1??????E1??2.048M?????·????PCM±à????
2??????E1?????¤??256??bit,·???32???±?????????±????8??bit??
3????????8k??E1?????¨??????????8K*256=2048kbps??
4???????±????E1??????8bit??8*8k=64k????????E1??????32??64K??
E1???á??
E1??????,??????????????????·???,????????E1????0?±????????????????????,???à31???±?????????????????§????;??????????E1??,??????0?±????,??16?±??????????????????,??????1??15,??17????31??30???±???????????????§????;????????????E1??,?ù??32???±?????????????????§????.
???? E1?ù??????
E1?????????á???ò??
??E1????????8bit×é???????±???¨TS??????32???±??×é???????????¨F??,16?? ??×é???????????¨MF????????????????TS0?÷?????????????¨???????¨FAS????CRC-4?¨???·???à???é??????????????????TS16?÷?????????·?????¨CAS?????????¨ ??????????????????????????TS1??TS15??TS17??TS31??30???±???????°???ò???? ??????????????TS1??TS15??TS17??TS31???°?????±??TS0??TS16???°???ú?±?? ?????????????????????????¨CCS????TS16???§???????????????????????±???????????????????????????±???á??????????TS1??TS31?????ú????TS0????
??PCM±à???é??E1??
??PCM±à????E1???±?????÷??????E1??·?32???±??TS0-TS31???????±????64K??????TS0??±???????????Si, Sa4, Sa5, Sa6,Sa7,A±???????, ????????????CRC???é???òSi±???????????CRC???é????TS16???????±??, ?±??????????(???·?????ò???·????)?±,???±??????????????, ???§???????????????????ù??2M??PCM??????
?? PCM30 : PCM30???§?????±????30??, TS1-TS15, TS17-TS31??TS16????????????CRC???é??
?? PCM31: PCM30???§?????±????31??, TS1-TS15, TS16-TS31??TS16??????????????CRC???é??
?? PCM30C: PCM30???§?????±????30??, TS1-TS15, TS17-TS31??TS16????????????CRC???é??
?? PCM31C: PCM30???§?????±????31??, TS1-TS15, TS16-TS31??TS16??????????????CRC???é??
CE1,????°?2M??????·?????30??64K???±??????°?????N*64???????????????????????±????????????????n??64K??±???????ce1/pri????
CE1----×??à????31?????????????? timeslots 1----31 timeslots 0 ??????

???? ????
G??703·???????75 ohm????????120 ohm2??????
???? ????E1??????·?·¨??
1?? ??????2M??×÷???????·????DDN 2M??
2?? ??2M??×÷??????64k?°??×é??????128K??256K??????????CE1??
3?? ????×÷?????????ú????×??????±????????E1×?±???????·¨????°?????E1×÷??32??64K???????????±??0???±??15????×÷signaling???????????ù??????E1??????30?·?°????PRI??????????×???????????????·?????±ê×???PRA??????
??2611???????ò???????¨????V.35-G.703×????÷??E1???????ù????±?????±?E1?¨???????°DDN??2M???????·?¨??????HDSL???·???????§?à.
E1?????????è±????????????????§?à???????ú?á??E1·???.
???? ????×???????
E1?????????±????·???E1?????????????§/???§??/?????§??/????????????????·???E1??????????±????ê?????????ò????±??????????????????????á?????????ò???????¨???????????????????á?ì???????¨???????¨/?ó??/????/?§?????é?????????????????÷??????×è??/ ???á??/CRC4???é??×è??75ohm??120ohm?????????á????PCM31/PCM30/???????????????????????ú????PCM31??PCM30·?±??è????CCS??CAS???????±?????????????±????CCS????·?????CRC???é?????é???????????ü????·??????????ù????±??¤???í??????????
???? ????
?? ?? lzx (??????) ???ó×÷???á??: ??
: questions:
: 1. E1 ?? CE1?????????????????????????????à?????§?è±??????§?à???¨???ó?§??????
: ?????????????? ·?±?????????
?×???????????¨?????????á??E1??CE1???????·??????°????§??E1???·????
CE1????·?????±???????E1?????ó?????????è±??ù???¨??CE1?????±E1??????
E1????????×÷CE1??
: 2. CE1 ??32???±??????????°???
CE1??0??16?±??????,0????????????,16?????????ü??,??????????????30??
?±??1-15??16-30
: 3. E1/CE1/PRI??????????·??????¨??????2M??????????DDN??2M??????????°???
E1 ??CE1 ????E1???·±ê×???PRI??ISDN?÷????????30B+D??DDN??2M?????÷???·
?????????????????????é??
E1??CE1????±????±????????·??±??????
: 4. E1/CE1/PRI?????????±????????
E1??CE1??????32?±????30?±????0??16·?±?????????????????????????PRI????
30B+D ??30B????????D?????????????? E1????CAS?á????????????????PRI??????
????·?????????????????????
: 5. CE1??·???E1??
CE1 ??E1 ?±??????????????CE1±??è?±E1??????????·??±????????
: 6. ??????????CE1???????????à???????????±???????¨??2M?????÷·??§??????
N*64K<2M,·??§???í???????????? ???????????????·????????·???????????????
?????è±?????·??±??????????????????????????·????ù???ù???±?????ò?????? ???è??°??????á?????±?????ò??·??§???????????????????±????DDN???·???????? ·??§??????????
: 7.CE1??????·??±??????E1?????????????·???÷??E1???????¨
: .................?¨??????????
????
8??Cisco 7000????????ME1??Cisco 2600/3600????E1?? CE1????????±???
?? ?? Cisco 7000????ME1????????E1?? CE1?? ??Cisco 2600/3600????E1??CE1???§??×???????????
?ù?? ????
??????
?????ú??·¨?? ???????????????ú???????á????????G703×?v35×????÷????????????
or BNC??DB15??BNC??RJ45 ?????? CE1