Methods and apparatus to decode dual-tone signals
US8391469B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 11, 2008 |
| Grant date | Mar 5, 2013 |
| Priority date | — |
| Expiry date | Jan 3, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/4575
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus to decode dual-tone signals are disclosed. An example receiver to decode a dual-tone signal includes a tone detector to detect a start of a first tone, a first counter to count first cycles of the first tone, a second counter to count second cycles of a system clock while the first counter is counting and the first count is less than a first threshold, state control logic to start the second counter counting third cycles of the clock when a time period elapses, the third count being substantially equal to the second count, the first counter to count fourth cycles of a second tone while the third cycles are counted, and a decoder to compare the fourth count to a second threshold to identify an event represented by the signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.