Delta modulation method and system for signal compression
First Claim
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1. A system for expanding floating zero delta modulated compressed information signals corresponding to original information time domain signals, said system comprising:
- memory means for storing said compressed information signals;
storage means for temporarily storing a signal representative of the amplitude of a sample point on a synthesized waveform corresponding to one of said original information time domain signals, said storage means having an output terminal for manifesting the signals stored therein;
means for contemporaneously accessing successive compressed information signals corresponding to three adjacent sample points of said original information signals;
means coupled to said accessing means for comparing said successive compressed information signals accessed from said memory means and for generating an incremental signal value restricted to one of a predetermined confined number of values when the difference between said successive compressed information signals is within the most positive one half of said confined number of values and restricted to the negative of said one of a predetermined confined number of values when said difference is within the most negative one half of said confined number of values;
adder means coupled to said generating means and said storage means for algebraically combining said incremental signal value with said synthetic waveform sample point signal to produce a successive synthesized waveform sample point signal; and
timing and control means for replacing the contents of said storage means with said successive synthesized waveform sample point signal and for enabling said accessing means to contemporaneously access the next successive compressed information signals corresponding to the next adjacent sample points.
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Abstract
This delta modulation system uses the differences between three successive samples of a waveform (the i-1, i, and i+1) such that the number of bits per digitization is reduced from four to two. The value vi of the ith sample is calculated by the equation vi =vi -1+f(Δi-1, Δi), and f is a special function defined by 16 values stored in a read-only memory.
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Citations
8 Claims
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1. A system for expanding floating zero delta modulated compressed information signals corresponding to original information time domain signals, said system comprising:
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memory means for storing said compressed information signals; storage means for temporarily storing a signal representative of the amplitude of a sample point on a synthesized waveform corresponding to one of said original information time domain signals, said storage means having an output terminal for manifesting the signals stored therein; means for contemporaneously accessing successive compressed information signals corresponding to three adjacent sample points of said original information signals; means coupled to said accessing means for comparing said successive compressed information signals accessed from said memory means and for generating an incremental signal value restricted to one of a predetermined confined number of values when the difference between said successive compressed information signals is within the most positive one half of said confined number of values and restricted to the negative of said one of a predetermined confined number of values when said difference is within the most negative one half of said confined number of values; adder means coupled to said generating means and said storage means for algebraically combining said incremental signal value with said synthetic waveform sample point signal to produce a successive synthesized waveform sample point signal; and timing and control means for replacing the contents of said storage means with said successive synthesized waveform sample point signal and for enabling said accessing means to contemporaneously access the next successive compressed information signals corresponding to the next adjacent sample points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification