Data compression method and apparatus
Patent 4546342 Issued on October 8, 1985. Estimated Expiration Date: 
December 14, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 14, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3588836 3750024 Signal coding for telephone communication system Run length encoding of facsimile signals Gain control apparatus for digital telephone line circuits Patent #: 4272648 InventorsAssigneeApplicationNo. 06/561723 filed on 12/14/1983US Classes:341/51, Adaptive coding341/67, To or from variable length codes360/32, CONVERTING AN ANALOG SIGNAL TO DIGITAL FORM FOR RECORDING; REPRODUCING AND RECONVERTING375/240BANDWIDTH REDUCTION OR EXPANSIONExaminersPrimary: Miller, Carl S.Attorney, Agent or FirmInternational ClassH03M 7/42 (20060101)AbstractA music data compression system is disclosed which includes an analog to digital converter for converting the analog music signal to digital sample signal form, a digital compression filter for compression filtering the digital sample signals, and an encoder for truncated Huffman encoding the compression filter output. An entropy setting unit is included in the system for step control of the signal supplied to the digital compression filter in accordance with one or more threshold levels of the envelope of the music signal, and for reducing the entropy of the signal with increases in the energy level of the music signal. Different codes may be implemented in accordance with the threshold(s), and an identifying code word is inserted in the Huffman encoded stream. A decoder, digital reconstruction filter, and digital to analog converter are used to reconstruct the analog music signal. The identifying code word in the encoded signal stream to the decoder is used to select the necessary algorithm for decoding, and an entropy setting unit is included for step control of the gain of the digital reconstruction filter output under control of the identifying code word when step gain control is included prior to compression filtering.Other References
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