research article high resolution software defined radar

Hindawi Publishing CorporationJournal of Electrical and Computer EngineeringVolume 2013 Article ID 573217 7 pageshttpdxdoiorg1011552013573217

Research ArticleHigh Resolution Software Defined Radar System forTarget Detection

S Costanzo1 F Spadafora1 A Borgia1 H O Moreno2 A Costanzo1 and G Di Massa1

1 Dipartimento di Ingegneria Informatica Modellistica Elettronica e Sistemistica Universita della Calabria 87036 Rende Italy2 Facultad de Informatica y Electronica Escuela Superior Politecnica de Chimborazo Riobamba EC060155 Ecuador

Correspondence should be addressed to S Costanzo costanzodeisunicalit

Received 10 May 2013 Revised 14 July 2013 Accepted 25 August 2013

Academic Editor Alvaro Rocha

Copyright copy 2013 S Costanzo et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The Universal Software Radio Peripheral USRP NI2920 a software defined transceiver so far mainly used in Software DefinedRadio applications is adopted in this work to design a high resolution L-Band Software Defined Radar system The enhancedavailable bandwidth due to the Gigabit Ethernet interface is exploited to obtain a higher slant-range resolution with respect tothe existing Software Defined Radar implementations A specific LabVIEW application performing radar operations is discussedand successful validations are presented to demonstrate the accurate target detection capability of the proposed software radararchitecture In particular outdoor and indoor test are performed by adopting ametal plate as reference structure located at differentdistances from the designed radar system and results obtained from the measured echo are successfully processed to accuratelyreveal the correct target position with the predicted slant-range resolution equal to 6m

1 Introduction

Radar systems have been employed for a long time mainly inmilitary operation like target detection target recognitionsurveillance and other specific applications such as meteo-rology and air-traffic control However especially in the lastrecent years new kind of large-scale commercial applicationsis requiring the standard radar systemoperations but accord-ing to significant cost reduction and strong adaptabilityMedical diagnostics and automotives are just some examplesof the possible application fields According to this newoperating context Software Defined Radar (SDRadar) couldrepresent a new challenge in radar technology due to thepossibility of performing most of the basic operations (iemixing filtering modulation and demodulation) by simplyemploying software modules in order to strike out most ofthe specific hardware [1] Themain goal of a software definedapproach is related not only to a clear cost reduction but alsoto a significant increase of the versatility of the system sincesignal generation and signal processing parameters may beeasily adapted on the fly to the task under consideration Newresearches are recently conducted to implement a SDRadar

for target distance detection [2 3] but they are based on theuse of sophisticated FPGA andor DSP thus being not able toguarantee the required cost reduction

A possible solution for a low cost SDRadar systemdevelopment can be obtained by the adoption of theUniversalSoftware Radio Peripheral (USRP) transceiver A first attemptto apply USRP for target detection is performed in [4]however due to the bandwidth limitations imposed by theavailable USB connection a limited slant-range resolutionequal to 75m is obtained Interesting results are presentedin [5ndash8] where different characterizations of the USRPN200 e N210 are employed as SDRadar systems Howeverthese transceivers are not able to easily design a compactdevice moreover a full adaptability of the software codeon the fly for different scenarios can be scarcely achievedNational Instruments (NI) has recently manufactured twonew generation devices the USRPNI2920 andUSRPNI2921successfully combining the NI LabVIEW software and theUSRP hardware to deliver an affordable and easy-to-usesoftware-reconfigurable RF platform potentially suitable forexperimentation research and rapid prototyping [9] Thesedevices as yet used for teaching communication andmainly

2 Journal of Electrical and Computer Engineering

Controller

Motor

Antenna

Circulator

USRP NI 2920

SBC

5302

PA

LNA

MXE

5 V

12 V

Figure 1 Block diagram of the proposed SDRadar system

in Software Defined Radio applications [10] are consideredin this work as a potential transceiver for a compact andversatile SDRadar In particular as described in Section 2USRP NI2920 is employed in a SDRadar design for targetdetection

Since one of the most relevant problems of SDRadardeveloping is related to a low slant-range resolution due tothe low speed of its interface the main goal of this work is toexplore the potentialities of the NI new generation USRP inorder to enhance this specific parameter taking advantage oftheGigabit Ethernet Interface A LabVIEWcode is developedto both control the features of the SDRadar system as well asto perform a signal processing compression technique (notcompletely suitable for the first generation USRP interfacecapabilities) thus achieving a strongly enhanced slant-rangeresolutionwith respect to the previous systems Furthermoreexperimental indoor and outdoor tests are performed inorder to validate the system behavior in terms of targetdetection capability A possible application scenario of thedesigned L-Band SDRadar system can be represented by thelandslides monitoring in the presence of vegetated areas

2 Proposed SDRadar System

The software radar architecture proposed in this work isdeveloped to create a low cost compact and flexible solutionfor an accurate target detection potentially this scheme canbe easily adopted in different scenarios without significanthardware modification thus leading to create a multipurposeradar system The complete block diagram of the proposedSDRadar system is reported in Figure 1 The USRP 2920platform is used to transmit and receive data by a linear arrayantenna with specific bandwidth and directivity featuresuseful for the prescribed application [11ndash16]

One of the main motivations for the choice of theUSRP NI2920 is due to the enhanced available bandwidth(25MHz) when compared to the first version (2MHz) withthe possibility to significantly enhance the radar slant-rangeresolution The whole system is controlled by a LabVIEWapplication running on a compact single board computer(SBC) It is able to perform the required processing fortarget detection but it is designed also to control a motorsystem guaranteeing the antenna thus giving a scanningfeature useful for an accurate surface monitoring in differentdirections A power amplifier (PA) and a low noise amplifier

(LNA) increase the signal power along both the transmissionand the receiving paths and a circulator can also be adoptedto use a single antenna in both the transmission and thereceiving paths thus further reducing the total hardwarecosts and the size of the entire device

3 Signal Processing Algorithm

A stretch processor (SP) approach [17] according to thediagram scheme of Figure 2 is adopted to implement thesignal processing stage First the radar echo signal is mixedwith a replica (reference signal) of the transmitted waveformThen a low pass filtering (LPF) and a coherent detectionare performed in order to avoid the high frequency responsecoming from the mixer output Analog to digital (AD)conversion is subsequently applied and a bank of narrowband filters is adopted to extract the tones proportional tothe target range Finally a Fast Fourier Transform (FFT) isapplied to derive the amplitude spectrum whose peaks arerelated to the targets positions

The adopted transmitted signal is a linear frequencymodulated waveform expressed by the following equation

119904 (119905) = cos [2120587 (1198910119905 +120583

2

1199052)] 0 lt 119905 lt 120591

1015840 (1)

where 120583 = 1198611205911015840 is the LFM coefficient119861 gives the bandwidth1198910is the chirp start frequency and 1205911015840 is the chirp durationThe slant-range resolution Δ119877 is then provided by the

expression [17]

Δ119877 =

119888

2119861

(2)

thus being strictly related to the system bandwidth 119861As imposed by (2) the use of USRP NI 2920 offers a

maximum available bandwidth of 25MHz leading to havea slant-range resolution Δ119877 = 6m which is significantlyenhanced when compared to the value Δ119877 = 75m achievedwith the first generation USRP having a bandwidth 119861 =2MHz [4]

On the basis of the outlined SP technique a sophisticatedalgorithm implementing both the signal processing codeand the motor control operations is developed in LabVIEWcode (Figure 3) to obtain the proposed scanning SDRadar inFigure 1 In particular the radar system is designed to performN distinct scannings on different frames of the area underanalysis (eg mountain landslide topography surfaces andglaciers) through the controlled rotation of the radar antenna(Figure 4)

The main steps of SDRadar algorithm whose blockdiagram is given in Figure 5 can be summarized as follows

(1) Parameters definition

(i) Footprint (antenna illuminating area) of eachscan defined in terms of distance between theradar antenna and the analyzed area azimuthand elevation antenna beamwidths grazingangle and operating frequency

Journal of Electrical and Computer Engineering 3

Freq

uenc

y

fr

Trec

Referen

ce ch

irp

Time

1 2 3Local

oscillator

Frequency

Am

plitu

de

Low passfilter

Coherentdetectionand AD

SidelobeweightingMixer FFT

Freq

uenc

y

Freq

uenc

y

Return 3

f0 f1

f2

f3

120591998400

Δt

Return 2

Return 1 Return 3

Return 2Return 1

f3 = fr minus f0

f2 = fr minus f0 + uΔt

f3 = fr minus f0 + 2uΔt

TimeTime

Trec = receive windowTrec

Figure 2 Block diagram of the Stretch Processor technique

Figure 3 LabVIEW SDRadar application window

Figure 4 Schematic view of SDRadar antenna scanning

(ii) Receiving window that ensures the correctrecognition of any type of topology relative tothe surface under analysis defined by 119877min and119877max (minimum and maximum required targetrange)

(iii) Total area size giving the exact number N ofradar scannings necessary to retrieve the totaltopology

(2) Matrix definitions

The Matrix is composed by 119873 rows corre-sponding to the 119873 produced scanning and Mcolumns depending on the receiving angularwindows

(3) Main loop implementing the SP algorithm and themotor control operations

Once completing thematrix a color assignment is performedlike in a radar gram [18] Colors are helpful for the remoteview of the overall topology

4 Experimental Validations

The performance of the SDRadar system proposed in Sec-tion 2 is tested in order to verify the proper distancedetection between the radar device and a testmetal plate withdimensions equal to 122m times 091m placed orthogonally tothe direction of propagation of the radar transmitted wavesIn this particular scenario antennas are linearly polarized andthe operating central frequency is equal 18GHz so the deviceoperates as an L-band radar

Specific outdoor tests are performed on the basic systemcomposed by a PC USRP 2920 and two antennas in orderto validate the correct behavior of the transceiver in thisscenario and further indoor tests are performed on thecomplete system described in Figure 1 with the adoption ofthe same test target in order to confirm the enhanced radarresolution

41 Outdoor Tests A scheme of the outdoor test setup isreported in Figure 6 A broadband ridged horn is adoptedas transmitting antenna while a broadband logarithmic


Start Parameters definition

YesMatrix completedcolor assignment Stop

Matrix definition

0

N

(1) Stretch processor(2) Targets recognitions(3) Filling matrix

Motor movement

No

Ntimes M

Rmin

Rmax

n = 0 for n le N

n++

N scans M range

n = N

Figure 5 Block diagram of the scanning SDRadar algorithm

PC USRPTX antenna

RX antenna

Target-SDR system

Target

distance

Figure 6 Scheme of the basic system for outdoor test

Figure 7 Photograph of outdoor test setup

antenna with the same linear polarization is used in thereceiving path

With reference to the general block diagram of Figure 1the circulator the amplifiers and SBC are excluded in thisfirst validation case in order to test only theUSRPbehavior interms of radar capabilities A calibration step is preliminarilyperformed in the absence of the test target in order tocharacterize and subsequently remove the undesired reflec-tions due to the open measurement environment otherwiseproducing ldquofalserdquo peaks The test metal plate is subsequentlyplaced at three different reference distances (6m 12m and18m) from the transmittingreceiving platform in order totest the SDRadar slant-range resolution A noncongestedpedestrian zone (Figure 7) is chosen as test location in orderto have negligible contribution of multipath The results ofthe FFT processing on the receiving echo for different target

Table 1 Real and retrieved target positions with the NI-USRP 2920

Real target position [m] Retrieved target position [m]0 divide 6 66 divide 12 1212 divide 18 18

positions are illustrated in Figure 8 while a comparisonbetween the true and the software retrieved target positionsis summarized in Table 1

The results relative to the reconstruction of the threetargets positions are represented in terms of SDRadar mapdescribed in Section 4 but assuming for simplicity 119873 = 1(single scan) The corresponding radar gram reported inFigure 9 properly displays the targets positions at 6m 12mand 18m with three different colors in a gray scale

The results shown in Figures 8 and 9 confirm the properdistance detection capabilities and a resolution equal to 6mthus being 12 times less with respect to that obtained by usingthe first generation USRP in a SDRadar system

42 Indoor Tests Similar measurements are performed intothe anechoic chamber of the Microwave Laboratory at Uni-versity of Calabria in order to test the correct behavior of theentire compact system illustrated in Figure 1 A broadbandlogarithmic antenna is adopted as both transmitting andreceiving device so the two paths are separated through theuse of a circulator A scheme of the relative test setup is shownin Figure 10 As in the outdoor tests a preliminary calibrationstep is performed to avoid false peaks due to reflections inthe path between circulator and antenna power amplifier andcirculator and USRP and power amplifier Again a coppersheet is assumed as reference target and positioned at variousdistances multiple of the theoretical range resolution equalto 6m

The results of FFT performed on the received signal areillustrated in Figures 11 and 12 for target positions equal to6m and 12m respectively

In both cases the relative amplitude peaks can be properlydistinguished in the diagrams thus confirming the correctvalue of the slant-range resolution


1090807060504030201

0minus80 minus60 minus40 minus20 0 20 40 60 80 100

Nor

mal

ized

ampl

itude

Target at 6Target at 12

Target at 18

(m)

Nor

mal

ized

ampl

itude 1

095

09

085minus15minus10 minus5 0 6 12 18 25 30 35 40

(m)

Figure 8 Retrieved signal peaks for different target positions

Effective distance (m)0 6 12 18 50 100 150

1

2

3

4

5

6

7

8

9

Nra

dar s

cann

ing

Figure 9 SDRadar map for a single scanning

Circulator

USRP NI 2920

SBC 5302

PA

LNATarget-SDR system

Target

distance

MXE

5 V

12 V

Figure 10 Scheme of indoor test setup

Finally two identical metal plates are both placed in thetest zone the first one at a distance between 0m and 6m andthe second one between 6m and 12m

Both relative target positions are accurately identified bythe two main peaks corresponding to 6m and 12m (Fig-ure 13) Other lower peaks in correspondence with higherdistances multiple of the slant-range resolution representmultipaths of the radar signal between the twometallic platesHowever the low signal corresponding to multipaths does

12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude

minus50 minus40 minus30 minus20 minus10 0 60

Figure 11 Retrieved signal peaks with the target placed at 6m

12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude


Figure 13 Retrieved signal peaks with two targets placed between0 and 12m


not prevent the correct interpretation of the scene so indoortests on the entire compact device confirm the validity ofproposed approach

5 Final Discussion

The strong limitation in terms of slant-range resolution dueto the low data rate available at the interface of the first gen-eration USRP and the low adaptability of similar transmitter-receiver devices into a compact device strongly prevent thepotential use of SDRadar in several new applications as aconsequence of this the resolution enhancement along withcompactness and low costs is becoming key factor in theSDRadar research In this work the use of the new generationNI 2920 USRP has been investigated to design a compactand low-cost SDRadar system able to provide appealing slant-range resolutions with a strong improvement (from 12mto 6m) when compared to the solutions existing in theliterature The effectiveness of the proposed approach hasbeen successfully proven by indoor and outdoor tests thusleading to the attractive possibility of creating multipurposeand adaptive low cost radar systems to be applied in differentcontexts

6 Conclusions and Future Works

A low cost flexible compact and versatile solution to createan L-Band SDRadar system has been proposed in this workThe USRP NI2920 platform has been adopted for the firsttime to realize a SDRadar system for target detection Themain result of integrating NI2920 in the proposed SDRadarsystem is related to the significant enhancing of slant-rangeresolution (6m) with respect to that achieved in the existingSDRadar solutions A specific LabVIEWapplication has beendeveloped to implement the radar processing algorithm aswell as to control the various components of the system Astretch processing approach has been implemented in thesystem to fully take advantage of the benefit of the availableenhanced bandwidth Outdoor tests using a basic version ofthe proposed SDRadar scheme have been performed correctdistance measurements between the SDRadar platform andsome metallic sheets have been obtained and the expectedslant-range resolution has been achieved Indoor experimen-tal validations have been also performed to demonstrate thecorrect working of the entire proposed system in the caseof single and multiple targets As a future extension of thiswork the proposed design will be updated by implementingsupplementary signal processing features on the proposedSDRadar for instance a Doppler shift frequency analysis willbe performed for movement detection so new functions willbe added to the proposed platform with no changes in thehardware design in order to create step by step a simple lowcost and multipurpose radar

Conflict of Interests

The authors state that there are no financial or competinginterests which could influence the validity of the presentresearch

Acknowledgment

This work has been carried out under the framework of PON01 01503 National Italian Project ldquoLandslides EarlyWarningrdquofinanced by the Italian Ministry of University and Research

References

[1] T Debatty ldquoSoftware defined RADAR a state of the artrdquo inProceedings of the 2nd International Workshop on CognitiveInformation Processing (CIP rsquo10) pp 253ndash257 Brussels BelgiumJune 2010

[2] Z Hui L Lin and W Ke ldquo24GHz software-defined radarsystem for automotive applicationsrdquo in Proceedings of the 10thEuropean Conference on Wireless Technology (ECWT rsquo07) pp138ndash141 Munich Germany October 2007

[3] D Garmatyuk J Schuerger and K Kauffman ldquoMultifunctionalsoftware-defined radar sensor and data communication sys-temrdquo IEEE Sensors Journal vol 11 no 1 pp 99ndash106 2011

[4] G Aloi A Borgia S Costanzo et al ldquoSoftware defined radarsynchronization issues and practical implementationrdquo in Pro-ceedings of the 4th International Conference on Cognitive Radioand Advanced Spectrum Management (CogART rsquo11) BarcelonaSpain October 2011

[5] C Prathyusha S N Sowmiya S Ramanathan et al ldquoImple-mentation of a low cost synthetic aperture radar using soft-ware defined radiordquo in Proceedings of the 2nd InternationalConference on Computing Communication and NetworkingTechnologies (ICCCNT rsquo10) Karur India July 2010

[6] M Fuhr M Braun C Sturmz L Reichardtz and F K JondralldquoAn SDR-based Experimental Setup for OFDM-based radarrdquo inProceedings of the 7th Karlsruhe Workshop on Software RadioKarlsruhe Germany March 2012

[7] MMullerM BraunM Fuhr and F K Jondral ldquoAUSRP-basedtestbed for OFDM-based radar and communication systemsrdquoin Proceedings of the 22nd Virginia Tech Symposium on WirelessCommunications Blacksburg Va USA June 2012

[8] V Fernandes ldquoImplementation of a RADAR System usingMATLAB and the USRPrdquo CSUN ScholarWorks 2012

[9] National Instruments Data-sheet NI USRP-2920 NI USRP-2921 httparabianicom

[10] U Pesovic D Gliech P Planinsiz Z Stamenkovic andS Randic ldquoImplementation of IEEE 802154 transceiver onsoftware defined radio platformrdquo in 20th TelecommunicationsForum (TELFOR rsquo12) Belgrade Serbia November 2012

[11] S Costanzo and A Costanzo ldquoCompact slotted antenna forwideband radar applicationsrdquo Advances in Intelligent Systemsand Computing vol 206 pp 989ndash996 2013

[12] S Costanzo G A Casula A Borgia et al ldquoSynthesis of slotarrays on integrated waveguidesrdquo IEEE Antennas and WirelessPropagation Letters vol 9 pp 962ndash965 2010

[13] S Costanzo I Venneri G Di Massa and G ArriendolaldquoHybrid array antenna for broadband millimeter-wave applica-tionsrdquoProgress in Electromagnetics Research vol 83 pp 173ndash1832008

[14] F Venneri S Costanzo G Di Massa and G AmendolaldquoAperture-coupled reflectarrays with enhanced bandwidth fea-turesrdquo Journal of Electromagnetic Waves and Applications vol22 no 11-12 pp 1527ndash1537 2008

[15] F Venneri S Costanzo and G Di Massa ldquoTunable reflectarraycell for wide angle beam-steering radar applicationsrdquo Journal


of Electrical and Computer Engineering vol 2013 Article ID325746 7 pages 2013

[16] F Venneri S Costanzo and G DiMassa ldquoDesign of a reconfig-urable reflectarray unit cell for wide angle beam-steering radarapplicationsrdquo Advances in Intelligent Systems and Computingvol 206 pp 1007ndash1013 2013

[17] B R Mahafza and A Z Elsherbeni Simulations for RadarSystems Design Chapman amp HallCRC New York NY USA1999

[18] M Skolnik Radar Handbook McGraw Hill San FranciscoCalif USA 3rd edition 2008

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



Controller

Motor

Antenna

Circulator

USRP NI 2920

SBC

5302

PA

LNA

MXE

5 V

12 V

Figure 1 Block diagram of the proposed SDRadar system

in Software Defined Radio applications [10] are consideredin this work as a potential transceiver for a compact andversatile SDRadar In particular as described in Section 2USRP NI2920 is employed in a SDRadar design for targetdetection

Since one of the most relevant problems of SDRadardeveloping is related to a low slant-range resolution due tothe low speed of its interface the main goal of this work is toexplore the potentialities of the NI new generation USRP inorder to enhance this specific parameter taking advantage oftheGigabit Ethernet Interface A LabVIEWcode is developedto both control the features of the SDRadar system as well asto perform a signal processing compression technique (notcompletely suitable for the first generation USRP interfacecapabilities) thus achieving a strongly enhanced slant-rangeresolutionwith respect to the previous systems Furthermoreexperimental indoor and outdoor tests are performed inorder to validate the system behavior in terms of targetdetection capability A possible application scenario of thedesigned L-Band SDRadar system can be represented by thelandslides monitoring in the presence of vegetated areas

2 Proposed SDRadar System

The software radar architecture proposed in this work isdeveloped to create a low cost compact and flexible solutionfor an accurate target detection potentially this scheme canbe easily adopted in different scenarios without significanthardware modification thus leading to create a multipurposeradar system The complete block diagram of the proposedSDRadar system is reported in Figure 1 The USRP 2920platform is used to transmit and receive data by a linear arrayantenna with specific bandwidth and directivity featuresuseful for the prescribed application [11ndash16]

One of the main motivations for the choice of theUSRP NI2920 is due to the enhanced available bandwidth(25MHz) when compared to the first version (2MHz) withthe possibility to significantly enhance the radar slant-rangeresolution The whole system is controlled by a LabVIEWapplication running on a compact single board computer(SBC) It is able to perform the required processing fortarget detection but it is designed also to control a motorsystem guaranteeing the antenna thus giving a scanningfeature useful for an accurate surface monitoring in differentdirections A power amplifier (PA) and a low noise amplifier

(LNA) increase the signal power along both the transmissionand the receiving paths and a circulator can also be adoptedto use a single antenna in both the transmission and thereceiving paths thus further reducing the total hardwarecosts and the size of the entire device

3 Signal Processing Algorithm

A stretch processor (SP) approach [17] according to thediagram scheme of Figure 2 is adopted to implement thesignal processing stage First the radar echo signal is mixedwith a replica (reference signal) of the transmitted waveformThen a low pass filtering (LPF) and a coherent detectionare performed in order to avoid the high frequency responsecoming from the mixer output Analog to digital (AD)conversion is subsequently applied and a bank of narrowband filters is adopted to extract the tones proportional tothe target range Finally a Fast Fourier Transform (FFT) isapplied to derive the amplitude spectrum whose peaks arerelated to the targets positions

The adopted transmitted signal is a linear frequencymodulated waveform expressed by the following equation

119904 (119905) = cos [2120587 (1198910119905 +120583

2

1199052)] 0 lt 119905 lt 120591

1015840 (1)

where 120583 = 1198611205911015840 is the LFM coefficient119861 gives the bandwidth1198910is the chirp start frequency and 1205911015840 is the chirp durationThe slant-range resolution Δ119877 is then provided by the

expression [17]

Δ119877 =

119888

2119861

(2)

thus being strictly related to the system bandwidth 119861As imposed by (2) the use of USRP NI 2920 offers a

maximum available bandwidth of 25MHz leading to havea slant-range resolution Δ119877 = 6m which is significantlyenhanced when compared to the value Δ119877 = 75m achievedwith the first generation USRP having a bandwidth 119861 =2MHz [4]

On the basis of the outlined SP technique a sophisticatedalgorithm implementing both the signal processing codeand the motor control operations is developed in LabVIEWcode (Figure 3) to obtain the proposed scanning SDRadar inFigure 1 In particular the radar system is designed to performN distinct scannings on different frames of the area underanalysis (eg mountain landslide topography surfaces andglaciers) through the controlled rotation of the radar antenna(Figure 4)

The main steps of SDRadar algorithm whose blockdiagram is given in Figure 5 can be summarized as follows

(1) Parameters definition

(i) Footprint (antenna illuminating area) of eachscan defined in terms of distance between theradar antenna and the analyzed area azimuthand elevation antenna beamwidths grazingangle and operating frequency


Freq

uenc

y

fr

Trec

Referen

ce ch

irp

Time

1 2 3Local

oscillator

Frequency

Am

plitu

de

Low passfilter



Freq

uenc

y

Freq

uenc

y

Return 3

f0 f1

f2

f3

120591998400

Δt

Return 2

Return 1 Return 3

Return 2Return 1

f3 = fr minus f0



TimeTime


















Matrix definition

0

N


Motor movement

No

Ntimes M

Rmin

Rmax

n = 0 for n le N

n++

N scans M range

n = N


PC USRPTX antenna

RX antenna

Target-SDR system

Target

distance














1090807060504030201


Nor

mal

ized

ampl

itude


Target at 18

(m)

Nor

mal

ized

ampl

itude 1

095

09


(m)



1

2

3

4

5

6

7

8

9

Nra

dar s

cann

ing


Circulator

USRP NI 2920

SBC 5302

PA


Target

distance

MXE

5 V

12 V




12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude





5 Final Discussion






Acknowledgment


References























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Freq

uenc

y

fr

Trec

Referen

ce ch

irp

Time

1 2 3Local

oscillator

Frequency

Am

plitu

de

Low passfilter



Freq

uenc

y

Freq

uenc

y

Return 3

f0 f1

f2

f3

120591998400

Δt

Return 2

Return 1 Return 3

Return 2Return 1

f3 = fr minus f0



TimeTime


















Matrix definition

0

N


Motor movement

No

Ntimes M

Rmin

Rmax

n = 0 for n le N

n++

N scans M range

n = N


PC USRPTX antenna

RX antenna

Target-SDR system

Target

distance














1090807060504030201


Nor

mal

ized

ampl

itude


Target at 18

(m)

Nor

mal

ized

ampl

itude 1

095

09


(m)



1

2

3

4

5

6

7

8

9

Nra

dar s

cann

ing


Circulator

USRP NI 2920

SBC 5302

PA


Target

distance

MXE

5 V

12 V




12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude





5 Final Discussion






Acknowledgment


References























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Matrix definition

0

N


Motor movement

No

Ntimes M

Rmin

Rmax

n = 0 for n le N

n++

N scans M range

n = N


PC USRPTX antenna

RX antenna

Target-SDR system

Target

distance














1090807060504030201


Nor

mal

ized

ampl

itude


Target at 18

(m)

Nor

mal

ized

ampl

itude 1

095

09


(m)



1

2

3

4

5

6

7

8

9

Nra

dar s

cann

ing


Circulator

USRP NI 2920

SBC 5302

PA


Target

distance

MXE

5 V

12 V




12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude





5 Final Discussion






Acknowledgment


References























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










1090807060504030201


Nor

mal

ized

ampl

itude


Target at 18

(m)

Nor

mal

ized

ampl

itude 1

095

09


(m)



1

2

3

4

5

6

7

8

9

Nra

dar s

cann

ing


Circulator

USRP NI 2920

SBC 5302

PA


Target

distance

MXE

5 V

12 V




12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude



12 20 30 40 50

02

04

06

08

1

Range (m)

Nor

mal

ized

ampl

itude





5 Final Discussion






Acknowledgment


References























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











5 Final Discussion






Acknowledgment


References























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









research article high resolution software defined radar

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