The University of Nebraska has developed a random noise radar system which transmits an ultrawideband random noise waveform with a uniform power spectral density (PSD) in the 1-2 GHz frequency range. Simulation studies and controlled laboratory tests confirm the system\u27s ability to preserve the instantaneous phase of the received signal [l, 2]. The potential of the system to characterize the Doppler shift of moving targets exhibiting varying linear and rotational velocities was clearly demonstrated [2]. This paper provides with the results of recent field experiments at a range of about 200 m which confirm the ability of the system to be used as a Doppler radar in operational scenarios

Dawood, Muhammad

Narayanan, Ram M.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Publications from the Department of Electrical and Computer Engineering Electrical & Computer Engineering, Department of 1999 Doppler Measurements Using a Coherent Ultrawideband Random Noise Radar Muhammad Dawood University of Nebraska-Lincoln Ram M. Narayanan University of Nebraska-Lincoln Follow this and additional works at: https://digitalcommons.unl.edu/electricalengineeringfacpub  Part of the Electrical and Computer Engineering Commons Dawood, Muhammad and Narayanan, Ram M., "Doppler Measurements Using a Coherent Ultrawideband Random Noise Radar" (1999). Faculty Publications from the Department of Electrical and Computer Engineering. 144. https://digitalcommons.unl.edu/electricalengineeringfacpub/144 This Article is brought to you for free and open access by the Electrical & Computer Engineering, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Department of Electrical and Computer Engineering by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Doppler Measurements Using a Coherent Ultrawideband Random Noise Radar Muhammad Dawood' and Ram M. Narayanan Department of Electrical Engineering and Center for Electro-optics University of Nebraska, Lincoln, NE 68588-0511 Tel 402-472-5141, Fax: 402-472-4732, Email: rnarayananQunl.edu 1 Introduction The University of Nebraska has developed a random noise radar system which transmits an ultrawideband random noise waveform with a uniform power spectral density (PSD) in the 1-2 GHz frequency range. Simulation studies and controlled laboratory tests confirm the system's ability to preserve the instantaneous phase of the received signal [l, 21. The potential of the system to characterize the Doppler shift of moving targets exhibiting varying l i a r  and rotational velocities was clearly demonstrated [2]. This paper provides with the results of recent field experiments at a range of about 200 m which confirm the ability of the system to be used as a Doppler radar in operational scenarios. . 2 Radar System Description A simplified block diagram of the random noise Doppler rad= is shown in Fig. 1. The noise source OSCl produces a signal with a Gaussian amplitude distribution, constant PSD, and average output level of 0 dBm (1 mW) in the 1-2 GHz frequency range. The noise source output is split into two equal i n - p h e  components in power divider PD1. A 10 Watts transmit power is achieved through a TWT broadband amplifier AMP1 and transmitted via a horn antenna ANT1. The second output of PD1 is connected to a combination of a fiber optic (FO) fixed delay line DL1 and a digitally controlled variable delay line DL2. The k e d  delay line provides 1.5 psec delay, while the variable delay line can be programmed for delays from 0 to 19.968 ns in 0.156 ns steps. The delay line output is mixed with the output of a 160 MHz phase-locked oscillator OSC2 in a lower sideband upconverter MXR1, whose outputs feed each receive chain via PD3. A 1-2 GHz signal received by antenna ANT2 provides the second input t o  mixer MXR2. the mixing operation. The 160 MHz output of MXR2 is filtered in a 160 MHz bandpass filter FL1 and split in power divider PD5. One of the outputs of PD5 is amplified in logarithmic amplifier AMP7 to yield the signal amplitude, and the other output is fed to I/Q detector IQDl to yield the in-phase (1) and quadrature (Q) components of the received signal. A similar receiver is used for the second receive chain connected to antenna ANTJ. The E/H plane beamwidths and gain of all antennas at 1.5 GHz are 23O, 34O, and 17 dB respectively. 3 Theoretical Considerations The transmit waveform of the system can be modeled as [l, 21: = a@) cos ( 2 ~  (fo f af) t + $ t }  (1) where a(t) represents the Gaussian amplitude distribution, j o  is the center frequency at 1.5 GHz, b j  is uniformly distributed over the f0 .5  GHz fkequency range, and $q is the arbitrary transmitter phase. If the target is in motion, the in-phase I and quadrature Q components of the received waveform can be shown to be [2]: 0-7803-5639-W99/$10.00 Q1999 IEEE. 2226 Published in IEEE Antennas and Propagation Society International Symposium, 1999.  Vol. 4, pp. 2226 – 2229; doi: 10.1109/APS.1999.789252  Copyright 1999 IEEE. Used by permission. Figure 1: .Block diagram of coherent ultrawideband random noise radar. where kr and kQ represent the amplitudes of the I and Q components respectively, and the instantaneous wavelength X E c/(fo f 6f). Note that Doppler frequency is not constant, but varies due to the varying nature of the instantaneous wavelength A. 4 Experimental Setup A large corner reflector with 45.7 cm tides with aradar crossection (RCS) value of 6.6 dEsm at 1.5 GHz mean frequency was chosen as the target. Since each radar range bin is 15 cm long, a linear array of such comer reflectors was mounted at a height of 3 meter atop a van. The radar system was mounted inside another van, and the antennas were mounted on top of the 10-m high telescopic boom. The distance between the stationary radar van and the moving target van was approximately 200 m. The overall geometry of these experiments is shown in Figure 2. 5 Experimental Results The target van approached the radar van along the boresight direction with approximate uniform velocities of 4.5 m/sec and 9 m/sec with corresponding mean Doppler frequencies of 45 H z  and 90 H z ,  respectively. Each experiment was also repeated at 1.5 GHz k e d  frequency, and using 1.41.6 GHz random frequency. At each speed, ten trials were carried out and h a l  results are depicted in Figures 3 and 4. These figures show the individual trials along with the extracted mean Doppler. The solid line is the averaged Doppler from ten individual trials (dotted). It can be seen that: (1) the Doppler frequency associated with a moving target can be extracted using the (2) the estimated Doppler using comparatively narrow bandwidth (i.e. 200 MHz) is (3) the Doppler spread increases at higher bandwidths and higher target velocities. UWB random noise system developed by UNL, almost identical to that using fixed frequency, and 2227 TOPVIEW ............. ..................................... " ........................... + - m 3 i  ,.+ TqaVm ................................................................. SDEVIEW .. - -203 m- Figure 2: Geometry of field experiments for Doppler measurements. 6 Conclusions The experiments demonstrate the potential of random noise radar to be used as a Doppler radar. The radar's unique concept synergistically combines the advantages of random noise transmission with the power of coherent signal processing to yield a powerful technique for velocity tracking and scanning applications. The advantages of random noise radar, such as its small size, low power and immunity from interference, make it a promising candidate for civilian and military applications. Acknowledgments This work was supported by Office of Naval Research(0NR) contract # N00014-97-1-0200. We appreciate the helpful comments provided by Dr. William Miceli of ONR. We acknowl- edge the help and cooperation extended by Dr. Steve Pappert of SPAWAR for providing us with the fiber optic delay line system. We also acknowledge the assistance of Doug Kramer, Dmitriy Garmatyuk, Daryl Bell, Evgueni Borissov and other members of Environmental Remote Sensing Lab (ERSL) of UNL during the field measurements. , References [I] R. M. Narayanan, R. D. Mueller and R. D. Palmer, "Random noise radar interferom- etry", Proc. SPIE Conference on Radar Processing, Technology, and Applications, (W. Miceli, Ed.), Volume 2845, pp. 75-82, August 1996. 121 R. M. Narayanan, M. Dawood, R. D. Mueller and R. D. Palmer, "Doppler estimation using a coherent ultrawideband random noise radar", Proc. SPIE Conference on Rador Processing, Technology, and Applications II, (W. Miceli, Ed.), Volume 3161, pp. 70-76, August 1997. 2228 I '  ' ' ' ' " 1 '  " I  (a) Transmit Frequency 1.5 GHz (fixed) I '  " " ' '  " " 1  .-awclm (b) Transmit Frequency 1.4-1.6 GHz (random) (c) 'Itansmit Frequency 1-2 GHz (random) Figure 3: Doppler spectra of target moving at  4.5 m/sec n I . .  , .Im .* 0 w tm -IM I (a) 'Itansmit Frequency 1.5 GHz (fixed) (b) 'hansmit Frequency 1.41.6 GHz (random) I "  (c) llansmit Frequency 1-2 GHz (random) Figure 4: Doppler spectra of target moving at 9 m/sec 2229 

Doppler Measurements Using a Coherent Ultrawideband Random Noise Radar

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University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Faculty Publications from the Department of 
Electrical and Computer Engineering 
Electrical & Computer Engineering, Department 
of 
1999 
Doppler Measurements Using a Coherent Ultrawideband Random 
Noise Radar 
Muhammad Dawood 
University of Nebraska-Lincoln 
Ram M. Narayanan 
University of Nebraska-Lincoln 
Follow this and additional works at: https://digitalcommons.unl.edu/electricalengineeringfacpub 
 Part of the Electrical and Computer Engineering Commons 
Dawood, Muhammad and Narayanan, Ram M., "Doppler Measurements Using a Coherent Ultrawideband 
Random Noise Radar" (1999). Faculty Publications from the Department of Electrical and Computer 
Engineering. 144. 
https://digitalcommons.unl.edu/electricalengineeringfacpub/144 
This Article is brought to you for free and open access by the Electrical & Computer Engineering, Department of at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from 
the Department of Electrical and Computer Engineering by an authorized administrator of 
DigitalCommons@University of Nebraska - Lincoln. 
Doppler Measurements Using a Coherent 
Ultrawideband Random Noise Radar 
Muhammad Dawood' and Ram M. Narayanan 
Department of Electrical Engineering and Center for Electro-optics 
University of Nebraska, Lincoln, NE 68588-0511 
Tel 402-472-5141, Fax: 402-472-4732, Email: rnarayananQunl.edu 
1 Introduction 
The University of Nebraska has developed a random noise radar system which transmits 
an ultrawideband random noise waveform with a uniform power spectral density (PSD) in 
the 1-2 GHz frequency range. Simulation studies and controlled laboratory tests confirm 
the system's ability to preserve the instantaneous phase of the received signal [l, 21. The 
potential of the system to characterize the Doppler shift of moving targets exhibiting varying 
l i a r  and rotational velocities was clearly demonstrated [2]. 
This paper provides with the results of recent field experiments at a range of about 
200 m which confirm the ability of the system to be used as a Doppler radar in operational 
scenarios. 
. 
2 Radar System Description 
A simplified block diagram of the random noise Doppler rad= is shown in Fig. 1. The noise 
source OSCl produces a signal with a Gaussian amplitude distribution, constant PSD, and 
average output level of 0 dBm (1 mW) in the 1-2 GHz frequency range. The noise source 
output is split into two equal i n - p h e  components in power divider PD1. A 10 Watts 
transmit power is achieved through a TWT broadband amplifier AMP1 and transmitted 
via a horn antenna ANT1. The second output of PD1 is connected to a combination of a 
fiber optic (FO) fixed delay line DL1 and a digitally controlled variable delay line DL2. The 
k e d  delay line provides 1.5 psec delay, while the variable delay line can be programmed for 
delays from 0 to 19.968 ns in 0.156 ns steps. The delay line output is mixed with the output 
of a 160 MHz phase-locked oscillator OSC2 in a lower sideband upconverter MXR1, whose 
outputs feed each receive chain via PD3. 
A 1-2 GHz signal received by antenna ANT2 provides the second input t o  mixer MXR2. 
the mixing operation. The 160 MHz output of MXR2 is filtered in a 160 MHz bandpass filter 
FL1 and split in power divider PD5. One of the outputs of PD5 is amplified in logarithmic 
amplifier AMP7 to yield the signal amplitude, and the other output is fed to I/Q detector 
IQDl to yield the in-phase (1) and quadrature (Q) components of the received signal. A 
similar receiver is used for the second receive chain connected to antenna ANTJ. The E/H 
plane beamwidths and gain of all antennas at 1.5 GHz are 23O, 34O, and 17 dB respectively. 
3 Theoretical Considerations 
The transmit waveform of the system can be modeled as [l, 21: 
= a@) cos ( 2 ~  (fo f af) t + $ t }  (1) 
where a(t) represents the Gaussian amplitude distribution, j o  is the center frequency at 1.5 
GHz, b j  is uniformly distributed over the f0 .5  GHz fkequency range, and $q is the arbitrary 
transmitter phase. 
If the target is in motion, the in-phase I and quadrature Q components of the received 
waveform can be shown to be [2]: 
0-7803-5639-W99/$10.00 Q1999 IEEE. 
2226 
Published in IEEE Antennas and Propagation Society International Symposium, 1999.  
Vol. 4, pp. 2226 – 2229; doi: 10.1109/APS.1999.789252  Copyright 1999 IEEE. Used by permission. 
Figure 1: .Block diagram of coherent ultrawideband random noise radar. 
where kr and kQ represent the amplitudes of the I and Q components respectively, and the 
instantaneous wavelength X E c/(fo f 6f). Note that Doppler frequency is not constant, 
but varies due to the varying nature of the instantaneous wavelength A. 
4 Experimental Setup 
A large corner reflector with 45.7 cm tides with aradar crossection (RCS) value of 6.6 dEsm 
at 1.5 GHz mean frequency was chosen as the target. Since each radar range bin is 15 cm 
long, a linear array of such comer reflectors was mounted at a height of 3 meter atop a van. 
The radar system was mounted inside another van, and the antennas were mounted on 
top of the 10-m high telescopic boom. The distance between the stationary radar van and 
the moving target van was approximately 200 m. The overall geometry of these experiments 
is shown in Figure 2. 
5 Experimental Results 
The target van approached the radar van along the boresight direction with approximate 
uniform velocities of 4.5 m/sec and 9 m/sec with corresponding mean Doppler frequencies 
of 45 H z  and 90 H z ,  respectively. Each experiment was also repeated at 1.5 GHz k e d  
frequency, and using 1.41.6 GHz random frequency. At each speed, ten trials were carried 
out and h a l  results are depicted in Figures 3 and 4. These figures show the individual 
trials along with the extracted mean Doppler. The solid line is the averaged Doppler from 
ten individual trials (dotted). 
It can be seen that: 
(1) the Doppler frequency associated with a moving target can be extracted using the 
(2) the estimated Doppler using comparatively narrow bandwidth (i.e. 200 MHz) is 
(3) the Doppler spread increases at higher bandwidths and higher target velocities. 
UWB random noise system developed by UNL, 
almost identical to that using fixed frequency, and 
2227 
TOPVIEW ............. ..................................... " ........................... 
+ - m 3 i  ,.+ TqaVm 
................................................................. 
SDEVIEW .. 
- -203 m- 
Figure 2: Geometry of field experiments for Doppler measurements. 
6 Conclusions 
The experiments demonstrate the potential of random noise radar to be used as a Doppler 
radar. The radar's unique concept synergistically combines the advantages of random noise 
transmission with the power of coherent signal processing to yield a powerful technique for 
velocity tracking and scanning applications. The advantages of random noise radar, such 
as its small size, low power and immunity from interference, make it a promising candidate 
for civilian and military applications. 
Acknowledgments 
This work was supported by Office of Naval Research(0NR) contract # N00014-97-1-0200. 
We appreciate the helpful comments provided by Dr. William Miceli of ONR. We acknowl- 
edge the help and cooperation extended by Dr. Steve Pappert of SPAWAR for providing us 
with the fiber optic delay line system. We also acknowledge the assistance of Doug Kramer, 
Dmitriy Garmatyuk, Daryl Bell, Evgueni Borissov and other members of Environmental 
Remote Sensing Lab (ERSL) of UNL during the field measurements. , 
References 
[I] R. M. Narayanan, R. D. Mueller and R. D. Palmer, "Random noise radar interferom- 
etry", Proc. SPIE Conference on Radar Processing, Technology, and Applications, (W. 
Miceli, Ed.), Volume 2845, pp. 75-82, August 1996. 
121 R. M. Narayanan, M. Dawood, R. D. Mueller and R. D. Palmer, "Doppler estimation 
using a coherent ultrawideband random noise radar", Proc. SPIE Conference on Rador 
Processing, Technology, and Applications II, (W. Miceli, Ed.), Volume 3161, pp. 70-76, 
August 1997. 
2228 
I '  ' ' ' ' " 1 '  " I  
(a) Transmit Frequency 1.5 GHz (fixed) 
I '  " " ' '  " " 1  
.-awclm 
(b) Transmit Frequency 1.4-1.6 GHz 
(random) 
(c) 'Itansmit Frequency 1-2 GHz (random) 
Figure 3: Doppler spectra of target moving 
at  4.5 m/sec 
n 
I . .  , 
.Im .* 0 w tm 
-IM 
I 
(a) 'Itansmit Frequency 1.5 GHz (fixed) 
(b) 'hansmit Frequency 1.41.6 GHz 
(random) 
I "  
(c) llansmit Frequency 1-2 GHz (random) 
Figure 4: Doppler spectra of target moving 
at 9 m/sec 
2229 


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Doppler Measurements Using a Coherent Ultrawideband Random Noise Radar

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