The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we ...

This Letter reports on a rotational Doppler effect obtained from rotating rod illuminated by fundamental Gaussian laser beam. More specifically, we decompose the transmitted light behind into Laguerre–Gaussian modes and investigate associated frequency shifts. The main contributing correspond to having same symmetry as object. Furthermore, their shifts equal topological charge of beam times Pot...

It is well established that light carrying orbital angular momentum (OAM) can be used to induce a mechanical torque causing an object to spin. We consider the complementary scenario: will an observer spinning relative to the beam axis measure a change in OAM as a result of their rotational velocity? Remarkably, although a linear Doppler shift changes the linear momentum of a photon, the angular...

In this paper we consider a matrix algebraic approach to derive the coded Multi-Carrier CDMA (MC-CDMA) system model for a Doppler shift channel. We derive the eeects of Doppler shift in a MC-CDMA system for low earth orbit (LEO) mobile-satellite communications and show the similarity of a MC-CDMA channel model under Doppler shift with that of the asynchronous DS-CDMA channel model. We therefore...

In this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow. A positive Doppler signal, i.e., a Doppler shift frequency of more than 1 kHz using a 5 MHz insonating frequency, was found in 34 of 57 patients with a carcinoma, and also in three patients with a benign condition. These results indicate...

The signal processing aspect of a 2-μm wavelength coherent Doppler lidar system under development at NASA Langley Research Center in Virginia is investigated in this paper. The lidar system is named VALIDAR (validation lidar) and its signal processing program estimates and displays various wind parameters in real-time as data acquisition occurs. The goal is to improve the quality of the current...