EP信号潜伏期变化的自适应相位谱估计方法

EP信号潜伏期变化的自适应相位谱估计方法 1997 ?? 9 ??J OURNAL O F DAL IAN RAIL WA Y INSTITUTESep . 1997 3 EP ?????????????????? 33#@???????? ?????? ?????? ?? 3##???/???? ?? ?????? 3 # @( )???????????? , ???????????? , ??????????????E???*?????( ) EP? ? ????????E????? ??????E???????????????????????. ?????????????? EP ???? ????E?E???????*???E????????????? ,?????????????? EP ????????E?E????????????????? ????????????????????????. ????????????*??????????*????????????E?E? ,???????????? ??????????????????????????????E???????????E?????????. ???????????????????/ ,???? ?????????????????? - 5dB ?? ,????E?E?????????????*? EP ??????E????????? ,???????E?? ????????. ????E?E??????????????? EP ??????E?????????. ??? :??E?E??? ; ??E???/ ?????* ; *????????????????? ; ?????????? ????? : TN911 . 7 ( ) ??E????? EP???????????????????????????????????????????????????????????? ??. ??E?????????E??????????????????????????????????????????!????????????????. ?? ?????????/ ,???????????!???????????????????????? ,????????E???????????????. ???? ?????/??E?????????E??? :??????E??????????????????????????? ,??????E???????E????? ????. ????E??????? ,??E?????????????????????????E????????? ,????E??????????????????????!??. ?????? ,??E?????????E??????????????????????????????????????????????? ???????!????. 1 . ????????E?????????E????????????????????? !?????E?????E?????????????E?E?2 ,3 ??????????????????????????????????. ???????????????????? ,????????????????E????? ??E??????? ,?????????????????E??. ?????????????/ ,*?????????????????E?E????????? ??????????E???????????????????. ???????????? - 20dB ?? ,*?????????????????E? E?????????????????E?????????????????*?????. ????????????*??????????*????????????E?E? ,??????????????????????????E????? ??E????????????? ,??????????????????????????????????????????????????E?E??????? .?????? ???????? :1997206205 . 3 ?????!*???????????*???????. ?????? ,?? ,1954 ???? ,?????? ,???? ;???? ,???????????????????????????????? ,116028 . ????1 () ???????????????????????????? ,??E??????????????????????????????? 1???? : ( )( ) ( )1a( )= s n + n n ( )x n + pn 1 1 1 ( ( ) )( )( = s n - D n( ) ( ))1bx n + n n+ pn2 2 2 ) ( ( ???? : s n????????E????????? , ?????? 500 ?????? EP ????????????????????. s n - D ( ) ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) nnn?? s n??????. nn?? nn??????????. ?? n n?!nn ????????E??????*???? ?????? , ???????????????????? s n????????. pn?? pn???????????? , ?????????? ??????????????*??? , ?? p?? p???????? :1 2 1 2 1 2 1 2 M ??(( ) ) sin 21 2p n= Pf n, i = , ( )2i i , m i , m !?m = 1 ( ) ( ???? : p m = 1 , 2 ,, M ?????? i ?????????????? m ????????????E??? , f m = 1 , 2 ,i , m i , m ) ( ) , M m , M . D n ?????? ???????????????? ???????????????????????????????????? , .?????????????? ??????E???????????????E????????? 0 , 10 T ,S ( ) D n =( ) ( ) n [ 10 - - 2001/ 20] T ,S ????0 ?? 3 ?????????? : EP ??????E????????????????????*????E?E?7( ) ( ) ( ) f f G?? s n??*??????* , F ??????????????. ???????*G???????????? :ss xx1 2 ( ) ??( )?f = - f D n2xx )(71 2 ( ) f ????????????????. ????x? ,,???????/ ??E????????????????????? ?????????? x1 2 ( ) ???????*?????? , ?????????????????????????? 8???? : ????( ) ( ) ( )8D^ n= - ^ f / f2x x 1 2 ( ?( ) ( ) ??) ???? ^ f f s n???? ??????. ????E??? , ?????? ??????????????????????????x x xx1 21 2 5 ,6 ( ) ?? - F IR ?????/??????. ???? F IR ?????? H f , ?? : 3 3 ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )Hf = f / f = f X f / X f X f = G x x f / G x x f XXX12 2 1 2 1111 21 2 ( )9 7 ( ) ( ) ???? , ?? 9Rot h ?????/??????. ???????? Hf ,:?? ???????????????????? ?? 12 ?( ) ( )( ) jf ]10= | HHf | exp12 1212 ?( ) ( ) ( ) ???? :f ?? Hf ??????????. ????*??????* G x x f ?????????? , ?????????? 0 , ??12 12 1 2 ( ) ( ) ?( ) Hf ?????????????????* G x x f ?????????? f ???? , ?? :12 1 2 x x1 2 ?( ) ?( )( )= f f 1112 x x1 2 ? ( ) ( ) ???? , ?????????????* G x x f ?????????????????* x x f ???????*????????E?E?1 2 1 2 ????*??????? Rot h ?????/???????????????????????? ,?? : ????( ) ( ) ( )D^ n= - ^ f / f212 ???????????? ,???????????????????*???????????????????? ,??????????????*??!?? ??E????????????????????????????? ,?????????????????????E?????????? : NN 2 ????( ) ( ) ( ) 12/]D^ n= / f ^ f f ( )13i12 i i!?!?i = 1i = 1 ???? : f ???????????? , N ?????????????????????????????? , N ??????????????????.i 212????? ( ) *??????????*????????E???????????????????????????????*??????????/????. ???? ??????????E????? 14???? : ( )e n( ) ( )= x n- y n 2 ( )14aT T ( ) ( ) ( ) ( )= H nX n= x nH n 1 ( )y n 1( ) ( )14b14c) ( ) ?( )( ( ) = H n+ H n + 12e nX n1 ?( ) ?????????? ???? :, e n ?? n ??????????????. T( ) ] hn( ) ( ) ( )( ) ( )M H n = h n h nhnhn ()14d- M - M +1 0 1 T ( ) ( )( ) ( ) ( )( ) ( )x n - M ] 14e1 X n = x n + M x n + M - 1x n x n - 11 1 1 1 1 ?( ) ( ) :, e nn . n , H n, ?????????? ???? ?? ?????????????????? ???????? ???? ?????????? ( ) ( ) ( ) ( ) f , H . , n D^ n.???? ???? ???? ???????? 12???? 13???? ?????????????? ( ) :?? 15????????*??????????*????????????????????E? T( ) ( )( )= kH k 15a( )X Y k 1 nnn ( )( ) ( )( )15bk- Y = X kEk n n 2 n ?? ???? ?? ?? ?? ?? ???? 18 ??8 ( )( )( ?( ( ) ) )15c= H k + 2Ek X !?k H kn +1 n n n 1 ???? , n = 1 , 2 ,, L ??????E????????????????? , k = 1 , 2 ,( ), K ??????????????. X k n 1 n ??( ( ( ) ) ) ?? X k E????????? n ???????????????? x n ?? x n ????????????????. ????n 2 1 2 ( ( ) ( ) ) ( ) H k 1213D^ n?????? , ????.???? ???? ???????????????????? ??????????3 311????? ( ) EP ???? s n???????????????????????????????????*???????? 1 ???? 2 ???? : ?? 1?? 1( ) ( ) ( ) ( ) s n?? x n??????????s n?? x n???????*????2 2 ( )( )SN R = - 5dB ,SIR = - 5dBSN R = - 5dB ,SIR = - 5dB ( ) ???? 1 ???? 2 ???????? , ??????????????????????E???????. ???????? s n ???? 500 ???? ( ) ( ) ( ) () () SN RS IR11617??*????? EP ??????????????. ?????????????*???????????? 0 ,E????? 1 . ?????? E? ???????? 0dB ?? - 5dB . ????????????????*/?????????? ,??????E????????? 50 Hz ,100 Hz ?? 150 Hz. ?????? ?????? - 5dB . ?????? ???????E???????????????? EP ???????? ????????????????????????. ??????????????E??????????? ???? ???? : 500 2 ( ) ( ) ( ) ( )D^ n ]Var 1500[ D^ n ] = / [ D^ n( )-16!?n = 1 100500 ( ) ( ) ( )( ) Mean 1200[ D^ n ] = / [ D^ n+ D^ n]( )17!?!?n = 1n = 401 ?? 3 ?????????????????????? ,????????????????????E???????????????E?E???????????. ???? 3 ???????? ,????????E?E?????????????????????????????. ?????????????????? ?? ,????????????*??E????????E???????????*?????????. 312???? ?? 3 ?????????? : EP ??????E????????????????????*????E?E?9 3 ?? ???????????????? ( )?????????????????????? ,????????E?E???????*?????????*??? EP ??????????E??? ????????*?????. *??????????/?????????????? s n ???????? 500 ???????? EP ???????????? ,?????????? ?????????? EP ????. ?? 4 ??????E?E???*??????????? ??E????????????????? ,??????????????. ???????4 ???? ,????????E?????????????E?E??????????? ?? 4 ??????????????????????. ?????????????????????????????? ????. ??????????*??????????*????????E?E? ,??????????????????????????????. ?????? ????????*??????????*?????????/????E???????. ( ) ????????*??????????/??. ???????? H k ?? K ??????????????????8 ,9 ,10 , ???? ??????????E???????. ??E??? ,????*??????????/??*????????????? ,??????*??????????? ???? L ???????????? , ????????????????. ????E??? , ?????/???????????????? , ???? , ???? ?????????????? , ??????????????????????*/?? , ?????????????????? , ???????????????? ????*/??. ????????E???????. ) , M , ????( ) ( ) pn = pn = p1 2 ( ???????????????????????????????? f m = 1 , 2 ,i , m ( ) n. ???? , ??????????*??????????????*E????? : ( )( )f ( ) ??( )( ) 18f f G= Gexp - j2f D n + G] ss ss v v1 2 ( )( )G( ) ( ) ( )f 19= Gf + Gf + Gf v vss n n p p 1 2 ?????????? , *??????????/?????????? : ()( ) ( ) ( ) ( )??) ( ) ( ) ( ) ( ) (20/ /]Hf = Gf Gf = Gf exp - j2f D+ Gf Gf + Gf + Gf v v v v ss pp ss nn pp opt 1 21 1 ( ) ???? Gf ???? M ????????????????????,???????????/?/????????????????????,??????????????,pp ?? ?? ?? ?? ?? ?? ?? ???? 18 ??10 ()( )p n????????????????????,??????????????????. ????,??20????????: f) (), N21a( !?f m = 0 1 ,,m ( ) ( ??( ) ( ( ) )( ) ) Hf = Gf exp - j2 D/Gf + Gf + Gf ,fss ss nn pp opt ( !?f m = 0 1 ,,m ) ()??( ( )( ( ( ( ) () ) ) ) ) f, N21bHf = Gf exp - j2f D+ Gf / Gf + Gf + Gf ,ss pp ss nn pp opt ( ) ?? Hf ???????????? :op t ??( ) ( )?( )( )f 22a= - 2f D n, f !? f m = 0 , 1 ,, N 12 m ?) = f , f)? ()( ), N ( f 22b( = f m = 0 , 1 ,12 m ?( ) ( ) ?????????????????????, N ???? ,f f = f ????????????. ????f m = 0 , 1 ,?? ???? m ( ) ( ) ??*/?? ??????????????*????????????????? ?? ???????????? ??????????, . pn pn , 1 2 ??????????????????. ???????? , *??????????*??????????E?E????????????????????????? ??????. ??5 , ??????????????*??????????*????????????E?E? ?????????????????????????????? ??E???????????????E???????*?????. ????E??? !????????????????????????/ :??????E?E? ?????????????!????????????????????E???????E????????????????? , ???????????????? ???????????????????? EP ??E???????. ???? 1Zhu L , Ko ng X , Kauf man B , Rog A. Estimatio n of latency changes for evo ked potential wit h morp hologicalvariatio ns. Proc of 17t h Int . Co nf . of I EEE EMBS ,1995 ,921!?9222Ko ng X , Thakor N V . Adap tive estimatio n of latency changes in evo ked potentials. I EEE Trans o n Bio medical () Engineering. 1996 ,43 2:189!?172 3Ko ng X , Zhu L , Kauf man B , Rog A. Adap tive estimatio n of evo ked potential latency under low SN R co ndi2tio ns. Proc. 16t h Int . Co nf . of I EEE , EMBS ,1994 ,213!?214 Piersol A G. Time delay estimatio n using p hase data . I EEE Trans o n ASSP ,1981 ,29 :471!?4774 5Chan Y T , Riley J M , Plant J B . A parameter estimatio n app roach to time delay estimatio n and signal detec2tio n. I EEE Trans o n ASSP ,1980 ,28 :8!?16 6Chan Y T , Riley J M , Plant J B . Modeling of t he delay and it s appicatio n to estimatio n of no nstatio nary de2lays. I EEE Trans o n ASSP ,1981 ,29 :577!?581 Rot h P R. Effective measurement s using digital signal analysis. I EEE Spect rum ,1971 ,8 :62!?707 Florian S ,Bershad N J . Aweighted normalized f requency do main L MS adap tive algorit hm. I EEE Trans o n AS28SP ,1988 ,36 :1002!?1007 Beaufays F. Transform - do main adap tive filters : an analytical app roach , I EEE Trans o n Signal Processing ,91995 ,41 :422!?431 10 Clar kso n P M . Op timal and Adap tive Signal Processing. Boca Rato n : CRC Press ,1993 . ?? 3 ?????????? : EP ??????E????????????????????*????E?E?11 The Study on the Est imat ion of Latency Changes in Evoked Potent ial s with Ada pt ive Filters 333@ #Q i u T i a ns h u a n g Ye J i aj i n W a n g L i a n D ai X i aoy a n B ao Hai pi n g ##X i a n g Deyou W a n g N aicha n g 3 # ( )( )Dalian Railway Instit uteDalian Medical U niversity @( )Dalian Teleco mmunicatio n Develop ment Co mpany ( ( ) ( ) ) Abstract Evo ked potentials EPhave been widely used to quantif y neurological system p roperties. Transient and time varying changes in latency may indicate impending neurological disease or injury. Traditio nal time aver2 aging technique used for detecting EP signals is very ineffecient since it can not t rack t he time varying latency. The correlatio n based met hod is also unreliable when t he external periodic interference is added to EP signals. Pro2 poses an adap tive p hase spect ral time delay estimatio n met hod to detect and estimate t he time varying latency changes when bot h of t he signal to noise ratio n SN Rand signal to interference ratio SIRare low . Experiment and co mp uter simulatio n show t hat t he p roposed met hod can t rack t he time varying latency changes effectively and accurately under t he co nditio n t hat bot h SN R are as low as - 5dB . Key words :evo ked potentials ; latency changes/ p hase spect rum ; adap tive time delay stimatio n ; periodic interfer2 encee