. . . .
, , . , : 0 1. , , . , . , , (modem MOD ulation/ DEM odulation, /).
(. 4.1).
4.1 . |
. 4.2. , , , . , , (. 4.2, 4.3).
. 4.2 |
, , , . . |
4.2 | 4.3 | |
, , . | , . , . |
(internal) (external). , . (. 4.4):
, (RS-232 Interface); | |
(R-J11 Interface). |
4.4 , (RS-232 Interface) (R-J11 Interface). |
. RS-232. RJ-11 (. 4.5).
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4.5 , (RS-232 Interface) (R-J11 Interface). |
, , (. 4.6).
4.6 , . R-J11. |
(communications channels) , . : , , , - , . . , ( /). , / , , (100% ) . , . , , , .
. , . (dial-up) . (. 4.7). , , . , 14 56 /. , , , , .
4.7 , , . , () , . |
, (dedicated) . , . , , (. 4.8). , . 64 512 /. . , , , .
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4.8 , . |
(coaxial cable), , , . , . , , . Ethernet. , - (10 20 /).
(twisted pare) . . , . (, ). , , 10 / 100 /. UTP5 (Unscrewed Twisted Pare , 5). , (, ), . , Ethernet Fast Ethernet.
- (fiber optic) , . , , 500 . , - , , ; , . , - , . (backbone), . , , (, ), .
, , . , . , , , , . () . , , , , -.
(microwave systems) , . , 40 50 - . .
(satellite communication systems) , . , . . , , , , . , Rite Aide , (Camp Hill), . , , , . , , .
, . , DirecPC. ( , " ") . DirecPC (. . 4.3), . 35 . (low-orbit satellites) , , . , . , .
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. 4.3 DirecPC |
(-) (infrared /IR-/ systems) , , . , , (1 8 ). , . , -, , .