We present a theoretical model to sufficiently investigate the optical rotational Doppler effect based on modal expansion method. We find that the frequency shift content is only determined by the surface of spinning object and the reduced Doppler shift is linear to the difference of mode index between input and output orbital angular momentum (OAM) light, and linear to the rotating speed of sp...

Quantitative data for Doppler-shift compensation by Pteronotus parnellii parnellii were obtained with a device which propelled the bats at constant velocities over a distance of 12 m. The bats compensated for Doppler shifts at all velocities tested (0.1-5.0 ms-1). The main findings were (1) that compensation was usually accomplished by a progressive lowering of the approximately 61 kHz second h...

This paper addresses the problem of optimum waveform design for multiple target detection. The notion of poly-semantic radar, which gave improved performance through coincidence detection, is analyzed for high resolution radar system in presence of high density additive noise and Doppler shift. These sequences are optimized by employing Hamming backtrack algorithm (HBT). The detection capabilit...

Superiority of poly-alphabetic sequences (PAS) for pulse compression radar over the binary and ternary sequences was established earlier. However, the enlarged alphabets in poly–alphabetic sequences deteriorate the noise and Doppler robustness at higher lengths in high resolution radar (HRR) systems. In this paper, poly-semantic sequences (PSS) with restricted alphabet {+1,-1} are considered an...

Preoperative continuous-wave Doppler spectral analysis was used to generate two parameters, peak frequency in the internal carotid artery (fmax) and the ratio of peak frequencies in the internal and common carotid arteries (carotid index). These were compared with direct measurement of residual lumen diameter in pathologic specimens obtained from carotid endarterectomy in 37 patients. Doppler s...

This paper reports the results of a survey of Doppler shift oscillations measured during solar flares in emission lines of S XV and Ca XIX with the Bragg Crystal Spectrometer (BCS) on Yohkoh. Data from 20 flares that show oscillatory behavior in the measured Doppler shifts have been fitted to determine the properties of the oscillations. Results from both BCS channels show average oscillation p...

A duplex scanner which consists of a real time two dimensional scanner and a pulsed Doppler flowmeter was used to measure superior mesenteric blood flow in 70 healthy subjects. By processing the Doppler shift signals, the instantaneous average Doppler shift frequency and then the instantaneous average velocity of the flow rate were calculated. Both diameter of the vessel and angle between vesse...

As we know, a moving target’s azimuth shift in synthetic aperture radar (SAR) image is proportional to the projected velocity of its across-track velocity in the slant-range plane. Therefore, we can relocate the moving target in SAR image after estimating its velocity. However, when the Doppler ambiguity occurs due to the limitation of the SAR system’s pulse repetition frequency (PRF), this rel...

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier digital modulation technique. It’s likely to be used in next generation high-speed railway communication system. When OFDM is used in the communication of high-speed railway user s, Doppler frequency shift will become an important technical barrier, because OFDM is sensitive to frequency offset. Especially in high-speed moveme...

Aberration and radiation pressure reflected by a moving mirror are examples of the Klein, one-way Doppler shift, and Poincaré, two-way Doppler shift, disc models of hyperbolic geometry, respectively. Aberration, like the Thomas precession, is related to the angular defect, and is a kinematical effect rather than relativistic. At the angle of parallelism, determined by a stationary observer look...