JPH0774803A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To select an installation place when radio wave interference can be evaded by previously selecting the installation place by providing a lamp which indicates the radio wave interference. CONSTITUTION:In the receiving circuit 120 of a slave equipment, a detecting circuit 126 supplies a signal CDET indicating whether or not there is an intermediate frequency signal Si to a CPU 140. When it is judged from the signal CDET that there is a carrier, the CPU 140 performs a terminating process on condition that its ID is detected. When its ID is not detected, the disturbing wave presence lamp 133 illuminates and a 4-second timer starts counting. When the carrier presence state exceeds four seconds, it is judged that a down control channel can not be used. Further, when there is not carrier or when a carrier continues within four seconds even if it is present, the master equipment is called from the slave equipment. When there is no answer from the master equipment, it is judged that there is the disturbing radio wave on an up control channel. Then the disturbing radio wave presence lamp 133 continues to illuminate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MCA type cordless telephone.

[0002]

2. Description of the Related Art For example, an MCA (multi-access system) cordless telephone using a low electric power radio wave has 87 communication channels and 2 control channels. These are composed of a master unit that connects to a telephone line and a movable slave unit.
Radio waves in the MHz band are transmitted, and radio waves in the 380 MHz band are transmitted from the handset to enable simultaneous uplink and downlink calls.

That is, the base unit receives the 380 MHz band,
The slave unit is receiving the 250 MHz band. Each frequency in these frequency bands is regulated by the technical standards established by the Ministry of Posts and Telecommunications.

FIG. 4 shows an example of such a cordless telephone. A handset type handset indicated by reference numeral 1 has a transmitting circuit (TX) 110 and a receiving circuit (RX) 120, and the transmitting circuit 110 starts from a microphone 111. The voice St and the command signal CMND are converted into the FM signal Su of the upstream channel and transmitted from the antenna 100. The receiving circuit 120 receives the FM signal Sd of the downlink channel, outputs the audio signal Sr from the speaker 121, and demodulates the command signal CMND. Then, the operating state is displayed by the lamp 133.

Further, the dial key 131 and the call key 13
2, the call key 132 is a non-lock type push switch, and each time the key 132 is pressed, the handset 1 switches between the standby mode and the call mode alternately. In the standby mode, the receiving circuit 120 is in the receiving state on the control channel. Further, it has a speaker 139 for calling, an oscillator 138 for outputting a ringing sound to the speaker 139, and a CPU 140 for controlling a slave unit. The CPU 140 allows / prohibits transmission, and a control signal for controlling a channel for transmitting / receiving wireless communication. TCTL and RCTL are also generated.

In FIG. 4, reference numeral 2 is a master unit, 3 is a telephone line, 21 is a radio unit (RF unit) in the master unit 2, and a transmitter circuit (TX) 210 and a receiver circuit (TX) to the slave unit 1 ( RX) 220. The receiving circuit 220 of the wireless unit 21 also stands by on the upstream control channel during standby. Reference numeral 23 is a telephone line interface circuit, and 24 is a master unit control CPU.

The interface circuit 23 includes a 4-wire / 2-wire conversion circuit (4/2) 231, a switch circuit 232 corresponding to a hook switch of a general telephone, a DTMF transmitter 233 for PB dial, and a bell signal detection circuit. 234
And so on. The master unit control CPU 24 is a slave unit control CP
While performing the same processing as U140, it also manages the operation of the cordless telephone as a whole, such as the usage statuses of the slave 1, the wireless channel, the wireless unit 21, and the telephone line 3.

[0008]

However, since this device uses a limited frequency, normal communication cannot be performed when an interfering radio wave of the same frequency as the corresponding frequency or noise is generated around the cordless telephone. There is. Especially, since there are only two control channels, this frequency,
In other words, if there is an interfering radio wave of a frequency corresponding to a total of four channels of two channels in the 380 MHz band and two channels in the 250 MHz band or noise is generated in the vicinity, the link of the control channel cannot be established, and thus communication is started. Was difficult. In recent years, the radio wave environment has been deteriorating and it is becoming difficult to escape interference. In such a case, it is not possible to make a call by making a call, so that it is known that the control channel is disturbed.

Therefore, the present invention is to provide a means for selecting the installation place when the interference can be escaped by preselecting the installation place even when there is the interference.

[0010]

In order to solve such a problem, the present invention provides a monitor for monitoring whether or not an interfering radio wave has continued for a predetermined time in a downlink control channel of a slave unit. Means (steps 101 and 115 in FIG. 2), communication means (steps 102 and 103 in FIG. 2) for communicating the control channel of the master unit to the slave unit when the master unit is normal, and the monitoring unit if there is no interference radio wave. A device provided with a display means (step 120) indicating that the child device is available when it is judged and when the communication means notifies that the control channel in the parent device is normally available (steps 118 and 119). Is.

[0011]

When the control channel of the slave is not disturbed, the control channel is used to call the master. If there is no interference in the control channel of the master unit, it can be normally received, and therefore by notifying the slave unit of that fact, it is possible to know that the control channel is normal in both up and down directions.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a receiver circuit 12 of a child device to which the present invention is applied.
0, the FM signal Sd of the downlink channel is received by the antenna 100 and supplied to the tuner circuit 126. The tuner circuit 126 is configured by a double super heterodyne system having a high frequency amplifier to a second mixer circuit, and its reception channel is a slave unit CP.
Controlled by the control signal RCTL from U140, the FM signal Sd of the channel according to this signal RCTL is converted into the second intermediate frequency signal Si and taken out.

Then, this signal Si is supplied to the FM demodulation circuit 123 through the second intermediate frequency amplifier 122, and the voice signal Sr or the command CMND is taken out. Then, the audio signal Sr is transmitted to the speaker 12 through the amplifier 124.
1 and the command signal CMND is supplied to the shaping circuit 125.
Is supplied to the child device CPU 140 via the.

Further, the intermediate frequency signal Si from the amplifier 122
Of the signal S and the signal Si is supplied to the detection circuit 126. For example, the signal S is obtained by performing AM detection and shaping.
The signal CDET indicating the presence / absence of i is taken out, and this signal C
The DET is supplied to the child device CPU 140. The signal C
Since DET is a signal indicating the presence or absence of the signal Si, it is also a signal indicating whether or not there is the FM signal Sd in the downlink channel designated by the control signal RCTL, and therefore the control signal RCT.
It is also a signal indicating whether the control channel or call channel designated by L is an idle channel.

Next, FIG. 2 shows a flowchart for detecting jamming of the control channel. First, as shown in step 100, the slave unit 1 is, for example, a downlink control channel 46 (380.775) at a position within a range where radio waves can reach the master unit sufficiently.
MHz). When the carrier detection CDET determines that there is a carrier in step 101, first, in step 107, it is checked whether or not there is a self ID.

If there is no self ID, as shown in step 108, the lamp with interference wave 133 (FIG. 1) is turned on to notify the operator that the transmission operation cannot be performed, and in step 109, the 4-second timer starts counting. . next,
When it is determined by the carrier detection CDET that the state with carrier exceeds 4 seconds, it is recorded in step 105 that the control channel 46CH cannot be used. Also,
If there is no carrier detection CDET, or if there is a carrier and it is within 4 seconds, as shown in step 102, the call response is confirmed from the slave unit 1 to the master unit 2 at 46CH.

If there is no response from the master unit in step 103, as shown in step 106, it is judged that there is an interfering radio wave in the upstream control channel 46CH (252.425 MHz), and the master unit 46CH cannot be used. Record that. When it is recorded in step 105 that the child device 46CH cannot be used, when it is recorded in step 106 that the parent device 46CH cannot be used, and when it is determined in step 103 that there is a response from the parent device , After that, 8 with the cordless handset in step 104
9CH is transmitted.

Then, after step 104, another control channel 89CH (downlink 381.3125
MHz, upstream 254.9625 MHz) 46C
As with H, interference detection is performed. Since this processing is the same as the above-mentioned processing, description thereof will be omitted. Finally, in step 118, the detection result is analyzed. The results of all combinations of detections are shown in FIG.

In FIG. 3, since there is one set of control channels that can be used for items 1 to 5, communication can be started. In this case, since communication is determined to be possible in step 119, as shown in step 120, the lamp 133 with jamming radio waves is turned off. If any of the items 6 to 8 results, communication cannot be performed, and thus the lamp with jamming radio wave 133 is continuously lit as shown in step 125.

After the detection process of such an interference wave is performed, as shown in step 121, the communication process between the parent and child is performed, and then, as shown in step 126, the pause timer for 4 seconds, for example, is paused as a star. . When the sleep timer expires, the above process is started again. The battery life can be extended by performing the intermittent operation in this way. When the self ID is detected in steps 107 and 130, the incoming call processing shown in step 135 is performed.

Although two control channels are monitored in this example, the present invention can be applied to a cordless telephone that uses only one control channel. Then, when the lamp 133 with an interfering radio wave is turned on, the child device or the parent device is moved to search for a place where the lamp goes off, so that the call can be made there.

[0022]

As described above, according to the present invention, since the lamp indicating that it cannot be used is turned on when there is radio interference in the control channel of the slave unit or the master unit, communication is required unless it is used. It is possible to eliminate the waste of whether or not it is possible, and even when the lamp is lit, it is possible to talk by searching for a place where the lamp is turned off by moving the master unit or the slave unit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a receiver to which the present invention has been applied.

FIG. 2 is a flow chart for explaining the operation of the present invention.

FIG. 3 is a diagram showing a detection result.

FIG. 4 is a block diagram showing an example of a conventional device.

[Explanation of symbols]

 1 Handset 110, 210 Transmission circuit (TX) 120, 220 Reception circuit (RX) 2 Base unit 3 Telephone line

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location 7304-5K H04B 7/26 113 Z

Claims (2)

[Claims] 1. In a cordless telephone composed of a master unit and a slave unit, each of which waits on a control channel, whether or not an interfering radio wave has continued for a predetermined time on a downlink control channel of the slave unit. Monitoring means for monitoring whether or not the control channel of the master unit is normal, and communication means for communicating it to the slave unit, and the monitoring means determines that there is no jamming radio wave and controls the master unit by the communication means. A cordless telephone characterized by comprising display means for displaying that the handset is available when it is notified that the channel is normally available. 2. The control device according to claim 1, wherein when the slave unit does not receive an interfering radio wave on the control channel, the slave unit transmits on the uplink control channel, and when the master unit receives the interference wave normally, the control channel of the master unit is normal. A cordless telephone characterized by determining that