{"id":5930,"date":"2021-11-20T10:12:20","date_gmt":"2021-11-20T03:12:20","guid":{"rendered":"https:\/\/www.vietlearn.org\/post\/?p=5930"},"modified":"2021-11-20T13:24:11","modified_gmt":"2021-11-20T06:24:11","slug":"radio-co-the-thu-duoc-am-thanh-cua-dai-truyen-hinh-khong","status":"publish","type":"post","link":"https:\/\/www.vietlearn.org\/kien-thuc\/radio-co-the-thu-duoc-am-thanh-cua-dai-truyen-hinh-khong\/","title":{"rendered":"Ra\u0111i\u00f4 c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c \u00e2m thanh c\u1ee7a \u0111\u00e0i truy\u1ec1n h\u00ecnh kh\u00f4ng?"},"content":{"rendered":"\n

C\u00f3 m\u1ed9t s\u1ed1 ra\u0111i\u00f4 ch\u1eb3ng nh\u1eefng c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c ti\u1ebft m\u1ee5c ph\u00e1t thanh c\u1ee7a c\u00e1c n\u01a1i trong c\u1ea3 n\u01b0\u1edbc, m\u00e0 c\u00f2n c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c ph\u00e1t thanh c\u1ee7a c\u00e1c \u0111\u00e0i n\u01b0\u1edbc ngo\u00e0i, song l\u1ea1i kh\u00f4ng thu \u0111\u01b0\u1ee3c \u00e2m thanh k\u00e8m theo truy\u1ec1n h\u00ecnh c\u1ee7a c\u00e1c \u0111\u00e0i truy\u1ec1n h\u00ecnh trong n\u01b0\u1edbc. \u0110\u00f3 l\u00e0 do t\u1ea7n s\u1ed1 c\u1ee7a ch\u00fang kh\u00e1c nhau.<\/p>\n\n\n\n

N\u00f3i chung s\u00f3ng ra\u0111i\u00f4 thu \u0111\u01b0\u1ee3c l\u00e0 s\u00f3ng trung v\u00e0 s\u00f3ng ng\u1eafn, ph\u1ea1m vi t\u1ea7n s\u1ed1 c\u1ee7a ch\u00fang t\u1eeb v\u00e0i tr\u0103m kil\u00f4hec (kHz) \u0111\u1ebfn h\u01a1n 20 megahec (MHz), b\u01b0\u1edbc s\u00f3ng c\u1ee7a v\u00e0i tr\u0103m m\u00e9t \u0111\u1ebfn m\u01b0\u1eddi m\u1ea5y m\u00e9t. C\u00f2n s\u00f3ng m\u00e0 \u0111\u00e0i truy\u1ec1n h\u00ecnh l\u00e0 s\u00f3ng si\u00eau ng\u1eafn, b\u01b0\u1edbc s\u00f3ng ch\u1ec9 c\u00f3 v\u00e0i m\u00e9t. V\u00ec v\u1eady, n\u00f3i chung ra\u0111i\u00f4 kh\u00f4ng thu \u0111\u01b0\u1ee3c \u00e2m thanh c\u1ee7a \u0111\u00e0i truy\u1ec1n h\u00ecnh.<\/p>\n\n\n\n

N\u1ebfu ch\u00fang ta s\u1eeda \u0111\u1ed5i m\u1ea1ch \u0111i\u1ec1u h\u01b0\u1edfng \u0111\u1ebfn d\u1ea3i s\u00f3ng si\u00eau ng\u1eafn, li\u1ec7u c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c \u00e2m thanh truy\u1ec1n h\u00ecnh kh\u00f4ng nh\u1ec9? V\u1eabn kh\u00f4ng \u0111\u01b0\u1ee3c.<\/p>\n\n\n\n

V\u00ec ph\u01b0\u01a1ng ph\u00e1p \u0111i\u1ec1u ch\u1ebf \u00e2m thanh c\u1ee7a ph\u00e1t thanh v\u00e0 truy\u1ec1n h\u00ecnh l\u00ean s\u00f3ng mang m\u1ed7i th\u1ee9 m\u1ed9t kh\u00e1c. N\u00f3i chung, ph\u00e1t thanh \u00e1p d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p \u0111i\u1ec1u bi\u00ean \u0111\u1ec3 ph\u1ee7 \u00e2m thanh l\u00ean s\u00f3ng mang, l\u00e0m cho \u0111\u1ed9 l\u1edbn c\u1ee7a bi\u00ean \u0111\u1ed9 s\u00f3ng mang bi\u1ebfn \u0111\u1ed5i theo \u0111\u1ed9 cao th\u1ea5p c\u1ee7a \u00e2m thanh. Khi ra\u0111i\u00f4 thu \u0111\u01b0\u1ee3c lo\u1ea1i s\u00f3ng mang \u0111\u00f3, li\u1ec1n theo quy lu\u1eadt bi\u1ebfn \u0111\u1ed5i bi\u00ean \u0111\u1ed9 c\u1ee7a n\u00f3 m\u00e0 t\u00e1ch ra v\u00e0 ho\u00e0n nguy\u00ean th\u00e0nh \u00e2m thanh. Trong truy\u1ec1n h\u00ecnh, \u00e2m thanh \u00e1p d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p \u0111i\u1ec1u t\u1ea7n, c\u00f3 ngh\u0129a l\u00e0 t\u1ea7n s\u1ed1 c\u1ee7a s\u00f3ng mang bi\u1ebfn \u0111\u1ed5i theo \u0111\u1ed9 cao th\u1ea5p c\u1ee7a \u00e2m thanh, c\u00f2n bi\u00ean \u0111\u1ed9 c\u1ee7a s\u00f3ng mang th\u00ec \u1ed5n \u0111\u1ecbnh kh\u00f4ng \u0111\u1ed5i. Lo\u1ea1i s\u00f3ng mang n\u00e0y cho d\u00f9 \u0111\u01b0\u1ee3c ra\u0111i\u00f4 thu v\u00e0o, c\u0169ng kh\u00f4ng t\u00e1ch \u0111\u01b0\u1ee3c t\u00edn hi\u1ec7u \u00e2m thanh ra, v\u00ec bi\u00ean \u0111\u1ed9 c\u1ee7a n\u00f3 kh\u00f4ng bi\u1ebfn \u0111\u1ed5i theo quy lu\u1eadt c\u1ee7a \u00e2m thanh.<\/p>\n\n\n\n

V\u1eady l\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 ra\u0111i\u00f4 c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c \u00e2m thanh c\u1ee7a truy\u1ec1n h\u00ecnh nh\u1ec9?<\/p>\n\n\n\n

Ch\u1ec9 c\u00f3 c\u00e1ch l\u00e0 d\u00f9ng ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n t\u00e1ch \u0111\u01b0\u1ee3c s\u00f3ng \u0111i\u1ec1u t\u1ea7n th\u00ec m\u1edbi thu \u0111\u01b0\u1ee3c \u00e2m thanh truy\u1ec1n h\u00ecnh. C\u1ed1 nhi\u00ean, ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n \u0111\u00f3 c\u00f2n ph\u1ea3i ch\u1ec9nh \u0111\u01b0\u1ee3c trong d\u1ea3i t\u1ea7n s\u1ed1 c\u1ee7a \u00e2m thanh k\u00e8m theo truy\u1ec1n h\u00ecnh.<\/p>\n\n\n\n

\u1ede Trung Qu\u1ed1c, d\u1ea3i t\u1ea7n s\u1ed1 c\u1ee7a s\u00f3ng ph\u00e1t thanh \u0111i\u1ec1u t\u1ea7n th\u00f4ng th\u01b0\u1eddng \u0111\u01b0\u1ee3c b\u1ed1 tr\u00ed trong kho\u1ea3ng 88 ~ 108 MHz. T\u1ea7n s\u1ed1 thu c\u1ee7a ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n c\u0169ng \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf<\/a> trong c\u00f9ng m\u1ed9t d\u1ea3i. V\u00ec v\u1eady, n\u1ebfu ph\u00e1t thanh \u0111i\u1ec1u t\u1ea7n n\u00e0o n\u1eb1m trong d\u1ea3i t\u1ea7n s\u1ed1 \u0111\u00f3 \u0111\u1ec1u \u0111\u01b0\u1ee3c ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n thu nh\u1eadn.<\/p>\n\n\n\n

C\u0103n c\u1ee9 v\u00e0o ph\u1ea1m vi t\u1ea7n s\u1ed1 c\u1ee7a k\u00eanh truy\u1ec1n h\u00ecnh m\u00e0 Trung Qu\u1ed1c quy \u0111\u1ecbnh th\u00ec ph\u1ea1m vi t\u1ea7n s\u1ed1 s\u00f3ng v\u00f4 tuy\u1ebfn \u0111i\u1ec7n c\u1ee7a truy\u1ec1n h\u00ecnh k\u00eanh n\u0103m l\u00e0 84 ~ 92 MHz, \u1edf trong d\u1ea3i t\u1ea7n s\u1ed1 thu c\u1ee7a ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n. V\u00ec v\u1eady, \u00e2m thanh k\u00e8m theo ti\u1ebft m\u1ee5c truy\u1ec1n h\u00ecnh k\u00eanh n\u0103m c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n thu nh\u1eadn v\u00e0 ph\u00e1t ra. C\u00f2n d\u1ea3i t\u1ea7n s\u1ed1 s\u00f3ng v\u00f4 tuy\u1ebfn \u0111i\u1ec7n c\u1ee7a truy\u1ec1n h\u00ecnh k\u00eanh 20 l\u00e0 526 ~ 534 megahec, \u1edf ngo\u00e0i d\u1ea3i t\u1ea7n s\u1ed1 thu c\u1ee7a ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n, ra\u0111i\u00f4 \u0111i\u1ec1u t\u1ea7n \u0111\u00e0nh ch\u1ecbu b\u00f3 tay, kh\u00f4ng thu \u0111\u01b0\u1ee3c \u00e2m thanh k\u00e8m theo ti\u1ebft m\u1ee5c truy\u1ec1n h\u00ecnh k\u00eanh 20.<\/p>\n\n\n\n

T\u1eeb kho\u00e1: Ra\u0111i\u00f4; K\u00eanh truy\u1ec1n h\u00ecnh; \u0110i\u1ec1u bi\u00ean; \u0110i\u1ec1u t\u1ea7n; S\u00f3ng mang.<\/p>\n\n\n\n

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

C\u00f3 m\u1ed9t s\u1ed1 ra\u0111i\u00f4 ch\u1eb3ng nh\u1eefng c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c ti\u1ebft m\u1ee5c ph\u00e1t thanh c\u1ee7a c\u00e1c n\u01a1i trong c\u1ea3 n\u01b0\u1edbc, m\u00e0 c\u00f2n c\u00f3 th\u1ec3 thu \u0111\u01b0\u1ee3c ph\u00e1t thanh c\u1ee7a c\u00e1c \u0111\u00e0i n\u01b0\u1edbc ngo\u00e0i, song l\u1ea1i kh\u00f4ng thu \u0111\u01b0\u1ee3c \u00e2m thanh k\u00e8m theo truy\u1ec1n h\u00ecnh c\u1ee7a c\u00e1c \u0111\u00e0i truy\u1ec1n h\u00ecnh trong n\u01b0\u1edbc. \u0110\u00f3 l\u00e0 do t\u1ea7n […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[15,7],"tags":[],"class_list":["post-5930","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-vat-ly"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/5930","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=5930"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/5930\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=5930"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=5930"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=5930"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}