JPH0555948A - Communication equipment - Google Patents

Abstract

PURPOSE:To realize a cordless telephone set whose power consumption is saved and in which radio wave interception is prevented by devising a slave set and a master set such that they send with a required and sufficient transmission power for each communication in the cordless telephone set comprising the master set and the slave set ' from the master set and making communication by radio wave. CONSTITUTION:The equipment is featured to be provided with a means 17 measuring an electric field strength or S/N of a reception radio wave from an opposite telephone set, a means 16, 17 sending the measured electric field strength or the S/N to the opposite telephone set without giving effect onto the talking state, and means 20, 21 controlling succeeding transmission power of its own station based on the electric field strength or the S/N received from the opposite telephone set, and the transmission power of its own station is controlled and sent based on the electric field strength or the S/N of the radio wave received from the opposite telephone set of each of the slave set and the master set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmission power control of a communication device, in which a plurality of transmitters / receivers can transmit power with a transmission power that is necessary and sufficient for a call between them, thereby saving power and eavesdropping on the call. The present invention relates to a communication device that can prevent the above.

[0002]

2. Description of the Related Art In recent years, with the development of electronic devices, personal wireless communication devices have rapidly spread. In particular, in the conventional transmission power control of cordless telephones, which had a remarkable spread to the spread of cordless telephones, many of them always transmitted radio waves at a constant power. That is, this type of cordless telephone is also called a low power cordless telephone, and for example, transmission of 10 mW (full power) was the standard.

Further, there are not only cordless telephones that always control transmission power with constant power but also cordless telephones that can variably control transmission power.
In this type of cordless telephone, the electric field strength or the signal-to-noise ratio of the radio wave received from the other telephone is usually measured, and the measurement result is transmitted to the other telephone for controlling the transmission power of the other telephone. Then, the other party's telephone controls the transmission power based on the measurement result.

In this case, the measurement of the electric field strength or the signal-to-noise ratio of the radio wave received from the other party's telephone is performed by using the call signal during the call. The measurement result is transmitted by stopping the call signal of the own station. Therefore, in the conventional cordless telephone, when transmitting the signal for controlling the transmission power of the other telephone, the transmission of the call signal of the own station is stopped.

Alternatively, even in a cordless telephone capable of transmitting a measurement result signal for controlling the transmission power of the other telephone without stopping the call signal of its own station, normally, the control signal is transmitted at regular intervals or the received radio wave is received. Either only when there is a significant change in the electric field strength or the signal-to-noise ratio of the signal, or only when the call starts, there is no one that always transmits the measurement result signal. ..

[0006]

As described above, in the conventional cordless telephone which constantly transmits radio waves with a constant transmission power, when the master unit and the slave unit are talking at a short distance. However, since the transmission power is always constant, there is a risk that call radio waves are unnecessarily transmitted over a long distance and the content of the call is eavesdropped.

Further, in the case of transmitting the measurement result signal for controlling the transmission power of the other party's telephone, the conventional cordless telephone which stops the transmission of the call signal of its own station is unnatural during an important conversation, for example. There was a problem such as interruption.

Further, the conventional cordless system, in which a control signal is transmitted at regular intervals, is transmitted only when there is a significant change in the electric field strength of the received radio wave or the signal-to-noise ratio, or is transmitted only at the beginning of a call. In a telephone, for example, when the electric field strength of the received radio wave or the signal-to-noise ratio is rapidly reduced due to the movement of the child device, the control signal is not transmitted, or even if it is performed, the control is delayed and the communication quality is deteriorated. However, there was a problem that the call dropped in the worst case.

That is, as described above, the measurement of the electric field strength or the signal-to-noise ratio of the radio wave received from the other party's telephone is performed using the call signal during the call. Also, the measurement result must be transmitted at the same time as the call signal of the local station. However, in a conventional cordless telephone, a transmission frequency band of a call voice signal is 300 Hz to 3.
In the band of 4 KHz, since the signal for power control of the other telephone was also trying to be transmitted at the same time, the call voice signal and the signal for power control could not be transmitted together.

The present invention has been made to solve the above problems, and a measurement result signal for power control of a partner transceiver is transmitted in a band different from an audible band which is a transmission frequency band of a voice signal. , And the voice signal and the measurement result signal can be transmitted at the same time at all times, and each of the transmitters and receivers can transmit at the necessary and sufficient transmission power for each other's call, thereby saving electricity. It is an object of the present invention to provide a communication device that can prevent the wiretapping of radio waves.

[0011]

In order to achieve the above object, a communication apparatus according to the present invention comprises means for measuring the electric field strength or signal-to-noise ratio of a radio wave received from a partner transceiver, and the means for measuring by the means. Means for transmitting the received electric field strength or signal-to-noise ratio to the partner transceiver at the same time as the call signal without affecting the call state, and the following automatic transmission based on the field strength or signal-to-noise ratio received from the partner transceiver. Means for controlling the transmission power of the station, and controls and transmits the transmission power of the own station based on the electric field strength or the signal-to-noise ratio of the radio wave received from the partner transceiver.

[0012]

Therefore, according to the communication device of the present invention, the electric field strength or the signal-to-noise ratio of the reception radio wave of the partner transceiver is measured, and the measurement result signal is transmitted as a voice signal for power control of the partner transceiver. By transmitting in a band different from the audible band which is the frequency band, it is possible to always transmit the voice signal and the measurement result signal at the same time. Then, the measurement result signal is received, the power control signal is generated, the transmission power of the local station thereafter is controlled, and it is possible to transmit with the transmission power that is necessary and sufficient for continuous communication.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a master unit and a slave unit of a cordless telephone which is an embodiment of a communication device according to the present invention.

Referring to FIG. 1, a cordless telephone of the present invention has a slave unit and a master unit, an antenna 10 for transmitting and receiving radio waves such as a calling signal of a predetermined frequency or a call signal, and FM demodulating the radio waves received from the antenna 10. Receiving circuit (RX) 11 that converts the internal signal into a high-pass filter (HPF) 12 that cuts the internal signal of the internal signal input from the receiving circuit 11 below 300 Hz, and the audio signal output from the high-pass filter 12 A speaker (SP) 13 which is converted into a sound and is sounded to an operator, a microphone (MIC) 14 which collects a sound sounded by the operator and converts the sound into a sound signal, and a sound signal of 300 Hz or less input from the microphone 14. A high-pass filter (HPF) 15 that cuts the signal of the above, an audio signal from the high-pass filter 15, and a modulator (MOD) 18 described later. An internal signal received by the transmission circuit (TX) 16 that receives the electric field intensity measurement result signal, which is the result of measuring the electric field intensity of the radio wave received from the other party's telephone, which is subjected to high frequency processing and is sent to the antenna 10, and the reception circuit 11. An electric field strength measurement circuit (MES) 17 for measuring the electric field strength of a received radio wave from a signal, and a field strength measurement result signal of the received electric wave from the partner telephone detected by the electric field strength measurement circuit 17 is modulated and output to the transmission circuit 16. Modulator (MOD) 1
8 and 300 Hz from the internal signal received by the receiving circuit 11
Low-pass filter (LPF) 1 that cuts the above signals and extracts the electric field strength measurement result signal transmitted by the other telephone
9, a demodulator (DET) 20 that demodulates the electric field strength measurement result signal from the partner telephone extracted by the low-pass filter 19 and also generates a power control signal that controls the transmission power of the local station thereafter, and a demodulator A transmission power control circuit (PC) 21 that controls the transmission power based on the power control signal generated by 20.

Furthermore, the master unit of the cordless telephone connects the cordless telephone to the telephone line in addition to the above circuits.
A line-to-line conversion circuit (HYB) 22 is configured.

Next, in the cordless telephone of the present invention configured as described above, the operation in which the transmission power of the own station is controlled by the electric field strength of the radio wave received from the partner telephone will be described. First, in the calling operation, the slave unit and the master unit each output the calling signal from the transmission circuit 16 at the maximum output, that is, 10 mW (full power).

For example, when the slave unit makes a call to the master unit, the master unit receives the call signal of the slave unit via the antenna 10 and the receiving circuit 11
To establish a call channel with the handset. And
After establishing the communication channel with the slave, the master controls the receiving circuit 11 of the master thereafter to constantly measure the electric field strength of the radio wave received from the slave. Similarly, the slave unit receives the incoming call completion signal from the master unit, recognizes that the call channel has been established, and then receives the electric field strength of the radio wave received from the master unit by the receiving circuit 11 of the slave unit thereafter. Is controlled so that is always measured.

Then, in the subsequent calls, the slave unit and the master unit cut out the input signals received by the receiving circuit 11 from the input signal received by the receiving circuit 11 by the high-pass filter 12 after cutting the signal of 300 Hz or less, and output the voice from the speaker 13. It is converted and pronounced by the operator. On the other hand, the electric field strength of the input signal is measured by the electric field strength measuring circuit 17, and the electric field strength measurement result signal is continuously input to the modulator 18, and the modulator 18
Modulates the electric field strength measurement result signal into a signal of 300 Hz or less and inputs it to the transmission circuit 16.

On the other hand, an operator who receives a call from the speaker 13 makes a call through the microphone 14, and the voice signal thereof is cut into a signal of 300 Hz or less by the high-pass filter 15 and then input to the transmission circuit 16. The transmitting circuit 16 synthesizes the electric field strength measurement result signal of 300 Hz or less from the modulator 18 and the audio signal from which the signal portion of 300 Hz or less from the high-pass filter 15 is cut, and transmits it to the other telephone through the antenna 10. To do.

Then, the receiving telephone set 1 receives the call signal in which the electric field strength measurement result signal and the voice signal are combined.
1 to perform the above-mentioned operation and the input signal output from the receiving circuit 11 to 30 by the low-pass filter 19.
Cut off signals above 0 Hz. That is, the voice signal portion is removed from the call signal, and only the electric field strength measurement result signal from the partner telephone is extracted and input to the demodulator 20. The demodulator 20 demodulates the extracted electric field strength measurement result signal and generates a power control signal for controlling the transmission power of the local station. The power control signal generated by the demodulator 20 is input to the power control circuit 21, and the power control circuit 21 controls the transmission power of the transmission circuit 16.

The transmission circuit 16 is a transmission power control circuit (PC).
According to the control of 21, the electric field strength measurement result signal of 300 Hz or less from the modulator 18 and the voice signal from which the signal portion of 300 Hz or less from the high-pass filter 15 is cut are combined, and the result is transmitted to the other telephone through the antenna 10. Send. Therefore, in the cordless telephone of the present invention, the above operation is continued until the call channel is cut off, and when the handset is moved away from the base unit as the operator moves, the electric field strength of the received radio wave of the base unit weakens. However, since the slave unit controls the transmission power based on the electric field strength measurement result signal transmitted from the master unit, the slave unit is always corrected to an appropriate transmission power.

As described above, in the cordless telephone of the present invention, the electric field strength of the radio wave received from the partner telephone is measured and the electric field strength measurement result signal is transmitted in a band different from the transmission frequency band of the voice signal. , A voice signal and a measurement result signal can be transmitted at the same time at all times, and the receiving telephone receiving the measurement result signal generates a power control signal from the measurement result signal to control the transmission power of its own station thereafter. It becomes possible to transmit with a sufficient transmission power that is necessary for continuous calls. That is, the transmission power is increased when the electric field strength of the received radio wave is weak, and the transmission power is decreased when the electric field strength is strong.

In the cordless telephone of the present invention, the reception circuit 11 does not output a reception signal even if there is a reception radio wave received from the antenna 10 during standby before the call channel is established. The electric field strength measurement result signal from the other party's telephone is not input to the demodulator 20, and the electric field strength measuring circuit 17 does not output the electric field strength of the received radio wave to the modulator 18.

Further, in the above embodiment, the control of the transmission power of the own station is performed by the electric field strength measurement result signal of the radio wave received from the partner telephone, but it may also be controlled by the signal-to-noise ratio of the radio wave received from the partner telephone. it can. FIG. 2A shows an electric field strength measuring circuit 17 in the cordless telephone of the present invention.
2B is a block diagram showing the configuration of a signal-to-noise ratio measuring circuit for received radio waves, which is an alternative circuit thereof.

Further, in the above embodiment, as a method for simultaneously transmitting the electric field strength measurement result signal and the voice signal, the electric field strength measurement result signal is transmitted at a frequency of 300 Hz or less, that is, 300 Hz to 3. Four
The method of synthesizing with a voice signal obtained by cutting a signal portion of 300 Hz or less at a frequency outside the band of KHz has been described. However, the method of transmitting the electric field strength measurement result signal and the voice signal at the same time is not limited to that. For example, the voice signal is modulated by the FM method, and the electric field strength measurement result signal is modulated by the AM method and combined. It is obvious that it is also possible by modulating the electric field strength measurement result signal at a frequency exceeding 3.4 KHz which is the transmission frequency band of the voice signal and transmitting the signal.

[0026]

As described above, according to the communication device of the present invention, the transmission power of the local station is continuously and continuously in real time by the electric field strength of the radio wave received from the partner transceiver or the signal-to-noise ratio. I configured it to control,
Each of the child device and the parent device can transmit with sufficient transmission power that is necessary and necessary for the mutual call, and there is an effect that it is possible to save electricity and prevent eavesdropping of radio waves.

Further, since the electric field strength measurement result signal and the voice signal are independently and simultaneously transmitted, there is an effect that the call signal is not interrupted due to the transmission of the electric field strength measurement result signal.

[Brief description of drawings]

FIG. 1 is a block diagram of a cordless telephone showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a field strength measuring circuit 17 and a signal-to-noise ratio measuring circuit of a received radio wave which is an alternative circuit thereof in the cordless telephone of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 antenna 11 receiving circuit 12,15 high-pass filter 13 speaker 14 microphone 16 transmitting circuit 17 electric field strength measuring circuit 18 modulator 19 low-pass filter 20 demodulator 21 transmission power control circuit 22 2-wire 4-wire conversion circuit

Claims (2)

[Claims] 1. In a communication device in which a plurality of transceivers are connected by a wireless line, means for measuring the electric field strength or signal-to-noise ratio of received radio waves between the transmitters and receivers, and the electric field strength or signal pair measured by the means. A method of transmitting the noise ratio to the receiver at the same time as the call signal without affecting the call state, and the electric field strength of the own station received by the receiver of the receiver received from the transmitter or the signal-to-noise ratio. Based on the following means for controlling the transmission power of the local station, each of the plurality of transceivers received from the partner transmitter to the field strength or signal-to-noise ratio of the own station received by the partner receiver Based on this, continuously control the transmission power of its own station,
A communication device characterized by transmitting. 2. The communication device according to claim 1, wherein the transceiver is a master unit and a slave unit of a cordless telephone.