A FMCW-FSK Combined Waveform for Multi-Target Detection in FMCW Radar

Transcription

1 217 2 n Inernaional Conerence on Compuer Engineering, Inormaion Science an Inerne Technology (CII 217) ISBN: A FMCW-FSK Combine Waveorm or Muli-Targe Deecion in FMCW Raar TAO SHEN, WENQUAN CHE, KUAN DENG an WENJIE FENG ABSTRACT Frequency moulae coninuous wave (FMCW) raar has been wiely applie in many iels. Moulae waveorm is usually esigne o solve he coupling problem o range an velociy in muli-arge siuaion. A FMCW-FSK combine waveorm is propose in his work, which akes he avanages o FMCW waveorm an FSK waveorm. Compare o he FMCW waveorm an FSK waveorm, his meho can reuce he ghos arges an he misse arges urhes wih minor error an less calculaion cos. INTRODUCTION The esign o he requency-moulae waveorm has an inluence on he number o ghos arges an misse arges. Traiional FMCW raar ransmis a muli-perio symmeric riangular requency-moulae wave. I has large aa volume. To aress his issue, a slope-changeable riangular requency-moulae meho was propose in [2]. I only nees wo or hree perios o requencymoulae wave an hus has low compuaional complexiy. However, i woul bring ou some ghos arges an misse arges as well. A FMCW-CW combine waveorm [3] was propose o reuce he ghos arges while misse arges sill exis easily. Anoher waveorm is Frequency-shi keying (FSK) wave [4]. I provies a high velociy resoluion an avois ghos arge bu canno isinguish ixe arge or moving arges wih same velociy. A new waveorm is propose in his work. I can reuce ghos arges an misse arges simulaneously, while i has minor error an less calculaion cos. WAVEFORM DESIGN IN CW RADAR For CW raar, he requency an phase o echo signal are ieren rom ransmie signal because o he range an velociy o he arges. The range an velociy can be calculae by he ierence o requency an phase. PRINCIPLE OF LFMCW RADAR DETECTION The common LFMCW raar uses he moulae waveorm as Figure 1. Compare o ransmie signal, echo signal has a elay an a Doppler requency Tao Shen, Wenquan Che, Wenjie Feng, Nanjing Universiy o Science an Technology, Jiangsu, China Kuan Deng, Jinling Universiy o Technology, Jiangsu, China 76

2 B Echo signal or ixe arge Echo signal or moving arge b T 2T Figure 1. Principle o LFMCW waveorm. shi. The bea requencies an be expresse as ollows, b b (1) Here b cause by he isance o arge is expresse as b 4 BR / Tc an is expresse as 2 v/. Then isance R an velociy v can be calculae by ct R ( ), c v ( ) 8B (2) 4 Where is he carrier saring requency, B is he moulae banwih, is lengh o wave, an T is he moulae perio. PRINCIPLE OF FSK WAVEFORM DETECTION The ransmie signal o FSK raar consiss o wo iscree requencies A an B. FSK raar uses he moulae waveorm as Figure 2. There are wo ajacen perios o requency signal in Figure 2. B Echo signal A T 2T Figure 2. Principle o FSK waveorm. The bea signal o he ajacen perios has a phase ierence cause by he isance o arges. The isance R is calculae by he ollowing equaion: c R (3) 4 sep 77

3 THE PROPOSED MODULATED WAVEFORM 1 B1 2 3 B3 B B4 Echo signal T 2T 3T 4T 5T 6T Figure 3. Principle o LFMCW-FSK waveorm. Figure 3 shows he propose FMCW-FSK waveorm which consiss o six segmens in each perio: segmen 2 an 5 are wo up ramps while segmen 3 an 6 are own ones. The corresponing slopes are expresse as k1, k2, k 3 an k 4. The remaining segmen 1 an 4 are wo la pars wih a requency sep. The process o his meho above is lise as below an shown Figure 4. Sep 1: For each segmen, 124-poin FFT is carrie ou o ge a series o peak requencies. For segmen 2 an 5, he number o peak requencies are m1 an m2 while segmen 3 an 6 are n1 an n2. For segmen 1 an 4, he number o peak requencies is y. So y groups o range an velociy can be obaine. Sep 2: Then x is he maximum o m1, m2, n1, n2. I x is bigger han y, i comes o sep 3-2 oherwise sep 3-1. Sep 3-1: In his siuaion, m is he maximum o m1 an m2 while n or n1 an n2. The corresponing slopes are k m an k n. We can ge m n groups o range an velociy. An we use he y resuls rom FSK waveorm o mach he m n groups. Sep 3-2: In his siuaion, we mach m1 n1 groups an m2 n2 groups irs o ge a maching resul. Then we use he velociy rom y resuls o mach he maching resul above. Bea signal : segmen1 o segmen6 FFT Compare x > y? Mach or FMCW-CW Mach or FMCW-FSK SIMULATION RESULTS Figure 4. Process o LFMCW-FSK waveorm. We assume wo siuaions as Table 1. Oher parameers are as ollows: B1=1MHz, B2=99MHz, B3=24MHz, B4=25MHz, T=1ms, 1MHz. Aer FFT in siuaion 1, m1=n1=m2=n2=5, y=2 while m1=2, n1=5, m2=3, n2=2, y=5 in siuaion 2. 78

4 TABLE I. PARAMETERS OF SIMULATION. Siuaion 1 Siuaion 2 Range(m) Velociy(m/s) Range(m) Velociy(m/s) Figure 5. Resuls o simulaion. The resuls o simulaion are shown in Figure 5. An imaginary line a zero velociy is use o in he ixe arges. From Figure 5, we can see here are ive arges eece in siuaion 1 an siuaion 2. The black arrows show he eece arges. CONCLUSION A FMCW-FSK combine waveorm or muli-arge eecion is propose in his work. This meho akes he avanages o boh FMCW waveorm an FSK waveorm. I reuces he number o ghos arges an misse arges wih minor error an less calculaion cos. The simulaion resuls show ha he real arges can be eece accuraely. ACKNOWLEDGEMENTS This work is suppore by Naional Naural Science Founaion o China ( ). Corresponing auhor: Wenquan Che, Nanjing Universiy o Science an Technology, Jiangsu, China REFERENCES 1. R. H. Rasshoer an K. Gresser, Auomoive Raar an Liar Sysem or Nex Generaion Driver Assisance Funcions, Av. Raio Sci., vol. 3, pp , Jian Li, Wenquan Che, Tao Shen, An improve waveorm or muli-arge eecion in FMCW vehicle raar, 7 h Inernaional Conerence on Mecharonics, Conrol an Maerials (ICMCM),

5 3. D. Duraj, M. Ploka, M. Rzymowski, K. Nyka, L. Kulas, Measuremen o Disance, Velociy an Angle o Arrival using FMCW-CW Combine Waveorm, s Inernaional Conerence on Microwave, Raar an Wireless Communicaions (MIKON), Hermann Rohling, Marc-Michael Meinecke, Waveorm Design Principles or Auomoive Raar Sysems, 21 CIE Inernaional Conerence on Raar Proceeings, 21, pp