JPH05292017A - Cordless telephone set - Google Patents

Abstract

(57) [Abstract] [Purpose] The difficulty in connecting wireless circuits is eliminated by continuously and automatically adjusting the carrier sense levels of the control channels of the master and slave units. A bandpass filter 1 for extracting a noise component included in a received voice signal and a rectifier for converting the extracted noise component into a direct current are provided in a carrier sense system circuit provided in a base unit and a handset of a cordless telephone. 2, a comparator 4 that compares the level of the DC noise component obtained from the rectifier 2 with a reference value to generate a binary signal, and 2
A carrier detection confirmation output circuit 5 that determines the presence or absence of a carrier according to a value signal and outputs a determination signal, and an RF microcomputer 6 that changes the reference value according to the level of the DC noise component are provided. ing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone composed of a master unit and a slave unit.

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a carrier sense system circuit of a conventional cordless telephone. In FIG.
Reference numeral 1 is a bandpass filter for a noise squelch circuit, 2 is a rectifier for a noise squelch circuit, 3 is a comparator, and 4 is an output circuit for confirming carrier detect, and these constitute a carrier sense system circuit. The operations of 3 and 4 are controlled by the RF microcomputer 5.

Next, the operation of the above conventional example will be described.
After the slave unit performs the off-hook operation, it sends a call signal to the master unit, and the master unit in the standby state sends a call response signal to the slave unit after detecting the call signal from the slave unit. At this time, the carrier sense system circuit shown in FIG. 2 receives the frequency corresponding to the control channel in order to confirm the vacancy of the control channel to be used in advance, and extracts the noise component from the received audio signal A into the noise squelch circuit. It is extracted by the band pass filter 1 for noise and converted to a DC level by the rectifier 2 for the noise squelch circuit. Then, the direct current level is compared with a reference value, and the comparator 3 is used as a boundary with the reference value.
H "or" L "is determined and supplied to the carrier detect confirmation output circuit 4. If the value is" H "in the carrier detect confirmation output circuit 4, it is determined that the channel is in use (that is, carrier is present). Is "L"
If so, it is determined that the channel is empty (no carrier), and the determination signal B is output. In addition, after the master unit detects a call signal from the line, it sends an incoming call signal to the slave unit, and the slave unit in the standby state detects the incoming call signal from the master unit and then sends an incoming call response signal to the master unit. Is sent. At this time, the carrier sense system circuit
The same operation is performed when checking the availability of the control channel to be used in advance.

[0004]

However, in the above-mentioned conventional cordless telephone, the emission time of the radio wave of the control channel frequency is within 4 seconds for the master unit and within 1.3 seconds for the slave unit (calling) according to the law. If the control signal is transmitted subsequently to the signal), and the carrier sense level is fixed to a certain fixed value in advance,
When the slave unit sends an outgoing call signal to the master unit after the off-hook operation, and when the standby master unit sends a call response signal to the slave unit after detecting the outgoing call signal from the slave unit, Although the control channel is used, if the noise in the actual use environment corresponds to the frequency of the control channel, the carrier sense circuit system always determines that the channel is in use (carrier is present), and the slave unit, parent There is a problem that wireless connection by the control channel between machines is not made in time.

The present invention solves such a conventional problem, and when the carrier sense system circuits of the master unit and the slave unit confirm the availability of the control channel to be used in advance, before the wireless communication, If the noise in the actual usage environment corresponds to the frequency of the control channel, the microcomputer of the master and slave will continuously set the carrier sense level within the legally stipulated range (+2.0 μV or less). It is an object of the present invention to provide an excellent cordless telephone capable of avoiding a difficulty in connecting a wireless circuit by automatically adjusting to.

[0006]

In order to achieve the above object, the present invention provides a carrier sense system circuit of a master unit and a slave unit according to a DC level converted by a rectifier 2 for a noise squelch circuit. A control device for automatically changing the reference value of the comparator is provided, and the operation of the control device is controlled by the microcomputer, so that the carrier sense level is kept in an optimum state.

[0007]

According to the present invention, therefore, the carrier sense system circuit carries out the transmission of the incoming / outgoing call signal, the incoming / outgoing call response signal, etc. prior to the wireless communication. The sense level is set within the legally stipulated range (+2.0 μV or less), and the microcomputer of the master and slave units has a function to continuously and automatically adjust to avoid the difficulty of connecting wireless circuits. It

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, 1 is a bandpass filter for a noise squelch circuit that receives a received audio signal A, 2 is a rectifier for a noise squelch circuit, 3 is a comparator reference value automatic control device, 4 is a comparator, and 5 is carrier detect confirmation. Is an output circuit for use as a carrier sense circuit. Further, 3 and 5 are RF microcomputers 6.
Its operation is controlled by.

Next, the operation of the above-mentioned conventional example will be described. First, the slave unit sends an outgoing call signal to the master unit after the off-hook operation, and the standby master unit sends a call response signal to the slave unit after detecting the call signal from the slave unit. .. At this time,
The carrier sense system circuit receives the frequency corresponding to the control channel in order to confirm the availability of the control channel to be used in advance, and extracts the noise component from the received audio signal by the noise squelch circuit bandpass filter 1. , The noise squelch circuit rectifier 2 converts to a DC level. At this time, the RF microcomputer 6 compares the DC level input to the comparator reference value automatic control device 3 with the reference value for the comparator 4 to determine "H" or "L". Then, the reference value of the comparator 4 is changed in proportion to the DC level input to the comparator reference value automatic control device 3. As a result, the value detected as "H", that is, the channel is in use (carrier is present) or "L", that is, the channel is vacant (no carrier) is also changed by the carrier detect confirmation output circuit 5. Therefore,
When the noise in the actual use environment corresponds to the frequency of the control channel to be used, the DC level input to the comparator reference value automatic control device 3 increases, so
The RF microcomputer 6 controls the comparator reference value automatic control device 3 so as to set the reference value of the comparator 4 high. As a result, the carrier detect confirmation output circuit 5 discriminates between "H" and "L", and the reference value at the time of outputting the discrimination signal is set to a high value. Is confirmed.

Also, after the base unit detects a calling signal from the line,
The incoming call signal is sent to the child machine, and the child machine in the standby state
After detecting the incoming call signal from the parent device, an incoming call response signal is sent to the parent device. At this time, the same operation is performed also when confirming the vacancy of the control channel used in advance by the carrier sense system circuit.

As described above, according to the above embodiment, the RF microcomputer 6 compares the DC level input to the comparator reference value automatic control device 3 with the reference value of the comparator 4, and the comparator reference value automatic control device 3 is compared. Since the reference value of the comparator 4 corresponding to the input level is set, the value detected as "H" or "L" is also changed by the carrier detect confirmation output circuit 5. Therefore, the master and slave microcomputers set the carrier sense level within the range stipulated by law (+ 2.m) according to the noise input voltage corresponding to the frequency of the control channel in the actual use environment. Since the automatic adjustment is continuously performed at 0 μV or less), there is an effect that wireless connection by the control channel between the child device and the parent and child can be surely performed.

[0013]

As is apparent from the above embodiment, the present invention regulates the carrier sense level according to the received input voltage of the noise corresponding to the frequency of the control channel in the actual use environment. Within range (+ 2.0μV
In the following), the function of continuously and automatically adjusting is provided in the microcomputer of the master unit and the slave unit.Before wireless communication, outgoing and incoming call signals, outgoing and incoming call response signals, etc. are reliably sent. This has the effect of making it possible to avoid difficulty in connecting wireless circuits.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a carrier sense system circuit of a cordless telephone according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a carrier sense system circuit of a conventional cordless telephone.

[Explanation of symbols]

 1 Noise squelch circuit band pass filter 2 Noise squelch circuit rectifier 3 Comparator reference value automatic controller 4 Comparator 5 Carrier detect confirmation output circuit 6 RF microcomputer

Claims (1)

[Claims] 1. A cordless telephone comprising a master unit connected to a central office line and one or more slave units connected to the master unit by a radio circuit, wherein the master unit and the slave unit are connected to each other. In the provided carrier sense system circuit, a bandpass filter for extracting a noise component included in the received voice signal, a rectifier for converting the extracted noise component into a direct current, and a level of a direct current noise component obtained from the rectifier A comparator that generates a binary signal by comparing with a reference value, an output circuit that determines the presence or absence of a carrier according to the binary signal and outputs a determination signal, and the reference value according to the level of the DC noise component. A cordless telephone having a control device for changing the.