The start-stop approximation is a standard tool for processing radar data in synthetic aperture imaging. It assumes that the antenna is motionless when a pulse is emitted and the scattered signal received, after which the antenna moves to its next sending/receiving position along the flight track. However, when the antenna is mounted on a satellite, as opposed to an airplane, its relatively hig...

Kozyrev and van der Weide (KvdW) [1] claim that waves with spatial harmonics associated with wave vectors outside of the first Brillouin zone are the source of the anomalous Doppler shift observed by Seddon and Bearpark (SB) [2]. We show that this is incorrect. KvdW argue with a phase-matching analysis (Eq. 11) that the inverse Doppler effect in their quasicontinuum system could be due to highe...

Car-to-car and car-to-infrastructure (henceforth called C2X) communications are constantly gaining importance for roadsafety and other applications. In order to design efficient C2X systems, an understanding of realistic C2X propagation channels is required, but currently, only few measurements have been published. This paper presents a description of an extensive measurement campaign recently ...

This year we celebrate 60 years since Shigeo Satomura published the first measurements of the Doppler shift of ultrasonic signals from a beating heart. He demonstrated that Doppler signals can be retrieved from heart movements when insonated with 3 MHz ultrasonic waves. Later, togheter with Ziro Kaneko, he constructed the first Doppler flowmeter to measure the blood flow velocities in periphera...

In orthogonal frequency division multiplexing (OFDM) systems with differential phase shift keying (DPSK), it is possible to apply differential modulation either in the time or frequency domain depending on the condition of fading channels, such as the Doppler frequency shift and the delay spread. This paper proposes a simple calculation method, that is, an approximate closed-form equation of th...

The longitudinal Doppler shift is a measure of hyperbolic distance. Transformations of uniform motion are determined by the Doppler shift, while its square root transforms to a uniformly accelerated frame. A time-velocity space metric is derived, by magnifying the Beltrami coordinates with the geometric time, which is similar to the one obtained by Friedmann using Einstein’s equations in which ...

We propose a method for photoacoustic flow measurement based on the Doppler effect from a flowing homogeneous medium. Excited by spatially modulated laser pulses, the flowing medium induces a Doppler frequency shift in the received photoacoustic signals. The frequency shift is proportional to the component of the flow speed projected onto the acoustic beam axis, and the sign of the shift reflec...

Doppler echocardiography provides a noninvasive technique by which blood flow in cardiac chambers and vessels can be characterized, and the timing and direction of flow can be determined. Transvalvular pressure gradients can be quantified noninvasively by Doppler echocardiography. Combined imaging and Doppler allow quantification of volume flow rates. Intracardiac pressures and cardiac function...