Doppler velocimetry system design and FPGA realization
Zhilong Deng
School of Electronics
and Information
Northwestern
Polytechnical
University
Xi'an ,China
626601575@qq.com
Liyan Liu
Department of
Automation
Northwestern
Polytechnical
University
Xi'an ,China
626601575@qq.com
Ruijun Jing
Department of
Automation
Northwestern
Polytechnical
University
Xi'an ,China
626601575@qq.com
Litao Jiao
Department of
Automation
Northwestern
Polytechnical
University
Xi'an ,China
626601575@qq.com
Abstract—In order to improve the accuracy of
Measuring Velocity from Doppler Radar, the method
of extraction proposed is based on the cycle frequency
spectrum of the center of gravity for the frequency
spectrum. The collected doppler radar signal is used
to make simulations for Periodogram Method and the
frequency spectrum of gravity method. The core of
FFT in IPCore of FPGA i s used to implement
algorithm to complete the design combined with
signal conditioning circuitry and A/D data acquisition.
Experimental results show that the center of gravity
of the frequency spectrum of the frequency extraction
methods improve the accuracy for measuring velocity.
Keywords-Power spectral center of gravity;
Velocimetry of Radar; FPGA
I. INTRODUCTION
Nowadays, with the increasingly widespread
application of radar, Microwave doppler radar plays
an increasingly important role in civilian areas.
With strong penetrating power of microwave
signals, the signal such as speed and distance can be
output all day long. In the test of speed and time,
the method sp ectrum analysis is used, which can
extract useful signal from complex background
interference and noise to improve test precision,
reliability and anti-interf erence ability. Fast Fourier
(FFT) and kalman filter were used to process signal
to get the frequency of the target, because it needs
to establish state equations and observation
equations, the statistical problems[4] for noise
observation could b e caused by processing the data.
The phase difference method[3] needs higher
signal-to-noise ratio. , to estimate the frequency and
initial phase of the signal by measuring the
instantaneous phase in the time domain needs
higher signal-to-noise ratio. This paper uses the
periodogram method of classic spectrum analysis
method[5] to make some progress in frequency
identification and more accuracy speed can be get.
The system with FPGA is based on the above
algorithm.
II. R
ADAR SPEED MEASURING PRINCIPLE AND
ALGORITHM ANALYSIS
A. Microwave radar speed measuring principle
System uses 24 GHZ k-band continuous wave
radar, let the transmitting signal expressed as:
0
(t) Acos(2 t )sf
(1)
where A is amplitude,
0
f
is the frequency
of the signal,
is the initial phase.
The echo signal
(t)
r
S
that radar antenna
receives can be expressed as:
0
S(t) (t t) kAcos[2 (t t) ]
rr r
ks f
where
2/C
r
tR
,
R
is the distance
between the target and the radar transmitter,
k
is
attenuation coefficient of the reflected wave. If the
target is stationary,
R
is constant, the phase
between the echo signal and the transmitted wave is
fixed.
When faced with the moving target at the
radial velocity
r
v
, the generated doppler frequency
d
f
can be expressed as:
0
[2 (C )]
drr
ffv v
(2)
Generally,
r
Cv
,so
0
/2
rd
vf
,where
00
Cf
is the wavelength of the
electromagnetic wave. Because
r
v
is known, the
speed of the target object could b e r ealized by
knowing
d
f
.
B. Periodogram method
Schuster first proposed periodogram in 1899,
the limited observations
0, 1, , 1xx xN
of
the stationary random signal
Xn
are taken to
estimate the power spectrum
S
:
2014 Sixth International Conference on Computational Intelligence and Communication Networks
978-1-4799-6929-6/14 $31.00 © 2014 IEEE
DOI 10.1109/.210
999
2014 Sixth International Conference on Computational Intelligence and Communication Networks
978-1-4799-6929-6/14 $31.00 © 2014 IEEE
DOI 10.1109/CICN.2014.210
998
2014 Sixth International Conference on Computational Intelligence and Communication Networks
978-1-4799-6929-6/14 $31.00 © 2014 IEEE
DOI 10.1109/CICN.2014.210
997