Bell 202 - modem and modem communication protocol .
Developed by Bell System Corporation. Used to remotely configure telecommunications equipment and determine the caller's Caller_ID number. Uses frequency modulation with frequency division channels. It can work in the following modes:
- single-ended duplex: 1200 bps forward channel, 5 bps reverse channel
- single-ended duplex: 1200 bps forward channel, 150 bps reverse channel
- half duplex 1200 bps.
The logical unit (MARK) encodes the harmonic frequency of 1200 Hz.
The logical zero (SPACE) codes the harmonic frequency of 2200Hz.
Literature
- Bell System Technical Reference PUB 41212, Data Sets 202S and 202T Interface Specification, July 1976
Links
- Yashkardin V.L. Bell 202 - interface specification. SoftElectro (2010). Archived April 18, 2012.