JPH09154173A - Cordless telephone set and cordless master-slave telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain transmission-reception where a speech in a slave set and a master set is not disable by selecting a combination of a reception frequency and a transmission frequency not causing beat disturbance among all combinations obtained by plural reception frequencies and plural transmission frequencies. SOLUTION: A high frequency signal received by an antenna 101 of a slave set (a) is separated by a duplexer 102 and given to a mixer 105. The received signal is mixed with a local oscillation signal generated by a local oscillator 104 in the mixer 105, an intermediate frequency signal is obtained, it is amplified by a reception section 106 and detected and demodulated by a detector 107, a voice signal is amplified by an SP amplifier 108 and transduced into sound by a speaker 109. On the other hand, a microphone 110 transduces a voice into a voice signal, a transmission section modulation circuit 115 converts the voice signal into a high frequency signal, amplified by a transmission section RF amplifier 116, and the result is sent from the antenna 101 via the duplexer 102. Furthermore, a control section 111 selects a combination of a transmission frequency and a reception frequency among combinations of plural transmission frequencies and reception frequencies in pairs and designates the selected combination to the local oscillation circuit 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone and a cordless parent-child telephone which communicate by using carrier waves of different frequencies for transmission and reception between the parent and child devices.

[0002]

2. Description of the Related Art In recent years, various studies have been made on a communication control method in the field of analog cordless telephones. Generally, in an analog cordless telephone, a frequency (hereinafter, referred to as “channel”) of a carrier wave (hereinafter, referred to as “carrier”) that can be used for a call is determined in advance depending on a region or the like. For example, in an analog cordless telephone used in North America, the channels that can be used for transmission from the master side to the slave side are in the range of 43 to 47 MHz, and
48 channels can be used for transmission from the slave side to the master side.
In the range of ˜50 MHz, 25 channels are assigned to each.

FIG. 5 shows a list of frequency allocation of channels in the North American region. In the figure, "BASE" is the base unit,
"REMOTE" represents a child device. "CH" is the channel number, "TX
"FREQ" is the transmission frequency, "RX FREQ" is the reception frequency, and "RX
"LOCAL" indicates the local oscillation frequency for reception. For example, in the case of channel 16, the transmission and reception frequencies of the master unit are 46.610 MHz and 49.670 MHz, respectively, and the transmission and reception frequencies of the slave unit are the opposite combinations. Channels 16 to 25 in the figure are channels that have been conventionally used, while channels 1 to 15 are channels newly added in June 1995.

In the communication between the master unit and the slave unit, "TX FREQ" and "RX FREQ" of the same channel in the figure are used. When the transmission frequency of the master unit is 46.730 MHz, the reception frequency is (49.875 MHz).

[0005]

By the way, the above-mentioned conventional parent-child telephone uses the transmission frequency and the reception frequency of the same channel shown in FIG. 5, and uses one channel out of a total of 25 combinations. . Especially channel 1
The 10 channels from 6 to 25 are standardized to use the transmission frequency and the reception frequency of the same channel.

However, the newly added channels 1 to 15 are used in the same channel as before, although it is not necessary to use the same channel.
There is a problem that the transmission frequency and the reception frequency are not effectively used. In view of the above problems, it is an object of the present invention to provide a cordless telephone and a cordless parent-child parent-child telephone which have flexibility in a combination of a transmission frequency and a reception frequency and effectively use a limited frequency.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 is a cordless telephone for performing communication using carrier waves of different frequencies for transmission and reception with respect to a master device, and a plurality of reception devices. Among all combinations obtained from the frequency and the plurality of transmission frequencies, a storage unit that stores a combination that does not cause beat interference and a selection unit that selects the reception frequency and the transmission frequency from the stored combinations are provided. Prepare

A second aspect of the present invention is a cordless parent-slave telephone that performs communication using carrier waves of different frequencies for transmission to the master unit and reception from the master unit, wherein one of the master unit and the slave unit is A reception frequency selecting means for selecting the reception frequency of the own station and a transmission means for transmitting information indicating the selected reception frequency to the partner station, and the other of the master unit and the slave unit has a plurality of reception frequencies. Of all combinations obtained from a plurality of transmission frequencies, storage means for storing a combination that does not cause beat interference, receiving means for receiving the information from the partner station, and the frequency indicated by the received information as the transmission frequency. In this case, the selection means for selecting the reception frequency from the combination stored in the storage means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a block diagram showing the configuration of a cordless telephone handset according to an embodiment. The slave unit includes a duplexer 102 that separates and supplies a high-frequency signal transmitted and received from an antenna 101, a receiver RF amplifier 103 that amplifies the separated high-frequency signal, and a receiver RF amplifier 103.
A local oscillation circuit 104 that generates a local oscillation signal corresponding to a designated reception frequency, and a mixer 1 that mixes the amplified high frequency signal and the local oscillation signal and converts them into an intermediate frequency signal.
05 and the IF IF amplifier 10 for receiving the intermediate frequency signal
6, a detector 107 that detects the amplified intermediate frequency signal and demodulates it into an audio signal, an SP amplifier 108 that amplifies the audio signal, a speaker 109 that converts the amplified audio signal into audio, and a reception frequency. A control unit 111 that specifies a transmission frequency, controls incoming and outgoing calls, and controls the entire child device, a display unit 112, an operation unit 113, a microphone 110 that converts voice into a voice signal, modulates a voice signal, and further designates it. Transmitter modulation circuit 11 for converting into a high frequency signal of the generated transmission frequency
5, and a transmitter RF amplifier 11 that amplifies the high frequency signal
6, a battery 117, a constant voltage circuit 118, and a switch that turns on and off the power supply to the transmitter and the receiver, and wirelessly communicates with the master unit using different reception frequencies and transmission frequencies. Make a call.

The local oscillator circuit 104 and the mixer 105
Consists of two sets of oscillator circuits and a mixer to realize the double superheterodyne system. The control unit 1
The reference numeral 11 further includes a memory 1111 inside which stores a combination of a reception frequency and a transmission frequency. Memory 111
1 stores the combinations that can be used as a pair of the reception frequency and the transmission frequency for channels 1 to 15 shown in “REMOTE” of FIG. 5, and the combinations shown in the same figure for channels 16 to 25. I remember. The control unit 111 selects a transmission frequency and a reception frequency from the pairs stored in the memory 1111 and specifies them to the local oscillation circuit 104.

FIG. 1B is a block diagram showing the configuration of the base unit of the cordless telephone of this embodiment. In FIG. 7B, the hybrid transformer 208 that outputs the voice signal from the detector 207 to the public line and the voice signal from the public line to the transmission section modulation circuit 213, and the smoothing circuit 215 that rectifies the voltage from the AC power source. The configuration other than the control unit 209 includes the same components as in FIG. The description of the same components will be omitted, and different points will be mainly described below.

The hybrid transformer 208 is connected to the public line, and outputs the voice signal from the detector 207 to the public line and outputs the voice signal from the public line to the transmitter modulation circuit 213. The control unit 209 controls the reception frequency and the transmission frequency, controls incoming and outgoing calls, and controls the entire base unit.
11 and the master unit as a whole and has a memory 2091 inside. The memory 2091 stores combinations that can be used as a pair of the reception frequency and the transmission frequency for the channels 1 to 15 shown in "BASE" of FIG. 5, and the channels 16 to 25 shown in FIG. Remember the combination. The control unit 209 selects a transmission frequency and a reception frequency from the pair stored in the memory 2091 and specifies them to the local oscillation circuit 204.

FIG. 2 shows a memory 1111 and a memory 209.
3 is an explanatory diagram showing combinations of transmission frequencies and reception frequencies of channels 1 to 15 stored in FIG. In the figure, 1 to 15 on the vertical axis and the horizontal axis are the channel numbers shown in FIG. The vertical axis represents the transmission frequency of the slave unit, that is, the reception frequency of the master unit, and the horizontal axis represents the reception frequency of the slave unit, that is, the transmission frequency of the master unit. The figure shows 255 combinations of transmission frequencies and reception frequencies in channels 1 to 15.

The column marked with X in the figure indicates that beat interference may occur when the combination of the transmission frequency and the reception frequency is used. Here, the beat interference refers to a phenomenon in which high-frequency components of a plurality of electromagnetic waves generated inside the slave or master interfere with each other, and the difference between them appears in the audio signal as noise. Whether or not there is a possibility of beat disturbance is the result of judgment based on whether or not the value on the right side and the value on the left side in the following equation are almost equal (in this equation, it means that = is almost equal). Rxf = | Txf · M / 16-10.24 · N | where Rxf is a reception frequency, Txf is a transmission frequency, and Mx is
Is a multiple of the harmonic of the transmission frequency, 1/16 is an internal frequency division number in the local oscillation circuits 104 and 204, 10.24 is a second local oscillation frequency at the time of reception, and N is a multiple of the second local oscillation frequency. . Therefore, since the right side represents the harmonic component of the transmission frequency, if this value is close to the value on the left side, it means that beat interference may occur.

For example, in the master unit, M = 18, N = 0,
In the case of Txf = 43.74 MHz (channel 2), the above equation is as follows. Rxf = | 43.74 · 18 / 16-10.24 · 0 |
= 49.2075MHz This formula means that when Rxf is channel 9 (49.200MHz), it suffers a beat disturbance of 0.0075MHz (7.5kHz). In other words, combining the channel 2 Txf and the channel 9 Rxf in the parent device may cause beat interference.

FIG. 2 shows a calculation result using the orders of M and N in which harmonic components are likely to occur. That is, when N = 1 to 20 is combined with M = 1 to 20,
= 1 to 20, 32, 48, 64, 80, 96, 112,
N = 1 to 1 for each of 128, 144, and 160
The calculation result when 0 is combined is described. The combination of channels obtained by such calculation is shown in FIG.
This is the column marked with x. In the above calculation, since relatively high-order harmonic components are calculated, the possibility of beat interference is mixed from high to low, so beat interference may occur in actual slave units and master units. It also includes combinations that do not occur.

FIG. 3 shows the result of an experiment on whether or not beat interference occurs in the actual slave unit and master unit. In the experiment,
It is determined that a normal call cannot be made at a distance of 200 m. As shown in the figure, 2
The 07 combinations were found to be usable. The reason why the x mark is smaller than that in FIG. 2 is mainly due to the following reason. (1) In Fig. 2, since higher harmonics (M and N are large) are taken into consideration, combinations that have a low possibility of beat interference should be included. (2) Depending on the wiring pattern shape of the circuit board, harmonic components may or may not be generated. (3) Depending on the proximity of the receiving system wiring pattern and the wiring pattern that generates harmonic components, beat interference may or may not occur.

Therefore, in the actual machine, the combinations other than the X mark can be used without any problem in the experimental result as shown in FIG. Further, when the experimental result cannot be obtained, it is desirable to avoid the combination of X marks in FIG. In this embodiment, the memory 1111 of the child device and the memory 2091 of the parent device are
Memorize combinations other than the cross mark.

The operation of the parent-child telephone of this embodiment configured as described above will be described. FIG. 4 is a flowchart showing a process in which the reception frequency and the transmission frequency are selected by the control unit 111 and the control unit 209 at the start of an incoming / outgoing call. The left side of the figure shows the process when the slave unit makes a call, and the right side shows the process when the base unit accepts the call from the slave unit.

When the user wants to initiate a call by off-hook or the like in the slave unit, the control unit 111 randomly selects the reception frequency (step 10).
0). Regarding the transmission frequency, the control unit 111 holds, for example, information indicating the transmission frequency used in the last call in an internal register (not shown) as the current transmission frequency. The control unit 111 determines whether or not the selected pair of the reception frequency and the transmission frequency is stored in the memory 1111. If the pair is not stored (step 101: n
o) If the reception frequency is randomly selected again and stored (step 101: yes), whether the reception frequency is used by another telephone or the like in the vicinity by further measuring the reception field strength of the reception frequency. To determine.

As a result of the judgment, when it is judged that the frequency is being used (step 102: yes), the receiving frequency is randomly selected again, and when it is judged that the frequency is not being used (step 102: no), it is selected. Information indicating the reception frequency is transmitted to the parent device at the transmission frequency (step 103).
Specifically, when it is determined that the frequency is not being used, the control unit 111 specifies the transmission frequency of the carrier by specifying the local oscillation frequency corresponding to the transmission frequency in the local oscillation circuit 104, and the reception frequency information is specified. The frequency is modulated by the wave detector 107, and the reception frequency information is transmitted to the master unit via the reception unit IF amplifier 106, the mixer 105, the reception unit RF amplifier 103, and the duplexer 102.

After transmitting the reception frequency information, the control unit 111
Waits for a response from the master unit at the selected reception frequency. Specifically, the reception frequency of the carrier wave is specified by specifying the local oscillation frequency corresponding to the reception frequency in the local oscillation circuit 104, and the antenna 101 and the transmission unit RF amplifier 1 are specified.
16. The presence / absence of a response is constantly sensed via the transmitter modulation circuit 115 (step 104).

On the other hand, the control unit 209 of the master unit holds information indicating the previous transmission frequency of the master unit in an internal register (not shown), and senses the reception frequency of the master unit constantly or intermittently. doing. When receiving the reception frequency information from the slave unit (step 200), the control unit 209 updates the transmission frequency of the internal register to the frequency indicated by the received reception frequency information (step 201).

Further, the control unit 209 randomly selects a reception frequency and determines whether or not the pair of the selected reception frequency and the updated transmission frequency is stored in the memory 2091. If not stored (step 2
(03: no) When the reception frequency is randomly selected again and stored (step 203: yes), it is used by other telephones in the vicinity by further measuring the reception electric field strength of the reception frequency. It is determined whether or not there is.

If it is determined that the frequency is being used (step 204: yes), the reception frequency is randomly selected again,
When it is determined that it is not used (step 204:
No), information indicating the selected reception frequency is transmitted to the slave unit at the updated transmission frequency (step 205). In the slave unit, when the reception frequency information from the master unit is received as a response (step 104), the control unit 111 updates the frequency indicated by the reception frequency information in the internal register and causes the local oscillation circuit 104 to transmit the transmission frequency. Specify the local oscillation frequency corresponding to.

After that, the control unit 111 of the child device and the control unit 209 of the parent device respectively perform call control such as transmission of dial numbers, control of telephone conversation, and call termination according to the usual procedure. In this way, the control unit 111 of the slave unit selects the reception frequency and the transmission frequency that have no possibility of beat interference. In the above description of the operation, the slave unit is described as the calling side. However, the process of selecting the transmission frequency and the reception frequency when the master unit receives a call from the public line and further calls the slave unit will be described in the flow of FIG. The left side is the master unit, the right side is the slave unit processing,
Exactly the same.

As described above, according to the parent-child telephone in this embodiment, the transmission and reception frequencies that can be actually used are selected from a large number of combinations of transmission frequencies and reception frequencies stored in the memory 1111. Therefore, the selection range is greatly expanded, and the frequency selection can be performed more flexibly. Specifically, in this embodiment, the conventional 2
The selection range is greatly expanded from 5 ways to 217 ways. For example, if any of the conventional 25 combinations has a poor reception state in one of the slave unit and the master unit, the call becomes impossible. However, according to the master-slave telephone of the present embodiment, the reception is performed in each of the slave unit and the master unit. There is an effect that a frequency with a good condition can be selected.

In addition, a more appropriate frequency combination can be selected by excluding a combination having a possibility of beat interference from the memory. In addition, it is possible to use a larger number of combinations by excluding combinations that are theoretically unsuitable for use in actual slave units and master units, rather than theoretically possible beat interference.

In the above embodiment, the reception frequency information transmitted between the child device and the parent and child may be the channel number itself shown in FIG. In that case, memory 1
Reference numeral 111 stores the channel number shown in FIG. 5 and the transmission frequency Txf and reception frequency Rxf of the slave unit in association with each other, and the memory 2091 stores the channel number shown in FIG. The control unit 111 and the control unit 209 may refer to the memory 1111 and the memory 2091 to specify the frequency from the channel number.

Further, the memory 1111 and the memory 20.
The combinations of usable transmission frequencies and reception frequencies stored in 91 may also store the channel number of the transmission frequency and the channel number of the reception frequency as a pair. Also in this case, the content of FIG. 5 may be set aside as described above.

[0031]

According to the invention of claim 1, the actually usable transmission and reception frequencies are selected from a large number of combinations of the transmission frequencies and the reception frequencies stored in the storage means. The frequency can be greatly expanded, and the frequency selection by the selection unit can be performed more flexibly. Specifically, since the reception frequency and the transmission frequency do not have a one-to-one correspondence, the selection range is greatly expanded. For example, if any one of the combinations corresponding to one-to-one is in a poor reception state in one of the slave unit and the master unit, the call becomes impossible. However, according to the master-slave telephone of the present embodiment, the slave unit and the master unit are Since there are combinations of frequencies with good reception conditions in each case, there is an effect that the frequencies can be flexibly selected so that the call cannot be disabled and the frequencies can be effectively used.

In addition, since the storage means excludes combinations that may cause beat interference, it is possible to select a more appropriate frequency combination. In addition, it is possible to use a larger number of combinations by excluding combinations that are theoretically unsuitable for use in actual slave units and master units, rather than theoretically possible beat interference.

According to the invention of claim 2, there is the same effect as that of claim 1.

[Brief description of the drawings]

FIG. 1A is a block diagram showing a configuration of a cordless telephone handset according to an embodiment. (B) It is a block diagram which shows the structure of the main | base station of the cordless telephone of the same embodiment.

FIG. 2 is an explanatory diagram showing combinations of transmission frequencies and reception frequencies of channels 1 to 15 stored in a memory 1111 and a memory 2091.

FIG. 3 shows a result of an experiment on whether or not beat interference occurs in an actual slave unit and a master unit.

FIG. 4 is a flowchart showing a process in which a reception frequency and a transmission frequency are selected by the control unit 111 and the control unit 209 at the start of an incoming / outgoing call.

FIG. 5 shows a list of channel frequency allocations in the North American region.

[Explanation of symbols]

 103 receiver RF amplifier 104 local oscillator circuit 105 mixer 106 receiver IF amplifier 107 detector 108 SP amplifier 109 speaker 110 microphone 111 control unit 1111 memory 112 display unit 113 operation unit 115 transmitter modulation circuit 116 transmitter RF amplifier 117 battery 118 constant voltage circuit 204 local oscillation circuit 207 detector 208 hybrid transformer 209 control unit 2091 memory 213 transmission unit modulation circuit 215 smoothing circuit 2901 memory

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Inozaki 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A cordless telephone that performs communication using carrier waves having different frequencies for transmission and reception with respect to a master unit, wherein beat interference among all combinations obtained from a plurality of reception frequencies and a plurality of transmission frequencies. A cordless telephone, comprising: a storage unit that stores a combination that does not generate a noise, and a selection unit that selects a reception frequency and a transmission frequency from the stored combinations. 2. A cordless master-slave telephone that performs communication using carrier waves of different frequencies for transmission to the master unit and reception from the master unit, wherein one of the master unit and the slave unit is the reception of its own station. The reception frequency selection means for selecting a frequency and the transmission means for transmitting information indicating the selected reception frequency to the partner station are provided, and the other of the master unit and the slave unit has a plurality of reception frequencies and a plurality of transmission frequencies. Of all the combinations obtained from, the storage means for storing the combination that does not cause beat interference, the receiving means for receiving the information from the partner station, and the storage when the frequency indicated by the received information is the transmission frequency A cordless parent-child telephone, comprising: selecting means for selecting a reception frequency from a combination stored in the means.