Digital programmable tone detector
US4021653A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 14, 1975 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Oct 14, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R23/15
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved detection arrangement for detecting the presence of a given tone in a received input signal. A reference generator, in the form of a reference clock and a programmable divider, produces a first reference frequency, equal to the frequency of the tone, and at an arbitrary phase angle thereto. A second generator output is in quadrature to the first. Each reference signal is product detected with the input signal via exclusive OR gates. A unique digital low pass filter, operating in a time multiplex mode, receives the gate outputs, removes all high frequency components therefrom, and produces pairs of output binary number encoded signals, each of which is representative of a vector component of a detected tone. Threshold detector circuitry monitors the outputs indicating an above threshold condition at its output in response to predetermined combinations of the binary numbers. The combinations represent all input vectors whose resultant absolute magnitude exceeds a chosen threshold. A second detector samples the threshold detector output, recording the number of samples over threshold during a given interval. If the number exceeds a selected minimum an output signal is prod…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.