Time filter

Source Type

Worcester, MA, United States

Progri I.F.,Giftet Inc.
Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI

This paper presents the complete original definition of first generation Variable Binary Offset Carrier generalized multidimensional geolocation modulation waveforms, to improve the standardization of the United States DoD GPS, European Galileo, Russian GLONASS, Chinese Compass, Indian IRNSS in the L-band (1-2 GHz), and the United Nations International Telecommunications Union (ITU) GNSS or geolocation waveforms in the S-band (2-4 GHz) and C-band (4-8 GHz). In the paper it is argued that the selection of BOC(1,1) on the GPS L1 civil data code and BOC(10,5) (or the military code or M-Code) on both GPS L1 and L2 frequencies is entirely arbitrary because BOC modulation is a special case of for or ; hence, all the current state-of-the-art GNSS waveforms exhibit sub-optimal signal design performance even at the end-user when generalized global objective functions are applied. pure signal design or broad definition of generalized autocorrelation function (ACF) and power spectral density (PSD) offers a unique signal design methodology and provides the necessary framework for ACF pure signal optimization to fill in substantial signal design gaps; hence, improving the GNSS signal design and standardization. Index Terms-Pulse generation, pulse amplitude modulation, pulse width modulation, multidimensional sequences, signal design, signal analysis, generalized functions, time-frequency analysis, minimization methods, optimization methods. Source

Wang G.H.,Yantai Naval Aeronautical and Astronautical University | Chen L.,Yantai Naval Aeronautical and Astronautical University | Jia S.Y.,Yantai Naval Aeronautical and Astronautical University | Progri I.,Giftet Inc.
Journal of Navigation

For mobile 3-D radar installed on a gyro-stabilized platform, its measurements are usually contaminated by the systematic biases which contain radar offset biases (i.e., range, azimuth and elevation biases) and attitude biases (i.e., yaw, pitch and roll biases) of the platform because of the errors in the Inertial Measurement Units (IMU). Systematic biases can NOT be removed by a single radar itself; however, fortunately, they can be estimated by using two different radar measurements of the same target. The process of estimating systematic biases and then compensating radar measurements is called error registration. In this paper, the registration models are established first, then, the equivalent radar measurement error expressions caused by the attitude biases are derived and the dependencies among attitude biases and offset biases are analysed by using the observable matrix criterion. Based on the analyses above, an Optimized Bias Estimation Model (OBEM) is proposed for registration. OBEM uses the subtraction of azimuth and yaw bias as one variable and omits roll and pitch biases in the state vector, which decreases the dimension of the state vector from fourteen of the All Augmented Model (AAM), (which uses all the systematic biases of both radars as state vector) to eight and has about 80% reduction in calculation costs. Also, OBEM can decrease the coupling influences of roll and pitch biases and improve the estimation performance of radar elevation bias. Monte Carlo experiments were made. Numerical results showed that the bias estimation accuracies and the rectified radar raw measurement accuracies can be improved. Copyright © The Royal Institute of Navigation 2012. Source

Progri I.F.,Giftet Inc.
Institute of Navigation International Technical Meeting 2015, ITM 2015

This paper examines common optimization algorithms, such as sum and mean square sense applied to the optimization of the autocorrelation functions (ACF) of GPS M-code like signals such as the variable binary offset carrier (VBOC). Before the different versions are examined for efficiency, on GPS M-code like signals such as VBOC2 which vary with the parameter of signal design and optimization alpha, they are checked to make sure that their corresponding ACFs are valid via a set of conditions known as continuity theorems. Afterwards, by employing any of the optimization algorithms such as sum and mean square sense on GPS M-code like signals such as VBOC2 we are able to produce ACFs that are one ninety four percent more efficient than the corresponding ACFs of the GPS M-code signals. Source

Progri I.F.,Giftet Inc. | Huang P.,University of Electronic Science and Technology of China | Pi Y.,University of Electronic Science and Technology of China | Xia X.,Huazhong University of Science and Technology
Institute of Navigation International Technical Meeting 2016, ITM 2016

Indoors, GNSS signal encounters severe multipath power loss and fading which leads to significant signal degradation of the amplitude and phase to perform GPS (or GNSS) signal acquisition. To overcome these effects, piling up received GPS (or GNSS) data is a traditional (or conventional) method; however, it exhibits two shortcomings (drawbacks or limitations): instable detection performance, such as the probability of false alarm (PFA) fluctuates due to changes of the signal-to-noise ratio (SNR); and elongated acquisition time caused by extended accumulation duration and over repetitive FA occurrence (or "penalty"). To overcome the first shortcoming, an adaptive structure is employed in GNSS signal acquisition that enables constant FA rate (CFAR) criteria to guarantee a stable detection performance on the GNSS signal acquisition. To overcome the second shortcoming, an adaptive determination on accumulation length is employed to minimize the accumulation duration; therefore, a double-dwell structure (DDS) is used to reduce the processing time "penalty" caused by FA. Simulation results illustrate that an adaptive, stable detection implementation and DDS reduce the average acquisition time by almost fifty percent (or by half or a factor of two). Other important significant unique accomplishments found in this paper are as follows: Dr. Progri for the first time provides the closed form expressions of generalized modified Bessel function distributions of the cumulative distribution functions (cdf) of the first and second kinds and for the first time introduces the very powerful utility of the Kampé de Fériet function and parabolic cylinder function in the navigation community. © 2016 by Institute of Navigation. All right reserved. Source

Chen L.,Yantai Naval Aeronautical and Astronautical University | Wang G.H.,Yantai Naval Aeronautical and Astronautical University | Progri I.F.,Giftet Inc.
Journal of Electrical and Computer Engineering

For mobile radar, offset biases and attitude biases influence radar measurements simultaneously. Attitude biases generated from the errors of the inertial navigation system (INS) of the platform can be converted into equivalent radar measurement errors by three analytical expressions (range, azimuth, and elevation, resp.). These expressions are unique and embody the dependences between the offset and attitude biases. The dependences indicate that all the attitude biases can be viewed as and merged into some kind of offset biases. Based on this, a unified registration model (URM) is proposed which only contains radar "offset biases" in the form of system variables in the registration equations, where, in fact, the "offset biases" contain the influences of the attitude biases. URM has the same form as the registration model of stationary radar network where no attitude biases exist. URM can compensate radar offset and attitude biases simultaneously and has minor computation burden compared with other registration models for mobile radar network. © 2014 Lei Chen et al. Source

Discover hidden collaborations