Programmable detector for tone signals
US4467277A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 4, 1982 |
| Grant date | Aug 21, 1984 |
| Priority date | — |
| Expiry date | Feb 4, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q1/457
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A detector circuit (10) is programmed to produce an output signal when an input signal is at a predetermined frequency. The input signal is provided to an inverter (14) to produce an inverse signal. The input signal together with the inverse signal are provided to two switches (16, 18). The switches (16, 18) are driven by first and second drive signals produced by a drive generator (60). The output terminals (24, 28) of the switches are alternately connected to the input terminals in synchronism with the corresponding drive signals. The output signals from the switches (16, 18) are transmitted through low pass filters (26, 30) and the resulting signals are combined to produce a summation signal by a summation circuit (36). The summation signal is passed through an absolute value circuit (40) to produce an absolute value signal. The absolute value signal is examined by a threshold detector circuit (44) which produces an output when the absolute value signal exceeds a preset threshold. An oscillator (52) provides a reference signal to a programmable divider ( 56) that produces a selected rate signal for the drive generator (60). The programmable divider (56) is set such that the sele…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.