Electrical audio signal processing systems and devices – One-way audio signal program distribution – Public address system
Patent
1986-11-06
1989-03-21
Salce, Patrick R.
Electrical audio signal processing systems and devices
One-way audio signal program distribution
Public address system
381 46, 3645135, 379351, 341143, G10L 506
Patent
active
048151378
ABSTRACT:
A signal is classified as being one among a plurality of classifications by employing a prescribed relationship between absolute moments of a complex low-pass version of the signal. Specifically, the prescribed relationship is related to the second order moment of the magnitude of the complex low-pass version being normalized by the first order moment squared. This results in a so-called normalized variance which is compared to predetermined threshold values to classify the signal as having one of a plurality of modulation schemes, e.g., FSK, PSK or QAM.
In another embodiment, a signal is classified as being speech or voiceband data. This is achieved by employing a phase relationship, i.e., the sign, of the autocorrelation of a complex low-pass version of the signal and the normalized variance. If the autocorrelation has a prescribed phase or the normalized variance is greater than a predetermined value the signal is speech, otherwise it is voiceband data.
REFERENCES:
patent: 4281218 (1981-07-01), Chuang et al.
patent: 4297533 (1981-10-01), Gander et al.
"Visual Pattern Recognition by Moment Invariants", M. K. Hu, I.R.E. Transactions on Information Theory, Feb. 1962, pp. 179-187.
IEEE Transactions on Communications, vol. COM-30, No. 4, Apr. 1982--Highly Sensitive Speech Detector and High-Speed Voiceband Data Discriminator in DSI-ADPCM Systems by Yohtaro Yatsuzuka.
IBM Technical Disclosure Bulletin vol. 26, No. 1, Jun. 1983--Voice/Data Detector and Discriminator for Use in Transform Speech Coders by D. R. Irvin.
American Telephone and Telegraph Company
AT&T Bell Laboratories
Salce Patrick R.
Stafford Thomas
Todd Voeltz Emanuel
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