Automatic telephone dialer for use in intrusion detection systems
US4145581A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 10, 1978 |
| Grant date | Mar 20, 1979 |
| Priority date | — |
| Expiry date | Apr 10, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/276
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An automatic telephone dialer is described which includes a dial tone detection circuit. The dial tone detection circuit responds to a series of tones which are prerecorded on a magnetic tape. The dial tone detection circuit operates to detect the tones and to provide a signal suitable to activate a dialing relay for tone bursts on the tape of a suitable predetermined duration. Upon receipt of a suitable duration tone burst, the tone detection circuit provides an accurate duration signal to provide a relatively identical delay at the beginning and end of a dialing pulse to thereby maintain an accurate dial mark/space ratio determined by the requirements of the telephone line which is accessed by the dialer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.