การส่งข้อมูลผ่าน pstn dte : data terminal equipment is any device...
Post on 19-Jan-2016
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การส่�งข้อมู�ลผ่�าน PSTN
DTE : Data Terminal Equipment is any device that is a source of or destination for binary digital data (PC)
DCE : Data Circuit-terminating Equipment is any device that transmits or receives data in the form of an analog or digital signal through a network (Modem)
DTE DCE PSTN DTEDCE
Data communication interfacing DTE -DCE InterfacingRequirement : Use the same encoding
scheme and have common standards Mechanical characteristics : plugs,
circuits Electrical characteristics : voltage-level,
timing Functional characteristics : meaning of
each interchange circuits เช่�นขา 7 คือ Ground
V.24/EIA-232 (RS 232)
Electronic Industries Association (EIA)
(ISO 2110) 25-pin connector (but can be substituted by 9-pin (DB-9) : 8, 3, 2, 20, 7, 6, 4, 5, 22)
Mechanical characteristics
Electrical characteristics -3 to -15 V=binary 1 or OFF condition +3 to 15 V =binary 0 or ON condition Maximum bit rate 20 kbps
0
1 1
Functional specification
Control SignalName To Function
Request to send
DCE DTE wishes to transmit
Clear to send DTE DCE is ready to receive
DCE ready DTE DCE is ready to operate
DTE ready DCE DTE is ready to operate
Ring indicator DTE DCE is receiving a ringing signal
Received line signal detector
DTE DCE is receiving a signal(carrier)
Null modem
MODEMS MOdulator/DEModulator
Bandwidth 600 Hz to 3000 Hz
PSTN
Dial-up operation
20
DTE
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