A-2 APPENDIX A: MODEM SPECIFICATION AND INTERFACE PIN ASSIGNMENTS

Data Input

Serial binary. Complies with CCITT V.28. Accepts levels ±3 volts to ±25 volts. (+)= space (-)= mark. Single wire ground return. 3000 to 7000 ohms load.

Data Output

Serial binary. Complies with CCITT V.28 ±12 volts nominal. Output impedance 300 ohms.

Synchronization

RTS/CTS delay dependent on modulation format.

Equalizer

Automatic adaptive equalizer.

Error correction

V.42 LAPM and MNP4.

Data compression

V.42bis and MNP5.

Autodial - Autoanswer

Method

Pulse dial. 10 pps rate. Make period 33 msec. Break period 67 msec (UK version). Interdigit period 800msec. Tone dial. On time 85 msec. ID time 85 msec. Duty cycle 50%.

Line Interface

600 ohm impedance. Bell tinkle suppression provided. Old and new dial tone detection. Secondary dial tone detection for PABX use. Progress tones and answer tone detection.

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3Com 980/000048/001 manual Autodial Autoanswer