivers. Both the amplitude and phase characteristics of this antenna are studied to determine its suitability for various GPS applications such as in hydrography and aviation where peculiar constraints may be placed upon the near-and-below-horizon response.

Least Mean Square (LMS) algorithm is the most popular adaptive algorithm (AA) for realization of a digital adaptive filter (AF). In digital implementation of AF, finite word length hardware is unavoidable. This finite precision (FP) effect on the performance of the AF is crucial in the sense that, if proper word length is not used the performance in terms of the mean square error (MSE) of the filter degrades substantially. In this paper, a new approach based on the probability theory is used to analyze the FP effect of the LMS based finite impulse response (FIR) AF. An expression of the adaptation failure in terms of word length and the step size is derived. Simulation study of a FP LMS adaptive equalizer is carried out to demonstrate and verify this effect. This study provides an important guide-line to the designers for selecting the optimum word length for a specific application for a given MSE criterion.

The car navigation service has opened through the global positioning system (GPS). People's lives have changed through car navigation services, and this service is indispensable nowadays. GPS provides reliable location accuracy in open space, but its location accuracy is degraded where multipath and other error factors are present. In particular, since GPS signals must be received in order to calculate the position, the navigation system cannot calculate the position in an indoor space such as underground parking lot, subway or tunnel where GPS signals are cut off. When car navigation is performed in an indoor parking lot where GPS signals are not transmitted, the user cannot calculate the current location, so the user has to go out by relying on the traffic sign because he does not know the current location. Also, when the user leave the parking lot, the car navigation system has problems. In an urban canyon, it is difficult to calculate accurate current position due to multipath. Because the route is calculated through the current location and route, the car navigation system provides the wrong route to the user. In addition, when entering a tunnel while using car navigation, the car navigation system calculates the position using the initial tunnel entry velocity estimated by the GPS. As the speed of the user increases or decreases, the position error also increases. Then the position suddenly changes when passing through the tunnel. And it is difficult to provide a proper guidance at the branch road or exit in the tunnel because of the positioning error. People are demanding a complete car navigation service, but the current navigation service provides the wrong route and position information to the user where the GPS signal quality is poor. In order to solve the above problem, in this paper, we have studied to improve the user's position accuracy by using LTE signal and mobile phone internal sensor. In general, observed time difference of arrival (OTDOA) technique is applied for the LTE based positioning. Because this method gives tens of meters of error, it is difficult to be used for the car navigation service. In our research, we estimate the position using the LTE signal strength. The difference from conventional fingerprinting method is that instead of using only current signal strength, the signal strength pattern accumulated while moving is utilized to estimate the user position. The signal strength increases as the user approach the access point (AP), and decreases as the user move away from the AP. Therefore, when a user moves and stores signal strength with respect to a specific AP, a pattern that could occur only in the corresponding region is saved. There are many similar candidates in the database when using only the current signal strength. However, when using a pattern, similar candidates exist only around the true position. And, when using several LTE signals, the positioning accuracy could be increased. Since the user receives multiple LTE signals, the pattern becomes surface. The surface is compared with the database, and the position with the highest correlation value is estimated as the current position. We call this method surface correlation (SC). In order to verify the performance of the proposed method, experiments were conducted in the Gangnam beltway tunnel in Seoul. The testbed consisted of three tunnel and total distance is almost 11.8 Km. In the tunnel, repeater and several antennas are installed to widen the area of the LTE signal. When an LTE signal is received by the vehicle, the largest signal strength is received every time when the vehicle passes the nearest antenna. As a result, for a specific LTE signal, when the vehicle has passed through the LTE signal region, a unique pattern with multiple peaks is generated. In order to estimate the position, we first estimate the position with the SC technique. Then, the estimated position is corrected by comparing the peak of the currently received pattern with the peak of the database. Through this method, the position was estimated with an error of less than 50meter in the tunnel. Conclusion In this research, the LTE signal strength based positioning technology is presented. Especially, this technology, SC, provides the positioning performance that could be used for the car navigation in the tunnel where GPS signal is blocked. We expected that user would be use the accurate car navigation service through this technology in the GPS challenging environment.

The global positioning system (GPS) has become the most extensively used positioning and navigation tool in the world. Applications of GPS abound in surveying, mapping, transportation, agriculture, military planning, GIS, and the geosciences. However, the positional and elevation accuracy of any given GPS location is prone to error, due to a number of factors. The applications of Global Positioning System (GPS) positioning is more and more popular, especially the intelligent navigation system which relies on GPS and Dead Reckoning technology is developing quickly for future huge market in China. In this paper a practical combined positioning model of GPS/DR/MM is put forward, which integrates GPS, Gyro, Vehicle Speed Sensor (VSS) and digital navigation maps to provide accurate and real-time position for intelligent navigation system. This model is designed for automotive navigation system making use of Kalman filter to improve position and map matching veracity by means of filtering raw GPS and DR signals, and then map-matching technology is used to provide map coordinates for map displaying. In practical examples, for illustrating the validity of the model, several experiments and their results of integrated GPS/DR positioning in intelligent navigation system will be shown for the conclusion that Kalman Filter based GPS/DR integrating position approach is necessary, feasible and efficient for intelligent navigation application. Certainly, this combined positioning model, similar to other model, can not resolve all situation issues. Finally, some suggestions are given for further improving integrated GPS/DR/MM application.

An adaptive filter is the utmost essential filter castoff in statistical signal dealing. The fine-tuning of the filter factor in relation to the response signal is the adaptive filter's key feature due to fewer calculations, Least Mean Square (LMS) adaptive filters are widely used to remove noise from Electrocardiograms (ECG). The adaptive filters are realized as signal processing algorithms in Digital Signal Processors (DSPs) or in VLSI Signal Processors (VSPs). The technique provides a way to create a folded adaptive lattice LMS filter, which requires less hardware than an adaptive lattice filter. Folding is an algorithm that uses a time scheduling technique that combines arithmetic operations into one operation which reduces Register and silicon chip areas. The design and implementation of a folded lattice adaptive filter remove Power Line Interference (PLI) noise from ECG signals. The MATLAB Xilinx System Generator tool is used to design the Adaptive Lattice LMS Filter and Folded Adaptive Lattice LMS Filter with Folding Order K = 2 and K = 4 and realized in the Virtex 5 FPGA KIT. The results of the folded architecture show that the area is reduced for K = 2 and K = 4 by 82.60% and 91.05%, respectively compared with a normal adaptive lattice filter.

The widespread availability of global positioning system (GPS) technology in recent years has fundamentally altered the way in which spatial data are collected. GPS can fairly accurately locate and report planar coordinates for a particular point as well as altitude, date, time, speed, and heading. Transportation-related GPS applications are numerous, and range in complexity from simple-uses, such as collection of bus stop locations, to sophisticated uses, such as real-time vehicle tracking for intelligent vehicle systems (ITS). The chapter describes how GPS is used by numerous agencies including metropolitan planning organizations (MPOs), Departments of Transportation (DOTs), county and local government agencies, and transportation engineering consultants. GPS is increasing being used for transportation applications by the private sector as well, with the advent of in-vehicle navigation systems and fleet-tracking systems. Several applications of GPS in the transportation sector have been discussed in this chapter, and an overview of centerline mapping, inventory management, automatic vehicle location (AVL), safety applications, and locating environmentally sensitive features are provided.

This paper aims to apply adaptive filtering algorithms in sensor array processing for underwater surveillance and detection systems with linear arrays. Adaptive filters are iterative in nature and continuously update the filter taps to minimize the error signal based upon certain criterion. Adaptive filters are used in beamforming to place the main beam in the direction of desired signal and place nulls in the direction of unwanted signals. Adaptive filters are also used in spectral analysis of acoustic signals for background noise cancellation. This paper evaluates the performance of three adaptive filtering algorithms with respect to sensor array design parameters i.e. number of sensors, sensor spacing, number of incident signals and their angular separation. The three adaptive filtering algorithms namely least mean square (LMS), normalized LMS (NLMS), and sample matrix inversion (SMI) have been compared in the context of linear array beamforming. The paper provides detailed discussions on the simulation results of these adaptive algorithms in terms of convergence speed, beamwidth, null depths and maximum side lobe levels. In addition the paper illustrates a practical example of applying adaptive filters in underwater sensor array processing systems for detection of target’s acoustic signatures.

The utilization of Global Navigation Satellite System (GNSS) is becoming an attractive navigation approach for geostationary orbit (GEO) satellites. A high-sensitivity receiver compatible with Global Position System (GPS) developed by the United States and BeiDou Navigation Satellite System (BDS) developed by China has been used in a GEO satellite named TJS-5 to demonstrate feasibility of real-time navigation. According to inflight data, the GNSS signal characteristics including availability, position dilution of precision (PDOP), carrier-to-noise ratio (C/N0), observations quantity and accuracy are analyzed. The mean number of GPS and GPS + BDS satellites tracked are 7.4 and 11.7 and the mean PDOP of GPS and GPS + BDS are 10.24 and 3.91, respectively. The use of BDS significantly increases the number of available navigation satellites and improves the PDOP. The number of observations with respect to C/N0 is illustrated in detail. The standard deviation of the pseudorange noises are less than 4 m, and the corresponding carrier phase noises are mostly less than 8 mm. We present the navigation performance using only GPS observations and GPS + BDS observations combination at different weights through comparisons with the precision reference orbits. When GPS combined with BDS observations, the root mean square (RMS) of the single-epoch least square position accuracy can improve from 32.1 m to 16.5 m and the corresponding velocity accuracy can improve from 0.238 m/s to 0.165 m/s. The RMS of real-time orbit determination position accuracy is 5.55 m and the corresponding velocity accuracy is 0.697 mm/s when using GPS and BDS combinations. Especially, the position accuracy in x-axis direction reduced from 7.24 m to 4.09 m when combined GPS with BDS observations.

The active control suspension system can improve both the riding comfort and handling safety in various operation conditions. In this paper, according to the evaluation method of riding comfort and handling safety of vehicle, the acceleration of the sprung mass, dynamic tyre load between wheels and the unsprung mass are determined as the evaluation targets of suspension performance. The least mean squares (LMS) adaptive algorithm is used in active suspension system. With adjusting the weight of the adaptive filter, the minimum quadratic performance index is obtained. For two-DOF vehicle suspension model, the sky-hook control, generalized adaptive control and LMS adaptive control are studied. The simulation results show that LMS adaptive control algorithm is not only simple but also remarkably effective.

As the development of the Global Positioning System (GPS), it has gained in popularity in navigation, geology, survey and map, for its all-weather, high accuracy capability. Application of GPS in agriculture is a hot topic at present. An automatic guidance system is described in this paper. The precision of the system mainly depends on the GPS positioning precision. To improve the precision of the system, statistics is introduced to the program. An experiment was carried out to figure out the distribution model of the error of GPS. The experiment shows that the distribution of error matches the normal distribution model approximately. On the assumption that the error distribution is normal, the filtering module is introduced to the program. It calculates the confidence interval on real time and filters out the GPS data with big accident error. Following that the structure of the system and the working course are described in detail. Finally, the experiment was carried out. From the experiment we could see the precision of the system improved significantly with the filtering.

This paper is aimed to develop a model navigation and application of Global Positioning System (GPS) and Global System Mobile (GSM) in the model system of the fishing guide. Furthermore, this paper describes what and how a major role in popularizing a fishing guide system model. Modifications that should be made in each unit to get a way to use the GPS and GSM according to fishermen dynamic environment is described. Modifications were made in the system model unit fishing guides also assist in finding a reliable and accurate planimetric solution in the case of poor visibility of GPS and GSM satellite, which is usually common in the fishing environment. In the model system models fishing guide fishing guide system based on GPS and GSM can be successfully implemented in an environment designed for fishermen in developing regions. This, if implemented in a planned will bring a significant increase in the revolutionary Indonesian Fisheries. The Model of Fishermen Guidance System Based GPS and GSM that has been built allowing an institution or an individual to be able to control, monitor and communicate in a geographic coordinate system (map). Validation by experts and users indicate that the system is operationally feasible to use the results of the feasibility level of 87.61% and 81.67% of the expert user and both showed good category. The operator will log into the appropriate application access rights are allowed. The resulting device system has several characteristics including: Easy to use (user friendly), Easy to carry (mobile handsets), Informative, Applicative, High Technology, and Network Wide. Based on daily monitoring, coordinate information distributed to the fishermen either via GPS, SMS (Short Massage Services) or through a printed map. Generally the fishermen using a printed map, due to the reading simpler and faster. Performance is based on the acquisition of fish fisherman fishermen after the data supplied koordiant previously, there were no reports that the fishermen do not get fish. With location information of fish that are easily achieved the goal of capturing the fisherman turned fish into taking fish. Basically the fishermen helped with the fish location information from the beginning. Location of fish that are informed by much more than the previous system in which fishermen have fish location data based on experiences.

Adaptive filters, as part of digital signal systems, have been widely used, as well as in applications such as adaptive noise cancellation, adaptive beam forming, channel equalization, and system identification. However, its implementation takes a great deal and becomes a very important field in digital system world. When FPGA (Field Programmable Logic Array) grows in area and provides a lot of facilities to the designers, it becomes an important competitor in the signal processing market. In general FIR structure has been used more successfully than IIR structure in adaptive filters. However, when the adaptive FIR filter was made this required appropriate algorithm to update the filter’s coefficients. The algorithm used to update the filter coefficient is the Least Mean Square (LMS) algorithm which is known for its simplification, low computational complexity, and better performance in different running environments. When compared to other algorithms used for implementing adaptive filters the LMS algorithm is seen to perform very well in terms of the number of iterations required for convergence. This phenomenon can be achieved by a sufficient choice of bit length to represent the filter’s coefficients. This paper presents a lowcost and high performance programmable digital finite impulse response (FIR) filter. It follows the adaptive algorithm used for the development of the system. The architecture employs the computation sharing algorithm to reduce the computation complexity.