Voice activated circuit and radio using same
AssigneeMotorola, Inc.
InventorJing Fang
Life of this patent
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Abstract
A voice-activated circuit such as a VOX circuit (100) includes a quadratic detector (108). Quadratic detector (108) uses a sum of weighted instantaneous autocorrelation with multiple lags and where the instantaneous autocorrelation is the product of the signal or a time-advanced version of the signal multiplied by a time delayed version of itself. In one embodiment of the invention a quantized delayed signal is used where changing the sign of the signal without using real multiplication forms the quantized delayed signal. By avoiding the use of multipliers, the complexity and therefore the cost of the VOX circuit (100) is significantly reduced.
Claims9
A voice-activated circuit, comprising:
- an input port for receiving a signal;
- a quadratic detector coupled to the input port and the quadratic detector implements the equation:
- ∑ m ω m x ( k ) x ( k - m ) ,
- where
- x(k) is the signal in time (k) and ωm is a weighting coefficient in lag (m);
- and
- wherein said quadratic detector comprises a quantizer and a finite impulse response (FIR) filter with Canonical Signed Digit (CSD) coefficients coupled in parallel.
A radio, comprising:
- a transmitter;
- and
- a VOX circuit coupled to the transmitter, said VOX circuit comprising:
- a quadratic detector responsive to a signal and that implements the equation:
- ∑ m ω m x ( k ) x ( k - m ) ,
- where
- x(k) is the signal in time (k) and ωm is a weighting coefficient in lag (m);
- and
- wherein said quadratic detector comprises a quantizer and a finite impulse response (FIR) filter with Canonical Signed Digit (CSD) coefficients coupled in parallel.
A voice-activated circuit, comprising:
- an input port for receiving a signal;
- and
- a quadratic detector coupled to the input port and the quadratic detector implements the equation:
- ∑ m ω m x ( k + m ) x ( k - m ) ,
- where
- x(k) is the signal in time (k) and ωm is a weighting coefficient in lag (m);
- and
- wherein said quadratic detector comprises a quantizer and a finite impulse response (FIR) filter with Canonical Signed Digit (CSD) coefficients coupled in parallel.
A radio, comprising:
- a transmitter;
- and
- a VOX circuit coupled to the transmitter, said VOX circuit comprising:
- a quadratic detector responsive to a signal and that implements the equation:
- ∑ m ω m x ( k + m ) x ( k - m ) ,
- where
- x(k) is the signal in time (k) and ωm is a weighting coefficient in lag (m);
- and
- wherein said quadratic detector comprises a quantizer and a finite impulse response (FIR) filter with Canonical Signed Digit (CSD) coefficients coupled in parallel.
Dependencies are inferred from the claim text.