JPH06197074A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To prevent interception without interruption of a voice signal by storing a prescribed number of idle channels in advance, confirming the presence of a voice signal for each prescribed time and selecting the stored idle channel when the talking is not finished. CONSTITUTION:Speech channels are scanned in the idle state and a prescribed number of idle channels are stored in a memory 14. Then every time an idle channel is set to the speech channel, a timer 70 is started to start time count for a prescribed time. Then the presence of a voice signal is confirmed for each prescribed time counted during talking and when it is discriminated that the conversation is not finished, one of idle channels stored in the memory 14 is selected. Then the revision of talking to the selected idle channel is informed to a destination telephone set and the busy channel at present is released and the selected idle channel is used. Thus, interception is prevented without interrupting the voice signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone device having a wiretapping prevention function.

[0002]

2. Description of the Related Art Generally, a cordless telephone device is capable of wireless communication between a master unit and a slave unit within a certain range (usually within a radius of 100 to 500 m). In addition, a cordless telephone system has also been developed in which such a handset is used as a mobile station and can communicate with other telephones over a wide range through a base station installed outdoors. In such a cordless telephone system, usually M
Communication by the CA method (multi-channel access method) is performed, and after detecting the idle state of a plurality of call channels (usually 87 channels) through a dedicated control channel (usually 2 channels) on the calling side telephone, the empty channels are detected. The information is transmitted to the called telephone, and the call channel used between the two telephones is set.

By the way, since the cordless telephone device uses radio waves for communication, a third party may accidentally receive the signal or intentionally intercept it during a call. Therefore, some cordless telephone devices have a wiretapping prevention function. There are several methods for preventing eavesdropping, and one of them is forcibly switching the communication channel at regular time intervals. According to this method, the call channel used between the master unit and the slave unit set through the control channel remains constant for a certain period (for example, 30
Every second), it is switched to another call channel, making it difficult for the call contents to be intercepted.

[0004]

However, in the case of the wiretapping prevention method as described above, the call channel is forcibly switched at regular intervals, so that the voice during a call is periodically interrupted and "puzzling" occurs. There is a problem in that the transmission and reception of voice becomes extremely unnatural because the abnormal noise is generated and the flow of conversation is divided.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a cordless telephone device capable of switching a call channel at regular time intervals without interruption of voice. There is.

[0006]

In order to achieve the above object, the present invention is a cordless telephone device capable of communicating with a plurality of telephones and transmitting and receiving control data by wireless communication, and a predetermined number of empty spaces are available during standby. An empty channel detecting / storing means for detecting and storing a channel, a timer for starting a time measurement of a fixed time each time one empty channel is set as a call channel, and a constant time measured by the timer during a call. In addition, a conversation end determination means for checking the presence or absence of voice in the call channel and determining the end of the conversation, and a predetermined number stored by the empty channel detection storage means when it is determined that the conversation has not ended. Free channel selection means to select one free channel from among the free channels of An idle channel, a channel transition notifying means for notifying that the call channel is to be changed, and a call channel switching means for opening the current call channel and switching the call channel to the selected empty channel I am trying.

[0007]

According to the above construction, the idle channel detection storage means detects an idle channel during standby, and further stores a predetermined number of the idle channels. Also,
Each time one free channel is set as the call channel, the timer starts counting a fixed time.

During a call, the conversation end judging means confirms whether or not there is a voice in the call channel currently in use, and judges whether or not the conversation has ended, at regular intervals measured by a timer. When it is determined that the conversation has not ended, the free channel selection means selects one free channel from the predetermined number of free channels stored previously. Then, the channel shift notifying means notifies the telephone of the called party that the selected vacant channel and the channel is to be changed to the vacant channel. Further, the call channel switching means releases the call channel currently in use and switches the call channel to the selected empty channel.

As a result, the call continues using the switched call channel. Therefore, during a call, the call channel is smoothly switched at regular intervals, the voice during the call is not interrupted, and the wiretapping prevention can be effectively performed without dividing the conversation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a child device in a cordless telephone device according to the present invention. Regarding the configuration of the master unit, in addition to the configuration of the slave unit,
Since the configuration is such that a connection block for connecting to the telephone line is added, description thereof will be omitted here.

This slave unit includes a transmission / reception antenna 1 for transmitting and receiving radio waves, an antenna coupler 2 having a transmission filter for passing signals in the transmission frequency band and a reception filter for passing signals in the reception frequency band, and a reception signal. Is converted into a predetermined intermediate frequency signal and detected, and various data included in the signal from the reception unit 3 (generally composed of split-coded digital signals in order to reduce DC components). A demodulation unit 4 that digitally demodulates the transmission signal, a modulation unit 5 that modulates various kinds of data into a transmission signal into a predetermined transmission signal format (for example, a split code format), and a signal from the modulation unit 5 to a predetermined carrier signal. To modulate
A transmitter 6 for amplifying to a predetermined transmission level and a timer 70
For receiving the data demodulated by the demodulation unit 4 and the modulation unit 5
Control unit 7 which is composed of a microcomputer for supplying transmission data to the transmission unit 6 and transmission level data to the transmission unit 6, and audio signal processing for compressing, expanding, amplifying the audio signal and detecting the presence or absence of the audio signal. Part 8 and speaker 9 for ringer
, The receiving speaker 10, and the transmitting microphone 11
A key input unit 12, a display unit 13 for performing various displays,
And a memory 14 for storing empty channels.

FIG. 2 is a flow chart showing the contents of processing performed by the cordless telephone device according to the present invention.
First, after performing initialization processing (S1), in an idle state before line connection, a call channel is constantly scanned to check an empty state, and, for example, about 30 to 50 empty channels are stored in the memory 14. (S2). Next, when making a call (Yes in S3), one of the available communication channels is selected and set as the first communication channel to be used (S4). And
Timer 7 that sets the count value to 20 seconds, for example
0 is started (S5), and conversation processing is executed while monitoring whether 20 seconds have elapsed (S6, S7). Then, every 20 seconds (Yes in S7), the presence / absence of voice is confirmed (S8), and if there is no voice, whether or not the conversation has ended (specifically, a disconnection message). (Whether or not received) is confirmed (S9). Then, when the conversation is completed (Yes in S9), the process returns to the idle state of S2 again.

If the conversation has not ended (No in S9), one call channel N is randomly selected from the call channels stored in the memory 14 (S10). . Then, it is confirmed whether or not the selected communication channel N is an empty channel at that time (S11). Here, if N is not an empty channel (in the case of S11), the channel number is incremented by 1 (S12), the process returns to S11 again, and the next candidate channel N corresponding to the channel number is the empty channel. Confirm whether or not

In this way, when the next candidate empty channel N is determined (Yes in S11), the channel information of the determined channel N is transmitted to the other party (S13). Then, when a reply indicating that the channel information has been received is received from the other party (S14).
In the case of Yes), the call channel currently in use is released (S15), and the call channel is switched to N (S16). After that, the process returns to S4 again, and the call is restarted this time with N as the call channel.

On the other hand, if the call is not made (No in S3)
In the case of), after confirming that there is an incoming call (S21
In the case of Yes), the call channel is set according to the received channel information and the conversation process is performed (S2).
2). Then, when it is confirmed that the conversation with the other party has ended (Yes in S23), S2 is again executed.
Return to the idle state. If the conversation has not ended (No in S23), it is confirmed whether or not the information of the call channel N which is the next candidate has been received from the other party (S24), and if the information has been received (S24). In the case of Yes), the fact is transmitted to the other party (S2).
5). Then, the call channel currently in use is released (S
26), and switches the call channel to N (S27).
Then, the process returns to S22 again, and the call is restarted this time with N as the call channel.

[0016]

When the cordless telephone device according to the present invention is used, an idle channel is detected in advance during standby.
A predetermined number of channels among them are stored. When switching the call channel to prevent eavesdropping during a call, the presence / absence of voice is confirmed at regular intervals. One free channel is selected. Therefore, there is no need to newly scan an empty channel. Furthermore, after the call destination telephone is notified that the selected empty channel and the call channel to be changed to that channel, the call channel currently in use is released, and the call is switched to the selected empty channel. Switching channels is done smoothly.

As a result of the above, it is possible to effectively prevent the wiretapping without interrupting the voice and dividing the flow of conversation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a slave unit in a cordless telephone device according to the present invention.

FIG. 2 is a flowchart showing the contents of processing performed by the cordless telephone device according to the present invention.

[Explanation of symbols]

 7 Controller 14 Memory 70 Timer

Claims (1)

[Claims] 1. In a cordless telephone device capable of communicating with a plurality of telephones and transmitting / receiving control data by wireless communication, an idle channel detection storage means for detecting and storing a predetermined number of idle channels during standby, and an idle channel A timer that starts measuring a fixed time each time it is set as a call channel, and during a call, for each constant time measured by the timer, check whether there is sound in the call channel,
Conversation end judging means for judging the end of the conversation, and when it is judged that the conversation has not ended, one empty channel is selected from the predetermined number of empty channels stored by the empty channel detection storage means. Free channel selection means, a channel transfer notification means for notifying the destination phone of the call to the selected free channel and the fact that the call channel is changed to that channel, and the current call channel is released and the selected free channel A cordless telephone device, comprising: a call channel switching means for switching a call channel.