polyphase is a common class of pulse compression waveforms in the radar systems. oppermann code is one of the used codes with polyphone pattern. after compression, this code has little tolerant against doppler shift in addition to its high side lobe level. this indicates that the use of oppermann code is an unsuitable scheme to radars applications. this paper shows that the use of amplitude wei...

We show how to calculate the encountered wave period distribution for a ship traveling with constant speed on a Gaussian random sea with a directionally distributed frequency spectrum.  1998 Elsevier Science Ltd. All rights reserved.

In this paper we propose a joint space-Doppler parameter estimation algorithm for fast-fading multipath DS-CDMA communication systems. The Doppler shifts induced by the relative motion between the transmitter and the receiver, together with the associated direction-of-arrival (DOA), are jointly estimated by a semi-blind subspace-type method. The Doppler effect is successfully eliminated by a sp...

Figure 1. Spectral analysis and the Doppler display. The fast Fourier transform (FFT) separates the Doppler signal into its component Doppler-shift frequencies and determines the amplitude at each frequency. Most ultrasound machines calculate Doppler-shifted frequencies over 5 msec increments and convert this to velocity information. These velocities are then displayed in a bin whose brightness...

The value of transesophageal pulsed Doppler echocardiography (PDE) was studied in six patients with competent mitral valve and in 12 patients with angiographically proved mild to moderately severe mitral regurgitation. The results were compared with those from the standard transthoracic method of investigation. The advantages of the esophageal over the transthoracic approach in the detection of...

OBJECTIVES This study was conducted to assess the diagnostic role of Doppler echocardiography in constrictive pericarditis. BACKGROUND It has been observed that patients with constrictive pericarditis have a characteristic Doppler pattern of respiratory variation in ventricular filling and central venous flow velocities. However, the observation was based on a small number of patients with kn...

Spin transfer appears to be a promising tool for improving spintronics devices. Experiments that quantitatively access the magnitude of the spin transfer are required for a fundamental understanding of this phenomenon. By inductively measuring spin waves propagating along a permalloy strip subjected to a large electrical current, we observed a current-induced spin wave Doppler shift that we rel...

F. Rohlfing,1 G. Tkachov,2,* F. Otto,1 K. Richter,2 D. Weiss,1 G. Borghs,3 and C. Strunk1 1Institute for Experimental and Applied Physics, Universität Regensburg, D-93040 Regensburg, Germany 2Institute for Theoretical Physics, Universität Regensburg, D-93040 Regensburg, Germany 3Interuniversity Micro-Electronics Center (IMEC), Kapeldreef 75a, B-3001 Leuven, Belgium Received 27 February 2009; re...

With the use of a two-dimensional range-gated pulsed-Doppler ultrasound system, Doppler examinations of the aorta and cerebral arteries were performed in 20 normal newborn infants and in 54 infants with various forms of congenital heart disease (i.e. patent ductus arteriosus, coarctation of the aorta, critical aortic stenosis, pulmonary atresia, truncus arteriosus). In the cerebral artery Doppl...

conclusions we did not find significant differences in ventricular function or ventricular septal thickness in the fetuses of mothers who were referred to our hospital with a previous diagnosis of diabetes mellitus compared with the fetuses of non-diabetic mothers. this could be due to early identification, appropriate treatment, and tightly controlled diabetes in our study population. it shoul...