Transformerless data access arrangement

Details Transformerless data access arrangement Transformerless data access arrangement

1997-03-07

1999-02-23

Chan, Wing F.

Telephonic communications

Telephone line or system combined with diverse electrical...

Having transmission of a digital message signal over a...

379 9305, H04M 1100

Patent

active

058752358

ABSTRACT:
A transformerless data access arrangement (DAA) device facilitates data transfer between a high speed modem device and a central office telephone line (i.e., a phone line). The DAA device uses D/A and A/D converters in conjunction with a pair of nonlinear opto-couplers that function as an isolation barrier. The A/D converter converts an analog signal received from the phone line into a one-bit modulated digital signal. The digital signal is relayed by the nonlinear opto-couplers to a processor. Since the relayed signal is digital, the use of nonlinear opto-couplers does not result in unacceptable levels of noise and distortion. This is relevant since high speed modems have stringent noise and distortion requirements. A phone line supply voltage is regulated internally and used to power the DAA device. When the processor detects a ring signal on the phone line, the processor generates a control signal which places the A/D and D/A converters in idle mode while sending a caller ID directly to the processor. The processor also initiates a control signal to place the DAA device in and out of its normal operation mode if an off-hook condition is detected.

REFERENCES:
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patent: 5117452 (1992-05-01), Callele et al.
patent: 5369687 (1994-11-01), Farkas
Krypton, "Krypton K.sup.2 930G/K.sup.2 930GW Chipset--Low Cost All Silicon DAA (Data Access Arrangement)", Jan. 15, 1996.
Schweber, Bill, "Testing the Telephony Interface", Mar. 28, 1996, EDN.
Mitel, "Line Interface Circuit Preliminary Information", Apr. 1995, Issue 5, MH88422.
Mitel, "Calling Number Identification Circuit 2 Preliminary Information", Feb. 1995, Issue 1, CMOS MT8843.

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