Transmission system with speech encoder with improved pitch detection
First Claim
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1. A transmission system comprising:
- a transmitter including an encoder for deriving a coded signal from a quasi-periodic signal, the transmitter being arranged for transmitting the coded signal to a receiver via a transmission medium, the encoder comprising a pitch detector for deriving pitch information from the quasi-periodic signal, wherein the pitch detector comprises selecting means for selecting a characteristic auxiliary portion of an auxiliary signal, that is representative of the quasi-periodic signal, search means for searching for at least a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and means for deriving the pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur.
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Abstract
A transmission system contains a speech coder which utilizes a pitch detector that is arranged to select a characteristic auxiliary signal portion from the signal to be coded in order to improve the quality of the pitch detection. The pitch is found by searching in the speech signal for signal portions that correspond to the characteristics auxiliary signal portion and by calculating the time difference between the respective signal portions.
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Citations
20 Claims
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1. A transmission system comprising:
- a transmitter including an encoder for deriving a coded signal from a quasi-periodic signal, the transmitter being arranged for transmitting the coded signal to a receiver via a transmission medium, the encoder comprising a pitch detector for deriving pitch information from the quasi-periodic signal, wherein the pitch detector comprises selecting means for selecting a characteristic auxiliary portion of an auxiliary signal, that is representative of the quasi-periodic signal, search means for searching for at least a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and means for deriving the pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- 10. Encoder for deriving a coded signal from a quasi-periodic signal, the encoder comprising a pitch detector for deriving pitch information from the quasi-periodic signal, characterized in that the pitch detector comprises selecting means for selecting a characteristic auxiliary portion of an auxiliary signal, which auxiliary signal is representative of the quasi-periodic signal, search means for searching for at least a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and means for deriving the pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur.
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12. Arrangement for calculating the period of a quasi-periodic signal, comprising selecting means for selecting a characteristic auxiliary portion of an auxiliary signal which is representative of the quasi-periodic signal, search means for searching for at least a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and means for deriving the pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur.
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13. Coding method for deriving a coded signal from a quasi-periodic signal which comprises:
- selecting a characteristic auxiliary portion of an auxiliary signal which auxiliary signal is representative of the quasi-periodic signal, searching at least for a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and deriving pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur.
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14. A pitch detector for deriving pitch information from a quasi-periodic signal comprising:
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means for deriving from the quasi-periodic signal an auxiliary signal representative of the quasi-periodic signal, energy measuring means responsive to the auxiliary signal so as to produce a signal E n! calculated as a running energy function of a segment of the auxiliary signal, selecting means responsive to the auxiliary signal and to the signal E n! thereby to select a characteristic auxiliary portion of the auxiliary signal, search means responsive to the characteristic auxiliary signal portion and to the auxiliary signal for searching for at least a further signal portion of the auxiliary signal that sufficiently corresponds to the characteristic auxiliary signal portion, and means coupled to an output of the search means for deriving the pitch information from the instants at which the characteristic auxiliary signal portion and the further signal portion occur. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification