JPH05327614A - Data communication method in cordless communication equipment - Google Patents

Abstract

PURPOSE:To reduce the time when the user is forced to be listened to unpleasant noise by limiting a communication signal amplitude before modulation to be smaller than a control signal amplitude at a sender side and fetching a signal whose amplitude is larger than a prescribed amplitude from a reception signal after demodulation as the control signal at a receiver side so as to reduce the transmission time of the control signal. CONSTITUTION:A transmitter 10 consists of a circuit sending a voice signal SS from a speaker 14 to a modulator 17 via a voice amplifier 15 and a limiter 16 and a circuit sending a control signal CS from a CPU 9 to the modulator 17 via a semi-fixed resistor 18. Then an amplitude of the input voice signal SS of an RF amplifier 19 is selected to be an amplitude smaller than an amplitude of a control signal CS sent from the CPU 9 and satisfying a specific condition. Moreover, a data detector 25 of a receiver 7 receives only a signal whose amplitude is larger than a setting value among demodulated signals. Thus, even when the control signal is sent according to a high speed communication sequence, a receiver side does not mix the control signal and the voice signal and no malfunction takes place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless communication device (cordless telephone, pager, cordless FA) comprising a stationary device and a mobile device wirelessly connected to the stationary device.
X, cordless computer, cordless answering machine, etc.).

[0002]

2. Description of the Related Art In a cordless telephone, for example, control data may be sent using the same wireless channel during voice transmission (during a call) between a base unit (fixed unit) and a handset unit (mobile unit). That is, for example, in a telephone service that allows interruption incoming from a third party, if there is an incoming call from a third party during a call, the parent device first receives the incoming call, Is sent as a message sound to the handset by adding it to the voice during a call. The caller who hears this message sound accepts the incoming call from the third party,
The fact that the current line needs to be released is notified to the master unit side by keying in a predetermined button on the slave unit. The control signal emitted from the handset unit at this time is a digital pulse signal (for example, the format shown in FIG. 5) including data corresponding to the key pressed by the caller in the above operation. Since the same channel as the channel is used for transmission on the same carrier, if the digital pulse is transmitted by a high-speed communication sequence (for example, a speed of several 100 bps), the frequency of several 100 bps is converted into a voice frequency on the receiving side. Since it is in the band, it may be indistinguishable from voice and may malfunction.

Therefore, conventionally, several bits (start bits) at the head of the control signal are transmitted by using a special low-speed communication sequence (for example, about 20 to 30 bps). In this way, on the receiving side, the start bit can be easily distinguished from the voice, and the digital pulse signal after that can be clearly distinguished and recognized as the control signal, so that no malfunction occurs.

[0004]

However, the method of transmitting the control signal by using the special low-speed sequence as described above has a drawback that it takes time to transmit one control signal. In addition, transmitting a control signal from the handset during a call means that the caller hears a side tone from the earpiece, and therefore hears unpleasant noise when the control signal is transmitted. There is also a drawback that the noise generation time is inevitably long. Therefore, the present invention is intended to provide a novel data transmission / reception method in which the time for transmitting a control signal is short and the time for listening to unpleasant noise is short accordingly.

[0005]

SUMMARY OF THE INVENTION The present invention is a data communication method for a cordless communication device comprising a fixed device wire-connected to a communication line and a mobile device wirelessly connected to the fixed device. When transmitting and receiving a control signal instead of the signal in communication or by superimposing the signal during communication between both units using one wireless channel, the transmitter side controls the amplitude of the communication signal before modulation. This is a method in which the amplitude is limited to a smaller value, and a signal having a larger amplitude than a predetermined amplitude is taken in as a control signal from the demodulated received signal on the receiving side. Another object of the present invention is to provide a stationary or mobile device of a cordless telephone using the above communication method.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a cordless telephone embodying the present invention will be described below with reference to the drawings. In FIG. 1, (1) is a base unit (fixed unit) connected to the telephone line (2),
(3) is a child device (mobile device) wirelessly connected to the parent device (1). NCU (telephone line control unit) in the base unit (1)
(4), CPU (5), transmitter (6), receiver (7) and the like are provided, and the detailed configuration of the receiver (7) will be described later. (8) is an antenna.

A CPU (9), a transmitter (10), a receiver (11), and a key input device (12) such as a numeric keypad connected to the CPU (9) are provided in the slave unit (3). The detailed configuration of the transmitter (10) will be described later. (13) is an antenna.

FIG. 2 (a) shows the structure of the transmitter (10) (particularly the transmitter on the slave (3) side). The transmitter (10) sends a sound signal (SS) from a speaker (14) to a modulator (FM modulator) (17) via a sound amplifier (15) and a limiter (16), and a CPU.
It is composed of a circuit for sending the control signal (CS) from (9) to the modulator (17) via the semi-fixed resistor (18). (19) is an RF amplifier,
The amplitude of the audio signal (SS) can be adjusted by the above limiter (16) to the CPU
The amplitude is smaller than the amplitude of the control signal (CS) transmitted from (9) and is limited to the amplitude that satisfies the following condition.

That is, the voice signal (S
The maximum degree of modulation by the modulator (17) in (S) is ± ±
It is set to 3.5 KHz, and the control signal (CS) from the CPU (9) is set so that the modulation degree by the modulator (17) is just ± 4.5 KHz.

FIG. 3 shows a specific example of the limiter (16). The limiter (16) of this example is an ordinary operational amplifier (20), constitutes a symmetrical swing amplifier, and can reduce the dynamic range by the variable resistor (21).

Next, the receiver (7) (especially the receiver on the side of the master unit (1))
The configuration is shown (Fig. 2 (b)). The receiver (7) is an RF amplifier (2
2) and the signal demodulated via the demodulator (23) to the audio amplifier.
Circuit to send to NCU (4) via (24) and data detector (25)
And a circuit for sending it to the CPU (5) via the. The data detector (25) has a function of taking in only a signal having an amplitude larger than a certain set value out of the demodulated signal, and in this example, only a signal having a modulation degree of more than ± 4.0 KHz is received. It is designed to be captured.

FIG. 4 shows a specific example of the data detector (25).
The data detector (25) of this example is a waveform shaping circuit using an ordinary operational amplifier, and by setting the resistance (R) to a large value, a large amplitude (modulation degree greater than ± 4.0 KHz is generated. The voice signal (SS) having a relatively small amplitude (the modulation degree is less than ± 4.0 KHz) is not captured through only the control signal (CS).

Next, the operation of this embodiment having the above-mentioned structure will be described. That is, when the user presses any key of the key input device (12) during a call on the slave unit (3) side through the speaker (14), the CPU (9) recognizes the key-in and immediately switches ( The S) is turned off to block the voice input, and the CPU (9) transmits the digital data corresponding to the pressed key together with other bits at a high speed of several hundred bps. Therefore, the signal before being input to the modulator (17) is as shown in FIG.
The control signal is emitted in a high-speed communication sequence including the start bit, but after passing through the modulator (17), the voice signal (SS) is limited in amplitude by the limiter (16) in advance. Therefore, the maximum modulation degree is within ± 3.5 KHz, and the control signal (CS) has a fixed frequency of ± 4.5 KHz. When the transmission of one control signal is completed, the CPU (9) turns off the switch (S) again.

The signal which is modulated and radiated through the modulator (17) and received by the master unit (1) is demodulated by the demodulator (23),
The signal becomes the one shown in FIG. 6 again. The signal is amplified by the audio amplifier (24) and sent to the NCU (4), but depending on the detector (25), the modulation degree is ± 4.0 KHz as described above.
Since only the larger one is selected and sent to the CPU (5), the CPU (5) accurately takes in only the control signal (CS) and recognizes its contents without being confused with the voice signal (SS).
The control signal (CS) part flows to the audio output system as noise, but all of it is a high-speed communication sequence, so it can be done in a short time. As the limiter 16 and the data detector 25, an appropriate IC or semiconductor circuit other than the operational amplifier may be used.

In the above description, the case where the signal being communicated is a voice signal has been described. However, the signal being communicated is a data signal generated by scanning a still image like a fax, a pager or a computer data signal. It doesn't matter.

[0016]

As is apparent from the above description, according to the data communication method in the cordless communication device of the present invention, even if the control signal is sent in the high speed communication sequence, the control signal and the voice signal are received by the receiving side. There is no confusion with and no malfunction occurs. Moreover, since the entire control signal can be sent in a high-speed sequence, the time when it is heard as noise is very short, and the user does not feel much discomfort.

[Brief description of drawings]

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

2A is a block diagram showing a configuration of a transmitter, and FIG. 2B is a block diagram showing a configuration of a receiver.

FIG. 3 is a circuit diagram as a specific example of a limiter.

FIG. 4 is a circuit diagram as a specific example of a data detector.

FIG. 5 is a diagram showing a format of a control signal.

FIG. 6 is a diagram showing waveforms of a voice signal and a control signal.

[Explanation of symbols]

 (1) Master (fixed) (3) Slave (mobile) (7) Receiver (10) Transmitter (12) Key input device (14) Speaker (16) Limiter (17) Modulator (23) Demodulator (25) Data detector (SS) Voice signal (CS) Control signal

Claims (3)

[Claims] 1. A method for transmitting and receiving data in a cordless communication device comprising a fixed device wire-connected to a communication line and a mobile device wirelessly connected to the fixed device, wherein one wireless channel is used. When transmitting and receiving a control signal instead of the signal being communicated or by superimposing during communication between the two devices, the transmitter side limits the communication signal amplitude before modulation to a value smaller than the control signal amplitude, A data communication method in a cordless communication device, wherein a signal having a larger amplitude than a predetermined amplitude is taken in as a control signal from a demodulated received signal on the receiving side. 2. A stationary device of a cordless communication device, which uses the data communication method according to claim 1. 3. A mobile device of a cordless communication device, which uses the data communication method according to claim 1.