JPS59231A - Sensitivity controlling system - Google Patents

Abstract

PURPOSE:To set automatically sensitivity of a voice detector corresponding to the environment in which a caller exists, and to hold a calling state even when sensitivity of the detector is low, by controlling said detector so that the sensitivity of the voice detector rises. CONSTITUTION:A sound signal from a transmission line 3 is detected by a PCM coder 5, is converted to a digital code train, is subjected to a necessary delay by a delaying circuit 6, and also is converted to an analog sound signal by a PCM decoder 7. Also, a digital signal of the coder 5 is applied to a comparing circuit 9, is compared with a threshold level of a threshold level generating circuit 10, and when it exceeds a prescribed threshold level, a detecting signal is applied to a voice detecting circuit 13. When a signal of the circuit 9 is continued for a prescribed time or more in this circuit 13, it is decided that a voice exists, a transmission start signal is generated and is applied to a transmitter 8 and an antenna switch 14. In case when the circuit 13 does not decide that a voice exists, no start signal is generated, the switch 14 is switched to a receiver 16 side, a receiving time is monitored by a receiving time monitoring timer 17, and when it exceeds a prescribed time, it is applied to a threshold level controlling circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a sensitivity control method % type % for controlling the sensitivity of a voice detector in a radio telephone device that switches between transmission and reception by detecting voice in a voice detector. Technology and Problems A wireless telephone device that switches between transmitting and receiving based on the output when a voice is detected by a voice detector is a system in which calls are made from a two-wire telephone via a single-frequency simplex wireless device. It is used in communication systems.

Conventionally, a voice detector used for the purpose of switching between transmission and reception using voice has a fixed or semi-fixed sensitivity, and the sensitivity is usually kept constant during use.

However, the environment in which a call requester accessing a wireless telephone device is located is not always constant, and the amount of background noise often varies. Therefore, by keeping the sensitivity of the voice detector constant, it is possible to prevent the voice detector from malfunctioning due to background noise due to the sensitivity being too high and causing the transmitter to continue to be activated unduly, or conversely to prevent the sensitivity from becoming too low. - This sometimes caused problems such as voice transmission activation not being carried out smoothly.

OBJECT OF THE INVENTION The present invention attempts to solve the problems of the prior art, and its purpose is to provide a wireless telephone device in which transmission and reception are switched based on the output when a voice is detected by a voice detector. , the sensitivity of the voice detector is automatically set according to the environment in which the caller is placed by controlling the sensitivity of the voice detector to be increased;
It is therefore an object of this invention to provide a method that can prevent the transmitter from not being activated because the voice detector does not determine that there is voice when the voice level of the caller is low.

Structure of the Invention The sensitivity control method of the present invention is based on the fact that in normal conversation, there are syllable breaks, and the time a speaker continues to utter continuously is at most a few seconds, and never for several tens of seconds. Focusing on this, we monitor the amount of time that the sound detector determines that there is no sound and the receiver continues to receive radio waves, and if this state continues even after a certain period of time has elapsed,
It determines that the voice detector is not working properly because the sensitivity of the voice detector is too low, and automatically adjusts the sensitivity to the appropriate level by gradually increasing the sensitivity of the voice detector. 6 Embodiments of the Invention FIG. 1 shows the configuration of a radio telephone device to which the present invention is applied, as an embodiment of the sensitivity control method of the present invention. This wireless telephone device shares one frequency for transmission and reception, activates the transmitter only when the voice detector determines that there is voice, connects the antenna to the transmitter using the antenna switcher, sends out a call signal, and transmits the voice signal. If the detector does not determine that there is audio, an antenna is connected to the receiver to receive signals from the terminal.

In FIG. 1, IA, -, IN are telephones, 2 is an exchange, 3 is a sending line, 4 is a receiving line, 5 is a PCM coder, 6 is a delay circuit, 7 is a PCM decoder, 8 is a transmitter, 9 is a comparison circuit, 10 is a dark value generation circuit, 11 is a first dark value control circuit,
12 is a second threshold control circuit, 13 is a voice detection circuit, 14
15 is an antenna switch, 16 is a receiver, 17 is a listening time monitoring timer, and 18 is a level comparison circuit.

In Fig. 1, for example, the voice signal of the telephone l^ is exchanged f
It is transmitted and received between the sending channel 3 and the receiving channel 4 via i2. The audio signal on the transmission channel 3 passes through a PCM coder 5, and is encoded into an 8-bit digital code string including one polarity bit every 125 μs, and is given the required delay through a delay circuit 6 consisting of a memory. Thereafter, the signal is converted to an analog audio signal again via the PCM decoder 7 and input to the transmitter 8. At this time, the digital signal from the PCM coder 5 is applied to the comparison circuit 9 and digitally compared with the threshold signal from the threshold generation circuit 10. The comparison circuit 9 has P
Seven bits indicating the amplitude of the digital audio signal of the CM coder 5 excluding the polarity bit are compared with the threshold output of the dark value generation circuit 10, and when the audio signal exceeds the threshold, the audio detection circuit 13 detects the audio. send a signal. When the signal from the comparison circuit 9 continues for a predetermined period of time or more, the voice detection circuit 13 determines that there is voice, generates a transmission start signal, and applies it to the transmitter 8 and the antenna switch 14. As a result, the antenna switch 14 is switched to the transmitter 8 side, and the transmitter 8 is activated to generate a radio frequency signal consisting of a modulated wave signal by the analog audio signal of the PCM decoder 7, and this signal is transmitted to the antenna. 15 and then sent to the terminal. on the other hand,
When the voice detection circuit 13 does not determine that there is voice, the transmission activation signal is not generated, the antenna switch 14 is switched to the receiver 16 side, the receiver 16 is activated, and the radio frequency signal from the terminal is switched to the receiver 16 side. The signal is converted into a voice signal by the receiver 16, output through the receiver line 4, and transmitted to the telephone 1^ via the exchange 2.

In this way, in the radio telephone device shown in FIG.
In order to combine a single frequency simplex wireless device and a two-wire telephone, a voice detector is used to determine the presence or absence of voice.
The transmitter is activated to transmit a call, but due to a delay in detection at the voice detector, a delay in the start of transmission at the transmitter, and a delay in the start of AGC at the receiver on the terminal side, there is a delay between the generation of the voice and the reception at the terminal. There is a slight delay in the beginning of the conversation, resulting in the so-called phenomenon of cutting off at the beginning of a conversation. In FIG. 1, a delay circuit 6 is provided to compensate for all such delays and to prevent the beginning of a conversation.

FIG. 2 shows an example of the hangover characteristic of the voice detection circuit 13 in the radio telephone device of FIG.
The horizontal axis indicates time, and the vertical axis indicates the time for maintaining the voice detection state after the voice disappears, that is, the hangover time. In the figure, (A) shows a state where there is no call. (B
) indicates one phase during voice detection, providing a hangover time that increases linearly with the duration of the voice detection signal. (c) shows phase 2 during audio detection, which is given a relatively small constant hangover time for a certain period of time. (D) indicates that a call is in progress, and the digital signal from the PCM coder 5 continues to be smaller than the dark value signal of the dark value generation circuit during voice detection period 1 and voice detection period 2, resulting in hangover time. Unless it becomes zero, at the end of the voice detection period 2, a sufficiently large hangover time, for example, several hundred times ago, is given, and it is determined that a call is in progress, and a transmission activation signal is generated. During the call 2
The reason why the small hangover time is maintained for a certain period of time in this phase is to prevent the voice detection circuit from operating in a relaxed manner due to short-term noise or the like and determining that a call is in progress.

In the radiotelephone device shown in FIG. 1, the determination of the presence or absence of voice in the voice detection circuit depends on the output of the comparison circuit, as described above. Therefore, by changing the dark value level of the dark value generation circuit, the sensitivity of the audio detector can be controlled. FIG. 3 shows a dark value generation memory in the threshold value generation circuit 10.

In the same figure, 21, 22, 23 and 24 are the first memory. Second. The third and fourth blocks are shown. Each block consists of 16 words, so each block has 1 dB step, for example.
Six levels of darkness can be generated as a 7-bit code. These 16 types of threshold values are set to gradually increase in order from the lowest address number to the highest address number, and one of the blocks is selected based on the control of the threshold value control circuit 12 and is controlled by the dark value control circuit 11. One threshold value in the selected block is selectively output.

On the other hand, the dark value control circuit 11 controls the dark value generation circuit 10 based on the signal from the listening time monitoring timer 17.

The listening time monitoring timer 17 receives a signal from the voice detection circuit 13 indicating that it is not determined that there is voice, and a signal from the receiver 16 indicating that a wireless signal from the terminal is being received, such as a carrier wave detection signal. When the time exceeds a predetermined time, a signal is generated and inputted to the threshold control circuit 11. The dark value control circuit 11 thereby controls the dark value generating circuit 1o to lower the dark value. , the dark value control circuit 11 repeats such control based on the output of the listening time monitoring timer 17.
The voice detection circuit 13 does not determine that there is voice and the receiver 16
The sensitivity of the voice detector is increased by controlling the voice detector until the time during which the voice detector is receiving the wireless signal from the terminal becomes less than a predetermined time, for example, 20 seconds. This is because in normal conversation, the time during which syllables occur consecutively is limited and is usually only a few seconds. Therefore, the time during which it is not determined that there is voice on the sending channel and the receiver is in the receiving state is longer than the above-mentioned period. If it continues for more than a certain amount of time, the phone determines that the voice detector is too sensitive to enter the transmitting state even though the caller is transmitting, and the voice detector is activated. By controlling the sensitivity to gradually increase, the audio detector can be placed in optimal operating conditions.

In this case, the initial value of the threshold value in the dark value generation circuit 10 is
For example, it may be set to a constant value at the end of a call so that control starts from a constant value for each call.

Further, in FIG. 1, the level comparison circuit 18 is connected to the receiver 1.
The level of the received voice No. 6 is compared with a reference value, and a discrimination output is generated in four stages. The dark value control circuit 12 selects a block in the dark value generation circuit 10 in response to the four-stage discrimination output of the level comparison circuit 18. The second block 22 in the threshold generation memory has a respective dark value 3 dB higher than the corresponding dark value in the first block 21, the third block 23 has a respective dark value 6 dB higher than the corresponding dark value in the first block 21, The fourth block 24 has a respective darkness value that is 11 dB higher than the corresponding darkness value in the first block 21, so that for the same audio signal level from the PCM coder 5, depending on the received audio level of the receiver 16, The magnitude of the dark value of the value generation circuit 10 changes. This is because the sending path 3 and the receiving path 4 are connected to the telephone set via a hybrid in the exchange 2, which causes detours from the receiving path to the sending path, and therefore it is necessary to reduce the sensitivity of the voice detector. This is because the higher the received audio level, the greater the feedback, so the darkness value needs to be increased accordingly. In this way, the dark value generated by the threshold generation circuit IO is determined according to both the audio signal level of the sending channel and the audio signal level of the receiving channel.

As described in detail of the invention, according to the sensitivity control method of the present invention, in a wireless telephone device that activates a transmitter and transmits a call when a voice is detected by a voice detector, the voice detector detects a voice. By controlling the sensitivity of the voice detector to increase so that it does not judge that there is a sound and the time that the receiver is in the receiving state is monitored and the time is kept below a predetermined time.
The sensitivity of the voice detector is automatically set according to the environment in which the caller is placed, and this prevents the transmitter from starting even though the caller is talking because the sensitivity of the voice detector is too low. This is extremely effective because it prevents the user from entering the transmitting state.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a radio telephone device to which the present invention is applied as an embodiment of the sensitivity control method of the present invention, Fig. 2 is a diagram showing hangover characteristics of a voice detection circuit, and Fig. 3 is a diagram showing threshold generation. FIG. 3 is a diagram showing a dark value generation memory in the circuit. 1^, -, IB: Telephone, 2: Exchange, 3: Transmission line,
4: Receiving line, 5: PCM coder, 6: Delay circuit, 7: P
CM decoder, 8: Transmitter, 9: Comparison circuit, lO: Dark value generation circuit, 11.12 + Dark value control circuit, 13: Audio detection circuit, 14: Antenna switch, 15: Antenna, 16: Receiver, 17: Listening time monitoring timer, 18-level comparison circuit patent applicant Fujitsu Limited

Claims (1)

[Claims] A radiotelephone device that connects an antenna to a transmitter when detecting a voice signal on a transmission channel and activates the transmitter to set the transmitting state, and connects the antenna to a receiver and sets the receiving state when no sound signal is detected. a dark value generating means that sequentially generates dark values of specific levels in response to a control signal, and a dark value generating means that compares the level of the audio signal in the transmission path with the dark value of the threshold value generating means to determine whether the audio signal is at the threshold level. a voice detector that activates the transmitter to enter the transmitting state when the signal exceeds the time limit, a timer means for counting the time during which the voice detector does not detect a voice signal and the receiver is in the receiving state; and the timer means. and a dark value control means for generating a control signal to sequentially lower the dark value level generated by the dark value generating means one step at a time when the counting time exceeds a predetermined time. .