{"id":17988,"date":"2014-08-31T22:23:06","date_gmt":"2014-08-31T15:23:06","guid":{"rendered":"https:\/\/banbientan.com\/?p=17988"},"modified":"2014-08-31T22:23:06","modified_gmt":"2014-08-31T15:23:06","slug":"cac-mach-bien-doi-tan-so","status":"publish","type":"post","link":"https:\/\/hunglong.banbientan.com\/?p=17988","title":{"rendered":"C\u00e1c m\u1ea1ch bi\u1ebfn \u0111\u1ed5i t\u1ea7n s\u1ed1"},"content":{"rendered":"
\n

GI\u1edaI THI\u1ec6U<\/h1>\n

Trong k\u1ef9 thu\u1eadt th\u00f4ng tin v\u00f4 tuy\u1ebfn \u0111i\u1ec7n, khi mu\u1ed1n truy\u1ec1n th\u00f4ng tin \u0111i xa ng\u01b0\u1eddi ta ph\u1ea3i chuy\u1ec3n t\u1ea7n s\u1ed1 c\u1ee7a t\u00edn hi\u1ec7u tin t\u1ee9c l\u00ean m\u1ed9t t\u1ea7n s\u1ed1 cao h\u01a1n r\u1ea5t nhi\u1ec1u l\u00e0 v\u00ec c\u00f4ng su\u1ea5t c\u1ee7a s\u00f3ng \u0111i\u1ec7n t\u1eeb khi b\u1ee9c x\u1ea1 ra t\u1ef7 l\u1ec7 v\u1edbi t\u1ea7n s\u1ed1 c\u1ee7a s\u00f3ng. Do v\u1eady v\u1edbi tin t\u1ee9c c\u00f3 t\u1ea7n s\u1ed1 th\u1ea5p th\u00ec kh\u1ea3 n\u0103ng b\u1ee9c x\u1ea1 r\u1ea5t y\u1ebfu v\u00e0 kh\u00f4ng c\u00f3 kh\u1ea3 n\u0103ng truy\u1ec1n \u0111i xa.<\/p>\n

Ph\u01b0\u01a1ng ph\u00e1p \u0111\u1ec3 th\u1ef1c hi\u1ec7n chuy\u1ec3n ph\u1ed5 c\u1ee7a t\u00edn hi\u1ec7u tin t\u1ee9c l\u00ean v\u00f9ng c\u00f3 t\u1ea7n s\u1ed1 cao h\u01a1n \u0111\u00f3 l\u00e0 \u0111i\u1ec1u ch\u1ebf (\u0111i\u1ec1u ch\u1ebf bi\u00ean \u0111\u1ed9, \u0111i\u1ec1u t\u1ea7n, \u0111i\u1ec1u pha), c\u00e1c m\u1ea1ch tr\u1ed9n t\u1ea7n.<\/p>\n

\u1ede ph\u00eda m\u00e1y thu ph\u1ea3i c\u00f3 m\u1ed9t qu\u00e1 tr\u00ecnh chuy\u1ec3n \u0111\u1ed5i ng\u01b0\u1ee3c l\u1ea1i, t\u1ee9c l\u00e0 chuy\u1ec3n ph\u1ed5 t\u00edn hi\u1ec7u tin t\u1ee9c \u0111ang \u1edf t\u1ea7n s\u1ed1 cao v\u1ec1 \u0111\u00fang v\u1edbi t\u1ea7n s\u1ed1 g\u1ed1c ban \u0111\u1ea7u, qu\u00e1 tr\u00ecnh \u0111\u00f3 l\u00e0 t\u00e1ch s\u00f3ng (gi\u1ea3i \u0111i\u1ec1u ch\u1ebf). V\u1edbi m\u1ed7i ki\u1ec3u \u0111i\u1ec1u ch\u1ebf s\u1ebd c\u00f3 c\u00e1c m\u1ea1ch t\u00e1ch s\u00f3ng t\u01b0\u01a1ng \u1ee9ng.<\/p>\n

Ngo\u00e0i ra, trong m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p kh\u00f3 th\u1ef1c hi\u1ec7n vi\u1ec7c chuy\u1ec3n ph\u1ed5 t\u1ea7n s\u1ed1 m\u1ed9t l\u1ea7n \u0111\u1ebfn \u0111\u00fang t\u1ea7n s\u1ed1 mong mu\u1ed1n, ng\u01b0\u1eddi ta th\u01b0\u1eddng d\u00f9ng c\u00e1c m\u1ea1ch tr\u1ed9n t\u1ea7n. Trong c\u00e1c m\u00e1y thu \u0111\u1ed5i t\u1ea7n th\u00f4ng th\u01b0\u1eddng c\u0169ng s\u1eed d\u1ee5ng c\u00e1c m\u1ea1ch tr\u1ed9n t\u1ea7n \u0111\u1ec3 chuy\u1ec3n t\u1ea7n s\u1ed1 s\u00f3ng mang (t\u1ea7n s\u1ed1 cao) v\u1ec1 m\u1ed9t t\u1ea7n s\u1ed1 trung gian (t\u1ea7n s\u1ed1 trung t\u1ea7n), sau \u0111\u00f3 khu\u1ebfch \u0111\u1ea1i t\u00edn hi\u1ec7u l\u00ean nhi\u1ec1u l\u1ea7n tr\u01b0\u1edbc khi \u0111\u01b0a v\u00e0o m\u1ea1ch t\u00e1ch s\u00f3ng.<\/p>\n

T\u1ea5t c\u1ea3 c\u00e1c qu\u00e1 tr\u00ecnh bi\u1ebfn \u0111\u1ed5i t\u1ea7n s\u1ed1 \u0111\u1ec1u d\u1ef1a v\u00e0o m\u1ed9t t\u00ednh ch\u1ea5t r\u1ea5t quan tr\u1ecdng c\u1ee7a linh ki\u1ec7n b\u00e1n d\u1eabn \u0111\u00f3 l\u00e0 t\u00ednh ch\u1ea5t phi tuy\u1ebfn. T\u00ednh ch\u1ea5t phi tuy\u1ebfn \u1edf \u0111\u00e2y \u0111\u01b0\u1ee3c hi\u1ec3u l\u00e0 khi ch\u00fang ta t\u00e1c \u0111\u1ed9ng m\u1ed9t t\u1ea7n s\u1ed1\u00a0v\u00e0 linh ki\u1ec7n b\u00e1n d\u1eabn th\u00ec n\u00f3 s\u1ebd cho ra nhi\u1ec1u t\u1ea7n s\u1ed1 l\u00e0 b\u1ed9i c\u1ee7a\u00a0t\u1ee9c l\u00e0\u00a0nf\u00a0<\/em>v\u1edbi n = 1, 2, 3,..<\/p>\n<\/div>\n

\n

N\u1ed8I DUNG<\/h1>\n
\n

KH\u00c1I NI\u1ec6M V\u1ec0 \u0110I\u1ec0U CH\u1ebe<\/h2>\n

\u0110i\u1ec1u ch\u1ebf l\u00e0 qu\u00e1 tr\u00ecnh ghi tin t\u1ee9c v\u00e0o dao \u0111\u1ed9ng cao t\u1ea7n nh\u1edd bi\u1ebfn \u0111\u1ed5i m\u1ed9t th\u00f4ng s\u1ed1 n\u00e0o \u0111\u00f3 nh\u01b0 bi\u00ean \u0111\u1ed9, t\u1ea7n s\u1ed1 hay g\u00f3c pha c\u1ee7a dao \u0111\u1ed9ng cao t\u1ea7n theo tin t\u1ee9c.<\/p>\n

Th\u00f4ng qua \u0111i\u1ec1u ch\u1ebf, tin t\u1ee9c \u1edf mi\u1ec1n t\u1ea7n s\u1ed1 th\u1ea5p \u0111\u01b0\u1ee3c chuy\u1ec3n l\u00ean v\u00f9ng t\u1ea7n s\u1ed1 cao \u0111\u1ec3 b\u1ee9c x\u1ea1 truy\u1ec1n \u0111i xa.<\/p>\n

– Tin t\u1ee9c \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf.<\/p>\n

– Dao \u0111\u1ed9ng cao t\u1ea7n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 t\u1ea3i tin hay t\u1ea3i t\u1ea7n.<\/p>\n

– Dao \u0111\u1ed9ng cao t\u1ea7n mang tin t\u1ee9c g\u1ecdi l\u00e0 dao \u0111\u1ed9ng cao t\u1ea7n \u0111\u00e3 \u0111i\u1ec1u ch\u1ebf.<\/p>\n

\u0110\u1ed1i v\u1edbi t\u1ea3i tin \u0111i\u1ec1u ho\u00e0, ta ph\u00e2n bi\u1ec7t ra hai lo\u1ea1i \u0111i\u1ec1u ch\u1ebf l\u00e0 \u0111i\u1ec1u bi\u00ean v\u00e0 \u0111i\u1ec1u ch\u1ebf g\u00f3c, trong \u0111\u00f3 \u0111i\u1ec1u ch\u1ebf g\u00f3c bao g\u1ed3m c\u1ea3 \u0111i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha.<\/p>\n<\/div>\n

\n

\u0110I\u1ec0U BI\u00caN<\/h2>\n
\n

Ph\u1ed5 c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean<\/h3>\n

\u0110i\u1ec1u bi\u00ean l\u00e0 qu\u00e1 tr\u00ecnh l\u00e0m cho bi\u00ean \u0111\u1ed9 t\u1ea3i t\u00edn hi\u1ec7u bi\u1ebfn \u0111\u1ed5i theo tin t\u1ee9c. \u0110\u1ec3 \u0111\u01a1n gi\u1ea3n, gi\u1ea3 thi\u1ebft tin t\u1ee9c\u00a0u<\/em>S<\/em>\u00a0v\u00e0 t\u1ea3i tin\u00a0u<\/em>t<\/em>\u0111\u1ec1u l\u00e0 dao \u0111\u1ed9ng \u0111i\u1ec1u ho\u00e0 v\u00e0 t\u1ea7n s\u1ed1 tin t\u1ee9c bi\u1ebfn thi\u00ean t\u1eeb\u00a0\u03c9<\/em>Smin<\/em>\uf0b8<\/em>\u03c9<\/em>Smax<\/em>, ta c\u00f3:<\/p>\n

\"bien<\/p>\n

Do \u0111\u00f3 t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean:<\/p>\n

\"bien<\/p>\n

trong \u0111\u00f3: m=\u00dbS<\/span>\/\u00dbt\u00a0<\/span>l\u00e0 h\u1ec7 s\u1ed1 \u0111i\u1ec1u ch\u1ebf (hay \u0111\u1ed9 s\u00e2u \u0111i\u1ec1u ch\u1ebf).<\/span><\/p>\n

H\u1ec7 s\u1ed1 \u0111i\u1ec1u ch\u1ebf ph\u1ea3i tho\u1ea3 m\u00e3n \u0111i\u1ec1u ki\u1ec7nm\u22641. Khi m>1 th\u00ec m\u1ea1ch c\u00f3 hi\u1ec7n t\u01b0\u1ee3ng qu\u00e1 \u0111i\u1ec1u ch\u1ebf l\u00e0m cho t\u00edn hi\u1ec7u b\u1ecb m\u00e9o tr\u1ea7m tr\u1ecdng. (h\u00ecnh 6-1).<\/p>\n

\u00c1p d\u1ee5ng bi\u1ebfn \u0111\u1ed5i l\u01b0\u1ee3ng gi\u00e1c ta \u0111\u01b0\u1ee3c:<\/p>\n

\"bien<\/p>\n

Nh\u01b0 v\u1eady, ngo\u00e0i th\u00e0nh ph\u1ea7n t\u1ea3i tin, t\u00edn hi\u1ec7u \u0111i\u1ec1u khi\u1ec3n c\u00f2n c\u00f3 hai bi\u00ean t\u1ea7n. Bi\u00ean t\u1ea7n tr\u00ean c\u00f3 t\u1ea7n s\u1ed1 t\u1eeb (\u03c9<\/em>1<\/em>\u00a0+\u00a0<\/em>\u03c9<\/em>Smin<\/em>) \u0111\u1ebfn (\u03c9<\/em>1<\/em>\u00a0+\u00a0<\/em>\u03c9<\/em>Smax<\/em>) v\u00e0 bi\u00ean t\u1ea7n d\u01b0\u1edbi t\u1eeb (\u03c9<\/em>1<\/em>–<\/em>\u03c9<\/em>Smin<\/em>) \u0111\u1ebfn (\u03c9<\/em>1<\/em>\u00a0–\u00a0<\/em>\u03c9<\/em>Smax<\/em>).<\/p>\n

\"bien<\/p>\n<\/div>\n

\n

Quan h\u1ec7 n\u0103ng l\u01b0\u1ee3ng trong \u0111i\u1ec1u bi\u00ean<\/h3>\n

Trong t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean, c\u00e1c\u00a0bi\u00ean t\u1ea7n<\/span><\/a><\/strong>\u00a0<\/span> ch\u1ee9a tin t\u1ee9c, c\u00f2n t\u1ea3i tin kh\u00f4ng mang tin t\u1ee9c. Ta x\u00e9t xem n\u0103ng l\u01b0\u1ee3ng \u0111\u01b0\u1ee3c ph\u00e2n b\u1ed1 th\u1ebf n\u00e0o trong t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean.<\/p>\n

C\u00f4ng su\u1ea5t c\u1ee7a t\u1ea3i tin<\/strong>:<\/strong>\u00a0l\u00e0 c\u00f4ng su\u1ea5t trung b\u00ecnh trong m\u1ed9t chu k\u1ef3 t\u1ea3i tin.<\/p>\n

\"bien<\/p>\n

C\u00f4ng su\u1ea5t bi\u00ean t\u1ea7n<\/strong>\u00a0:<\/strong><\/p>\n

\"bien<\/p>\n

C\u00f4ng su\u1ea5t c\u1ee7a t\u00edn hi\u1ec7u \u0111\u00e3 \u0111i\u1ec1u bi\u00ean l\u00e0 c\u00f4ng su\u1ea5t trung b\u00ecnh trong m\u1ed9t chu k\u1ef3 c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf.<\/p>\n

\"bien<\/p>\n

Ta th\u1ea5y r\u1eb1ng c\u00f4ng su\u1ea5t c\u1ee7a t\u00edn hi\u1ec7u \u0111\u00e3 \u0111i\u1ec1u bi\u00ean ph\u1ee5 thu\u1ed9c v\u00e0o h\u1ec7 s\u1ed1 \u0111i\u1ec1u ch\u1ebf\u00a0m<\/em>. H\u1ec7 s\u1ed1 \u0111i\u1ec1u ch\u1ebf m c\u00e0ng l\u1edbn th\u00ec c\u00f4ng su\u1ea5t t\u00edn hi\u1ec7u \u0111\u00e3 \u0111i\u1ec1u bi\u00ean c\u00e0ng l\u1edbn. Khi\u00a0m<\/em>\u00a0=1 th\u00ec ta c\u00f3 quan h\u1ec7 c\u00f4ng su\u1ea5t hai bi\u00ean t\u1ea7n v\u00e0 t\u1ea3i t\u1ea7n nh\u01b0 sau:<\/p>\n

\"bien<\/p>\n

\u0110\u1ec3 gi\u1ea3m m\u00e9o h\u1ec7 s\u1ed1 \u0111i\u1ec1u ch\u1ebf\u00a0m<\/em>\u00a0< 1 do \u0111\u00f3 c\u00f4ng su\u1ea5t c\u00e1c bi\u00ean t\u1ea7n th\u1ef1c t\u1ebf ch\u1ec9 kho\u1ea3ng m\u1ed9t ph\u1ea7n ba c\u00f4ng su\u1ea5t t\u1ea3i tin. Ngh\u0129a l\u00e0 ph\u1ea7n l\u1edbn c\u00f4ng su\u1ea5t ph\u00e1t x\u1ea1 \u0111\u01b0\u1ee3c ph\u00e2n b\u1ed5 cho t\u1ea3i tin, c\u00f2n c\u00f4ng su\u1ea5t c\u1ee7a tin t\u1ee9c ch\u1ec9 chi\u1ebfm ph\u1ea7n nh\u1ecf. \u0110\u00f3 l\u00e0 nh\u01b0\u1ee3c \u0111i\u1ec3m c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean so v\u1edbi t\u00edn hi\u1ec7u \u0111\u01a1n bi\u00ean.<\/p>\n<\/div>\n

\n

6C\u00e1c ch\u1ec9 ti\u00eau c\u01a1 b\u1ea3n c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean<\/h3>\n

H\u1ec7 s\u1ed1 m\u00e9o phi tuy\u1ebfn<\/p>\n

\"bien\u00a0<\/span>\"\"<\/span><\/p>\n

l\u00e0 th\u00e0nh ph\u1ea7n d\u00f2ng \u0111i\u1ec7n \u1ee9ng v\u1edbi h\u00e0i b\u1eadc cao c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf.<\/p>\n

\"\"<\/p>\n

l\u00e0 bi\u00ean \u0111\u1ed9 c\u1ee7a c\u00e1c th\u00e0nh ph\u1ea7n bien tan<\/a>\u00a0(th\u00e0nh ph\u1ea7n s\u00f3ng c\u01a1 b\u1ea3n).<\/p>\n

\"bien<\/p>\n

\u0110\u1ec3 gi\u1ea3m m\u00e9o phi tuy\u1ebfn bu\u1ed9c ph\u1ea3i gi\u1ea3m \u0111\u1ed9 s\u00e2u \u0111i\u1ec1u ch\u1ebf.<\/p>\n

H\u1ec7 s\u1ed1 m\u00e9o t\u1ea7n s\u1ed1<\/p>\n

\u0110\u1ec3 \u0111\u00e1nh gi\u00e1 ta d\u1ef1a v\u00e0o \u0111\u1eb7c tuy\u1ebfn bi\u00ean \u0111\u1ed9 – t\u1ea7n s\u1ed1<\/p>\n

\"bien<\/p>\n

H\u1ec7 s\u1ed1 m\u00e9o t\u1ea7n s\u1ed1 x\u00e1c \u0111\u1ecbnh theo bi\u1ec3u th\u1ee9c:<\/p>\n

\"bien\n<\/div>\n

\n

C\u00e1c m\u1ea1ch \u0111i\u1ec1u bi\u00ean<\/h3>\n

C\u00e1c m\u1ea1ch \u0111i\u1ec1u bi\u00ean th\u01b0\u1eddng s\u1eed d\u1ee5ng c\u00e1c ph\u1ea7n t\u1eed b\u00e1n d\u1eabn v\u1edbi t\u00ednh ch\u1ea5t phi tuy\u1ebfn c\u1ee7a ch\u00fang. T\u00ednh ch\u1ea5t phi tuy\u1ebfn \u1edf \u0111\u00e2y \u0111\u01b0\u1ee3c hi\u1ec3u l\u00e0 khi ch\u00fang ta cho hai t\u00edn hi\u1ec7u v\u1edbi hai t\u1ea7n s\u1ed1 kh\u00e1c nhau t\u00e1c \u0111\u1ed9ng l\u00ean linh ki\u1ec7n b\u00e1n d\u1eabn th\u00ec n\u00f3 s\u1ebd sinh ra c\u00e1c th\u00e0nh ph\u1ea7n l\u00e0 t\u1ed5ng v\u00e0 hi\u1ec7u c\u1ee7a c\u00e1c t\u1ea7n s\u1ed1 t\u00e1c \u0111\u1ed9ng.<\/p>\n

\"bien<\/p>\n

V\u1ec1 l\u00fd thuy\u1ebft th\u00ec t\u00edn hi\u1ec7u \u0111\u1ea7u ra c\u00f3 t\u1ea7n s\u1ed1\u00a0n.f<\/em>1<\/em>\u00a0+ m. f<\/em>2<\/em>v\u1edbi\u00a0m, n<\/em>\u00a0=1, 2,\u2026<\/p>\n

C\u00f3 c\u00e1c ki\u1ec3u \u0111i\u1ec1u bi\u00ean nh\u01b0 \u0111i\u1ec1u bi\u00ean c\u00e2n b\u1eb1ng v\u00e0 \u0111i\u1ec1u bi\u00ean v\u00f2ng, \u0111i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean\u2026<\/p>\n

– M\u1ea1ch \u0111i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean ch\u1ec9 d\u00f9ng m\u1ed9t ph\u1ea7n tr\u1edf t\u00edch c\u1ef1c nh\u01b0 \u0111i\u1ed1t ho\u1eb7c tranzito.<\/p>\n

– M\u1ea1ch \u0111i\u1ec1u bi\u00ean c\u00e2n b\u1eb1ng c\u00f3 \u01b0u \u0111i\u1ec3m gi\u1ea3m \u0111\u01b0\u1ee3c m\u00e9o phi tuy\u1ebfn.<\/p>\n

\u0110i\u1ec1u bi\u00ean c\u00e2n b\u1eb1ng<\/p>\n

Theo h\u00ecnh 6-3a \u0111i\u1ec7n \u00e1p \u0111\u1eb7t l\u00ean c\u00e1c \u0111i\u1ed1t\u00a0D<\/em>1<\/em>, D<\/em>2<\/em>\u00a0l\u1ea7n l\u01b0\u1ee3t l\u00e0:<\/p>\n

\"bien<\/p>\n

D\u00f2ng \u0111i\u1ec7n qua m\u1ed7i \u0111i\u1ed1t \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n theo chu\u1ed7i Taylor:<\/p>\n

\"bien<\/p>\n

\"bien<\/p>\n

D\u00f2ng \u0111i\u1ec7n ra: i = i1<\/span>\u00a0\u2013 i2<\/span><\/p>\n

\"26539\"<\/a><\/p>\n

trong \u0111\u00f3:<\/p>\n

\"bien<\/p>\n

M\u1ea1ch \u0111i\u1ec1u ch\u1ebf v\u00f2ng<\/p>\n

M\u1ea1ch \u0111i\u1ec1u ch\u1ebf v\u00f2ng: th\u1ef1c ch\u1ea5t l\u00e0 hai m\u1ea1ch \u0111i\u1ec1u ch\u1ebf c\u00e2n b\u1eb1ng chung t\u1ea3i.<\/p>\n

G\u1ecdi d\u00f2ng \u0111i\u1ec7n ra c\u1ee7a m\u1ea1ch \u0111i\u1ec1u ch\u1ebf c\u00e2n b\u1eb1ng\u00a0D<\/em>1<\/em>, D<\/em>2<\/em>\u00a0l\u00e0\u00a0i<\/em>I<\/em>\u00a0v\u00e0 d\u00f2ng \u0111i\u1ec7n ra c\u1ee7a m\u1ea1ch \u0111i\u1ec1u ch\u1ebf c\u00e2n b\u1eb1ng\u00a0D<\/em>3<\/em>, D<\/em>4<\/em>\u00a0l\u00e0\u00a0i<\/em>II<\/em>.<\/em><\/p>\n

V\u1edbi m\u1ea1ch \u0111i\u1ec1u ch\u1ebf ki\u1ec3u n\u00e0y ta c\u00f3 \u0111\u01b0\u1ee3c:<\/p>\n

\"bien<\/span>\n<\/div>\n

\n

\"bien<\/p>\n

\u0110i\u1ec1u ch\u1ebf v\u00f2ng cho m\u00e9o nh\u1ecf nh\u1ea5t v\u00ec n\u00f3 kh\u1eed \u0111\u01b0\u1ee3c c\u00e1c h\u00e0i b\u1eadc l\u1ebb c\u1ee7a \u03c9S<\/span>\u00a0v\u00e0 c\u00e1c bi\u00ean t\u1ea7n 2\u03c9t<\/span>.<\/p>\n

\u0110i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean<\/p>\n

– Kh\u00e1i ni\u1ec7m:<\/p>\n

Ph\u1ed5 c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean g\u1ed3m t\u1ea3i t\u1ea7n v\u00e0 hai bi\u00ean t\u1ea7n, trong \u0111\u00f3 ch\u1ec9 c\u00f3 bien tan<\/a>\u00a0mang tin t\u1ee9c. V\u00ec hai d\u1ea3i bi\u00ean t\u1ea7n mang tin t\u1ee9c nh\u01b0 nhau n\u00ean ch\u1ec9 c\u1ea7n truy\u1ec1n \u0111i m\u1ed9t bi\u00ean t\u1ea7n l\u00e0 \u0111\u1ee7 th\u00f4ng tin v\u1ec1 tin t\u1ee9c. T\u1ea3i t\u1ea7n ch\u1ec9 c\u1ea7n d\u00f9ng \u0111\u1ec3 t\u00e1ch s\u00f3ng, do \u0111\u00f3 c\u00f3 th\u1ec3 n\u00e9n to\u00e0n b\u1ed9 ho\u1eb7c m\u1ed9t ph\u1ea7n t\u1ea3i t\u1ea7n tr\u01b0\u1edbc khi truy\u1ec1n \u0111i. Qu\u00e1 tr\u00ecnh \u0111i\u1ec1u ch\u1ebf \u0111\u1ec3 nh\u1eb1m t\u1ea1o ra m\u1ed9t d\u1ea3i bi\u00ean t\u1ea7n g\u1ecdi l\u00e0 \u0111i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean.<\/p>\n

\u0110i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean tuy t\u1ed1n k\u00e9m nh\u01b0ng c\u00f3 c\u00e1c \u01b0u \u0111i\u1ec3m sau:<\/p>\n

+ \u0110\u1ed9 r\u1ed9ng d\u1ea3i t\u1ea7n gi\u1ea3m m\u1ed9t n\u1eeda.<\/p>\n

+ C\u00f4ng su\u1ea5t b\u1ee9c x\u1ea1 y\u00eau c\u1ea7u th\u1ea5p h\u01a1n c\u00f9ng v\u1edbi m\u1ed9t c\u1ef1 ly th\u00f4ng tin. V\u00ec c\u00f3 th\u1ec3 t\u1eadp trung c\u00f4ng su\u1ea5t c\u1ee7a t\u1ea3i t\u1ea7n v\u00e0 m\u1ed9t bi\u00ean t\u1ea7n cho bi\u00ean t\u1ea7n c\u00f2n l\u1ea1i.<\/p>\n

+ T\u1ea1p \u00e2m \u0111\u1ea7u thu gi\u1ea3m do d\u1ea3i t\u1ea7n c\u1ee7a t\u00edn hi\u1ec7u h\u1eb9p h\u01a1n.<\/p>\n

Bi\u1ec3u th\u1ee9c c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean tr\u00ean l\u00e0:<\/p>\n

\"bien<\/p>\n

trong \u0111\u00f3 k = \u00dbS\u00a0<\/span>\/ \u00dbt<\/span>\u00a0\u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 h\u1ec7 s\u1ed1 n\u00e9n t\u1ea3i tin,\u00a0k\u00a0<\/em>c\u00f3 th\u1ec3 nh\u1eadn c\u00e1c gi\u00e1 tr\u1ecb t\u1eeb 0 \uf0b8 \u221e.<\/p>\n

– \u0110i\u1ec1u ch\u1ebf \u0111\u01a1n bi\u00ean theo ph\u01b0\u01a1ng ph\u00e1p l\u1ecdc.<\/p>\n

T\u1eeb s\u1ef1 ph\u00e2n t\u00edch ph\u1ed5 c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean r\u00f5 r\u00e0ng mu\u1ed1n c\u00f3 t\u00edn hi\u1ec7u \u0111\u01a1n bi\u00ean ta ch\u1ec9 c\u1ea7n l\u1ecdc b\u1edbt m\u1ed9t d\u1ea3i bi\u00ean t\u1ea7n. Nh\u01b0ng th\u1ef1c t\u1ebf kh\u00f4ng l\u00e0m \u0111\u01b0\u1ee3c nh\u01b0 v\u1eady. Khi t\u1ea3i t\u1ea7n l\u00e0 cao t\u1ea7n th\u00ec v\u1ea5n \u0111\u1ec1 l\u1ecdc \u0111\u1ec3 t\u00e1ch ra m\u1ed9t d\u1ea3i bi\u00ean t\u1ea7n g\u1eb7p kh\u00f3 kh\u0103n. Th\u1eadt v\u1eady, gi\u1ea3 thi\u1ebft t\u1ea7n s\u1ed1 th\u1ea5p nh\u1ea5t c\u1ee7a tin t\u1ee9c\u00a0f<\/em>Smin<\/em>\u00a0= 200Hz<\/em>, l\u00fac \u0111\u00f3 kho\u1ea3ng c\u00e1ch gi\u1eefa hai bi\u00ean t\u1ea7n l\u00e0 \u0394f = 2f<\/em>Smin<\/em>\u00a0= 400Hz<\/em>\u00a0(xem h\u00ecnh 6-1b). N\u1ebfu t\u1ea3i t\u1ea7n\u00a0f<\/em>t<\/em>=10MHz<\/em>\u00a0th\u00ec h\u1ec7 s\u1ed1 l\u1ecdc c\u1ee7a b\u1ed9 l\u1ecdc<\/p>\n

\n
\n
\n
\n
\n
\n
\n
\n
X=\u0394f \/ ft=\u00a04.10^5<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

, kh\u00e1 nh\u1ecf. Khi \u0111\u00f3 s\u1ef1 ph\u00e2n b\u1ed1 c\u1ee7a hai bi\u00ean t\u1ea7n g\u1ea7n nhau \u0111\u1ebfn n\u1ed7i ngay d\u00f9ng m\u1ed9t m\u1ea1ch l\u1ecdc Th\u1ea1ch anh c\u0169ng r\u1ea5t kh\u00f3 l\u1ecdc \u0111\u01b0\u1ee3c d\u1ea3i bi\u00ean t\u1ea7n mong mu\u1ed1n. Do \u0111\u00f3 trong ph\u01b0\u01a1ng ph\u00e1p l\u1ecdc, ng\u01b0\u1eddi ta d\u00f9ng m\u1ed9t b\u1ed9 bi\u1ebfn \u0111\u1ed5i trung gian \u0111\u1ec3 c\u00f3 th\u1ec3 h\u1ea1 th\u1ea5p y\u00eau c\u1ea7u \u0111\u1ed1i v\u1edbi b\u1ed9 l\u1ecdc.
\n\"bien<\/p>\n

\u00a0\u0110I\u1ec0U T\u1ea6N V\u00c0 \u0110I\u1ec0U PHA<\/p>\n<\/div>\n<\/div>\n

\n

C\u00e1c c\u00f4ng th\u1ee9c c\u01a1 b\u1ea3n v\u00e0 quan h\u1ec7 gi\u1eefa \u0111i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha<\/p>\n

V\u00ec gi\u1eefa t\u1ea7n s\u1ed1 v\u00e0 g\u00f3c pha c\u1ee7a m\u1ed9t dao \u0111\u1ed9ng c\u00f3 quan h\u1ec7 nh\u01b0 bi\u1ec3u th\u1ee9c sau, n\u00ean d\u1ec5 d\u00e0ng chuy\u1ec3n \u0111\u1ed5i s\u1ef1 bi\u1ebfn thi\u00ean t\u1ea7n s\u1ed1 th\u00e0nh bi\u1ebfn thi\u00ean v\u1ec1 pha v\u00e0 ng\u01b0\u1ee3c l\u1ea1i.<\/p>\n

\"bien<\/p>\n

\u0110i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha l\u00e0 ghi tin t\u1ee9c v\u00e0o t\u1ea3i tin l\u00e0m cho t\u1ea7n s\u1ed1 ho\u1eb7c pha t\u1ee9c th\u1eddi c\u1ee7a t\u1ea3i tin bi\u1ebfn thi\u00ean theo d\u1ea1ng t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf.<\/p>\n

Khi \u0111i\u1ec1u ch\u1ebf t\u1ea7n s\u1ed1 ho\u1eb7c \u0111i\u1ec1u ch\u1ebf pha th\u00ec t\u1ea7n s\u1ed1 ho\u1eb7c g\u00f3c pha c\u1ee7a dao \u0111\u1ed9ng cao t\u1ea7n bi\u1ebfn thi\u00ean t\u1ef7 l\u1ec7 v\u1edbi t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf v\u00e0 ch\u00fang \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh l\u1ea7n l\u01b0\u1ee3t theo bi\u1ec3u th\u1ee9c:<\/p>\n

\"bien<\/p>\n

Trong \u0111\u00f3:\u00a0\u03c9<\/em>t<\/em>\u00a0l\u00e0 t\u1ea7n s\u1ed1 trung t\u1ea7n c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u t\u1ea7n<\/p>\n

k<\/em>\u0111t<\/span>\u00a0\u00dbS\u00a0<\/span>=\u0394\u03c9m<\/span>\u00a0v\u00e0 g\u1ecdi l\u00e0 l\u01b0\u1ee3ng di t\u1ea7n c\u1ef1c \u0111\u1ea1i.<\/p>\n

k<\/em>\u0111p<\/span>\u00a0\u00dbS\u00a0<\/span>=\u0394\u03c9m<\/span>\u00a0v\u00e0 g\u1ecdi l\u00e0 l\u01b0\u1ee3ng di pha c\u1ef1c \u0111\u1ea1i.<\/p>\n

Bi\u1ec3u th\u1ee9c c\u1ee7a dao \u0111\u1ed9ng \u0111i\u1ec1u t\u1ea7n:<\/p>\n

\"bien<\/p>\n

Bi\u1ec3u th\u1ee9c dao \u0111\u1ed9ng \u0111i\u1ec1u pha khi\u00a0\u03c9<\/em>\u00a0=\u00a0<\/em>\u03c9<\/em>t<\/em>\u00a0= const.<\/em><\/p>\n

\"bien<\/p>\n

L\u01b0\u1ee3ng di pha \u0111\u1ea1t \u0111\u01b0\u1ee3c khi \u0111i\u1ec1u pha \u0394\u03c6<\/span>=\u0394\u03c6m. Cos \u03c9S<\/span>t t\u01b0\u01a1ng \u1ee9ng c\u00f3 l\u01b0\u1ee3ng di t\u1ea7n l\u00e0:<\/p>\n

\"bien<\/p>\n

Nh\u01b0 v\u1eady ta th\u1ea5y \u0111i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha \u0111\u1ec1u l\u00e0m cho g\u00f3c pha thay \u0111\u1ed5i n\u00ean th\u01b0\u1eddng g\u1ecdi chung l\u00e0 \u0111i\u1ec1u ch\u1ebf g\u00f3c. \u0110i\u1ec3m kh\u00e1c nhau c\u01a1 b\u1ea3n gi\u1eefa \u0111i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha l\u00e0 l\u01b0\u1ee3ng di t\u1ea7n khi \u0111i\u1ec1u pha t\u1ef7 l\u1ec7 v\u1edbi bi\u00ean \u0111\u1ed9 c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf v\u00e0 t\u1ea7n s\u1ed1 \u0111i\u1ec1u ch\u1ebf, c\u00f2n l\u01b0\u1ee3ng di t\u1ea7n c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u t\u1ea7n t\u1ef7 l\u1ec7 v\u1edbi t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf m\u00e0 th\u00f4i.<\/p>\n<\/div>\n

\n

M\u1ea0CH \u0110I\u1ec0U T\u1ea6N V\u00c0 \u0110I\u1ec0U PHA<\/h2>\n
\n

M\u1ea1ch \u0111i\u1ec1u t\u1ea7n<\/h3>\n

C\u00f3 th\u1ec3 d\u00f9ng m\u1ea1ch \u0111i\u1ec1u t\u1ea7n tr\u1ef1c ti\u1ebfp hay \u0111i\u1ec1u t\u1ea7n gi\u00e1n ti\u1ebfp.<\/p>\n

M\u1ea1ch \u0111i\u1ec1u t\u1ea7n tr\u1ef1c ti\u1ebfp th\u01b0\u1eddng \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi c\u00e1c m\u1ea1ch tao dao \u0111\u1ed9ng m\u00e0 t\u1ea7n s\u1ed1 dao \u0111\u1ed9ng ri\u00eang c\u1ee7a n\u00f3 \u0111\u01b0\u1ee3c \u0111i\u1ec1u khi\u1ec3n b\u1eb1ng \u0111i\u1ec7n \u00e1p (VCO) ho\u1eb7c b\u1edfi c\u00e1c m\u1ea1ch bi\u1ebfn \u0111\u1ed5i \u0111i\u1ec7n \u00e1p – t\u1ea7n s\u1ed1. Nguy\u00ean t\u1eafc th\u1ef1c hi\u1ec7n \u0111i\u1ec1u t\u1ea7n trong c\u00e1c b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng l\u00e0 l\u00e0m bi\u1ebfn \u0111\u1ed5i tr\u1ecb s\u1ed1 \u0111i\u1ec7n kh\u00e1ng c\u1ee7a b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng theo \u0111i\u1ec7n \u00e1p \u0111\u1eb7t v\u00e0o. Ph\u01b0\u01a1ng ph\u00e1p ph\u1ed5 bi\u1ebfn nh\u1ea5t l\u00e0 d\u00f9ng \u0111i\u1ed1t bi\u1ebfn dung (varicap) v\u00e0 tranzito \u0111i\u1ec7n kh\u00e1ng.<\/p>\n

M\u1ea1ch \u0111i\u1ec1u t\u1ea7n tr\u1ef1c ti\u1ebfp d\u00f9ng \u0111i\u1ed1t bi\u1ebfn dung.<\/p>\n

\u0110i\u1ed1t bi\u1ebfn dung c\u00f3 \u0111i\u1ec7n dung m\u1eb7t gh\u00e9p bi\u1ebfn \u0111\u1ed5i theo \u0111i\u1ec7n \u00e1p \u0111\u1eb7t v\u00e0o.\u00a0C<\/em>D<\/em>\u00a0\u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh theo bi\u1ec3u th\u1ee9c:<\/p>\n

\"bien<\/p>\n

trong \u0111\u00f3\u00a0k –\u00a0<\/em>h\u1ec7 s\u1ed1 t\u1ef7 l\u1ec7.<\/p>\n

\u03c6<\/em>k<\/em>\u00a0– hi\u1ec7u \u0111i\u1ec7n th\u1ebf ti\u1ebfp x\u00fac m\u1eb7t gh\u00e9p, v\u1edbi \u0111i\u1ed1t Silic\u00a0\u03c6<\/em>k<\/em>\u2248 0,7V<\/span><\/p>\n

y – h\u1ec7 s\u1ed1 ph\u1ee5 thu\u1ed9c v\u1eadt li\u1ec7u.<\/p>\n

M\u1eafc \u0111i\u1ed1t song song v\u1edbi h\u1ec7 t\u1ea1o dao \u0111\u1ed9ng c\u1ee7a b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng, \u0111\u1ed3ng th\u1eddi \u0111\u1eb7t \u0111i\u1ec7n \u00e1p \u0111i\u1ec1u ch\u1ebf l\u00ean \u0111i\u1ed1t th\u00ec\u00a0C<\/em>D<\/em>\u00a0thay \u0111\u1ed5i theo \u0111i\u1ec7n \u00e1p \u0111i\u1ec1u ch\u1ebf, do \u0111\u00f3 t\u1ea7n s\u1ed1 c\u1ed9ng h\u01b0\u1edfng ri\u00eang c\u1ee7a b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng c\u0169ng bi\u1ebfn \u0111\u1ed5i theo. Tr\u00ean h\u00ecnh 6-6b l\u00e0 m\u1ea1ch \u0111i\u1ec7n b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng \u0111i\u1ec1u t\u1ea7n b\u1eb1ng \u0111i\u1ed1t bi\u1ebfn dung. Trong m\u1ea1ch \u0111i\u1ec7n n\u00e0y \u0111i\u1ed1t \u0111\u01b0\u1ee3c ph\u00e2n c\u1ef1c ng\u01b0\u1ee3c b\u1edfi ngu\u1ed3nE<\/em>2<\/em>.<\/p>\n

T\u1ea7n s\u1ed1 dao \u0111\u1ed9ng c\u1ee7a m\u1ea1ch g\u1ea7n b\u1eb1ng t\u1ea7n s\u1ed1 c\u1ed9ng h\u01b0\u1edfng ri\u00eang c\u1ee7a h\u1ec7 dao \u0111\u1ed9ng v\u00e0 \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh nh\u01b0 sau:<\/p>\n

\"bien<\/p>\n

\u0110i\u1ec7n \u00e1p \u0111\u1eb7t l\u00ean \u0111i\u1ed1t:<\/p>\n

\"bien<\/p>\n

\u0110\u1ec3 \u0111i\u1ed1t lu\u00f4n \u0111\u01b0\u1ee3c ph\u00e2n c\u1ef1c ng\u01b0\u1ee3c c\u1ea7n tho\u1ea3 m\u00e3n \u0111i\u1ec1u ki\u1ec7n:<\/p>\n

\"bien<\/p>\n

Nguy\u00ean l\u00fd ho\u1ea1t \u0111\u1ed9ng ch\u00ednh c\u1ee7a m\u1ea1ch l\u00e0 khi c\u00f3 \u0111i\u1ec7n \u00e1p tin t\u1ee9c us<\/span>\u00a0t\u00e1c \u0111\u1ed9ng v\u00e0o n\u00f3 s\u1ebd t\u00e1c \u0111\u1ed9ng m\u1ed9t \u0111i\u1ec7n \u00e1p ng\u01b0\u1ee3c l\u00ean \u0111i\u1ed1t bi\u1ebfn dung D v\u00e0 t\u1eeb \u0111\u00f3 gi\u00e1 tr\u1ecb \u0111i\u1ec7n dung c\u1ee7a \u0111i\u1ed1t s\u1ebd thay \u0111\u1ed5i l\u00e0m cho t\u1ea7n s\u1ed1 c\u1ed9ng h\u01b0\u1edfng c\u1ee7a m\u1ea1ch thay \u0111\u1ed5i.<\/p>\n

\"bien<\/p>\n

Khi \u0111i\u1ec1u t\u1ea7n b\u1eb1ng \u0111i\u1ed1t bi\u1ebfn dung ph\u1ea3i ch\u00fa \u00fd nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m sau:<\/p>\n

– Ch\u1ec9 ph\u00e2n c\u1ef1c ng\u01b0\u1ee3c cho \u0111i\u1ed1t \u0111\u1ec3 tr\u00e1nh \u1ea3nh h\u01b0\u1edfng c\u1ee7a\u00a0R<\/em>D<\/em>\u00a0\u0111\u1ebfn ph\u1ea9m ch\u1ea5t c\u1ee7a h\u1ec7 t\u1ea1o dao \u0111\u1ed9ng ngh\u0129a l\u00e0 \u0111\u1ebfn \u0111\u1ed9 \u1ed5n \u0111\u1ecbnh t\u1ea7n s\u1ed1 c\u1ee7a m\u1ea1ch.<\/p>\n

– Ph\u1ea3i h\u1ea1n ch\u1ebf khu v\u1ef1c l\u00e0m vi\u1ec7c trong \u0111o\u1ea1n tuy\u1ebfn t\u00ednh c\u1ee7a \u0111\u1eb7c tuy\u1ebfn\u00a0C<\/em>D<\/em>\u00a0= f(u<\/em>d<\/em>)<\/em>\u00a0c\u1ee7a \u0111i\u1ed1t bi\u1ebfn dung \u0111\u1ec3 gi\u1ea3m m\u00e9o phi tuy\u1ebfn. L\u01b0\u1ee3ng di t\u1ea7n t\u01b0\u01a1ng \u0111\u1ed1i khi \u0111i\u1ec1u t\u1ea7n d\u00f9ng \u0111i\u1ed1t bi\u1ebfn dung \u0111\u1ea1t \u0111\u01b0\u1ee3c kho\u1ea3ng 1%.<\/p>\n

– V\u00ec d\u00f9ng \u0111i\u1ed1t \u0111i\u1ec1u t\u1ea7n n\u00ean thi\u1ebft b\u1ecb \u0111i\u1ec1u t\u1ea7n c\u00f3 k\u00edch th\u01b0\u1edbc nh\u1ecf. C\u00f3 th\u1ec3 d\u00f9ng \u0111i\u1ed1t b\u00e1n d\u1eabn \u0111\u1ec3 \u0111i\u1ec1u t\u1ea7n \u1edf t\u1ea7n s\u1ed1 si\u00eau cao, kho\u1ea3ng v\u00e0i tr\u0103m MHz. Tuy nhi\u00ean \u0111\u1ed9 t\u1ea1p t\u00e1n c\u1ee7a tham s\u1ed1 b\u00e1n d\u1eabn l\u1edbn, n\u00ean k\u00e9m \u1ed5n \u0111\u1ecbnh.<\/p>\n

\u0110i\u1ec1u t\u1ea7n d\u00f9ng tranzito\u0111i\u1ec7n kh\u00e1ng.<\/p>\n

Ph\u1ea7n t\u1eed \u0111i\u1ec7n kh\u00e1ng dung t\u00ednh ho\u1eb7c c\u1ea3m t\u00ednh \u0111\u01b0\u1ee3c m\u1eafc song song v\u1edbi h\u1ec7 dao \u0111\u1ed9ng c\u1ee7a b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng l\u00e0m cho t\u1ea7n s\u1ed1 dao \u0111\u1ed9ng thay \u0111\u1ed5i theo t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf. Ph\u1ea7n t\u1eed \u0111i\u1ec7n kh\u00e1ng \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n nh\u1edd m\u1ed9t m\u1ea1ch di pha m\u1eafc trong m\u1ea1ch h\u1ed3i ti\u1ebfp c\u1ee7a m\u1ed9t tranzito.<\/p>\n

\"bien<\/p>\n

Ph\u1ea7n t\u1eed \u0111i\u1ec7n kh\u00e1ng l\u00e0 ph\u00e2n \u00e1p RC. Trong \u0111\u00f3\u00a0T<\/em>1<\/em>\u00a0l\u00e0 tranzito \u0111i\u1ec7n kh\u00e1ng,\u00a0T<\/em>2<\/em>\u00a0l\u00e0 tranzito dao \u0111\u1ed9ng. Tranzito \u0111i\u1ec7n kh\u00e1ng \u0111\u01b0\u1ee3c m\u1eafc m\u1ed9t ph\u1ea7n (tr\u00ean\u00a0L<\/em>1<\/em>) v\u1edbi h\u1ec7 dao \u0111\u1ed9ng. C\u0169ng c\u00f3 th\u1ec3 m\u1eafc hai tranzito \u0111i\u1ec7n kh\u00e1ng th\u00e0nh m\u1ed9t m\u1ea1ch \u0111\u1ea9y k\u00e9o \u0111\u1ec3 t\u0103ng l\u01b0\u1ee3ng di t\u1ea7n.<\/p>\n<\/div>\n

\n

M\u1ea1ch \u0111i\u1ec1u pha<\/h3>\n

M\u1ea1ch \u0111i\u1ec1u ch\u1ebf pha theo ArmStrong \u1edf h\u00ecnh 6-8 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n theo nguy\u00ean l\u00fd: t\u1ea3i tin t\u1eeb b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng th\u1ea1ch anh \u0111\u01b0\u1ee3c \u0111\u01b0a \u0111\u1ebfn b\u1ed9 \u0111i\u1ec1u bi\u00ean 1 (\u0110B1) v\u00e0 \u0111i\u1ec1u bi\u00ean 2 (\u0110B2) l\u1ec7ch pha nhau 900<\/span>, c\u00f2n t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf\u00a0u<\/em>S<\/em>\u00a0\u0111\u01b0a \u0111\u1ebfn hai m\u1ea1ch \u0111i\u1ec1u bi\u00ean ng\u01b0\u1ee3c pha.<\/p>\n

\"bien<\/p>\n

\u0110i\u1ec7n \u00e1p \u0111\u1ea7u ra tr\u00ean hai b\u1ed9 \u0111i\u1ec1u bi\u00ean l\u00e0:<\/p>\n

\"bien<\/p>\n

\u0110i\u1ec7n \u00e1p\u00a0u<\/em>\u0111p<\/em>\u00a0=\u00a0<\/em>u<\/em>\u0111b1<\/em>\u00a0+\u00a0<\/em>u<\/em>\u0111b2<\/em>. \u0110i\u1ec1u \u0111\u00f3 \u0111\u01b0\u1ee3c gi\u1ea3i th\u00edch b\u1eb1ng \u0111\u1ed3 th\u1ecb vect\u01a1.<\/p>\n<\/div>\n<\/div>\n

\n

T\u00c1CH S\u00d3NG<\/h2>\n
\n

Kh\u00e1i ni\u1ec7m<\/h3>\n

T\u00e1ch s\u00f3ng l\u00e0 qu\u00e1 tr\u00ecnh l\u1ea5y l\u1ea1i t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf. T\u00edn hi\u1ec7u sau t\u00e1ch s\u00f3ng ph\u1ea3i gi\u1ed1ng d\u1ea1ng t\u00edn hi\u1ec7u ban \u0111\u1ea7u. Th\u1ef1c t\u1ebf t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf\u00a0u<\/em>S<\/em>\u00a0sau khi qua \u0111i\u1ec1u ch\u1ebf v\u00e0 qua k\u00eanh th\u00f4ng tin \u0111\u01b0a \u0111\u1ebfn b\u1ed9 t\u00e1ch s\u00f3ng \u0111\u00e3 b\u1ecb m\u00e9o d\u1ea1ng th\u00e0nh\u00a0u<\/em>S<\/em>‘<\/em>. Do m\u00e9o phi tuy\u1ebfn trong b\u1ed9 t\u00e1ch s\u00f3ng, n\u00ean sau khi t\u00e1ch s\u00f3ng ta l\u1ea1i nh\u1eadn \u0111\u01b0\u1ee3c\u00a0u<\/em>S<\/em>“<\/em>\u00a0kh\u00e1c d\u1ea1ng\u00a0u<\/em>S<\/em>‘<\/em>. Nh\u01b0 v\u1eady t\u00edn hi\u1ec7u sau t\u00e1ch s\u00f3ng th\u01b0\u1eddng kh\u00e1c d\u1ea1ng t\u00edn hi\u1ec7u nguy\u00ean thu\u1ef7\u00a0u<\/em>S<\/em>‘<\/em>. V\u00ec v\u1eady m\u1ed9t trong nh\u1eefng y\u00eau c\u1ea7u c\u01a1 b\u1ea3n c\u1ee7a qu\u00e1 tr\u00ecnh t\u00e1ch s\u00f3ng l\u00e0 m\u00e9o phi tuy\u1ebfn nh\u1ecf.<\/p>\n

T\u01b0\u01a1ng \u1ee9ng v\u1edbi c\u00e1c lo\u1ea1i \u0111i\u1ec1u ch\u1ebf, ta c\u0169ng c\u00f3 c\u00e1c m\u1ea1ch t\u00e1ch s\u00f3ng sau \u0111\u00e2y: t\u00e1ch s\u00f3ng \u0111i\u1ec1u bi\u00ean, t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n, t\u00e1ch s\u00f3ng \u0111i\u1ec1u pha.<\/p>\n<\/div>\n

\n

T\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9<\/h3>\n

C\u00e1c tham s\u1ed1 c\u01a1 b\u1ea3n<\/p>\n

    \n
  • H\u1ec7 s\u1ed1 t\u00e1ch s\u00f3ng<\/em><\/li>\n<\/ul>\n

    \"bien<\/p>\n

    Trong \u0111\u00f3 :<\/p>\n

    \"bien<\/p>\n

    \u0110\u1ec1u g\u1ed3m c\u00f3 th\u00e0nh ph\u1ea7n m\u1ed9t chi\u1ec1u v\u00e0 th\u00e0nh ph\u1ea7n bi\u1ebfn thi\u00ean ch\u1eadm theo th\u1eddi gian:<\/p>\n

    \"bien<\/p>\n

    – Th\u1ef1c t\u1ebf, \u0111\u1ed1i v\u1edbi qu\u00e1 tr\u00ecnh t\u00e1ch s\u00f3ng ch\u1ec9 c\u1ea7n quan t\u00e2m \u0111\u1ebfn th\u00e0nh ph\u1ea7n bi\u1ebfn thi\u00ean ch\u1eadm (mang tin t\u1ee9c) m\u00e0 th\u00f4i, do \u0111\u00f3 th\u01b0\u1eddng x\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u00e1ch s\u00f3ng nh\u01b0 sau:<\/p>\n

    \"bien<\/p>\n

      \n
    • Tr\u1edf kh\u00e1ng v\u00e0o b\u1ed9 t\u00e1ch s\u00f3ng:<\/em><\/li>\n<\/ul>\n

      \"bien<\/p>\n

        \n
      • M\u00e9o phi tuy\u1ebfn:<\/em><\/li>\n<\/ul>\n

        \"bien<\/p>\n

        \u1ede \u0111\u00e2y kh\u00f4ng quan t\u00e2m \u0111\u1ebfn c\u00e1c s\u00f3ng h\u00e0i d\u00f2ng \u0111i\u1ec7n cao t\u1ea7n v\u00ec d\u1ec5 d\u00e0ng l\u1ecdc b\u1ecf ch\u00fang.<\/p>\n

        M\u1ea1ch \u0111i\u1ec7n b\u1ed9 t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9<\/p>\n

        X\u00e9t m\u1ea1ch t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9 d\u00f9ng m\u1ea1ch ch\u1ec9nh l\u01b0u m\u1eafc n\u1ed1i ti\u1ebfp h\u00ecnh 6-10. N\u1ebfu t\u00edn hi\u1ec7u v\u00e0o \u0111\u1ee7 l\u1edbn sao cho \u0111i\u1ed1t l\u00e0m vi\u1ec7c trong \u0111o\u1ea1n th\u1eb3ng c\u1ee7a \u0111\u1eb7c tuy\u1ebfn nh\u01b0 tr\u00ean h\u00ecnh 6-11 ta c\u00f3 qu\u00e1 tr\u00ecnh t\u00e1ch s\u00f3ng t\u00edn hi\u1ec7u l\u1edbn.<\/p>\n

        \"bien<\/p>\n

        Trong c\u00e1c s\u01a1 \u0111\u1ed3 h\u00ecnh 6-9 \u0111i\u1ed1t ch\u1ec9 th\u00f4ng \u0111\u1ed1i v\u1edbi n\u1eeda chu k\u1ef3 d\u01b0\u01a1ng c\u1ee7a dao \u0111\u1ed9ng cao t\u1ea7n \u1edf ph\u1ea7n \u0111\u1ea7u v\u00e0o. H\u00ecnh bao c\u1ee7a dao \u0111\u1ed9ng nh\u1eadn \u0111\u01b0\u1ee3c nh\u1edd s\u1ef1 ph\u00f3ng n\u1ea1p c\u1ee7a t\u1ee5 C (h\u00ecnh 6-10).<\/p>\n

        \"bien<\/p>\n

        Trong c\u00e1c s\u01a1 \u0111\u1ed3 h\u00ecnh 6-12 ph\u1ea3i ch\u1ecdn h\u1eb1ng s\u1ed1 th\u1eddi gian\u00a0\u03c4<\/em>\u00a0=\u00a0RC<\/em>\u00a0\u0111\u1ee7 l\u1edbn sao cho d\u1ea1ng \u0111i\u1ec7n \u00e1p ra t\u1ea3i g\u1ea7n v\u1edbi d\u1ea1ng h\u00ecnh bao c\u1ee7a \u0111i\u1ec7n \u00e1p cao t\u1ea7n \u1edf \u0111\u1ea7u v\u00e0o. Th\u00f4ng th\u01b0\u1eddng bi\u00ean \u0111\u1ed9 \u0111i\u1ec7n \u00e1p v\u00e0o l\u1edbn h\u01a1n 1 v\u00f4n hi\u1ec7u d\u1ee5ng v\u00e0\u00a0R >>R<\/em>i<\/em>,\u00a0R<\/em>V<\/em>\u00a0th\u00ec c\u00f3 th\u1ec3 t\u00e1ch s\u00f3ng \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p \u0111\u1ec9nh. Tuy nhi\u00ean c\u0169ng kh\u00f4ng \u0111\u01b0\u1ee3c ch\u1ecdn\u00a0\u03c4<\/em>\u00a0qu\u00e1 l\u1edbn \u0111\u1ec3 tr\u00e1nh m\u00e9o do \u0111i\u1ec7n dung t\u1ea3i g\u00e2y ra. \u0110i\u1ec1u ki\u1ec7n t\u1ed5ng qu\u00e1t \u0111\u1ec3 ch\u1ecdn \u03c4 l\u00e0:<\/p>\n

        \"bien<\/p>\n

        \"bien<\/p>\n

        Tr\u01b0\u1eddng h\u1ee3p ch\u1ecdn C l\u1edbn qu\u00e1 s\u1ebd g\u00e2y m\u00e9o t\u00edn hi\u1ec7u nh\u01b0 \u1edf h\u00ecnh 6-13.<\/p>\n

        \"bien<\/p>\n

        Th\u1ef1c t\u1ebf th\u01b0\u1eddng ch\u1ecdn\u00a0RC<\/em>\u00a0theo \u0111i\u1ec1u ki\u1ec7n:<\/p>\n

        \"bien<\/p>\n

        Mu\u1ed1n d\u1ec5 d\u00e0ng tho\u1ea3 m\u00e3n c\u1ea7n<\/p>\n

        \"bien\n<\/div>\n<\/div>\n

        \n

        T\u00c1CH S\u00d3NG \u0110I\u1ec0U T\u1ea6N V\u00c0 \u0110I\u1ec0U PHA<\/h2>\n

        T\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n v\u00e0 \u0111i\u1ec1u pha th\u01b0\u1eddng \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n theo m\u1ed9t trong nh\u1eefng nguy\u00ean t\u1eafc sau:<\/p>\n

          \n
        • Bi\u1ebfn \u0111\u1ed5i t\u00edn hi\u1ec7u \u0111i\u1ec1u t\u1ea7n ho\u1eb7c \u0111i\u1ec1u pha th\u00e0nh t\u00edn hi\u1ec7u \u0111i\u1ec1u bi\u00ean r\u1ed3i th\u1ef1c hi\u1ec7n t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9.<\/li>\n
        • Bi\u1ebfn \u0111\u1ed5i t\u00edn hi\u1ec7u \u0111i\u1ec1u t\u1ea7n th\u00e0nh t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf \u0111\u1ed9 r\u1ed9ng xung r\u1ed3i th\u1ef1c hi\u1ec7n t\u00e1ch s\u00f3ng t\u00edn hi\u1ec7u \u0111i\u1ec1u ch\u1ebf \u0111\u1ed9 r\u1ed9ng xung nh\u1edd m\u1ea1ch t\u00edch ph\u00e2n.<\/li>\n
        • L\u00e0m cho t\u1ea7n s\u1ed1 t\u00edn hi\u1ec7u c\u1ea7n t\u00e1ch s\u00f3ng b\u00e1m theo t\u1ea7n s\u1ed1 c\u1ee7a m\u1ed9t b\u1ed9 t\u1ea1o dao \u0111\u1ed9ng nh\u1edd h\u1ec7 th\u1ed1ng v\u00f2ng gi\u1eef pha PLL, \u0111i\u1ec7n \u00e1p sai s\u1ed1 ch\u00ednh l\u00e0 \u0111i\u1ec7n \u00e1p c\u1ea7n t\u00e1ch s\u00f3ng.<\/li>\n<\/ul>\n

          Ta x\u00e9t m\u1ed9t s\u1ed1 m\u1ea1ch c\u1ee5 th\u1ec3:<\/p>\n

          \n

          M\u1ea1ch t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n d\u00f9ng m\u1ea1ch l\u1ec7ch c\u1ed9ng h\u01b0\u1edfng<\/h3>\n

          H\u00ecnh 6-14 l\u00e0 s\u01a1 \u0111\u1ed3 m\u1ea1ch t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n s\u1ed1 d\u00f9ng m\u1ea1ch l\u1ec7ch c\u1ed9ng h\u01b0\u1edfng. \u0110\u1ea7u v\u00e0o hai b\u1ed9 t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9 (D<\/em>1<\/em>D<\/em>2<\/em>) l\u00e0 hai m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh t\u1ea1i c\u00e1c t\u1ea7n s\u1ed1\u00a0\u03c9<\/em>1<\/em>\u00a0v\u00e0\u00a0\u03c9<\/em>2<\/em>. N\u1ebfu g\u1ecdi t\u1ea7n s\u1ed1 trung t\u00e2m c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u t\u1ea7n \u0111\u1ea7u v\u00e0o l\u00e0 :<\/p>\n

          \"bien\"bien<\/span><\/p>\n

          S\u1ef1 \u0111i\u1ec1u chu\u1ea9n m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng l\u1ec7ch kh\u1ecfi t\u1ea7n s\u1ed1 trung b\u00ecnh c\u1ee7a t\u00edn hi\u1ec7u v\u00e0o l\u00e0m bi\u00ean \u0111\u1ed9 \u0111i\u1ec7n \u00e1p v\u00e0o c\u1ee7a hai b\u1ed9 t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9 (U<\/em>1<\/em>, U<\/em>2<\/em>)<\/em>\u00a0thay \u0111\u1ed5i ph\u1ee5 thu\u1ed9c v\u00e0o t\u1ea7n s\u1ed1 \u0111i\u1ec7n \u00e1p v\u00e0o.<\/p>\n

          T\u00e1ch s\u00f3ng d\u00f9ng m\u1ea1ch l\u1ec7ch c\u1ed9ng h\u01b0\u1edfng c\u00f3 nh\u01b0\u1ee3c \u0111i\u1ec3m l\u00e0 kh\u00f3 \u0111i\u1ec1u ch\u1ec9nh cho hai m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng ho\u00e0n to\u00e0n \u0111\u1ed1i x\u1ee9ng n\u00ean \u00edt \u0111\u01b0\u1ee3c d\u00f9ng.<\/p>\n<\/div>\n

          \n

          M\u1ea1ch t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n d\u00f9ng m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng gh\u00e9p<\/h3>\n

          M\u1ea1ch t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n d\u00f9ng m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng gh\u00e9p \u1edf h\u00ecnh 6-15. M\u1ea1ch \u0111i\u1ec7n l\u00e0m vi\u1ec7c theo nguy\u00ean t\u1eafc chuy\u1ec3n bi\u1ebfn thi\u00ean t\u1ea7n s\u1ed1 th\u00e0nh bi\u1ebfn thi\u00ean v\u1ec1 pha, sau \u0111\u00f3 th\u1ef1c hi\u1ec7n t\u00e1ch s\u00f3ng pha nh\u1edd t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9.<\/p>\n

          \"bien<\/p>\n

          T\u00e1ch s\u00f3ng d\u00f9ng m\u1ea1ch c\u1ed9ng h\u01b0\u1edfng gh\u00e9p \u00edt g\u00e2y m\u00e9o v\u00e0 d\u1ec5 \u0111i\u1ec1u ch\u1ec9nh v\u00ec c\u1ea3 hai m\u1ea1ch \u0111\u1ec1u c\u1ed9ng h\u01b0\u1edfng \u1edf t\u1ea7n s\u1ed1\u00a0f<\/em>0<\/em>. Tuy nhi\u00ean \u0111i\u1ec7n \u00e1p ra trong b\u1ed9 t\u00e1ch s\u00f3ng n\u00e0y v\u1eeba ph\u1ee5 thu\u1ed9c t\u1ea7n s\u1ed1 v\u1eeba ph\u1ee5 thu\u1ed9c bi\u00ean \u0111\u1ed9 t\u00edn hi\u1ec7u v\u00e0o |U1<\/span>| n\u00ean n\u00f3 sinh ra nhi\u1ec5u bi\u00ean \u0111\u1ed9. \u0110\u1ec3 kh\u1eafc ph\u1ee5c nh\u01b0\u1ee3c \u0111i\u1ec3m n\u00e0y, ph\u1ea3i \u0111\u1eb7t tr\u01b0\u1edbc m\u1ea1ch t\u00e1ch s\u00f3ng m\u1ed9t m\u1ea1ch h\u1ea1n ch\u1ebf bi\u00ean \u0111\u1ed9.<\/p>\n<\/div>\n

          \n

          M\u1ea1ch t\u00e1ch s\u00f3ng t\u1ef7 s\u1ed1<\/h3>\n

          M\u1ea1ch t\u00e1ch s\u00f3ng \u0111i\u1ec1u t\u1ea7n t\u1ef7 s\u1ed1 c\u00f3 s\u01a1 \u0111\u1ed3 \u1edf h\u00ecnh 6-16. C\u00e1c \u0111i\u1ed1t t\u00e1ch s\u00f3ng \u0111\u01b0\u1ee3c m\u1eafc n\u1ed1i ti\u1ebfp nhau. M\u1ea1ch v\u1eeba l\u00e0m nhi\u1ec7m v\u1ee5 t\u00e1ch s\u00f3ng v\u1eeba l\u00e0m nhi\u1ec7m v\u1ee5 h\u1ea1n ch\u1ebf bi\u00ean \u0111\u1ed9.B\u1ed9 t\u00e1ch s\u00f3ng t\u1ef7 s\u1ed1 kh\u00f4ng c\u00f3 ph\u1ea3n \u1ee9ng v\u1edbi c\u00e1c bi\u1ebfn thi\u00ean v\u1ec1 bi\u00ean \u0111\u1ed9 \u1edf \u0111\u1ea7u v\u00e0o n\u00ean tr\u00e1nh \u0111\u01b0\u1ee3c nhi\u1ec5u bi\u00ean \u0111\u1ed9.<\/p>\n

          \"bien<\/p>\n<\/div>\n

          \n

          M\u1ea1ch t\u00e1ch s\u00f3ng pha c\u00e2n b\u1eb1ng d\u00f9ng \u0111i\u1ed1t<\/h3>\n

          M\u1ea1ch t\u00e1ch s\u00f3ng pha c\u00e2n b\u1eb1ng l\u00e0 hai m\u1ea1ch t\u00e1ch s\u00f3ng bi\u00ean \u0111\u1ed9 d\u00f9ng \u0111i\u1ed1t gh\u00e9p v\u1edbi nhau h\u00ecnh 6-17. T\u00edn hi\u1ec7u c\u1ea7n t\u00e1ch s\u00f3ng ch\u00ednh l\u00e0 t\u00edn hi\u1ec7u \u0111\u00e3 \u0111i\u1ec1u pha,\u00a0u<\/em>dp<\/em>\u00a0\u0111\u01b0\u1ee3c so s\u00e1nh v\u1ec1 pha v\u1edbi m\u1ed9t dao \u0111\u1ed9ng chu\u1ea9n\u00a0u<\/em>ch<\/em>. Bi\u1ec3u th\u1ee9c\u00a0u<\/em>dp<\/em>\u00a0v\u00e0\u00a0u<\/em>ch<\/em>\u00a0nh\u01b0 sau:<\/p>\n

          \"bien<\/p>\n

          \u0110i\u1ec7n \u00e1p \u0111\u1eb7t l\u00ean hai b\u1ed9 t\u00e1ch s\u00f3ng t\u01b0\u01a1ng \u1ee9ng l\u00e0:<\/p>\n

          \"bien<\/p>\n

          Thay v\u00e0o ta c\u00f3:<\/p>\n

          \"bien<\/p>\n

          \u0110i\u1ec7n \u00e1p ra tr\u00ean b\u1ed9 t\u00e1ch s\u00f3ng:\u00a0u<\/em>S<\/span>\u00a0=\u00a0u<\/em>S1<\/span>\u00a0–\u00a0u<\/em>S2<\/span><\/p>\n

          \"bien<\/p>\n

          \"bien<\/p>\n

          V\u1eady tr\u1ecb s\u1ed1 t\u1ee9c th\u1eddi c\u1ee7a \u0111i\u1ec7n \u00e1p ra tr\u00ean b\u1ed9 t\u00e1ch s\u00f3ng ph\u1ee5 thu\u1ed9c hi\u1ec7u pha c\u1ee7a t\u00edn hi\u1ec7u \u0111i\u1ec1u pha v\u00e0 t\u00edn hi\u1ec7u chu\u1ea9n. Tr\u01b0\u1eddng h\u1ee3p\u00a0\u03c9<\/em>01<\/em>\u00a0=\u00a0<\/em>\u03c9<\/em>02<\/em>\u00a0v\u00e0\u00a0<\/em>\u03c6<\/em>01<\/em>\u00a0=\u00a0<\/em>\u03c6<\/em>02<\/em>\u00a0th\u00ec \u0111i\u1ec7n \u00e1p ra ch\u1ec9 c\u00f2n ph\u1ee5 thu\u1ed9c v\u00e0o pha c\u1ee7a t\u00edn hi\u1ec7u v\u00e0o\u00a0\u03c6<\/em>(t)<\/em>.<\/p>\n<\/div>\n<\/div>\n

          \n

          M\u1ea0CH \u0110I\u1ec0U CH\u1ebe XUNG<\/h2>\n

          \u0110i\u1ec1u ch\u1ebf xung th\u1ef1c hi\u1ec7n khi t\u00e1ch s\u00f3ng mang\u00a0u<\/em>t<\/span>\u00a0l\u00e0 c\u00e1c xung cao t\u1ea7n. Trong \u0111i\u1ec1u ch\u1ebf xung c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n \u0111i\u1ec1u bi\u00ean xung, \u0111i\u1ec1u ch\u1ebf \u0111\u1ed9 r\u1ed9ng xung, \u0111i\u1ec1u pha xung, nh\u01b0ng \u0111i\u1ec1u bi\u00ean xung \u00edt d\u00f9ng v\u00ec t\u00ednh ch\u1ed1ng nhi\u1ec5u k\u00e9m. S\u01a1 \u0111\u1ed3 kh\u1ed1i m\u1ea1ch \u0111i\u1ec1u ch\u1ebf xung \u0111\u01b0\u1ee3c m\u00f4 t\u1ea3 \u1edf h\u00ecnh 6-18. T\u00edn hi\u1ec7u \u0111i\u1ec1u r\u1ed9ng xung (\u0110RX) v\u00e0 t\u00edn hi\u1ec7u \u0111i\u1ec1u pha xung (\u0110PX) \u1edf h\u00ecnh 6-19.<\/p>\n

          \"bien<\/p>\n

          Cho\u00a0u<\/em>t<\/span>\u00a0l\u00e0 d\u00e3y xung tam gi\u00e1c cao t\u1ea7n c\u00f2n\u00a0u<\/em>S<\/span>\u00a0l\u00e0 tin t\u1ee9c. Sau m\u1ea1ch t\u1ed5ng ta \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p\u00a0u<\/em>a<\/span>\u00a0l\u00e0 d\u00e3y xung tam gi\u00e1c bi\u1ebfn \u0111\u1ed5i theo\u00a0u<\/em>S<\/span>. Qua m\u1ea1ch h\u1ea1n ch\u1ebf hai ph\u00eda m\u1ee9c kh\u00f4ng v\u00e0 m\u1ee9c\u00a0+E<\/em>\u00a0cho d\u00e3y xung h\u00ecnh thang vu\u00f4ng c\u00f3 \u0111\u1ed9 r\u1ed9ng thay \u0111\u1ed5i theou<\/em>S<\/span>(u<\/em>b<\/span>). D\u00e3y xung n\u00e0y qua m\u1ea1ch s\u1eeda xung \u0111\u01b0\u1ee3c d\u00e3y xung vu\u00f4ng c\u00f3 bi\u00ean \u0111\u1ed9 kh\u00f4ng \u0111\u1ed5i, \u0111\u1ed9 r\u1ed9ng thay \u0111\u1ed5i theo\u00a0u<\/em>S<\/span>, \u0111\u00f3 l\u00e0 t\u00edn hi\u1ec7u \u0111i\u1ec1u r\u1ed9ng xung\u00a0u<\/em>\u0110RX<\/span>. \u0110\u1ec3 c\u00f3 t\u00edn hi\u1ec7u \u0111i\u1ec1u pha xung cho d\u00e3y xung vu\u00f4ng tr\u00ean qua m\u1ea1ch vi ph\u00e2n v\u00e0 h\u1ea1n ch\u1ebf d\u01b0\u1edbi ta \u0111\u01b0\u1ee3c d\u00e3y xung c\u00f3 bi\u00ean \u0111\u1ed9, \u0111\u1ed9 r\u1ed9ng kh\u00f4ng \u0111\u1ed5i xu\u1ea5t hi\u1ec7n s\u1edbm mu\u1ed9n theo\u00a0u<\/em>S<\/span>, \u0111\u00f3 l\u00e0 t\u00edn hi\u1ec7u \u0111i\u1ec1u pha xung\u00a0u<\/em>\u0110RX<\/span>.<\/p>\n

          \"bien<\/p>\n<\/div>\n<\/div>\n

          <\/p>\n","protected":false},"excerpt":{"rendered":"

          GI\u1edaI THI\u1ec6U Trong k\u1ef9 thu\u1eadt th\u00f4ng tin v\u00f4 tuy\u1ebfn \u0111i\u1ec7n, khi mu\u1ed1n truy\u1ec1n th\u00f4ng tin \u0111i xa ng\u01b0\u1eddi ta ph\u1ea3i chuy\u1ec3n t\u1ea7n s\u1ed1 c\u1ee7a t\u00edn hi\u1ec7u tin t\u1ee9c l\u00ean m\u1ed9t t\u1ea7n s\u1ed1 cao h\u01a1n r\u1ea5t nhi\u1ec1u l\u00e0 v\u00ec c\u00f4ng su\u1ea5t c\u1ee7a s\u00f3ng \u0111i\u1ec7n t\u1eeb khi b\u1ee9c x\u1ea1 ra t\u1ef7 l\u1ec7 v\u1edbi t\u1ea7n s\u1ed1 c\u1ee7a s\u00f3ng. […]<\/p>\n","protected":false},"author":2,"featured_media":17989,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11499],"tags":[12809,12810],"class_list":["post-17988","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tin-tuc-tu-dong-hoa","tag-bien-doi-tan-so","tag-cac-mach-bien-doi-tan-so"],"_links":{"self":[{"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/wp\/v2\/posts\/17988","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=17988"}],"version-history":[{"count":0,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/wp\/v2\/posts\/17988\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=\/"}],"wp:attachment":[{"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=17988"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=17988"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hunglong.banbientan.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=17988"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}