Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1974-09-17
1977-08-16
Miller, Charles D.
Communications: electrical
Audible indication
Percussion-type sound producer
340347DA, 325 38B, 332 11D, H03K 1322
Patent
active
040429210
ABSTRACT:
An average peak slope companded delta codec for converting an analog signal to a corresponding digital signal and vice versa includes a comparator which receives an analog signal and a variable reconstruction signal and converts the analog signal into a digital data bit stream. A detector is provided for detecting the presence of preselected sequences of bits in the digital bit stream. An attack/decay signal is generated wherein the signal increases upon the occurrence of the preselected sequence and decreases upon the non-occurrence of the preselected sequence with the ratio of the increase to decrease of the attack/decay signal being in the range of 30:1 to 500:1. A converter means receives the attack/decay signal and generates a compand signal which is substantially an anti-logarithmic function of the attack/decay signal wherein the rate of increase of the compand signal is in the range of 0.75 dB/bit period to 3.0 dB/bit period. The compand signal is accumulated to form the variable reconstruction signal which is coupled to the input of the comparator. A means is provided for inverting the polarity of the compand signal when the reconstruction signal exceeds the analog input signal so that the reconstruction signal changes in value toward the value of the analog signal during each bit period. An average peak slope companded delta codec for converting a digital signal back to an analog signal is also disclosed.
REFERENCES:
patent: 3555423 (1971-01-01), Weston
patent: 3628148 (1971-12-01), Brolin
patent: 3727005 (1973-04-01), Franaszek
patent: 3729678 (1973-04-01), Glasbergen
patent: 3781685 (1973-12-01), Ching
patent: 3806806 (1974-04-01), Brolin
L.M. Ericsson Pty Ltd.
Miller Charles D.
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