21-11-2012, 06:17 PM
Implementation Of Zoom Fft
In Ultrasonic Blood Flow Analysis - Using Tms320c5x/6x(Code Composer) Dsp Processor.
34IMPLEMENTATION-OF-ZOOM-FFT-IN-ULTRASONIC-BLOOD-FLOW-A.pdf (Size: 227.45 KB / Downloads: 45)
ABSTRACT
An adequate blood flow supply is necessary for all organs of the body. Analysis of
the blood flow finds its importance in the diagnoses of diseases. There are many techniques
for analyzing the blood flow. These techniques are not affordable by the poor people
because of their high expense. So we have implemented a technique called Zoom-FFT.
This technique is simple and affordable to detect the blood clots and other diseases.
Human with his potential tries to get whichever is unexplored, explored, and till
now we are managing and succeeding using some technical ways. In the same way this is
one of the explorations made for scanning the intra details of some specific objects using
ultrasound named SONOGRAPHY, which is used as an alternative to x-ray photography.
In this paper, the method to zoom the image or the scanned data-using zoom FFT has been
discussed. It also explains the algorithm to get ZOOM FFT and how it can be obtained via
simulation. Real time experimentation and its applications, with basics of ultrasound
scanning are also explained. Here a specific application will be dealt i.e., ultrasonic blood
flow analyzer using ZOOM FFT.
INTRODUCTION
BASICS
“SOUND IS A COMPRESSIONAL WAVE” Sounds at frequencies above the
audible range, to say above 20 KHz are Ultrasonic wave, in the megahertz range. Above
which are supersonic sound.
DOPPLER EFFECT PHENOMENON
A shift in frequency (f) of the wave will be expected due to the source and
observers motion relative to each other. If the distance between them is reduced or
increased. That shift in frequency depends on the velocity of sound which also depends on
density of the medium, in which it propagates. When a small object is situated in the path
of the sound wave, the wave will be resisted (scattered). A direct measurement of this
velocity will provide useful information about the dynamic property of the medium. The
Velocity of sound in Blood is 1570 m/s. Perceived velocity is V’=V-V0
In terms of frequency (f), as a velocity dependent factor.
REAL BLOOD FLOW ANALYSIS:
In an Ultrasonic blood flow analysis, a beam of ultrasonic energy is directed
through a blood vessel at a shallow angle and its transit time is then measured.. More common
are the ultrasonic analyzers based on the Doppler principle. An oscillator, operating at a
frequency of several Mega Hertz, excites a piezoelectric transducer. This transducer is coupled
to the wall of an exposed blood vessel and sends an ultrasonic beam with a frequency F into
the flowing blood.
ADVANTAGES
1. Increased frequency domain resolution
2.Reduced hardware cost and complexity
3.Wider spectral range
In places where the frequency content has to be analyzed, this zooming FFT can
be utilized, mainly for the hidden glitches during signal frequency transition.
APPLICATIONS:
Ultrasonic blood flow analysis.
RF communications.
Mechanical stress analysis.
Doppler radar.
Bio-medical fields.
Side band analysis, and modulation analysis