The helicity-rotation coupling and its current empirical basis are examined. The modification of the Doppler effect due to the coupling of photon spin with the rotation of the observer is considered in detail in connection with its applications in the Doppler tracking of spacecraft. Further implications of this coupling and the possibility of searching for it in the intensity response of a rota...

With its several inherent advantages, an ultra-tightly coupled GPS/INS/PL system will have a dramatic increase in both commercial and defence applications. Integrating the correlator measurements, I (in-phase) and Q (quadrature), with position, velocity and attitude from INS in a Kalman filter characterises this type of system. The Doppler feedback derived from the corrected INS is then fed bac...

Single frequency Doppler radars are effective in distinguishing moving targets from stationary targets, but suffer from inherent range ambiguity. With a dual-frequency operation, a second carrier frequency is utilized to overcome the range ambiguity problem. In urban sensing applications, the dual-frequency approach offers the benefit of reduced complexity, fast computation time, and real time ...

We describe an automatic storm-tracking system to help Doppler radar system to detect severe storms such as thunderwith the forecasting of severe storms. In this article, we present the storms and tornadoes. The Doppler radar generates intensity and concepts of fuzzy point, fuzzy vector, fuzzy length of a fuzzy vector, radial velocity images, examples of which are shown in Figures and fuzzy ang...

We discuss a filtering technique for Teducing the two-way Doppler frequency jluctuations of noise sources localized in space (like the troposphere, or the master clock) that aflect the sensitivity of spacecraft Doppler tmcking searches for gravitational mdiation. This method takes advantage of the sinusoidal behavior of the tmnsfer function to the Doppler observable of these noise sources, whic...

Using sensors that only measure the bearing angle and range of an aircraft, a Kalman filter is implemented to track the range, range rate, bearing, and bearing rate of a maneuvering aircraft with unknown varying accelerations. Simulations will demonstrate the tracking performance of the Kalman filter with single and multiple prediction steps between the measurement step. Then, a Kalman filter w...

Pivot bearing friction and flex cable nonlinearity are the two major torque nonlinearities which lead to performance degradation in hard disk drive (HDD) tracking tasks. Based on a comprehensive model of typical voice-coil-motor (VCM) actuator, which explicitly captures the characteristics of pivot bearing friction and flex cable nonlinearity, this paper presents the design of a parameterized c...

In order to track the carrier phases of Global Navigation Satellite Systems (GNSS) signals in signal degraded environments, a dual antenna joint carrier tracking loop is proposed and evaluated. This proposed tracking loop processes inputs from two antennas, namely the master antenna and the slave antenna. The master antenna captures signals in open-sky environments, while the slave antenna capt...

Abstract The Einstein Equivalence Principle (EEP) is a cornerstone of general relativity and predicts the existence gravitational redshift. We report on new results measuring this shift with RadioAstron, space VLBI spacecraft launched into an evolving high eccentricity orbit around Earth geocentric distances reaching 353,000km. ground tracking stations at Pushchino, Russia, Green Bank, USA, wer...

Background: Myocardial contractility can be investigated using longitudinal peak strain. It can be calculated using the Doppler-derived TDI method and the non-Doppler method based on tissue tracking on B-mode images. Both are validated and show good reproducibility, but no comparative analysis of their results has yet been conducted. This study analyzes the results obtained from the basal segme...