JPH0528839Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a radio telephone device that is capable of continuing telephone communication even if the electric field strength decreases depending on the place of use. (b) Prior art A wireless telephone device consisting of a base unit connected to a telephone line and a slave unit that communicates wirelessly with the base unit can be used freely, but depending on the location, the electric field As a result, the strength of the signal changed, deteriorating the signal used for communication, and causing noise to be superimposed, deteriorating the communication quality. Such a deterioration in the communication condition can also be caused by a defect in the device, so it is difficult for the user to determine which is the cause of the deterioration in the communication condition. For this reason, recently, wireless telephone devices have been equipped with a function that emits an alarm when the field strength decreases and the call condition worsens, and notifies the user that the call condition can be returned to normal by changing the location of use. has appeared. An example of such technology is a wireless telephone device described in Japanese Patent Application Laid-Open No. 60-182228. Such wireless telephone equipment emits an alarm when the field strength becomes lower than a preset field strength during communication, and instructs the user to move to a place where the alarm stops within a certain period of time (for example, 10 seconds). The communication operation is automatically stopped if the user cannot move to a place where the alarm sound stops within a certain period of time. (c) Problems to be solved by the invention In a radio telephone device that operates as described above, it is difficult for the user to notify the user that the electric field strength has decreased by sounding an alarm. It is a convenient means of returning to . However, as the electric field strength gradually decreases, the amount of converter noise is gradually added to the signal applied to the speaker of the slave unit while the alarm is sounding, and the signal applied to the telephone line via the base unit. increase,
This is making the call condition worse. Under such conditions, the converter noise is a strong stimulus to the ears, so if you put up with the converter noise for a short time, you can make a call, but if you put up with the converter noise for a long time while talking, your ears will ring. It may also cause migraines. Therefore, one possible way to solve this problem is to mute the voice signal when the electric field strength decreases, but with this method, the conversation signal is muted when the electric field strength decreases, resulting in the conversation being interrupted midway. There is. The present invention aims to provide a wireless telephone device that solves this problem. (d) Means for solving the problems The wireless telephone device of the present invention includes a handset receiving circuit that receives signals transmitted from the base unit to the handset;
a first low-pass filter circuit connected to the handset receiving circuit and passing only signals in a specific frequency band from signals output from the handset receiving circuit; a first amplifier circuit that applies an output signal from the circuit to a speaker; and a first amplifier circuit connected to the slave receiver circuit;
A first electric field strength detection circuit that detects the electric field strength of a signal sent from the base unit and outputs a detection output when the electric field strength of the signal drops below a predetermined level; and a first electric field strength detection circuit connected to the first electric field strength detection circuit. , a first switch means for receiving the detection output and switching the first low-pass filter circuit to a state where only low-frequency signals within the specific frequency band are passed;
The base unit includes a base unit receiving circuit that receives signals sent from the slave unit, and a base unit receiving circuit that is connected to the base unit receiving circuit to receive only signals in a specific frequency band from the signals output from the base unit receiving circuit. a second low-pass filter circuit to pass through, a second amplifier circuit connected to the second low-pass filter circuit and applying an output signal from the second low-pass filter circuit to the telephone line, and connected to the base unit receiving circuit; connected to the second electric field strength detection circuit and a second electric field strength detection circuit that detects the electric field strength of the signal sent from the slave device and outputs a detection output when the electric field strength of the signal drops below a predetermined level; and second switch means for switching the second low-pass filter circuit to a state in which only low-frequency signals within the specific frequency band are passed through by receiving the detection output. (E) Effect When the handset and base unit are communicating wirelessly, the wireless telephone device of the present invention reduces the electric field strength of the communication signal.
When the electric field strength of the signal transmitted from the base unit falls below a predetermined level value, the slave unit
The field strength detection circuit narrows the frequency band of the signal detected and received by the first filter circuit to reduce noise and emit the sound from the speaker. When the level falls below a predetermined level value, the second field strength detection circuit in the base unit detects it, narrows the frequency band of the received signal in the second filter circuit, reduces noise, and transmits it to the telephone line. This is how it was done. (F) Embodiment An embodiment of the wireless telephone device of the present invention will be described with reference to FIGS. 1 and 2. Figure 1 shows handset 1 ,
Figure 2 shows the base unit 2 . First, in the handset 1 shown in FIG. 1 , 3 is an antenna, 4 is a handset antenna sharing circuit that allows the antenna 3 to be used for either transmitting or receiving operations, and 5 is a signal sent from the base unit 2 . a first front end 6 for selectively amplifying the signal received by the antenna 3 and converting it to an intermediate frequency in a handset receiving circuit for receiving the signal; and a first front end 6 for amplifying the output of the first front end 6. It is comprised of a first intermediate frequency amplification circuit 7 and a first detection circuit 8 which extracts a sound component signal from the output of the first intermediate frequency amplification circuit 7. 9 is a first electric field strength detection circuit that detects the electric field strength of the received signal via the first intermediate frequency amplification circuit 7, and the electric field strength of the signal transmitted from the base unit 2 decreases and noise is superimposed; It outputs an "H" level output signal that detects an electric field strength below the first level T ₁ (for example, about 30 dB), which makes it impossible for the owner of handset 1 to hear the voice of the other party through the speaker described later. At this time, an output signal of "L" level is output. 1
0 is a first low-pass filter circuit that receives the output signal of the handset receiving circuit 5 and normally passes the output signal and removes high-frequency noise, etc., and the first electric field strength detection circuit 9 is at the "H" level. When the output signal of
Do the following. ) is made narrower. 12
1 is a first amplifier circuit that amplifies the signal that has passed through the first low-pass filter circuit 10; 13 is a speaker that receives the output of the first amplifier circuit 12 and emits sound; 14 is the first electric field strength detector "H" of circuit 9
An alarm signal generation circuit 15 generates an alarm signal to notify the owner of the handset 1 that the electric field strength has decreased by becoming activated by receiving the output signal of the level. An alarm speaker 16 converts the alarm signal into an alarm sound and emits the alarm sound; 16 is a microphone; 17 is an alarm speaker that modulates the audio signal applied via the microphone 16, adds it to the slave unit antenna common circuit 4, and sends it to the base unit via the antenna 3; 18 is the “H” of the first electric field strength detection circuit 9;
This is a handset control circuit that puts the handset transmitting circuit 17 into an inoperable state when it receives a level output signal for a certain period of time (for example, 10 seconds) or more. Next, in the base unit 2 in FIG. 2, 19 is an antenna, 20 is a base unit antenna common circuit that allows the antenna 19 to be used for both transmitting and receiving operations, 2
Reference numeral 1 denotes a second front end 22 which selectively amplifies the signal received by the antenna 19 in a base unit receiving circuit for receiving signals sent from the slave unit 1 and converts it into an intermediate frequency; 2 a second intermediate frequency amplification circuit 2 that amplifies the output of the front end 22;
3, and a second detection circuit 24 which extracts the audio component signal from the output of the second intermediate frequency amplification circuit 23. 25 is a second electric field strength detection circuit that detects the electric field strength of the received signal via the second intermediate frequency amplification circuit 23, and the electric field strength of the signal transmitted from the handset 1 decreases and noise is superimposed;
A second person who feels that it is difficult to hear the voice of the person holding the handset 1 that is received and listened to by the other party through the base phone 2.
When an electric field strength below level T ₂ (same as or lower than the first level T ₁ set by the first electric field strength detection circuit 9 or lower in this embodiment) is detected, the "H" level is set. It outputs an output signal, and normally outputs an "L" level output signal.
26 receives the output signal of the base receiver circuit 21 ;
Normally, the output signal is passed through to remove high-frequency noise, etc., and when the second field strength detection circuit 25 outputs an "H" level output signal and the second transistor 27 is turned on, the frequency of the passing signal is A second low-pass filter circuit 28 operates to narrow the band (for example, 1 KHz or less) and reduce noise contained in the output signal. A second amplification circuit 29 for amplification is a hybrid circuit that connects the second amplification circuit 28 to the telephone line 30.
A relay circuit 31 modulates the signal from the telephone line 30 received via the hybrid circuit 29, and a relay circuit 31 which adds an output from the telephone line 30 and a voice signal from the other party to the base unit transmitting circuit to be described later. A base unit transmitting circuit 32 that transmits data from the antenna 19 to the slave unit 1 via the base unit antenna common circuit 20 receives the “H” level output signal of the second electric field strength detection circuit 25 for a certain period of time (for example, 10 seconds) or more. and a parent device control circuit that makes the parent device transmitting circuit 31 inoperable. The above-mentioned components constitute the wireless telephone of the present invention, and the operation of the wireless telephone will now be described. First, the operation switch of handset 1 (not shown)
In response to this operation, it is assumed that handset 1 and base unit 2 are connected wirelessly and are in a state where they can perform a good reception operation and make a call. In such a state, when a voice signal from the other party is transmitted via the telephone line 30 and applied to the hybrid circuit 29 of the base unit 2 ,
The audio signal is modulated by the base unit transmitting circuit 31 and transmitted from the antenna 19 to the slave unit 1 via the base unit antenna common circuit 20. As a result, in the handset 1 , the signal received by the antenna 3 is guided to the receiving side signal path by the handset antenna common circuit 4, and is applied to the handset receiving circuit 5 .
In the handset receiving circuit 5 , the received signal is applied to the first front end 6, selectively amplified, converted to an intermediate frequency, amplified by the first intermediate frequency amplification circuit 7, and then sent to the first detection circuit 8. extract the audio component signal. In such a state, the first electric field strength detection circuit 9 does not detect a decrease in the electric field strength from the signal applied to the first intermediate frequency amplification circuit 7, so that the first detection circuit 8 of the slave receiver circuit 5 outputs The generated signal corresponds to the "L" level output signal of the first electric field strength detection circuit 9, and passes through a first low-pass filter circuit 10 whose frequency band is raised to a high range, where radio noise is removed. 1 amplification circuit 12, and a speaker 13 emits the voice of the other party. on the other hand. When the owner of handset 1 listens to the voice of the other party and emits the voice to the microphone 16, the microphone 16 converts the voice into an audio signal.
In addition to the handset transmission circuit 17, the signal is modulated and transmitted from the antenna 3 to the base unit 2 via the handset antenna common circuit 4. Thereby, in the base unit 2 , the signal received by the antenna 19 is guided to the receiving side signal path via the base unit antenna common circuit 20, and is applied to the base unit receiving circuit 21 .
In the base unit receiving circuit 21 , the received signal is applied to the second front end 22, selectively amplified, and then converted to an intermediate frequency, and then sent to the second intermediate frequency amplification circuit 2.
3, and then the second detection circuit 24 extracts the audio component signal. In such a state, the second
The second signal applied to the intermediate frequency amplification circuit 23
Since the electric field strength detection circuit 25 does not detect a decrease in the electric field strength, the signal output from the second detection circuit 24 of the base receiver circuit 21 is the “L” level output of the second electric field strength detection circuit 25. Radio noise is removed through the second low-pass filter circuit 26 whose frequency band has been raised to a high range corresponding to the signal, amplified by the second amplifier circuit 28, and transmitted to the telephone line 30 through the hybrid circuit 29. Machine 1
Adds an audio signal from the owner. As described above, the owner of the handset 1 of the wireless telephone device can talk to the other party via the base unit 2 and the telephone line 30. Next, when a call is being made as described above, the wireless communication between handset 1 and base unit 2 deteriorates due to the moving location of the owner of handset 1 and the influence of surrounding objects, causing the signal to deteriorate. Suppose that the electric field strength has decreased overall. First, in the handset 1 , the electric field strength of the signal applied to the antenna 3 - the handset antenna common circuit 4 - the first front end 6 - the first intermediate frequency amplification circuit 7 is determined by the first electric field strength detection circuit 9. First level set in advance T ₁
If it drops below, speaker 13 of handset 1
A large amount of noise is superimposed on the emitted voice, making it difficult to hear. Therefore, the first electric field strength detection circuit 9 inverts the output signal and outputs an "H" level output signal. With such an output signal,
The first transistor 11 is in an on state while receiving an "H" level output signal, narrows the frequency band of the first low-pass filter circuit 10, cuts out high frequencies, and outputs low-frequency signals (below 1 KHz). Allows only the pass through. Furthermore, the alarm signal generation circuit 14 is also activated upon receiving the "H" level output signal of the first electric field strength detection circuit 9, and becomes in an operating state.
While receiving the "H" level output signal, an alarm signal is generated, and an alarm sound is emitted to the owner of the handset 1 via the alarm speaker 15 to notify the owner of the handset 1 that the electric field strength has decreased. In addition, the slave unit control circuit 1
8 starts counting for a certain period of time (approximately 10 seconds) when receiving the "H" level output signal from the first electric field strength detection circuit 9, and continues counting while receiving the "H" level output signal. In this state, the high-frequency noise that was superimposed on the voice of the other party emitted from the speaker 13 of the handset 1 is filtered out by the first low-pass filter circuit 10, and the conversation is completed although the sound quality is slightly degraded. Maintain a state in which you can recognize what the other person is doing. In such a state, the owner of the handset 1 receives the alarm by the alarm sound, and waits for a certain period of time (approximately 10
seconds) and reaches a position where the electric field strength is equal to or higher than the first level, the first electric field strength detection circuit 9
is inverted again and outputs an "L" level output signal.
Therefore, the first transistor 11 is turned off, and the first low-pass filter circuit 10 returns to the frequency band that also passes high-frequency signals, and transmits the voice of the other party to the owner of the handset 1 in the state before the electric field strength decreases. becomes audible. Furthermore, the alarm signal generation circuit 14 becomes inactive and the alarm speaker 15
Stops emitting the alarm sound. Further, the handset control circuit 18 stops counting and enters the reset state, and the handset 1 returns to the talking state before the electric field strength decreased. On the other hand, when the owner of handset 1 does not move despite being alerted by the alarm sound and the alarm continues to be emitted for a certain period of time (approximately 10 seconds), The handset control circuit 18 counts up, sends a control signal to the handset transmitter circuit 17, and sends a control signal to the handset transmitter circuit 1.
7 is put in an inoperative state, the radio circuit is put in a standby state, and the communication operation with the other party is stopped. As a result, the base unit 2 also enters the standby state. Next, the electric field strength of the signal applied to the antenna 19 - the main unit antenna common circuit 20 - the second front end 22 - the second intermediate frequency amplification circuit 23 in the base unit 2 is determined in advance by the second electric field strength detection circuit 25. Below the set second level T ₂ (the second field strength detection circuit 25 detects a decrease in the field strength before the first field strength detection circuit 9 of the handset 1 ), the wireless telephone device (2nd level _T2 < 1st level _T1 . A large amount of high-frequency noise is superimposed on the transmitted audio signal, making it difficult for the other party to hear the voice of the person holding the handset 1 . Therefore, the second electric field strength detection circuit 25 inverts the output signal and outputs "H".
Outputs a level output signal. Due to this output signal, the second transistor 27 is turned on while receiving the "H" level output signal, narrows the frequency band of the second low-pass filter circuit 26, cuts the high frequency range, and cuts the low frequency range. (1KHz or less) is set to pass only signals. Furthermore, when the parent device control circuit 32 receives the "H" level output signal from the second electric field strength detection circuit 25, the main device control circuit 32 also
10 seconds) and continues counting while receiving the "H" level output signal. In this state, the second low-pass filter circuit 26 cuts out the high-frequency noise superimposed on the voice signal transmitted from the handset 1 and sent out to the telephone line 30. As a result, although the quality of the sound emitted to the other party by the audio signal sent to the telephone line 30 is somewhat degraded, it becomes possible to recognize what the owner of the handset 1 is doing. In such a state, if the handset 1 moves and the electric field strength of the signal transmitted from the handset 1 decreases and then reaches a value equal to or higher than the _second level T2 within a certain period of time (about 10 seconds), The second electric field strength detection circuit 25 is inverted again and outputs an "L" level output signal. Therefore, the second transistor 27 is turned off, and the second low-pass filter circuit 26 returns to the frequency band that also passes high-frequency signals, and the sound received from the handset 1 is received in the state before the electric field strength decreases. A signal is sent to the telephone line 30.
Furthermore, the base unit control circuit 32 stops counting and enters the reset state, and the base unit 2 returns to the talking state before the electric field strength decreased. On the other hand, if the handset 1 does not move and the electric field strength of the signal received from the handset 1 does not reach the second level T2 _or higher within a certain period of time (approximately 10 seconds), the main unit control circuit 32 Counts up and the main unit transmitting circuit 31
sends a control signal to the base unit 2, makes the base unit transmitting circuit 31 inactive, stops transmission to the slave unit 1 , and transmits a control signal to the base unit 2.
is put into standby mode and ready to receive the next call. The operation of this embodiment is performed as described above. In this embodiment, when the first electric field strength detection circuit 9 of the handset 1 detects a decrease in the electric field strength below the first level _T1 , the frequency band of the first low-pass filter circuit 10 is narrowed to approximately 1KHz. This is a fixed value of 1KHz, which cuts out the band above 1KHz where noise components generally gather, and allows only the fundamental wave of the audio signal below 1KHz to pass. It is also possible to use a variable device that allows the user to set the frequency band to the one that provides the most audible sound during use when the electric field strength is reduced. Similarly to the first low-pass filter circuit 10, the second low-pass filter circuit 26 may be a variable circuit that can be set by the user. (g) Effects of the invention The radiotelephone device of the invention is capable of suppressing the electric field of the signal received by each of the handset and the base unit when the handset and the base unit are communicating by radio signals. The slave unit or the base unit is configured to lower the upper limit of the passing frequency of the first low-pass filter circuit or the second low-pass filter circuit when the intensity drops below a level value set in advance in each of the slave unit and the base unit. Therefore, even if the noise signal from the receiving circuit increases as the electric field strength decreases, the adverse effect of the noise signal on the telephone conversation can be suppressed.
Therefore, even if the electric field strength decreases during a call, it is possible to hear each other's voices, and the present invention has a very large effect on improving the performance of radio telephone equipment. In addition, if the electric field strength continues for a predetermined time or longer on the handset or the base unit, the wireless telephone device returns to the standby state, which has the advantage of not having any effect on the telephone line. This invention has. Furthermore, the present invention allows the slave device to switch the filter characteristics of the low-pass filter circuit and control the operation of the alarm signal generation circuit based on the detection output of the field strength detection circuit that detects a decrease in the field strength. This has the advantage of simplifying the circuit configuration. Since the handset uses batteries such as rechargeable batteries, the level of the transmitted radio waves decreases due to a drop in the power supply voltage. It can be recognized that the sound quality has deteriorated. Therefore, the person on the other end of the call can notify the owner of the handset of the deterioration of the sound quality by voice.
Even if the alarm generation circuit installed in the slave unit does not operate, it is possible to instruct the owner of the slave unit to move closer to the base unit, so the practical value of this invention is extremely high. It is something.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a handset in an embodiment of the wireless telephone apparatus of the present invention, and FIG. 2 is a block diagram showing a base unit in an embodiment of the radio telephone apparatus of the present invention. Explanation of main drawing numbers, 5 ...Slave receiver circuit, 9...
First electric field strength detection circuit, 10...First low-pass filter circuit, 21 ...Base receiver circuit, 25...
Second electric field strength detection circuit, 26... second low-pass filter circuit.

Claims (1)

[Scope of utility model registration request] A handset receiving circuit that is built into a handset that exchanges signals wirelessly with a base unit connected to a telephone line, and that receives signals transmitted from the base unit, and a handset receiving circuit that receives signals from the handset receiving circuit. a first low-pass filter circuit to which a signal is input and which can vary the upper limit of the passing frequency; a first amplifier circuit to which an output signal of the first low-pass filter circuit is input and which amplifies the signal; 1st
A speaker to which an output signal of the amplification circuit is applied and emits the signal; and a speaker connected to the handset receiving circuit to detect the electric field strength of the received signal, and generate a detection signal when the electric field strength decreases below a predetermined level. a first electric field strength detection circuit that outputs a detection signal; and a first switch means that becomes operational when a detection signal is output from the first electric field strength detection circuit and lowers the upper limit of the passing frequency of the first low-pass filter circuit. , an alarm signal generation circuit that enters an operating state and generates an alarm signal when a detection signal is output from the first electric field strength detection circuit;
A handset control circuit that enters an operating state and returns the radiotelephone to a standby state when a detection signal is output for a predetermined period of time or more from a field strength detection circuit, and a signal that is built into the base unit and transmitted from the handset. a base receiver circuit that receives the signal, and a second circuit that receives the signal output from the base receiver circuit and is capable of varying the upper limit of the passing frequency.
a low-pass filter circuit; a second amplifier circuit into which the output signal of the second low-pass filter circuit is input, amplifies the signal, and sends the signal to the telephone line; a second electric field strength detection circuit that is connected to detect the electric field strength and outputs a detection signal when the electric field strength decreases below a predetermined level; and a second electric field strength detection circuit that is activated when the second electric field strength detection circuit outputs the detection signal. and a second switch means for lowering the upper limit of the passing frequency of the second low-pass filter circuit, and when a detection signal is output from the second electric field strength detection circuit for a predetermined time or more, the wireless telephone device enters the operating state and the radio telephone device enters the standby state. A wireless telephone device comprising a base unit control circuit for returning to normal operation.