JPS61199341A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To expand the operating range by providing a digital processing circuit and an analog processing circuit to both a master set and a slave set respectively and using an operating means provided to the slave set so as to switch both the circuits in response to the quality of the transmission condition. CONSTITUTION:The master set (a) and the slave set (b) are provided with circuits 11, 31 ciphering a transmission/reception signal and applying digital processing to the result and circuits 12, 32 applying analog processing, the changeover is executed by changeover switches 33, 34 by the slave set and when the transmission condition is good, the digital system is used and when the transmission condition is bad, the analog system is used. In the said switching, a specific bit of a frame used at digital communication is utilized as an information bit. That is, in applying switching, the slave set uses the said bit to send switching operation information to the master set, and a control circuit 15 of the master set sends a control signal to the switches 13, 14 to change over the digital and analog systems. On the other hand, a control circuit 35 of the slave set sends a similar control signal to the switches 33, 34.

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]

Conventionally, this type of telephone equipment was manufactured by Nippon Telegraph and Telephone Public Corporation or by F.
Analog communication systems, including those based on the CC standard, generally use radio waves as electromagnetic waves, and preventing theft and eavesdropping between adjacent users is an important issue.

In response, the applicant had previously proposed a method for digitizing audio signals and transmitting them wirelessly (Japanese Patent Application No. 1983-
No. 254244). That is, in this system, by digitizing and encrypting the data, and by encrypting the data according to specific rules, it is easy to prevent theft and eavesdropping.

[Problem that the invention seeks to solve]

However, since cordless telephone devices use a wireless transmission path of poor quality, they can be used in locations with low field strength where radio waves are difficult to reach, or where interference waves and reflected waves are on the same level as direct waves. If the conditions are bad, the digital signal may become out of synchronization and the audio may become interrupted.
It is difficult to use under such conditions because the encrypted audio is decoded into a completely different audio frequency due to bit errors.

On the other hand, recently, a confidential communication RE has been developed to facilitate confidential communication using the analog signal system, but in that case as well, since a synchronization signal is sent together, it is difficult to communicate in areas where radio waves are weak, just like with the digital signal system. Inconveniences associated with synchronization may occur, such as hearing unpleasant sounds such as flops and blares.

[Failure to solve the problem]

In order to solve these problems, the present invention provides a digital processing circuit for encrypted digital processing of electromagnetic wave transmission/reception signals and an analog processing circuit for analog processing in both the base unit and the slave unit. Switching between these two circuits is performed by operating means provided at the.

[Effect]

Depending on the quality of transmission conditions, wireless communication can be performed by encrypting digital signals, or by transmitting analog signals themselves to narrow the wireless communication bandwidth and improve receiver sensitivity, making practical communication possible. By switching between increasing the distance and increasing the distance, the range of use can be expanded.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention.
&) shows the configuration of the base unit, and (b) in the figure shows the configuration of the slave unit. In this embodiment, the base unit is connected to the analog line 1, but in addition to the analog processing unit 11, it is equipped with a digital processing unit 12, and a control unit equipped with a processor unit such as a well-known microprocessor, memory, etc. Depending on the connection state of switches 13 and 14, which are changed over by a control signal from circuit 15, one of the outputs is selectively sent out. Similarly, the handset is equipped with an analog processing section 31 and a digital processing section 32, and depending on the connection state of the switches 33 and 34, which are switched in response to a control signal from a control circuit 35 equipped with a processor unit, memory, etc. Either output is selectively sent.

In FIG. 1(,), when the switches 13 and 14 are connected to the digital side, the reception signal R11 received from the line 1 via the interface circuit 16 and extracted by the hybrid circuit 17 is converted from analog to digital (
After being digitized by the A/D converter 121, it is encrypted by the encryption circuit 122 according to predetermined rules,
Furthermore, after being multiplexed with each control signal, synchronization signal, etc. from the control circuit 15 by the multiplexing circuit 123, the signal is input to the modulator 18 via the switch 13, and the high frequency carrier wave is modulated. After this modulated signal is amplified by a transmission amplifier 19 for high-frequency power amplification, it is transmitted from the antenna 20 to the slave device as an electromagnetic wave such as a radio wave or a guided radio wave.

Further, the electromagnetic waves received by the antenna 20 from the handset are inputted to the reception amplifier 22 for high frequency amplification via the bandpass filter 21, and after being amplified, the electromagnetic waves are retarded by the demodulator 23, resulting in 5 KM * hl. ) After only the digital signal is extracted by the high-pass filter 124 of
The latter is decrypted by an encryption/decryption circuit 126, converted into an analog signal by an analog-to-digital (A/D) converter 12γ, and then sent to the hybrid circuit 1T via a switch 14 as a transmission signal Ts. and sent to line 1 via interface circuit 16.

In this case, the control circuit 15 controls the interface circuit 16
In addition to detecting incoming calls and sending out dial signals, the demultiplexing circuit 125 performs incoming call detection and sending out dial signals, and also supplies encryption control pulses to the encryption circuit 122 and the encryption/decryption circuit 126. It receives and receives various separated control signals and synchronization signals, turns on/off the transmitting amplifier 19 and receiving amplifier 22, and controls the gain, etc., and normally only the receiving amplifier 22 is turned on and only the receiving system is in the operating state. However, in response to an incoming call from the line 1 or an outgoing call from the handset, the transmission amplifier 19 is turned on, the transmission system is also put into operation, and communication with the handset is completed. The control pulse to the encryption circuit 122 is created based on a locally generated synchronization signal, but the control pulse to the encryption/decryption circuit 126 is generated based on the reception synchronization signal separated by the demultiplexing circuit 125. Created based on signals.

On the other hand, in FIG. 3B, the electromagnetic waves from the base unit received by the antenna 36 are transmitted through the bandpass filter 2 of the base unit.
1 to a bandpass filter 37 similar to the D/A converter 127, a receiving amplifier 38, a demodulator 39, a bypass filter 321, a demultiplexing circuit 322, and an encryption/decryption circuit 32.
3 and the D/A converter 324, the signal is sent to the receiver amplifier 40 as a receiver signal Rs via the switch 33,
It is output from the receiver 41.

Further, the human power for transmitting the voice from the transmitter 42 is transmitted to the A/D converter 121 of the base unit as a transmitting signal Ta via the transmitting amplifier 43.
After passing through an A-to-power converter 325 similar to the multiplexing circuit 123, an encryption circuit 326, and a multiplexing circuit 327, the switch 34 further transmits a modulator 44 similar to the modulator 18 and a transmitting amplifier 45 similar to the transmitting amplifier 19. The signal is transmitted as electromagnetic waves from the antenna 36 to the base unit via the antenna 36.

At this time, the control circuit 35 performs the same control as the control circuit 15, and also sends control signals to the multiplexing circuit 327 according to the operation outputs of the various food switches and dials provided on the operation display section 46, and The tone ringer is driven according to the control signal separated by the analog processing separation circuit 322 to display an incoming call, but when a predetermined switching button provided on the operation display section 46 is operated to instruct switching to the analog processing system. In this case, a control signal indicating this is sent to the base unit. That is, during digital communication, in this embodiment, one frame is constructed by arranging eight subframes each having an 8-bit configuration in series, and the upper six bits of each subframe are assigned to the audio signal, and the signal is set such that the seventh bit is the information focus. Although a frame structure is used, eight information bits in one frame are used to transmit the switching operation information to the base unit. Therefore, the control circuit 15 of the base unit, which has received the switching operation information as a control signal separated by the multiplexing and demultiplexing circuit 125, sends a control signal to the switch 13.14 to connect these connections to the analog processing unit 11. switch to the side. On the other hand, similar control signals are sent to the control circuit 35ti and switches 33 and 34 on the handset side to connect these to the analog processing unit 31.
From then on, calls will be made using analog communication.

That is, the reception signal Rs received by the base unit from the line 1 receives a control signal sent from the control circuit 15 via the control signal processing circuit 24 in the control signal insertion circuit 111, and then is inserted from the switch 33. The signal is transmitted from an antenna 20 via a modulator 18 and a transmission amplifier 19. Further, the electromagnetic waves received by the antenna 20 are demodulated by the demodulator 23 and then inputted to the low-pass filter 113 by the control signal detection circuit 112 to become an audio signal of 3 KHz or less, which is sent to the line 1 through the switch 14. . On the other hand, the control signal is extracted by the control signal 112 and sent to the control circuit 15 via the control signal processing circuit 24.

On the handset side as well, the electromagnetic waves received by the antenna 36 are demodulated by the demodulator 39, and then the audio signal passes through the control signal detection circuit 311 and the low-pass filter 312, passes through the switch 33, and is output to the receiver 41. The force control signal is sent from the control signal processing circuit 41 to the control circuit 35. Further, the audio signal input from the transmitter 42 is amplified by the transmitting amplifier 43, and then a control signal is inserted in the control signal insertion circuit 313, and then transmitted from the antenna 36 through the switch 34.

In this state, if a switching operation to the digital system is to be performed on the operation display section 46, the control circuit 35 detecting this sends a control signal indicating this to the control signal processing circuit 4T, and inserts the control signal. The circuit 313 inserts the signal into the transmission signal and transmits it, and the control circuit 15 of the base unit, which receives and receives this signal via the control signal detection circuit 111, switches the switches 13 and 14 to the digital side. At the same time, the switches 33 and 34 on the handset side are also switched by the control circuit 35, and from then on, a telephone conversation is performed by digital communication. In addition, when switching communication systems like this, both control circuits 1
5.35 sends control signals to the display section 25 and operation display section 46, respectively, and lights up a predetermined display lamp to display whether the current call is by analog communication or digital communication.

Although the above-described embodiment is an example in which the base unit is connected to the analog line 1, this embodiment can be similarly applied to a case where the base unit is connected to a digital line. An example is shown in Figure 2.

That is, although FIG. 2 shows the configuration of the base unit connected to the digital line 2, the digital processing section 12 has an A/D
υ, where the converter 121 and the D/A converter 12γ are unnecessary;
Instead, the analog processing section 11 requires a D/A converter 114 that converts the reception signal R++' into an analog signal and a digital transmission signal T/output output A/D converter 115. The configuration of the parent device may be the same as that shown in FIG. 1 (-), and the slave device may have exactly the same configuration as that shown in FIG.

In the embodiments described above, the switching between the digital system and the analog system was done by placing a changeover switch in the output extraction section of each processing section, but it is also possible to switch each input, and of course, the input/output All of them may be switched.

〔Effect of the invention〕

As explained above, according to this embodiment, the base unit and the slave unit that communicate by transmitting and receiving electromagnetic waves are provided with a circuit that encrypts and digitally processes the transmitted and received signals, and a circuit that processes analog signals, and a circuit that performs analog processing by encrypting the transmitted and received signals. By making it possible to freely perform communication using the operating means of the handset, in normal cases when the transmission path conditions are good, it is possible to prevent eavesdropping and eavesdropping by using digital and encrypted signals. When transmission path conditions are poor, the range of use can be expanded by switching to analog communication, improving sensitivity by narrowing the band, and avoiding difficulty in hearing due to digital bit errors.

[Brief explanation of drawings]

1(a) and 1(b) are block diagrams of a base unit and a slave unit of a cordless telephone device showing one embodiment of the present invention;
The figure is a block diagram of a base unit showing another embodiment of the present invention. 1-・Fist・Analog line, 21III・・Digital line, 11.31・・・Analog processing section, 12゜32・・
...Digital processing section, 13, 14, 33° 34-...
Changeover switch, 15.35--Conflict control circuit, 20.
36 Book/S-Antenna, 41...Telephone receiver, 42...
...Telephone, 46...Operation display section, 122,326
... Encryption circuit, 126.323 ... Encryption decryption circuit. Patent applicant: Tamura Electric Manufacturing Co., Ltd. Agent: Masaki Hitoyama (and 2 others)

Claims (1)

[Claims] A cordless telephone device that consists of a base unit that has a connection function to a telephone line, and a handset that has at least a dialing function, an incoming call display function, and a calling function, and that communicates between the base unit and the handset by transmitting and receiving electromagnetic waves. In,
The base unit and the slave unit include a digital processing circuit that encrypts and digitally processes the transmitted and received signals of the electromagnetic waves, an analog processing circuit that processes the transmitted and received signals in analog form, and an analog processing circuit that processes the input and output of the transmitted and received signals between these digital processing circuits and analog The slave unit further includes an operating means for switching the switch circuit on the slave unit side and switching the switch circuit on the master unit side via electromagnetic waves. A cordless telephone device characterized by: