Modem with improved escape sequence mechanism to prevent escape

Pulse or digital communications – Repeaters – Testing

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179 2DP, 370 85, H04M 1108

Patent

active

045493022

ABSTRACT:
An FSK modem for coupling a standard data port (50) to a telephone line (45) in which the signal path between the phone line and the data port passes through a processor (55). When the modem is in a transparent mode of operation, for transmitting data, a timer (190) detects the passage of a predetermined period of time after the most recent data input signal input to a data port (50). If the next sequence of data signals corresponds to an escape character, the program (112) controlling the modem waits to see if a second occurrence of the predetermined period of time follows provision of the escape character. If this occurs, the modem switches to a command mode of operation in which it ceases to modulate and transmit signals and waits for commands to be entered at the data port. The same frequency detection apparatus (83, 192, 180) is used to both demodulate FSK encoded signals and detect the presence of a telephone ringing signal on the line. A pair of impedances (161, 162) provide alternate paths either through an input filtering network (167) or bypassing the network (135, 69) in a manner which allows the ring signals to pass directly to the input (69) of the frequency detector while assuring that only filtered FSK signals reach the input. Also shown is the use of the same frequency synthesizing apparatus (86, 253, 259) for generating FSK output signals and high group DTMF signals with appropriate switchable attenuation (88) provided in this signal path.

REFERENCES:
patent: 3774164 (1973-11-01), Osterberg
patent: 3825905 (1974-07-01), Allen
patent: 3851105 (1974-11-01), Willard et al.
patent: 3916384 (1975-10-01), Fleming
patent: 4009469 (1977-02-01), Boudreau et al.
patent: 4121052 (1978-10-01), Richard
patent: 4125872 (1978-11-01), Maxwell
patent: 4293948 (1981-10-01), Soderblom
patent: 4379294 (1983-04-01), Sutherland et al.
patent: 4387425 (1983-06-01), El-Giohary
patent: 4387444 (1983-06-01), Eaton
patent: 4410983 (1983-10-01), Cope
patent: 4429384 (1984-01-01), Kaplinsky
"A Mini-Computer Research Network", Lennon, Barrett, Spies, Procod. IEEE 7th Ann. Computer Conference, 1973.
"Control of Synchronous Communications Using Microcomputer Peripherals", Thomas, Proc. IEEE 15th Ann. Comp. Conf., 1977.
"Vadic Operation and Service Manual for VA831B RS232C Adaptor", Manual No. 18008-19, Issue 1, Dec. 1977.
"Intelligent Terminal Implemention for the S-100 Bus", from Doctor Dobbs' Journal of Computer Calisthenics, and Orthodontia, No. 26, pp. 4-16, 1978/1979.
Advertisment, North Star Computers (Horizon), from Personal Computing magazine, Apr., 1978.
Owner's Manual for Micromodem II, Hayes Microcomputer Product, Inc. (formerly D. C. Hayes Associates, Inc.), .COPYRGT.1978.

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