Transformerless data access arrangement
US5875235A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 7, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Mar 7, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/57
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.