ͨÐÅÔÀíÆÚÄ©¸´Ï°Ìâ
Ò»¡¢ ÉèËÄÔª»ù´øϵͳµÄ´«ÊäÌØÐÔΪ
1??1,f? TH?f????0,ÆäËüf?1¡¢ 2¡¢ 3¡¢
ÊÔÈ·¶¨ÔËÓøÃϵͳʱ£¬ÎïÀíÐŵÀµÄ¾ø¶Ô´ø¿í£» ÊÔÈ·¶¨¿ÉÒÔʵÏÖÎÞISIµÄ×î´ó´«ÊäËÙÂÊ£» Çó¸ÃϵͳµÄƵ´øÀûÓÃÂÊ¡£
½â£º 1¡¢ ÐŵÀµÄ¾ø¶Ô´ø¿íÊÇ,B?1T£»
2¡¢
ϵͳµÄƵÆ×ÌØÐÔÕýºÃΪ¹ö½µÉýÓàÏÒÆ×?ISI´«Ê䣬´«ÊäËÙÂÊΪRb?ϵͳµÄƵ´øÀûÓÃÂÊΪ?b??0£¬¿ÉÒÔʵÏÖÎÞ
2?2?4/Tbps T3¡¢
Rb?4bps/Hz BT?7f?5?10w/Hz£¬²ÉÓÃÒÖÖƶþ¡¢Ä³ÐŵÀ¾ßÓÐƽ̹µÄË«±ßÔëÉù¹¦ÂÊÆ×ÃܶÈP??nÔز¨µÄË«±ß´øÐźŽøÐд«Ê䣬²¢Éèµ÷ÖÆÐźŵÄ×î¸ßƵÂÊÏÞÖÆÔÚ5kHz£¬¶øÔز¨ÆµÂÊΪ100kHz£¬·¢Éä»úÊä³öµÄÒѵ÷ÐźŹ¦ÂÊΪ10kw£¬´«ÊäË¥¼õ30dB¡£Èô½ÓÊÕ»úµÄÊäÈëÐźÅÏȾ¹ýÒ»ÀíÏëBPFÂ˲¨ÔÙÏà¸É½âµ÷¡£ÊÔÎÊ
1¡¢¸ÃÀíÏëBPFÓ¦¾ßÓÐÔõÑùµÄ´«ÊäÌØÐÔH2¡¢½âµ÷Æ÷ÊäÈë¶ËµÄÐÅÔë±ÈÊǶàÉÙ£¿ 3¡¢½âµ÷Æ÷Êä³ö¶ËµÄÐÅÔë±ÈÊǶàÉÙ£¿ ½â£º1¡¢ ÀíÏëBPFÓ¦¾ßÓеĴ«ÊäÌØÐÔ
?f?£¬²¢»³ö½ÓÊÕ»ú¿òͼ
½ÓÊÕ»ú¿òͼ£º
?0W1 2¡¢ÊäÈëÐźŹ¦ÂÊ Si?10kW/100£¬
Êä
Èë
Ôë
Éù
¹¦
ÂÊ
Ni?2Pn?f??2B?2?5?10?7?2?5?103?10mW
Si?1000 ½âµ÷Æ÷ÊäÈë¶ËµÄÐÅÔë±ÈÊÇNi3¡¢ÒòΪ¶ÔÓÚDSBÐźÅGDEM?2
SoSi??2000 ½âµ÷Æ÷Êä³ö¶ËµÄÐÅÔë±ÈÊÇ
NoNiÈý¡¢²ÉÓà QPSKÐźÅÔÚÎÀÐÇÊÕ·¢»úÉÏ´«ËÍÊý¾Ý £¬Êý¾ÝËÙÂÊΪ30Mbps¡£ ÊÕ·¢»úµÄ´ø¿íΪ 24 MHz¡£
1¡¢Éè´«Êäϵͳ¾ßÓеÈЧÉýÓàÏÒÂ˲¨Æ÷ÌØÐÔ, ËùÐèµÄ¹ö½µÏµÊý ?ÊǶàÉÙ? 2¡¢ÊÇ·ñ¿ÉÕÒµ½Ò»¹ö½µÏµÊý ?Ö§³Ö50MbpsµÄÊý¾ÝÂÊ? ½â£º1¡¢ QPSK M=4, k=2
BT?2f0?1?r?
302(24)?24?(1?r)?(1?r)??1.6230
or r?0.6 2¡¢ BT?2f0?1?r?£©
?24?(1?r)5024?(1?r)? 225²»ÄÜÕÒµ½Ö§³Ö 50Mb/s ËÙÂʵĹö½µÏµÊýr¡£
ËÄ¡¢Ä³ÎÀÐÇͨÐÅϵͳ£¬²ÉÓÃQPSK´«Ê䣬Æ乤×÷Ƶ´ø´¦ÓÚ50MHzµ½52MHzÖ®
¼ä¡£
1.¸ÃϵͳÎÞISI´«ÊäµÄ×î´ó±ÈÌØÂÊÊǶàÉÙ£¿ 2.×î´óµÄƵÆ×ЧÂÊΪ¶àÉÙ£¿
½â£ºÓÉÓÚM=4£»K=2£¬BT?2MHz
BT1.Rb?KRs?K£¬µ±??0ʱ£¬´«ÊäËÙÂÊ×î´óΪ
1??Rbmax?22?4Mbps 1?02.?max?RbmaxBT?2bps/Hz
Îå¡¢ÒÑÖªÐÅÏ¢´úÂëΪ 1 1 1 0 0 0 0 0 1 1 0 0 0 0 1 1£¬ÇóÏàÓ¦µÄAMIÂë¡¢HDB3
Âë¡£²¢·Ö±ð»³öËüÃǵIJ¨ÐÎͼ¡£ ´ð£º
1 1 1 0 0 0 0 0 1 1 0 0 0 0 1 1
AMIÂ룺 +1 -1 +1 0 0 0 0 0 -1 +1 0 0 0 0 -1 +1 HDB3Â룺+1 -1 +1 0 0 0 +V 0 -1 +1 ¨CB 0 0 -V +1 -1
²¨ÐÎͼÈçÏ£º
ÐÅÏ¢Â룺
AMIÂ룺
HDB3Â룺 (0Âë²Î¿¼)
Áù. ijÏßÐÔµ÷ÖÆϵͳµÄÊä³öÐÅÔë±ÈΪ30dB,Êä³öÔëÉù¹¦ÂÊΪ10W,ÓÉ·¢Éä»úÊä³öµ½½âµ÷Æ÷ÊäÈë¶Ë×ܵĴ«ÊäËðºÄΪ60dB£¬ÊÔÇó£º (1)DSB-SCʱµÄ·¢Éä»úÊä³ö¹¦ÂÊ£» (2)SSB-SCʱµÄ·¢Éä»úÊä³ö¹¦ÂÊ¡£
SS´ð£º£¨1£©ÒÑÖªo?30dB o1000£¬No?10?9W£¬´«ÊäËðºÄL?60dB?106
NoNoS ¡à½ÓÊÕ»úµÄÊä³ö¹¦ÂÊSoΪ£ºSo?o?No?1000?10?9?10?6W
No-9
µ±²ÉÓÃDSB/SCʱ£¬½ÓÊÕ»úµÄÊäÈ빦ÂÊΪ£º
11 Si?m2(t)??4S0?2?10?6W
22 ¡à·¢Éä»úµÄÊä³ö¹¦ÂÊΪ£º
Po?Si?L?2?10?6?106?2W
£¨2£©µ±²ÉÓÃSSB/SCʱ£¬½ÓÊÕ»úµÄÊäÈ빦ÂÊΪ£º
11Si?m2(t)??16S0?4?10?6W
44¡à·¢Éä»úµÄÊä³ö¹¦ÂÊΪ£º
Po?Si?L?4?10?6?106?4W
Æß. һϵͳµÄ»ù´ø´«ÊäÌØÐÔÈçÏÂͼËùʾ £¨1£©×î´óÎÞÂë¼ä´®ÈÅ´«ÊäËÙÂÊRB£½£¿£» £¨2£©ÏµÍ³µÄƵ´øÀûÓÃÂÊr£½£¿
-1500 -1000 1 H£¨f£© 0.5 1000 1500 f(Hz) ´ð£º£¨1£©×î´óÎÞÂë¼ä´®ÈÅ´«ÊäËÙÂÊRB£½2¡Á1250=2500 B(»ò³Æ²¨ÌØ) £¨2£©??RB/B?2500/1500? 5/3?1.67 °Ë¡¢ÒÑÖªµ÷ÖÆÐźÅm(t)?0.8cos?1000?t?£¬Ôز¨ÆµÂÊΪ106Hz£¬·ù¶ÈAc?10V¡£
1£®Èç¹û½øÐÐFMµ÷ÖÆ£¬ÇÒµ÷ƵָÊý?FM?5£¬Çó£º
£¨1£©Òѵ÷Ðźŵıí´ïʽ £¨2£©·¢ËÍÐźŴø¿í; 2£®Èç¹û½øÐÐAMµ÷ÖÆ£¬Çó£º
£¨1£©Òѵ÷Ðźŵıí´ïʽ £¨2£©µ÷ÖÆЧÂÊ
£¨3£©Èç¹ûÐŵÀÖмÓÐÔ¸ß˹°×ÔëÉùµÄµ¥±ß¹¦ÂÊÆ×ÃܶÈΪ
N0?10?11W/Hz£¬²»¿¼ÂÇÐŵÀË¥¼õ£¬¼ÆËãÏà¸É½ÓÊÕ»úµÄÊä³öÐÅÔë±È¡£ ½â£º 1.£¨1£©?FM??fmaxfm??fmax?5?500?2500Hz