Dual tone multi-frequency detector

Details Dual tone multi-frequency detector Dual tone multi-frequency detector

1989-12-18

1992-08-11

Mai, Tan V.

Boots, shoes, and leggings

3647241, G06F 1531

Patent

active

051385694

ABSTRACT:
An apparatus for identifying a first tone and a second tone present in a dual-tone signal, the first tone being selected from a group of tones located within a low band and the second tone being selected from a second group of tones located within a high band, the low band and the high band each spanning a frequency range no greater than f.sub.0 wide, the apparatus including a first filter for isolating and downconverting the portion of the dual-tone signal falling within the low band so that it lies within a low frequency range extending from -f.sub.0 to F.sub.0 ; and a second filter for isolating and downconverting the portion of the dual-tone signal falling within the high band so that it lies within the low frequency range.

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patent: 4361875 (1982-11-01), Hertz et al.
S. L. Gay et al., "Algorithms For Multi-Channel DTMF Detection For The WE DSP32 Family", IEEE, 1989, pp. 1134-1137.
A. J. Grossman, "Snythesis of Tchebycheff Parameter Symmetrical Filters", Proceedings of the IRE, 1957, pp. 454-473.
A. G. Constantinides, "Spectral Transformations for Digital Filters", Proceedings of The Institution of Electrical Engineers, vol. 117, No. 8, pp. 1585-1590, (1970).
R. A. Valenzuela et al., "Digital Signal Processing Schemes for Efficient Interpolation and Decimation", IEE Proceedings, vol. 130, 1983, pp. 225-235.
R. A. Valenzuela Steude, "Techniques for Transmultiplexer Design", Thesis for Imperial Coll. of Sci. & Tech., 1982, pp. 1-211.
B. J. White et al., "A Monolithic Dual Tone Multifrequency Receiver", IEEE, vol. SC-14, No. 6, 1979, pp. 991-997.

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