JPH08204654A - VOX control device - Google Patents

Abstract

(57) [Summary] [Construction] When the received RF signal power is measured by the RF power measuring device 6 and the received RF signal power of the current burst is extremely smaller or larger than the power of the previous burst, The unique word detector 5 is controlled to widen the error tolerance range. [Effect] To provide a VOX control device in which the error tolerance rate of the unique word detecting means can be increased only when a unique word is detected, non-detection / erroneous detection of the unique word is reduced, and reliability is improved. You can

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VOX (Voice Operate) used in a mobile communication device using TDMA or TDD multiplex system such as a digital car telephone.
dTransmitter) receiving side control device.

[0002]

2. Description of the Related Art VOX is a method for detecting a silent / voiced section of a voice signal and not transmitting the voice information to the silent section, thereby reducing the power consumed by a power amplifier of a transmitter. It will be reduced.

FIG. 3 shows an example of transmission data in VOX control. The operation of the transmitter in VOX control will be described with reference to FIG.

Reference numeral 100 in FIG. 3A shows an example of a voice signal input to the transmitter. The VOX control unit outputs the audio signal 1
A sound / silence section is detected from 00. In a digital car telephone or the like, as shown in FIG.
Since a section of about msec is set as one frame and is encoded and transmitted for each frame, the VOX control in this case is also performed in frame units. Input voice is VO in transmitter
In a frame in which the X control device has detected a voiced section, voice encoded data 101 and control data 102 which is information necessary for call control are transmitted. Further, when silence is detected, the transmitter transmits a data pattern called a postamble indicating that it enters a silence section instead of the voice coded data, and the control data 103. After that, the transmission time is shortened by transmitting only the control data 104 until a frame with sound is detected, and power consumption is reduced.
Further, when a voiced frame is detected, the transmitter transmits a data pattern called a preamble indicating that the voiced section starts from the next frame and the control data 105, and voice coding starts from the next frame. Data and control data 102 are transmitted. The receiver side detects the postamble and the preamble and controls the decoding of the voice coded data.

The postamble and the preamble are collectively called a unique word. Generally, the unique word has a known data pattern on both the transmitter side and the receiver side. The data is compared with the stored unique word data pattern, and if the patterns match, it is determined that the unique word has been received.

[0006]

However, in mobile communication devices such as mobile phones, there is a problem that complete unique words cannot be detected because data is frequently erroneous due to fading or the like.

As a result, in the VOX control, when the postamble is not detected or the preamble is erroneously detected, an abnormal sound is generated because the audio signal is decoded by the completely unrelated data. is there. Further, when the postamble signal is erroneously detected or when the preamble is not detected, there is a problem that a voice signal is present and the conversation becomes impossible even though there is a voice signal.

Therefore, in an actual system, the unique word is detected while allowing a certain amount of error,
Even if the received data differs from the unique word data pattern stored in advance by several bits, it is determined as a unique word. However, if the error tolerance rate is set too high, the probability of false detection increases and the reliability decreases.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and detects a silent / voiced section of a voice signal and does not transmit the voice information to the silent section. By doing so, in the VOX control device that reduces the power consumed by the power amplifier of the transmitter, etc., a unique word such as a postamble and a preamble for performing VOX control is detected from the signal sent from the transmitter. A VOX control device comprising word detection means and power detection means for obtaining the power of this signal in the RF means, and controlling the error tolerance rate of the unique word detection in the unique word detection means by the power detected by the power detection means. Configured.

In addition, from the signals sent from the transmitter, V
A unique word detecting means for detecting a unique word such as a postamble or a preamble for performing OX control, and an envelope detecting means for detecting a change in an envelope in a burst of a received signal of this signal are provided and detected by the envelope detecting means. A VOX control device was constructed in which the error tolerance rate of the unique word detection in the unique word detection means was controlled by the change in the envelope level.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, voice data is coded every 20 msec using 3-channel TDMA, and the coded data is transmitted together with the control data to transmit 280 bits. In the VOX control, the control data is 54 bits in a silent section. Only the data is transmitted at the same transmission rate, the transmission time of the data is shortened, and the power consumption is reduced.

Specifically, as shown in FIG. 2, the voice coded data is interleaved over two frames and transmitted together with the control data. Therefore, in the voiced section, 2
A burst 20 including voice data interleaved over the frame is transmitted, and when a silent period is detected, a burst 21 including half of the voice coded data and half of the postamble data is transmitted, and then the remaining in the next frame. The burst 22 including the postamble data and the dummy data is transmitted. After that, a short burst 23 of only control data is transmitted until a voiced section is detected,
When a voiced section is detected, a burst 24 including half of the preamble data and dummy data is transmitted, and a burst 25 including half of the remaining preamble data and voice coded data is transmitted in the next frame. After that, the burst 20 of voice coded data and control data is transmitted again until a silent section is detected.

FIG. 1 is a block diagram of a receiver using the present invention. 1 is an antenna, 2 is an RF / IF circuit, 3 is a demodulator, 4 is a voice decoder including a channel decoder, and 5 is a voice decoder. A unique word detector, 6 is an RF power measuring device, and 7 is a speaker.

In this receiver, the three-channel TDMA signal described above is fetched in synchronization with its timing. The received signal is band-limited, amplified and frequency-converted in the RF / IF circuit 2, and then demodulated by the demodulator 3. The demodulated data is sent to the channel decoder 4
After being deinterleaved, error-corrected, and error-detected, the audio data is decoded into an analog signal, which is output from the speaker 7.

In this receiver, since VOX control is performed,
The data deinterleaved in the channel decoder 4 is taken into the unique word detector 5 and compared with the data pattern of the unique word stored in advance. When the unique word corresponding to the preamble or the postamble is detected, the channel decoding is performed. Control the vessel 4.

Further, this receiver needs to measure the received RF signal power called RSSI, and the RF power measuring device 6 does this. The received RF signal power is generally measured by extracting a band-limited received RF signal from the RF / IF circuit 2 and performing AM detection to detect the envelope level of the received RF signal and estimate the power. Method is used.

In the present invention, the estimated power of the received RF signal of one burst is taken into the unique word detector 5 from the RF power measuring device 6 and the error allowable range in the detection of the unique word is controlled.

Specifically, when the power of the received RF signal of the current burst is extremely smaller than the power of the previous burst, the probability that the data pattern sent in the previous burst is postamble data. Is high,
The unique word detector 5 is controlled to widen the error tolerance range. On the contrary to the above, when the power of the received RF signal of the current burst is extremely higher than the power of the previous burst, the probability that the data pattern sent in that burst is preamble data is high. Since it is high, control is performed so as to widen the error tolerance in the unique word detector 5. Then, the unique word detector 5 is controlled to widen the error allowable range, and after detecting the unique word, the original word allowable range is controlled to be returned. As a result, the error tolerance can be increased only when necessary.

As another embodiment, it is conceivable to detect a change in the envelope level in the burst of the received signal and thereby control the error tolerance rate in the unique word detector 5. This is because the burst signal when there is no sound has a shorter time (burst length is shorter) than the burst signal when there is sound, so that it is clear that the envelope within the burst changes to a convex shape.

[0021]

As described above, according to the VOX control device of the present invention, the error tolerance rate of the unique word detection in the unique word detection means is controlled by the power detected by the power detection means, or the envelope detection. By controlling the error tolerance rate of the unique word detection in the unique word detection means by changing the envelope level detected by the means, it is possible to increase the error tolerance rate of the unique word detection means only when the unique word is detected. VOX that improves reliability by reducing non-detection and false detection of unique words.
A control device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a receiver using a VOX control device of the present invention.

FIG. 2 is a diagram showing a burst signal transmitted from a transmitter during VOX control.

FIG. 3 is a data diagram transmitted from a transmitter during VOX control.

[Explanation of symbols]

1: Antenna 2: RF / IF circuit 3: Demodulator 4: Voice decoder 5: Unique word detector 6: RF power measuring device 7: Speaker 20: Burst signal including voice coded data and control data 21: Postamble Burst signal including half data, voice coded data and control signal 22: Half data of postamble and burst signal including dummy data and control signal 23: Burst signal of control signal only 24: Half data of preamble Burst signal including dummy data and control signal 25: Burst signal including half preamble data, voice coded data and control signal

Claims (2)

[Claims] 1. A VOX control for reducing power consumed by a power amplifier or the like of a transmitter by detecting a silent / voiced section of a voice signal and not transmitting the voice information to the silent section. In the apparatus, a unique word detecting means for detecting a unique word such as a postamble and a preamble for performing VOX control from a signal sent from a transmitter, and a power detecting means for obtaining the power of the signal by the RF means. A VOX control device, characterized in that the error detection rate of the unique word detected by the unique word detection means is controlled by the power detected by the power detection means. 2. A VOX control for reducing power consumed by a power amplifier of a transmitter by detecting a silent / voiced section of a voice signal and not transmitting the voice information to the silent section. In the device, a unique word detecting means for detecting a unique word such as a postamble or a preamble for performing VOX control from a signal sent from a transmitter, and a change in an envelope in a burst of a received signal of the signal are detected. And a envelope detecting means for controlling the error rate of the unique word detected by the unique word detecting means according to the change in the envelope level detected by the envelope detecting means.