Ultrasonically-calibrated fast-start echo canceller for cellular and pcs telephone car kits
US6510225B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1999 |
| Grant date | Jan 21, 2003 |
| Priority date | — |
| Expiry date | Feb 16, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M9/082
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The present disclosure describes an ultrasonically-calibrated fast-start adaptive echo canceller system. The system consists of at least one ultrasonic transducer for transmitting ultrasound signal and at least one ultrasonic receiver for receiving reflected ultrasound echo. The system also includes an echo pulse counter that operates constantly when the phone is on. The counter processes the reflected ultrasound echo from the ultrasonic receiver to determine optimum sets of ultrasonic delay and attenuation coefficients. A fast-start adaptive controller adaptively controls an algorithm stored in a random access memory to correlate sets of audio-frequency coefficients for transversal filter with predetermined sets of ultrasonic coefficients by using an ultrasound to audio-frequency conversion table. The resultant sets of audio-frequency coefficients are held on a stack.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.