Wirele Senor Nework, 9, 1, 93-99 doi:1.436/wn.9.1436 Publihed Online November 9 (hp://www.cirp.org/journal/wn). A New Mehod for Ani-Noie FM Inerference Abrac Changyong JIANG, Meiguo GAO, Defeng CHEN Deparmen of Elecronic Engineering, Beijing Iniue of Technology, Beijing, China Email: jiehi8@gmail.com Received May 3, 9; revied June, 9; acceped June 1, 9 Noie Frequency Modulaed (NFM) inerference caue a diaer o almo all ype of Radar yem. The echo ignal and he inerference are overlapped and becaue of rong energy of he NFM inerference nohing could be deeced excep he inerference in he Radar receiver yem. Up o now no good mehod again NFM ha been declared, convenional mehod are baed on he paive Radar o rack he inerference ource which are no applicable under mo condiion. Here a novel ani-noie FM mehod i propoed o uppre he NFM inerference, he mehod muliply he mixed ignal wo ime by differen reference ignal. The principle and ome key facor of he new mehod are analyzed in deail and ome rule for parameer deigning are given. Wha more, reul how ha he mehod can eradicae NFM effecively. Keyword: ECM, ECCM, NFM Inerference, Ani-NFM 1. Inroducion FM jamming i a common jamming form in oppreive jamming on radar yem [1 ]. Noie FM i a moly ued ECM mehod, and can caue diaer o nearly all ype of Radar yem. So, analyi of he performance of NFM in ECM and oluion again NFM in ECCM ha developed for year. [3] Propoed he noie FM jamming mehod. The effec of noie FM jamming again ISAR one or wo-dimenional imaging i decribed in deail, and he power requiremen of noie FM jamming i compared wih ha of RF noie jamming. Song [4] ue growh facor analyzed he capabiliy of radar MTI in noie FM jamming. Liu [5] ue ignal o jamming raio (SJR) gain dicued he performance of ani-noie FM jamming of PRC-BPM fuze. [6] ue he effec of Doppler frequency, peudo-random code widh, he effec of period peudo-random code erial and aiming frequency deviaion analyzed he performance of he peudo-random code binary phae modulaed (PRC- BPM) fuze. Xu [7] gave mehod of mulipah jammer racking wih a paive radar eeker. Chen [8] udied he formula of compoie phae-difference of wo noie FM jamming. Deergha Rao. K. [9] preened an approach baed on jammer inananeou frequency eimaion for uppreion of frequency modulaed jammer in pread pecrum yem. [1] Focu on Subpace Projecion Technique for uppreion of jamming in narrowband FM jammer, however, NFM inerference i a wideband inerference ha hi echnique in [1] canno be applied. [11] preened performance analyi of ubpace projecion array proceing echnique for uppreion of frequency modulaed (FM) jammer in GPS receiver, and baed on hi [1] made he approach applied o AM-FM jammer a well, however, he ubpace projecion echnique are no available under ome radar receiver. [13] offered a mehod again NFM baed on Square Tranformaion, however, i i only decribed in he applicaion of Peudo-random Coded Fuze and analog circui. Above all, hee reearche made big progre in finding oluion again NFM, bu he mehod canno oally reolve he problem in he radar yem. Baed on all he previou reearche, a mehod i propoed o eliminae NFM in hi paper. I muliply he mixed ignal by wo differen reference ignal wo ime and wih followed ignal proceing he needed ignal can be obained from he oupu. The paper i organized a follow. In Secion, he echo ignal model and NFM inerference model are decribed in deail. Secion 3 depic how he new mehod uppoed here excie NFM inerference and ome key facor of he mehod are analyzed. Secion 4 give he performance analyi of he mehod. And ome concluion are given in he la ecion.. Signal Model Noie FM i a commonly ued mehod for jamming wirele communicaion yem uch a Radar yem, GPS ec. I ha a rong uppre o he needed ignal and Copyrigh 9 SciRe.
94 C. Y. JIANG ET AL. i bandwidh i much wider han he needed ignal. The noie-fm i modeled a1 co A k f d (1) NFM i ci where A i i he ampliude of NFM inerference, ci i he carrier frequency of NFM inerference, and k i he FM lope. The bandwidh of he NFM inerference i BW i. The echo ignal from he arge i defined a ue u cock A where A u i he ampliude of he echo ignal, c i he carrier frequency of he echo ignal, and k i he FM lope (k = when he ignal ue () i CW and k when he ignal ue () i chirp ). The bandwidh of he echo ignal i BW. I i known ha in order o make he inerference more effecive, ci c, Ai A and u BWi BW mu be aified. Thu i i hard o obain he needed ignal ue () neiher from ime domain nor frequency domain. Wihou lo of generaliy, mixed ignal which ener he radar receiver i defined a NFM ue Thi par imply how wha he new mehod derivae from. I i uppoed ha wo variable, a and b are here. How o change each oher value wihou any oher variable? A imple decripion of olving hi queion i hown below. Fir, le a ab (4) Now he value of variable a become um of a and b, he value of variable b remain he ame. Second, le bab (5) hen he value of variable a remain he ame, he value of variable b become he value of a which i before Equaion (4). La, le a ab (6) And he aim of changing value of a and b i reached. () (3) where NFM () i defined in Equaion (1), ue () i defined in Equaion (). 3. Nfm Exciion 3.1. Baic Concep Similarly, if wo ignal are mixed ogeher, i i poible o eparae hem in he ame way above. 3.. Principle of he New Mehod A i known o all, i i eay o ge wo ignal added wih each oher in he frequency domain ju by muliplying each oher. Two ignal muliplied wih each oher in he ime domain mean ha heir frequencie are added wih each oher in he frequency domain. In hi way he new mehod conain wo ep which mainly coni of wo muliplicaion, o i i called double-muliplicaion mehod in he nex chaper. 3..1. The Fir Sep of Double-Muliplicaion Mehod The fir ep of double-muliplicaion mehod can be een from Figure 1. I conain a muliplicaion, a low pa filer and DC blocked module. The muliplicaion i M (7) And all par obained afer hi muliplicaion are a follow, direc curren: A / A / DC u i low frequency par: M1 i u ci c (8) AA co k f d k (9) he par whoe carrier frequency i nearly wice a large a : c 1 A / co M u c /co M Ai ci k f d (1) (11) AA co k f d k (1) M3 i u ci c Afer M () goe hrough a low pa filer and DC blocked module, ignal decribed in Equaion (8), (1), (11), (1) are filered and only M1 () i lef. 3... The Second Sep of Double-Muliplicaion Mehod The econd ep of double-muliplicaion mehod can be een from Figure 1. I conain a muliplicaion, a band pa filer. The econd muliplicaion i (13) M M1 And all he par obained are a follow. The par whoe carrier frequency i nearly he ame wih : c co (14) A A k k f d M1 u i c ci Copyrigh 9 SciRe. IJCNS
M AuAi co cik f d (15) i u ck 3 A A co M M4 i u ci c A A co k f d k C. Y. JIANG ET AL. 95 (16) (17) I i obviou ha M3 () i he needed ignal which ju only ha a differen ampliude wih ue (). Le M () go hrough a band pa filer (BPF) which ha a cener frequency of f c and a bandwidh of BW. A i known ha A i >>A u, M1 () and M () can be omied compared o M3 (). Wha more, a BW i >>BW and M4 () ha a bandwidh of BW i, M4 () lef lile afer he band pa filer. Thu he needed ignal i obained. The whole proce of he mehod i hown in Figure 1. 3.3. Analyi of Key Facor in Double- Muliplicaion Mehod The oupu ignal, ou (), from he proce of double-muliplicaion mehod conain four par which are decribed in Equaion (14), (15), (16) and (17). Uually he higher he inerference o ignal raio (ISR) i, he more effecively he inerference work; and he wider he bandwidh of NFM inerference i, he more effecively he inerference work. So he wo facor, ISR and he bandwidh of NFM inerference, are analyzed a follow. 3.3.1. Inerference o Signal Raio 1) Relaionhip beween ISR and SIR The inerference o ignal raio (ISR) i defined a ISR log1( Ai / A u) (18) From Equaion (18) i i known ha he higher he ISR i, he bigger he A i /A u i. According o Equaion (15), (16) and (17), among he oupu ignal M () he needed ignal o inerference raio i SIR 1log1 P M 3 / P M P M 4 log1 AA i u/ AA u i AA i ubw/ BW (19) i log1 1/ Au / Ai BW / BWi For a cerain bandwidh of NFM inerference, he BW/BW i i a conan. A ISR increae, A i /A u alo increae, hu SIR decribed in Equaion (19) increae, oo. Hence a concluion i obained: he higher he ISR i, + delay + DC M ou M M 1 LPF BPF A blocked B C D The fir ep The econd ep Figure 1. Srucure of double-muliplicaion mehod. he bigger he SIR i, which mean ha he higher he ISR i, he more efficien he new mehod i. ) Relaionhip beween ISR and low pa filer Wihin he fir ep of double-muliplicaion mehod, afer muliplicaion he power of M () o M1 () raio i MM1R log1 Au / A () i Alhough he carrier frequency of M () i nearly wice a large a c and M () i ou of he paband of LPF, if he opband aenuaion of LPF i maller han M 1 M1 R, he inerference ignal M () may no be filered from M1 () by he low pa filer. So he deign of opband aenuaion of LPF mu be bigger han M 1 M1 R db. Hence anoher concluion i obained: he higher he ISR i, he bigger he opband aenuaion of LPF mu be. Above all, wo concluion relaed o ISR are obained a follow. The higher he ISR i, he more efficien he double-muliplicaion mehod i. The higher he ISR i, he bigger he opband aenuaion of LPF mu be. 3.3.. Bandwidh of NFM Inerference For a cerain ISR, he A u /A i i a conan. A BW i, he bandwidh of NFM increae, SIR decribed in Equaion (19) increae, oo. So he bigger he bandwidh of NFM inerference i, he higher he SIR i, which mean ha he more efficien he double-muliplicaion mehod i. However, he bandwidh of NFM inerference i unknown under mo condiion. Thu he opband of he low pa filer canno be decided. If he opband of he LPF i maller han he bandwidh of NFM inerference, he oupu of he fir ep, i.e. M1 (), may no be correcly obained. There are wo way o olve hi problem: 1) Meauring he bandwidh of NFM inerference if he receiver yem i capable of hi; ) Deigning he LPF wih a high opband a poible a he receiver yem can. Above all, concluion relaed o bandwidh of NFM inerference are drawn a follow. The bigger he bandwidh of NFM inerference i, he more efficien he new mehod i. When bandwidh of NFM inerference i unknown, i i beer o meaure he bandwidh of NFM inerference, oherwie o deign he LPF wih a high opband a poible a he receiver yem can. 4. Performance Analyi Wihou lo of generaliy, conidering he echo ignal i CW ignal and A ue =1, f c =1.MHz. And imulaion reul are depiced a follow. Copyrigh 9 SciRe.
96 C. Y. JIANG ET AL. I i uppoed ha he bandwidh of NFM inerference i known a MHz and ISR i 4dB. Simulaion reul can be een from Figure and Figure 3. In Figuer he graph above i he pecrum of he mixed ignal which conained he echo ignal and he NFM inerference, he graph below how he pecrum of he ignal which i he oupu (a do B in Figure 1) afer he fir ep. In Figure 3 he graph above i he pecrum of ignal which i he oupu (a do C in Figure 1) afer he econd muliplicaion, he graph below how he pecrum of ignal which i he oupu (a do D in Figure 1) afer he whole proce of double-muliplicaion mehod. From he graph above in Figure i i obviou ha he echo ignal and NFM inerference are overlapped wih each oher and he echo ignal canno be diinguihed from he inerference. However, he graph below in Figure 3 how ha he oupu ignal i mainly he echo ignal afer he proce of double-muliplicaion mehod. 3 x 15 1 8 1 1 14 16 18 The pecrum of mixed ignal (MHz) 1.5.5 x 15 1 1 3 4 5 6 7 8 9 The pecrum of ignal afer he fir ep. (MHz) 1 Figure. Specrum of ignal a differen ime. 15 x 17 1 5 X: 1. Y: 1.38e+8 8 1 1 14 16 18 The pecrum of ignal afer he econd muliplicaion. (MHz) 6 x 17 4 X: 1. Y: 5.179e+7 8 1 1 14 16 18 The pecrum of oupu ignal. (MHz) Figure 3. Specrum of ignal a differen ime. Copyrigh 9 SciRe. IJCNS
C. Y. JIANG ET AL. 97 1 8 6 SIR (db) 4-1 3 4 5 6 7 8 9 1 ISR (db) Figure 4. SIR a differen ISR. 4.1. Simulaion of ISR A menioned above, when he ISR increae he opband aenuaion of LPF increae and he SIR increae. Thee wo relaionhip are imulaed a follow. 4.1.1. The Relaionhip beween ISR and SIR I i uppoed ha he ISR varie from ~1 db, he bandwidh of NFM inerference i known a MHz, and he bandwidh of band pa filer (BPF) i 1 MHz. Figure 4 how he SIR a differen ISR. I i obviou ha he larger he ISR i, he larger he SIR i, which confirm he concluion obained above. 4.1.. Deign of Sopband Aenuaion of LPF Conider he ISR varie from ~1 db, he opband aenuaion of LPF are db and 1 db. The graph below in Figure 5 how he reul when he opband aenuaion of i db and he graph above how he reul when he opband aenuaion of i 1 db. I i obviou ha a mall opband aenuaion of LPF will caue error o he oupu and high ISR need large opband aenuaion of LPF, which alo confirm he concluion above. NFM. Figure 6 how he frequency of oupu ignal wih differen bandwidh of NFM inerference. And a concluion i obained: if he opband of LPF i larger han he bandwidh of NFM inerference, he needed ignal can be go correcly. 4... Bandwidh of NFM Inerference i Unknown A he bandwidh of NFM inerference i unknown, i i uppoed ha i i MHz and MHz. Figure 7 how he obained frequency when he opband of LPF i MHz and Figure 8 how he obained frequency when he opband of LPF i MHz. From Figure 7 and Figure 8, i i known ha when he bandwidh of NFM inerference i unknown, o deign he opband of LPF a big a poible will help o make he mehod more efficien. (MHz) Frequency 1 11 1 99 1 3 4 5 6 7 8 9 1 ISR (db) 1.3 4.. Bandwidh of NFM Inerference Conider he bandwidh of NFM inerference varie from ~4 MHz, ISR i 4 db. 4..1. Bandwidh of NFM Inerference i Known A he bandwidh of NFM inerference i known, he opband of LPF i bigger han all he bandwidh of 1. 1.1 1 1 3 4 5 6 7 8 9 1 ISR (db) Figure 5. Frequency of oupu a differen ISR. Copyrigh 9 SciRe.
98 C. Y. JIANG ET AL. 11.5 11 1.5 1 99.5 99 5 1 15 5 3 35 4 Bandwidh of NFM (MHz) 1.6 1.5 1.4 1.3 1. 1.1 1 99.9 99.8 99.7 Figure 6. Frequency of oupu ignal. 99.6 5 1 15 5 3 35 4 Bandwidh of NFM (MHz) 11.5 11 1.5 1 99.5 Figure 7. Frequency of oupu ignal. 99 5 1 15 5 3 35 4 Bandwidh of NFM (MHz) 5. Concluion Figure 8. Frequency of oupu ignal. NFM inerference can uppre he ueful ignal boh in he ime domain and in he frequency domain. The new mehod uppoed in hi paper can eliminae he effec of he NFM inerference. Some concluion are obained: The higher he ISR i, he more efficien he double-muliplicaion mehod i. The higher he ISR i, he bigger he opband aenuaion of LPF mu be. The bigger he bandwidh of NFM inerference i, he more efficien he double-muliplicaion mehod i. When bandwidh of NFM inerference i unknown, i i beer o meaure he bandwidh of NFM inerference if poible, oherwie o deign he LPF wih a high opband a poible a he receiver yem can. Furher udie will focu on he ignal model for SAR/ISAR and he real applicaion on radar yem or oher communicaion yem. 6. Reference [1] G. S. Liu, X. Q. Shi, J. H. Lu, ec. Deign of noie FM-CW radar and i implemenaion, IEE Proc F, Vol. 138, No. 5, pp. 4 46, 1991. [] J. H. Lu and X. Q. Shi, The udy on he aionarine and he ergodiciy of zero IF ignal in Noie FM-CW Radar, Modern Radar, No. 4, pp. 8 36, 199. [3] C. X. Dong, S. Q. Yang, G. Q. Zhao, and Y. Zhang, Effec of noie FM jamming again ISAR imaging, CIE Inernaional Conference of Radar Proceeding, 7. [4] C. J. Song and J. Y. Zhang, The analyi of he performance of radar MTI in noie FM jamming environmen, Proceeding of ICSP, Beijing, pp. 1947 195,. [5] J. B. Liu, L. J. Wang, and H. C. Zhao, Performance analyi of ani-noie FM jamming of peudo-random code fuze, Journal of Elecronic & Informaion Technology, Vol. 6, No. 1, pp. 195 193, 4. [6] X. G. Zhou, H. C. Zhao, and Y. C. Tu, Performance analyi of ani-noie FM jamming of peudo-random code binary phae modulaion fuze baed on Doppler effec, IEEE 7 Inernaional Sym poium on Microwave, Anenna, Propagaion, and EMC Technologie for wirele communicaion, pp. 144 147. [7] S. T. Xu, and S. Q. Yang, Mulipah jammer racking wih a paive radar eeker, Syem Engineering and Elecronic, Vol. 5, pp. 31 19, 3. [8] X. Q. Chen, Direcion-finding echnology of wo noie FM jamming for paive eeker, Modern Defene Technology, Vol. 34, pp. 59 6, 6. [9] K. D. Rao, ec., Inananeou frequency baed nonlinear adapive filer for inerference uppreion in pread pecrum yem, The 47h Midwe Sympo- Copyrigh 9 SciRe. IJCNS
C. Y. JIANG ET AL. 99 ium on Circui and Syem, 4. [1] Monfared, Mohen Tavooi, Yargholi, and Moafa, Suppreion of jamming in GPS receiver uing ubpace projecion echnique, Proceeding of he Fifh IASTED Inernaional Conference on Communicaion, Inerne, and Informaion Technology, CIIT 6. [11] M. G. Amin, ec., Performance analyi of ubpace projecion echnique for ani-jamming GPS uing paio-emporal inerference ignaure, IEEE Workhop on Saiical Signal Proceing Proceeding, 1. [1] S. C. Jang, Loughlin, and J. Parick, AM-FM inerference exciion in pread pecrum communicaion via projecion filering, Euraip Journal on Applied Signal Proceing, 1. [13] S. N. Zhang, H. C. Zhao, and G. Xiong, The mehod of exciing noie frequency modulaion inerference for peudo-random coded fuze baed on quare ranformaion, Journal of Miile and Homing, 6. Copyrigh 9 SciRe.