Method and apparatus for detecting speech signals in the presence of noise
Abstract
Abstract A METHOD AND APPARATUS FOR DETECTING THE INSTANTANEOUS PEAK VALUES SOF A PCM CODED VOICE SIGNAL ABOVE A THRESHOLD LEVEL AND ENERGIZING A TRANSMITTER CARRIER IN RESPONSE THERETO, THEREBY CONSERVING CARRIER POWER DURING THE PERIODS WHEN NO VOICE SIGNAL IS PRESENT. THE THRESHOLD IS ESTABLISHED AT A LEVEL WHERE THE PROBABILITY OF THE INSTANTANEOUS VALUE OF A SPEECH SIGNAL EXCEEDING ITS RMS VALUE IS MUCH GREATER THAN THE PROBABILITY OF THE INSTANTANEOUS VALUE OF A WHITE GAUSSIAN NOISE SIGNAL EXCEEDING ITS RMS VALUE FOR EQUAL OF POWER. THE CIRCUIT MAINTAINS CARRIER POWER FOR A VARIABLE DELAY OR DEFERRED HANGOVER PERIOD AFTER EACH THRESHOLD VOICE DETECTION. THE HANGOVER PERIOD VARIES FROM A PREDETERMINED MINIMUM TIME DELAY TOA MAXIMUM TIME DELAY WHICH EQUALS THE LENGTH OF THE VOICE BURST NOT WXCEEDING 150 MILLISECONDS. ALTERNATELY, BECAUSE OF THE PARTICULAR CHARACTERISTICS OF SPEECH WAVEFORMS, THE THRESHOLD VOICE DETECTIONS MAY BE CONVENIENTLY COUNTED AND THE CARRIER TRANSMITTER ENERGIZED WHENEVER THE COUNT EXCEEDS A PREDETERMINED VALUE, WHICH FURTHER REDUCE THE MRAGIN OF NOISE TRIGGERING ERROR, IN ADDITION, THE DEFERRED, VARIABLE HANGOVER PERIOD MAY BE REPLACED BY A FIXED DELAY TO FURTHER SIMPLIFY THE CIRCUITRY REQUIRED.
Inventors
- 👤 E Fariello
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |