JPH07212296A - VOX control communication device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize VOX control with less talk breaks and malfunctions under high noise. [Structure] In step ST2-1, the voice detector calculates the difference between the average power of a silent frame and the input power, that is, the amount of change. In step ST2-2, the threshold value 1 is set so as to be inversely proportional to the average power of silent frames.
Is calculated. If the amount of change is smaller than the threshold value 1 and the absolute value of the primary reflection coefficient r1 is smaller than the threshold value 2, it is determined that the current frame is a silent frame (steps ST2-3 and ST2-4). ). When it is determined as a silent frame, the weighted average value of the average power of the current silent frame and the power of the current frame is set as the average power of the new silent frame in step ST2-5. Since the average power of the silent frame, which is the criterion for judgment, is updated, it is possible to adjust the VO appropriate for the noise level.
X control can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a VOX (Voice).
The present invention relates to a communication device under the control of an Operated Transmitter). In particular, it relates to a digital mobile communication device or the like by this VOX control.

[0002]

2. Description of the Related Art Conventionally, VOX (Voice Opera) has been used as a method for saving power consumption when transmitting data from a wireless device.
Ted Transmitter) is known. The VOX is a technique of detecting an input voice signal and turning on the power of the transmitter only when the voice signal is present, and turning it off when the voice signal is not present.

In particular, in mobile communication devices such as mobile phones, since the power is supplied by a battery, this VOX is widely used as a power saving technique.

In this VOX, if the rising time from the detection of the voice signal to the turning on of the electric power of the transmitter is too long, so-called head disconnection occurs and the voice becomes hard to hear on the receiving side. Therefore, the detection of the presence / absence of a voice signal is a very important problem.

In the conventional determination as to whether the voice is silent or voiced, a fixed threshold level is set for the input voice level, and the voice level is compared by comparing the magnitudes of these values. / Silence was being determined. Therefore, it is difficult to determine a low-level voice signal such as a consonant, and as a result, the speech head is lost and the sound quality deteriorates.

[0006]

As described above, the conventional V
In a communication device based on OX control, so-called head breakage under a high noise level is severe and the voice quality is extremely deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to perform VOX control with high efficiency by reducing breaks in speech under high noise and by reducing malfunctions due to noise.

[0008]

In order to solve the above problems, the first aspect of the present invention is to calculate a dynamic threshold value based on the average power of silent frames of an input signal. Means, dynamic threshold calculation means for calculating the dynamic threshold so as to be inversely proportional to the magnitude of the average power of the silent frame, the average power of the current frame of the input signal, and the silent frame A change amount calculating unit that obtains a difference from the average power and outputs a change amount indicating how much the average power of the current frame is larger than the average power of the silent frame; and the change amount from the dynamic threshold value. If it is small and the absolute value of the primary reflection coefficient is larger than a predetermined fixed threshold value, the current frame is judged to be a silent frame, and the frame judgment means determines When it is determined that the current frame is a silent frame, the average power of the silent frame is updated to an average value of the average power of the silent frame and the average power of the current frame, and updating means for updating. In the VOX control communication device, in the frame next to the current frame, the average power of the silent frame updated by the updating means is used in the dynamic threshold value calculating means.

In order to solve the above problems, a second aspect of the present invention is the VOX control communication apparatus according to the first aspect of the present invention, wherein the updating means sets the average power of the silent frame to the average power of the silent frame. The VO is updated to a weighted average value with the average power of the current frame.
It is an X control communication device.

[0010]

The dynamic threshold in the first aspect of the present invention is calculated based on the average power of silent frames. Then, the dynamic threshold calculation means calculates the value of the dynamic threshold so as to be inversely proportional to the average power. Then, the average power of the current frame and the average power of the silent frame are compared, and the change amount thereof is calculated by the change amount calculating means. Then, the current frame is a silent frame or a voiced frame by comparing this variation amount with the dynamic threshold value and comparing the primary reflection coefficient with a fixed threshold value. It is determined by the frame determination means.

Further, when it is determined that the frame is a silent frame, the average power of the silent frame is updated to a new value. This updating is performed by the updating means by taking an average value of the average power of the silent frame and the average power of the current frame (which is determined to be the silent frame). In this way, since the dynamic threshold value, which is one of the criteria for determining whether or not a frame is a silent frame, is updated for each frame, it is possible to cope with a slight power fluctuation of the input signal.

The updating means in the second aspect of the present invention sets a weighted average value of the average power of the silent frame and the average power of the current frame (which is determined to be the silent frame) as the average power of the new silent frame. Therefore, a more appropriate average power of silent frames can be obtained, and as a result, an appropriate dynamic threshold value can be calculated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a digital mobile communication device which is a preferred embodiment of the present invention. As shown in FIG. 1, in this digital mobile communication device, the analog input voice signal is first converted by the PCM encoder 1.
By 0, it is converted into a digital signal. The digital signal converted by the PCM encoder 10 is subjected to predetermined encoding in the voice encoder 20.

A feature of this embodiment is that the voice encoder 20 calculates the power value of the input voice signal and supplies it to the voice detector 3. Further, the voice detector 3 is supplied with the value of the primary reflection coefficient. Then, the voice detector 3 internally performs a predetermined calculation to determine whether the current frame is a voiced frame or a silent frame, and outputs the determination result. The result of this determination is supplied to the wireless unit 4 and used for controlling the power in the wireless unit 4.

The calculation of the power in the speech encoder 20 is performed by calculating the sum of squares of the converted digital signals.

The feature of this embodiment is that the threshold value, which is a reference for judging whether the frame is a voiced frame or a silent frame, is adaptively updated based on the power value of the input signal. , More appropriate determination of voiced / non-voiced, so as to prevent the so-called broken voice.
It should be noted that this threshold value is hereinafter referred to as threshold value 1.

Further, a characteristic of this embodiment is that
In the voice detector 3, the value of the primary reflection coefficient r1 is compared with a predetermined fixed threshold value. As a result, it is possible to more accurately determine the voiced / silent frame.

A flow chart of the internal processing of the voice detector 3 is shown in FIG.

In step ST2-1, the difference between the power of the current frame and the average power of a predetermined silent frame is obtained. As a result, in ST2-1, the amount of change representing how much the average power of the current frame is larger than the average power of the silent frame is calculated.

On the other hand, in step ST2-2, the threshold value 1 is calculated based on the average power of the silent frames. Threshold value 1 in step ST2-2
In the calculation of, the threshold value 1 is calculated so as to be inversely proportional to the power of the silent frame. That is, in this embodiment, the threshold value 1 is obtained as a linear function of the power of a silent frame, and the slope of this linear function is set to be negative.

Next, in ST2-3, the above-mentioned ST2
-2 is compared with the threshold value 1 obtained in -2 and the change amount obtained in ST2-1. As a result of this comparison, if it is determined that the change amount is smaller than the threshold value, a comparison with threshold value 2 is performed in step ST2-4 as described below, and the change amount is larger than the threshold value. If they are equal or equal, it is determined that the frame is a voiced frame in step ST2-6.

Next, in ST2-4, the absolute value of the primary reflection coefficient r1 is compared with a predetermined fixed threshold value 2. As a result of this comparison, if it is determined that the absolute value of the primary reflection coefficient r1 is smaller than the threshold value 2, the average power of the silent frames is updated in step ST2-5 as described below, and the primary power is updated. If the reflection coefficient r1 is greater than or equal to the threshold value 2, step ST2
At -7, the frame is determined to be a voiced frame.

In step ST2-5, the average power of silent frames is updated. The value of the average power of the silent frame updated here is obtained by the above-mentioned step S.
At T2-1, it is used to calculate the amount of change for the next frame. The update in step ST2-5 is performed by calculating a weighted average value of the average power of the silent frames up to that point and the average power of the current frame. The average value calculated in this way becomes the average power of the new silent frame. Here, the average power of the silent frame so far and the power of the current frame are given a predetermined weighting. However, for this weighting, an appropriate value should be selected depending on the noise level and the like. Is.

In step ST2-8, it is determined that the current frame is a silent frame, and the voice detector 3 outputs this determination signal to the radio section 4. The wireless unit 4 receives this determination signal and reduces the power consumed by the wireless unit 4.

On the other hand, if it is determined that the current frame is a voiced frame, steps ST2-6 and ST2.
At -7, a determination signal indicating that the frame is a voiced frame is supplied from the voice detector 3 to the wireless unit 4, and the wireless unit 4 sets the power consumption of the wireless unit 4 to a normal value by this determination signal.

As described above, in this embodiment, the average power of a silent frame, which is the basis for calculating the threshold value 1 which is a criterion for determining whether the frame is a silent frame or a voiced frame, Updated every time it was detected. Further, in addition to the comparison with the threshold value 1, the absolute value of the value of the primary reflection coefficient is compared with the fixed threshold value 2 to determine whether or not the frame is a silent frame.

As a result, there is an effect that it is possible to cope with a slight power fluctuation and it is less likely that the beginning of a talk begins with a consonant. Further, there is an effect that a highly efficient communication device with less malfunction due to noise can be obtained.

[0029]

As described above, according to the first aspect of the present invention, the current frame is determined based on the amount of change between the average power of silent frames and the power of the current frame. Then, the dynamic threshold value to be compared with this change amount is set to be in inverse proportion to the average power of the silent frame, and the average power of the silent frame is updated every time the silent frame is detected.

Further, not only the dynamic threshold value and the change amount but also the primary reflection coefficient and the fixed threshold value are compared with each other to determine that the frame is a silent frame.

Therefore, it is possible to realize a communication device in which the so-called head break is less likely to occur even at the head of a consonant. Further, since the dynamic threshold value is quantitatively changed, it is possible to obtain a communication device capable of performing highly efficient VOX control, since it is possible to deal with slight power fluctuations due to less malfunction due to noise. .

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a digital mobile communication device which is a preferred embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the voice detector 3.

[Explanation of symbols]

 3 voice detector 4 radio unit 10 PCM encoder 20 voice encoder

Claims (2)

[Claims] 1. Dynamic threshold calculating means for calculating a dynamic threshold based on an average power of a silent frame of an input signal, said dynamic threshold calculating means being inversely proportional to the magnitude of the average power of said silent frame. A dynamic threshold value calculating means for calculating a dynamic threshold value, a difference between the average power of the current frame of the input signal and the average power of the silent frame is obtained, and the average power of the current frame is equal to that of the silent frame. A change amount calculating means for outputting a change amount indicating how much larger than the average power, the change amount is smaller than the dynamic threshold value, and the absolute value of the primary reflection coefficient is a predetermined fixed threshold value. If it is larger, a frame determination unit that determines the current frame as a silent frame; and if the current frame is determined to be a silent frame by the frame determination unit, Updating means for updating the average power of the silent frame to an average value of the average power of the silent frame and the average power of the current frame, and, in a frame next to the current frame,
The VOX control communication device, wherein the average power of the silent frames updated by the updating means is used in the dynamic threshold value calculating means. 2. The VOX control communication device according to claim 1, wherein the updating unit sets the average power of the silent frame to a weighted average value of the average power of the silent frame and the average power of the current frame, A VOX control communication device characterized by updating.