Digital converter from pulse code modulation to continuous variable slope delta modulation
AssigneeUniversite de Snerbrooke
InventorsMichel Villeret, Hubert Stephenne, Pierre A. Deschenes
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Abstract
A digital converter for digitally converting a coded signal being at a PCM rate into another coded signal flowing at a delta rate. First, the code of the PCM signal is converted into an intermediate code, this intermediate code being at a rate corresponding to the PCM rate. Then, the rate of the intermediate coded signal is converted into the rate of the delta signal. And, finally, the code of the intermediate signal is changed into the code of the delta signal.
Claims10
A digital converter for converting a compressed pulse code modulation (PCM) signal provided from a pulse code modulation system and being at a predetermined rate into a delta signal flowing at a delta rate, said delta signal being supplied to a delta modulation telecommunication system, comprising:
- a. a first conversion means receiving said compressed PCM signal for converting the code thereof into a intermediate code, said intermediate code being at a rate corresponding to said PCM rate;
- b. a second conversion means connected to said first conversion means for converting the rate of said intermediate signal into the delta rate;
- and
- c. a third conversion means fed with said intermediate signal at said delta rate for converting the code thereof into the code of the delta signal, said third conversion means comprising:
- a comparator for comparing the intermedite signal at the delta rate with a feedback signal and for providing an output signal,
- a quantizer connected to receive the output signal of said comparator, said quantizer having an output for providing said delta signal at the delta rate, and
- means connected between the output of said quantizer and the comparator for providing said feedback signal to said comparator.
A digital converter for converting a compressed pulse code modulation (PCM) signal provided from a pulse code modulation system and being at a predetermind rate into a delta signal flowing at an adaptive delta rate, said delta signal being supplid to a delta modulation telecommunication system, comprising:
- a. a first conversion means receiving said compressed PCM signal for converting the code thereof into an intermediate code, said intermediate code being at a rate corresponding to said PCM rate;
- b. a second conversion means connected to said first conversion means for converting the rate of said intermediate signal into the delta rate, said second conversion means including an interpolator for sampling the intermediate signal at a predetermined sampling rate;
- and
- c. a third conversion means fed with said intermediate signal at said delta rate for converting the code thereof into the code of the delta signal, said third conversion means comprising:
- a comparator for comparing the intermediate signal at the delta rate with a feedback signal and for providing an output signal,
- a quantizer connected to receive the output signal of said comparator, said quantizer having an output for providing said delta signal at the delta rate, and
- means connected between the output of said quantizer and the comparator for providing said feedback signal to said comparator.
Dependencies are inferred from the claim text.