JPS61199342A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To prevent interception by a general receiver as well as a device of the same time by revising a specific code of both a master set and a slave set when they are incorporated. CONSTITUTION:In case of incorporation where the slave set 20 is contained in the master set 10, the both are connected by an ID code communication terminal 2, the both are separated normally and they are connected by an electromagnetic wave. A control circuit 141 detecting the incorporation by an incorporation detector 18 at the master set side adds a count of a timer counter and sends the count to the slave set at the same time through a terminal 2 for storage. The count is stopped when the slave set is separated from the master set and the said count is used as an ID code until the count is started by the next incorporation. During incorporation, the incoming call from the line is replied and in this case, the said timer counter is stopped and when the coincidence of the newest ID codes stored and confirmed between both the sets are coincident, the taking mode is obtained. Thus, the count of the timer counter being revised in this way, resulting that the ID code is subject to pseudo random and the probability coincident between adjacent users is very small.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a telephone device, and in particular to a cordless telephone device that communicates between a base unit connected to a telephone line and a slave unit having functions such as dialing and calling functions by transmitting and receiving electromagnetic waves. Relating to telephone devices.

[Conventional technology]

Although such cordless telephone devices are widely used mainly in Europe and the United States, theft and eavesdropping between adjacent users is a problem, and the following measures have been taken to prevent this. ing.

First, as a measure to prevent theft, 1) DIP switches are provided on each of the base unit and slave unit, the same unique code (ID code) is set, and communication is controlled based on the match.

■Use a ROM in which an ID code is stored in advance in place of the digital switch.

Also, as a measure to prevent eavesdropping, use digital wireless communications such as FSK (frequency modulation).

■Introduce encryption to the above digital radio (including measures to prevent theft).

■Delay the analog signal wave using analog radio, and set the DIP switch to the amount of delay (set the same on the base unit and slave unit).

[Problem that the invention seeks to solve]

Among these methods, ■ is the method adopted in American cordless telephone equipment according to the FCC standard, but it is possible to find the ID code of the adjacent user by changing the combination of dip switches with the same handset. If adjacent users do not know, plagiarism is possible. ! In case of (■), if there is no duplication of ID codes, it is impossible to use the same type of phone, but the number of ID codes becomes enormous, and in order to suppress this, it is necessary to use regional code allocation, etc. do not have. In any case, production and management must always be carried out by parent and child bears.
Since it is necessary to write an individual ID code, there are problems in production and management.

On the other hand, ■ can prevent eavesdropping on amateur radio, etc., but does not have the eavesdropping prevention function for telephone devices of the same type. ■There is a similar problem υ, and if the radio wave condition is poor, the synchronization will collapse,
Difficult to resynchronize. Furthermore, ■ has the same problem as ■.

[Means for solving problems]

In order to solve these problems, the cordless telephone device according to the present invention updates the unique codes of the base unit and slave unit when they are combined.

[Effect]

The ID code is updated and pseudo-randomized for each merger, and the probability that the ID codes will match between adjacent users is extremely small. Therefore, for example, if a call is allowed only when this ID code matches, theft can be prevented, and by encrypting the digitized audio signal based on the ID code, eavesdropping on a general receiver can be prevented. It also prevents eavesdropping using similar devices.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention. The figure shows a state in which the slave unit 20 is housed in the base unit 10 connected to the analog line 1, and the two are connected via the rD code communication terminal 2, which will be described later, but in normal use, the two are separated. and are communicated in the evening by sending and receiving electromagnetic waves.

That is, the receiving signal received from the line 1 via the interface circuit 11 and taken out by the hybrid circuit 12 is transmitted to the transmitter 13 by a control unit including a processor unit such as a well-known microprocessor and a memory, etc., which constitutes the control unit 14. It is digitized and encrypted according to the control signal from the circuit 141, and after adding a predetermined control signal, it is FSX modulated and sent to the antenna 15.
The signal is transmitted as a radio wave to the handset 20. Further, the radio waves from the handset 20 received by the antenna 15 are input to the receiving unit 1γ via the bandpass filter 16, demodulated and decoded, and then converted into an analog signal, which is sent to the hybrid circuit 12 as a transmission signal. and is sent to line 1 via interface circuit 11.

Ichiriki, half bird? 041! +1 is -8: Aokin performs intermittent reception by turning on the power of Sairai Riki's Imame 8 signal system for 1 second and off for 2 seconds, and receives continuously when there is a message, but it is received by antenna 21. The radio waves from the main device 10 are inputted via a bandpass filter 22 to a receiving section 23 similar to the receiving section 17 on the main device side, and are input to the control circuit 1 constituting the control section 24.
After being demodulated and decoded in accordance with a control signal from a control circuit 241 similar to 41, the signal is converted into an analog signal and output to the receiver 25 as a received signal. Also, the transmitter 2
The transmission signal from 6 is input to a transmission section 27 similar to the transmission section 13 on the base unit side, where it is converted into a digital signal and encrypted, and after adding a predetermined control signal, it is FSK-modulated. and is transmitted as radio waves from the antenna 21.

Here, the signals transmitted and received between the two machines are made up of eight subframes each having an 8-bit configuration in series, as shown in Figure 4.
The structure is such that the upper bits of each subframe are assigned to the audio signal, the seventh bit is used as an information bit, and various control information is included in this. Note that the 8th bit of each subframe is forcibly set to 1 as an empty bit.
1".Also, in actual transmission, the CMI transmission method is used, but at that time, a violation is performed at the 8th bit of the 8th subframe to ensure frame synchronization. ing.

That is, as shown in FIG. 5, the information bits of each subframe constitute 8-bit control information, and the information format is the same as shown in Tables 1 and 2. Table 1 shows what the base unit transmits, and Table 2 shows what the slave unit transmits. The ID code is always added as the lower four pits, except for the case of confirmation at . This ID code is set in advance to match in a pair of master unit and slave unit by a method described later and is stored in memory. Check the ID code received (in the case of an incoming call to the base unit, the ID code is sent from the base unit to the handset, and in the case of an outgoing call from the handset, the ID code is sent from the handset to the base unit). A call is permitted only when the ID code matches one's own ID code stored in a memory, and the call is interrupted if the ID code does not match during a call for a predetermined number of times.

Table 1 (Main unit transmission) Table 2 (Slave unit transmission) In Table 1.2, [Dial number return] indicates that the base unit returns the dial number received from the slave unit to confirm the dial number. "Dial number OKJ" is information that indicates that there is no mistake on the handset side that received this number. Also, F in the dial number indicates a function key, and in this example It corresponds to the dial.

In order to realize communication using the signal configuration as described above, the transmitting sections of both the base unit and the slave unit have the configurations shown in Figure 2, and the receiving units of both have the configurations as shown in Figure 3. has.

In Figure 2, line 1 (in the case of base unit) or transmitter 2
The audio signal from 6 (in the case of a slave unit) is amplified by an amplifier 31, converted to a digital signal by sampling every 125 μS by a CODEC 32, and then sent to an encryption circuit 3.
Encrypted with 3. In this embodiment, this encryption is performed by performing EX-OR (exclusive OR) with one pit in the ID code in subframe units. The ID code is 4
Since it is made up of bits, each bit is used repeatedly for encryption. Table 3 shows that the ID code is '1011n
An example of this encryption is shown below.

Table 3 Note that in addition to subframe units as described above, ID code and EX
-OR may be taken.

After such encryption, the information BIT switching circuit 34 converts the 7th bit of each subframe constituting the audio signal as shown in Table 1 or Table 2 based on the control signal from the control circuit. Forcibly replace each information pit with the corresponding one. Furthermore, after the subframe BIT switching circuit 35 forcibly switches the 8th bit of each subframe to 11, the CMI encoding circuit 36
Perform CMI code exchange. At this time, as mentioned above, the 8th
A violation is given to the 8th bit of the subframe.

Thereafter, the signal is modulated by an FSK modulator 37, amplified by an amplifier 38, and transmitted as a radio wave from an antenna.

On the other hand, in the receiving section, as shown in FIG. 3, the radio waves received by the antenna are input to an amplifier 51 via a bandpass filter, amplified, demodulated by an FSK demodulator 52, and a waveform shaping circuit 53. After undergoing waveform shaping, the signal is input to the CMI decoding circuit 54. The decoded output is sent to the information BIT extraction circuit 55, where control information consisting of the 7th bit of each subframe is extracted and sent to the control circuit, and the detection output of the violation detection circuit 56 is sent to the information BIT extraction circuit 55. Based on the control clock generated by the decryption clock generator 57, the decryption circuit 58 performs EX-OR with the ID code to decrypt the control clock. After that, in order to avoid the steel pits that are not used as audio signals, that is, the 7th and 8th bits of each subframe, from generating noise when there is no sound, these pits are replaced with steel B.
It is forcibly replaced with 100 in the IT replacement circuit 59.

Thereafter, the audio signal is converted into an analog signal by the CODEC 60, amplified by the amplifier 61, and sent to the line (in the case of a base unit) or the receiver 25 (in the case of a slave unit).

In addition, each clock of the receiving system and the transmitting system is 8°192
■The output of the h oscillator 39 is divided by υ by the frequency divider 40, and the reception system clock generation section 41 and the transmission system clock generation section 42 generate the generated clocks and supply them to each section. In order to synchronize with the signal,
It is created based on the detection output by the fall detection circuit 62 of the output of the waveform shaping circuit 53.

By incorporating EX-OR encryption, even if a third party attempts to eavesdrop, the encryption must be able to be decrypted.If this is not done and the audio signal is simply converted to analog, for example, as shown in Figure 6. The true signal level as shown in (b) in the figure is completely different from the true signal level shown in (a) in the figure, which makes no sense. Furthermore, since the encrypted ID code is the key, decryption is impossible unless this ID code is known.

Here, the ID used in this cordless telephone device
The code is not fixed, but is updated each time the parent device and child device are combined. In other words, in this embodiment, the power supply voltage required by the slave unit is determined by supplying charging current from the base unit connected to the commercial power source to the battery of the slave unit through a predetermined connector when the slave unit is housed in the base unit. However, the control circuit 141 detects such a combination of the parent device and the child device by the combination detector 18 on the parent device side, and the control circuit 141 detects the combination of the parent device and the slave device at regular intervals while the combination continues. For example, every minute, a part of the memory is used to add up the count value of a predetermined timer counter, and at the same time, it is updated to the slave device through the ID code communication terminal 2 provided in a part of the terminal of the connector. Transmit and store the count value.

When the child device is separated from the parent device, counting stops at that point.
The counted value is used as the ID code until counting starts again due to the next combination. During the combination, only incoming calls from the line will be answered, but in that case, the timer counter mentioned above will be stopped and the slave unit will be connected wirelessly or through the connector using the latest ID code that has been confirmed and memorized between the base unit and the slave unit. , and if the codes match, the call state will be entered.

As a result of using the count value of the timer counter that is updated at predetermined intervals during merging in this way, the ID codes are pseudo-randomized and the probability of matching between adjacent users becomes extremely small. For this reason, theft and eavesdropping are almost impossible even if devices of the same type are used.

It goes without saying that the cord communication terminal may be provided using a dedicated connector separate from the charging connector. Further, the code may be updated by subtracting the contents of a timer counter at predetermined intervals. Furthermore, a timer counter may be provided on the child device side and the counted value may be transmitted to the parent device side.

Although the example in which the base unit is connected to an analog line has been described above, the present invention is not limited to this, and can be similarly applied to a case where the base unit is connected to a digital line.

Further, in the above-described embodiment, the ID code is updated at regular intervals while the parent device and the child device are combined, but the updating method is not limited to this.
For example, the maximum number of updates or time may be specified, and updates may not continue even if merging continues beyond that time.
Alternatively, the information may be updated once every on-hook, for example.

In the above-described embodiment, a digital communication method is used to encrypt the wireless communication between the parent device and the child device, but it is also possible to use an analog communication method to directly transmit and receive data. Even in that case, a call cannot be made unless the ID codes match, and since the ID codes are pseudo-randomized, theft by identical telephone devices can be effectively prevented.

〔Effect of the invention〕

As explained above, according to the present invention, when the parent device and the child device are combined, the unique codes of both devices are updated through a predetermined connector, so that the unique code of each device is pseudo-randomized. Therefore, the probability of matching between adjacent users is very small, making plagiarism difficult. Furthermore, the configuration can be exactly the same at the time of production, and management is easy. In particular, digital communication methods are used for transmission and reception between the base unit and slave unit,
Furthermore, if encryption using the pseudo-randomized unique code as a key is implemented, not only eavesdropping with a general receiver but also eavesdropping with a circular telephone device becomes virtually impossible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a detailed diagram of its transmitting section, and FIG. 3 is a detailed diagram of its receiving section.
FIG. 4 is a diagram showing a signal frame structure, FIG. 5 is a diagram showing an information format, and FIG. 6 is a diagram for explaining the effect of encryption. 1...Analog line, 2...ID:! - terminal for communication, 10...base unit, 13.27...transmission section, 14.24...control section, 15゜21...antenna, 17.23...φ... Receiving unit, 18... Combination detector, 20... Handset, 25... Handset, 26...
...Transmitter. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) Consists of a base unit that has a connection function to a telephone line, and a slave unit that has at least a dialing function, an incoming call display function, and a calling function, and communication is established between the base unit and the slave unit by sending and receiving electromagnetic waves. In a cordless telephone device, the base unit and handset have corresponding unique codes, and when the base unit and handset are combined, the unique code is updated through a predetermined connector, and based on the updated unique code. 1. A cordless telephone device characterized in that the cordless telephone device is configured to identify a signal and make a call. (2) The base unit and the slave unit are equipped with an encryption circuit that encrypts the transmitted signal based on the proprietary code that they own, and a decryption circuit that decodes the received signal based on the proprietary code that they also own. 2. The cordless telephone device according to claim 1, wherein the cordless telephone device communicates by transmitting and receiving encrypted signals.