JPS58225733A - Sensitivity control system - Google Patents

Abstract

PURPOSE:To prevent the transmitter of a radio telephone equipment from starting improperly owing to background noise, etc., other than a talker's voice by performing control for decreasing the sensitivity of the voice detector, to set the sensitivity of a voice detector automatically according the environment surrounding the talker. CONSTITUTION:A transmission time monitoring timer 17 monitors the time when the voice detecting circuit 13 decides that there is incoming voice, and sends a signal to a threshold value control circuit when the monitored time exceeds a specific value. The threshold value control circuit 11 controls a threshold value generating circuit 10 by the signal to increase a threshold value by one level. The threshold value control circuit 11 repeats said control on the basis of the output of the transmission time monitoring timer 17 and carries on the control until the time when the voice detecting circuit 13 decides on the arrival of the voice decreases to shorter than a specific time, e.g. several seconds to decrease the sensitivity of the voice detector, preventing a voice detection signal for longer than the specific time from being outputted.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention provides a method for controlling the sensitivity of a voice detector in a wireless telephone device that activates a transmitter to transmit a voice when a voice is detected by a voice detector (1). This relates to a sensitivity control method for

Prior Art and Problems A wireless telephone device that uses the output of a voice detector to activate a transmitter to send a call when a voice is detected by a voice detector is capable of converting a two-wire telephone to a single-frequency simplex wireless device. This is used in a communication system where calls are made through a telephone.

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 hackground noise often varies. Therefore, by keeping the sensitivity of the audio detector constant, it is possible that the sensitivity is too high and background noise causes the audio detector to operate unnecessarily, causing the transmitter to continue to be activated, or conversely, the sensitivity is too low. Occasionally, voice transmission activation (2) could not be performed smoothly, resulting in problems.

OBJECT OF THE INVENTION The present invention attempts to solve the problems of the prior art, and its purpose is to develop a wireless communication system that activates a transmitter to make a call when a voice is detected by a voice detector. In a telephone device, the sensitivity of the voice detector is controlled to be lowered or lowered to automatically set the sensitivity of the voice detector according to the environment in which the caller is placed. An object of the present invention is to provide a system that can prevent a transmitter from being improperly activated due to background noise other than voice.

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 utters continuously is at most a few seconds, and never continues for tens of seconds. Focusing on this, we monitor the time t7 during which the voice detector determines that there is voice, and if the voice detector is still outputting the (3) determination that there is voice after a certain period of time has elapsed, , determines that the voice detector is malfunctioning due to a signal other than the caller's voice,
The sensitivity of the voicing detector is switched in stages and is automatically adjusted to an appropriate sensitivity in order from low to low.

Embodiment of the Invention Figure 1 shows an embodiment of the sensitivity control method of the present invention.
1 shows the configuration of a wireless telephone device to which the present invention is applied. 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 antenna switcher, connects the antenna to the transmitter, and makes a call. It is designed to send out signals.

In Fig. 1, IA, -, IN are telephones, 2 is alternating lj
! ! 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 dark value control circuit, 13 is an audio Detection circuit, 14 antenna switch, 15 antenna, 16 receiver,
17 is a timer for monitoring the transmission time, and 1st is a level (4) comparison circuit.

In FIG. 1, for example, a voice signal from a telephone set IA is transmitted and received between a sending path 3 and a receiving path 4 via an exchange 2. In FIG. 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. Later, PCM De”-
It is then converted back to an analog audio signal via a transmitter 8 and sent to a transmitter 8.
is input. At this time, the digital signal of the PCM coder 5 is applied to the comparison circuit 9 and digitally compared with the dark value signal of the dark value generation circuit 10. The comparison circuit 9 is a PC
Seven bits indicating the amplitude of the digital audio signal of the M coder 5 excluding the polarity bit are compared with the output of the dark value of the dark value generation circuit 10, and when the audio signal exceeds the dark value, the output is sent to the voice detection circuit 13. Send voice detection signal. Voice detection circuit 13b,
When the signal from the comparator circuit 9 continues for a predetermined period of time or more, it is determined that there is a voice, and a transmission start signal is generated and applied to the transmitter 8 and the antenna switch 14. This allows the antenna to be disconnected (
5) When the switching device 14 is switched to the transmitter 8 side, the transmitter 8 is activated and generates 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 at the receiver 16, outputted through the receiving line 4, and transmitted to the telephone set 18 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 message, but at this time, due to a delay in detection in the voice detector, a delay in the rise of transmission in the transmitter, a delay in the rise of the squelch circuit in the receiver on the terminal side, etc., there is a delay between the sound generation and the terminal. There is a considerable time delay before the message is received, resulting in the phenomenon of so-called "cutting off at the beginning of a conversation" (6). In FIG. 1, a delay circuit 6 is provided to compensate for all such delays and to prevent audio interruptions.

FIG. 2 shows an example of the bangover 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 period during which the voice detection state is maintained after the voice disappears, that is, the hangover time.

In the figure, (A) shows a state where there is no call. (
B) shows phase 1 during voice detection, with a hangover time that increases linearly with the duration of the voice detection signal. (C) shows phase 2 during voice detection, 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 continues to be smaller than the dark value signal of the dark value generation circuit during voice detection 1 and voice detection 2, resulting in a hangover. As long as the time does not reach zero, at the end of the voice detection period 2, a sufficiently large hangover time of, for example, several hundred D1s is given, and it is determined that 1In(7) is busy and a transmission activation signal is generated. During the call 2
The reason why a small hangover time is maintained for a certain period of time in this phase is to prevent the voice detection circuit from malfunctioning due to short-term noise or the like and determining that a call is in progress.

In the radio telephone device of FIG. 1, the determination of the presence or absence of voice by the voice detection circuit depends on the output of the comparison circuit, as described above. Therefore, the sensitivity of the voice detector can be controlled by changing the threshold (i*l/her) of the dark value generation circuit. FIG. 3 shows the dark value generation memory in the dark value generation circuit 10. There is.

In the same figure, numbers 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 dark 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 dark value control circuit 12, and the dark value (8) is controlled. One dark value falling in the selected block based on the control of the circuit 11 is selectively output.

On the other hand, the dark value control circuit 11 controls the dark value generating circuit 10 based on the signal from the sending time monitoring evening/timer 17.

The transmission time monitoring timer 17 monitors the time during which the voice detection circuit 13 determines that there is voice, and when the time exceeds a predetermined time, it generates a signal and inputs it to the threshold control circuit 11. The dark value control circuit 11 thereby controls the dark value generation circuit 10.
Control and raise the darkness value. Dark value control circuit 1
1 repeats such control based on the output of the speech time monitoring timer 17 until the time at which the voice detection circuit 13 determines that there is voice becomes a predetermined time, for example, several seconds or less, and the voice detection is performed. Decrease the sensitivity of the instrument.

This is because in an i+l' conversation, the time during which syllables occur consecutively is limited and is usually about the time mentioned above. Therefore, the output of the speech detection signal exceeding this time is due to malfunction of the speech detector due to noise. Therefore, in such a case, the sensitivity of the sound detector is gradually lowered so that the sound detection signal is not output for a predetermined amount of time (9), thereby detecting the sound. The device can be placed in optimal operating condition.

In this case, the initial value of the dark 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 16.
The level of the received audio is compared with a reference value, and a discrimination output is generated in four stages. The dark value control circuit 12 selects any one 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 dark value generation memory has a respective threshold value 3 dB lower 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 threshold value in the first block 21, and the fourth block 24 has a respective threshold value 11 dB higher than the corresponding dark value in the first block 21. Therefore, PCM coder 5
For the same audio signal level from the dark value generating circuit IO, the dark value (1
0) Size changes. This is because the transmitting channel 3 and the receiving channel 4 are connected to the telephone via a hybrid in the exchange 2, which causes detours from the receiving channel to the transmitting channel, and therefore it is necessary to reduce the sensitivity of the voice detector. This is because there is
This is because the higher the received audio level, the greater the feedback, so the darkness value needs to be increased accordingly.

As described in detail of the invention, according to the sensitivity control method of the present invention, in a wireless telephone device of a type in which a transmitter is activated to transmit a voice when a voice is detected by a voice detector, the voice detector The sensitivity of the voice detector is automatically adjusted according to the environment in which the caller is placed, by performing St and II control to lower the sensitivity of the voice detector so that the time it takes to determine that there is voice is a predetermined time. This is extremely effective, since it is possible to prevent the transmitter from being improperly activated due to hack ground noise or the like other than the voice of the caller.

[Brief explanation of the drawing]

(11) Fig. 1 is a diagram showing the configuration of a wireless telephone device using the present invention as an example of the sensitivity control method of the present invention, Fig. 2 is a diagram showing the hangover characteristic of the voice detection circuit, and Fig. 3 is a diagram showing the hangover characteristic of the voice detection circuit. FIG. 2 is a diagram showing a dark value generation memory in the dark value generation circuit. IA, -, 10: Telephone, 2: Exchange, 3: Transmission path, 4
: Receiving line, 5; PCM coder, 6: Delay circuit, 7: PC
M decoder, 8: transmitter, 9: comparison circuit, lO: dark value generation circuit, 11.12 F dark value control circuit, 13: voice detection circuit, 14: antenna switch, 15: antenna, 16; receiver, 17; Speech time monitoring timer, 18; Level comparison circuit patent applicant Fujitsu Limited agent Patent attorney Gobe Tamamushi (3 others) (12) Figure 2 Figure 3 Figure 7 Biwato code

Claims (1)

[Claims] In a wireless telephone device that activates a transmitter to enter a transmitting state when an audio signal is detected in a transmission path, the transmission path includes: a darkness value generating means that sequentially generates darkness values of specific levels in response to a control signal, and a transmission path. a voice detector that compares the level of the voice signal in the dark value generating means with the dark value of the dark value generating means and activates a transmitter to enter a transmitting state when the voice signal exceeds the dark value level, and the voice detector a timer means for counting the time during which the transmitter is activated; and when the counting time of the timer means exceeds a predetermined time, a control signal is generated to increase the dark value level generated by the threshold value generating means one step at a time. A sensitivity control method characterized by comprising a dark value control means for increasing the dark value.