Method for compression and expansion of analogue signals
View Patent ↗In an analog signal compression method with digital compression and digital expansion of linear based or sine-based linear signals, a signal coordination point is determined in a bi-adaptive scaleable mV/step and a time/step structured plane. To accomplish this, the linear or sine-based input signal is digitized, the breaks of the digitized linear or sine-based signal are detected, and the time difference and the amplitude difference of two successive breaks of the linear or sine-based signal are determined. This permits time differences and amplitude differences of successive breaks to be value coded as a data word on the basis of adaptive scaleable time-per-step tables and voltage-per-step tables so that the time-per-step tables and the voltage-per-step tables are selected depending on the absolute value of the determined time difference and amplitude difference, thus producing compressed data. An associated expansion method for reconstructing the original analog signal is also disclosed.
1. An audio signal compression method, comprising:
digitizing an audio input signal,
checking whether the audio input signal is linear-based or sine-based,
detecting all peaks of the digitized audio input signal,
determining a time difference and an amplitude difference of successive peaks for all pairs of successive peaks of the digitized audio input signal,
value coding the time difference and the amplitude difference of all successive peaks as a data word based on selectable time-per-step tables and voltage-per-step tables, and
selecting the time-per-step tables and the voltage-per-step tables depending on an absolute value of the time difference and amplitude difference determined so as to produce compressed data.
2. The method according to claim 1 , wherein the audio input signal is checked to determine if signal levels at two successive peaks are the same, and wherein the time difference between the two successive peaks is coded as gap information when the signal levels at the two successive peaks are the same.
3. The method according to claim 2 , wherein a value-coded data word is compared with a previous value-coded data word, and wherein a repeat command word, instead of a data word, indicating how many identical successive break position vectors were detected is generated when identical successive value-coded data words are detected.
4. The method according to claim 3 , wherein compressed data are expanded using the selectable time-per-step tables and voltage-per-step tables.
5. The method according to claim 4 , wherein the compressed data are expanded using the coded gap information.
6. The method according to claim 4 , wherein the compressed data are expanded using the repeat command word.
7. The method according to claim 4 , wherein a sine-based analog signal is reconstructed by fitting a cosine function to a reconstructed linear audio signal.