Title :
Pitch-tracked CELP speech coding with transparent DTMF signaling
Author_Institution :
COMSAT Lab., Clarksburg, MD, USA
Abstract :
A diagnostic analysis was conducted on code-excited linear prediction (CELP)-coded speech at 4.8 kbit/s for mobile radio communications. The occasional roughness in CELP-coded speech was traced to pitch contour infidelity, as well as the discontinuity of speech spectra. The use of a first-order integer-valued pitch filter also degraded the coded speech. A pitch-tracked CELP (PT-CELP) coding scheme was developed. Frame-to-frame variation of speech spectra was controlled in a smooth manner. An open-loop multiframe pitch tracker was employed, followed by closed-loop, third-order pitch filter analysis. PT-CELP demonstrated higher quality speech for enhanced mobile radio services. A simple algorithm was also developed for transparent dual-tone multifrequency (DFMT) signaling through the vocoder
Keywords :
linear predictive coding; mobile radio systems; speech coding; telecommunication signalling; vocoders; 4.8 kbit/s; closed-loop third-order pitch filter analysis; code-excited linear prediction; first-order integer-valued pitch filter; frame-to-frame variation; mobile radio communications; open-loop multiframe pitch tracker; pitch contour infidelity; pitch-tracked CELP; pitch-tracked CELP speech coding; speech quality; speech spectra discontinuity; transparent DTMF signaling; transparent dual-tone multifrequency signaling; vocoder; Communication system control; Degradation; Filters; Land mobile radio; Mobile communication; Open loop systems; Speech analysis; Speech coding; Speech enhancement; Vocoders;
Conference_Titel :
Personal, Indoor and Mobile Radio Communications, 1992. Proceedings, PIMRC '92., Third IEEE International Symposium on
Conference_Location :
Boston, MA
Print_ISBN :
0-7803-0841-7
DOI :
10.1109/PIMRC.1992.279849
