JP2510021B2 - Cordless phone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is directed to one master unit connected to a telephone line and a plurality of slave units connected to the master unit by wireless communication lines of different channels. And the main unit,
The present invention relates to a cordless telephone having a configuration in which a plurality of receiving units corresponding to the number of slave units are provided.

(Prior Art) In the current cordless handset cordless handset, only one set of a transmitter and a receiver is incorporated in the radio unit of the parent device. For this reason, if another mobile device transmits at the same time using the same frequency while transmitting and receiving with one slave device with a master device, mutual interference or suppression of weak radio waves may occur. The child machine could not be used at the same time.

Therefore, as a means for solving such a problem, a plurality of radio units of the master unit are built in according to the number of slave units, and transmission and reception are performed on different frequency channels in the frequency bands allocated for transmission and reception. By performing the above, it is possible to consider a system for performing simultaneous wireless communication between a plurality of slave units.

FIG. 3 shows a configuration example of a plurality of receiving sections in such a system. However, in the figure, the case where two receiving units are provided is illustrated as the simplest configuration example.

In the figure, an antenna 1 for transmitting and receiving to and from a plurality of slave units not shown is an antenna for sending a radio wave transmitted from a transmitter not shown to the antenna 1 and a radio wave received from the antenna 1 to a distributor 3. The output of the distributor 3 that is connected to the duplexer 2 and distributes the received radio wave from the antenna duplexer 2 is guided to the band pass filters 4 and 5 of the corresponding receiving units B ₁₁ and B ₂₁ .

The receivers B ₁₁ and B ₂₁ have the same configuration, and the outputs of the bandpass filters 4 and 5 are passed through the RF amplifiers 6 and 7 and the bandpass filters 8 and 9 to one of the first mixers 10 and 20. Led to the input of. The other input of the first mixer 10, 20 has a first
The first local oscillator signal from the local oscillators 11 and 21 is introduced,
The outputs of the first mixers 10 and 20 that create the difference signal between these two inputs are guided to one input of the second mixers 13 and 23 via the first IF bandpass filters 12 and 22. Second mixer 13,23
The second local oscillator signals from the second local oscillators 14 and 24 are introduced to the other input of, and the outputs of the second mixers 13 and 23 that create the difference signal between these two inputs are the second IF bandpass signals. filter
It is guided to the FM demodulators 17, 27 via 15, 25 and the second IF amplifiers 16, 26. The outputs of the FM demodulators 17 and 27 are led to the voice output terminals 18 and 28 for guiding the voice signal to the communication circuit and the data output terminals 19 and 29 for guiding the transmission / reception data to the control unit. Has become.

Next, the operation of the cordless telephone having the above-described multiple receiving section will be described.

Now, suppose that the base unit uses a call channel (for example, a transmission radio wave f _T1 , a reception radio wave f _R1 ) corresponding to a certain one of the slave units, and a transmission unit (not shown) and a reception unit B ₁₁ corresponding to the transmission unit. It is assumed that wireless communication is performed by operating each of them.

In this state, the received radio wave f input to the antenna 1
_{The R1} passes through the antenna duplexer 2 for transmission and reception, and further passes through the distributor 3 to be distributed to the receiving unit B ₁₁ and the receiving unit B ₂₁ .

The received radio wave f _R1 input to the receiving unit B ₁₁ passes through the band pass filter 4 that passes the frequency band allocated for reception, is high-frequency amplified by the RF amplifier 6, and further passes through the band pass filter 8 to generate the first radio wave. Input to the mixer 10. And where it is mixed with first local oscillation signal f _L1 produced by first local oscillator 11, the difference signal f _L1 -f _R1 = f
_1IF is created. Then, the difference signal f _1IF passes through the first IF bandpass filter 12 that passes only the first intermediate frequency (f _1IF ) and is input to the second mixer 13. Then, the second local oscillator signal f generated by the second local oscillator 14 is generated here.
It is mixed with _2L1, the difference signal f _1IF -f _2L1 = f _2IF is created. Then, the difference signal f _2IF passes through the second IF bandpass filter 15 that passes only the second intermediate frequency (f _2IF ) and is input to the second IF amplifier 16. This second IF amplifier
The signal that has been subjected to intermediate frequency amplification in 16 is demodulated in the next FM demodulator 17 and becomes an AF signal. The AF signal is branched into a voice signal and transmission / reception data, and the voice signal is input to the voice output terminal 18 and the transmission / reception data is input to the data output terminal 19.

In such an operating state, there is no problem if the receiving unit B ₂₁ is in the non-operating state or is receiving a channel having no received radio wave.

(Problems to be Solved by the Invention) By the way, when wireless communication is performed between one slave and the transmitter / receiver B _{11 in the} master as described above, when another slave is connected to another slave. , Consider the case where the corresponding call channel (for example, the transmitted radio wave f _T2 , the received radio wave f _R2 ) is used to operate the transmitting unit (not shown) and the corresponding receiving unit B ₂₁ respectively to make a wireless call. . In this case, receiver B
First local oscillation signal f _L2 of the first local oscillator 21 of _21, Dari jump directly to the first local oscillator 11 and the first mixer 10 of the receiver unit B ₁₁ becomes wave leakage to the receive input path, that is, the reception The bandpass filter 4, the RF amplifier 6, and the bandpass filter 8 of the receiving section B ₁₁ are passed through the first mixer 20, the bandpass filter 9, the RF amplifier 7, the bandpass filter 5, and the distributor 3 of the section B ₂₁ . Passes through while dampening 1st mixer 10
An inconvenient situation such as entering to Therefore, the first first the mixer 10, the receiving unit first local oscillation signal f _L1 and the reception section B ₂₁ together with the received radio wave f _R1 of B ₁₁ of the receiving unit B ₁₁
The local signal f _L2 and the received radio wave f _R2 are also mixed, and as a difference signal, f _L1 −f _R1 = f _1IF f _L2 −f _R2 = f _1IF f _L1 −f _R2 = f _IF2 ′ f _L2 −f _R1 = f _IF1 'and the like are generated, and the same first intermediate frequency _f1IF is generated. In other words, even if the receiving section B ₁₁ and the receiving section B ₂₁ have different receiving channels, the same first intermediate frequency is generated, so that depending on the strength of the receiving radio wave, the other receiving radio wave may be received. There is a problem of doing it. This kind of problem occurs when the receiver B _{21
The same} occurs when a wireless call is made with another cordless handset in ₁₁ .

The present invention has been made in view of the above circumstances, and an object of the present invention is to make the first local oscillator signal of an arbitrary receiving unit be the first one of other receiving units.
It is an object of the present invention to provide a cordless telephone in which interference does not occur in the receiving unit even when inputting to the mixing unit.

(Means for Solving the Problems) In order to solve the above problems, a cordless telephone according to the present invention is connected to one master unit connected to a telephone line and a wireless line of a frequency channel different from that of the master unit. A cordless telephone comprising a plurality of slaves, and the master is provided with a plurality of receivers corresponding to the number of slaves. Mixing with the first local oscillator signal of the first local oscillator
A first mixing section for producing a signal of an intermediate frequency, a first intermediate frequency filter for passing the produced signal of the first intermediate frequency, an output of the first intermediate frequency filter and a second station oscillation of a second local oscillator. And a second intermediate frequency filter for passing the generated second intermediate frequency signal, and at least the first mixing section. The first intermediate frequency created in 1) is set so as to be different for each receiving unit. Further, in the above-mentioned configuration, the oscillation frequency of the second local oscillator is further set so as to be a different frequency for each receiving section, and the second intermediate frequency is further made to be a different frequency for each receiving section. It has been set.

(Operation) At least a first mixing section, a first intermediate frequency filter,
A second mixing section and a second intermediate frequency filter are provided, and the first intermediate frequency created by the first mixing section is set to be different for each receiving section. As a result, even if the first local oscillator signal of an arbitrary receiving unit is input to the first mixing unit of another receiving unit, the first intermediate frequency created is different. Only the intermediate frequency is selected and guided to the subsequent signal processing system. Therefore, even if the first station-originated signal of any receiving unit is input, it is possible to prevent radio communication from interfering.

Even if the first intermediate frequency is different for each receiving unit, some leakage signals may flow into the next stage. In that case, the oscillation frequency of the second local oscillator is further set so as to have a different frequency for each receiving section, or the second intermediate frequency is further set so as to have a different frequency for each receiving section. To do. In this way, by setting the oscillation frequency of the second local oscillator and the second intermediate frequency to different frequencies for each receiving unit depending on the degree of the leak signal, the leak signal is greatly attenuated, and the interference of radio communication is further increased. To be prevented.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an electrical configuration of a base unit of a cordless telephone according to the present invention. However, in the present embodiment, a cordless telephone having the simplest configuration, that is, two cordless handsets and a master unit having two corresponding transmitters and receivers will be described.

In the figure, the wired telephone unit connected to the telephone line 38.
36 is bidirectionally connected to the AF section 35 having functions such as a speech path switching section, a filter section, a mute section, and a handset handset section of the parent device, and both the control section 37 for controlling the operation of each section. It is directionally connected. The wired telephone unit 36 is a telephone line
It is a block having functions such as a two-line to four-line conversion unit for transmitting and receiving communication with the 38, an incoming call detection unit, a dialer unit, a holding unit, and a line closing unit. The control unit 37 is a block having functions of a microcomputer unit (including ROM, RAM, I / O, etc.), a control unit for each block, a transmission data unit, a reception data unit, and the like.

The audio output from the AF unit 35 is guided to the transmission section A _1, A ₂ corresponding output of the transmission section A _1, A _2, the antenna 1 via the coupler 30 and duplexer 2 Have been led to.
The transmission units A ₁ and A ₂ are blocks that receive a voice signal transmitted through the telephone line 38 and transmission data from the control unit 37, modulate a carrier wave, and perform high frequency power amplification.

On the other hand, the antenna 1 that receives the signals from the slaves 40 and 41
Is guided to the corresponding receiving units B ₁ and B ₂ via the antenna duplexer 2 and the distributor 3, and the outputs of the receiving units B ₁ and B ₂ are
Guided by the AF unit 35. Further, the control signal from the control unit 37 is guided to the control inputs of the respective transmission units A ₁ and A ₂ and the respective reception units B ₁ and B ₂ , and the transmission data from the control unit 37 corresponds to the respective transmission units. It is guided by A ₁ and A ₂ . In addition, the reception data from each of the reception units B ₁ and B ₂ is guided to the reception data unit of the control unit 37.

In the above configuration, the slaves 40 and 41 and the master 39 can simultaneously perform wireless communication. That is, the handset 40
A radio wave received from the mobile device 41 or the slave device 41 is received by the antenna 1 of the master device 39, is input to the distributor 3 by the antenna duplexer 2 for transmission / reception, and passes through the distributor 3 to correspond to the respective receiving units B ₁ , B ₂
Will be distributed to. The receiving unit B ₁ selectively receives the signal from the slave unit 40, and the receiving unit B ₂ selectively receives the signal from the slave unit 41. Then, the signals respectively demodulated in the receiving units B ₁ and B ₂ are input to the AF unit 35, where the band is limited by the filter unit, muted as necessary by the mute unit, and the call path switching unit. Various communication paths are formed by switching the communication paths. That is, an external call between the handset and the telephone line 38, an extension call between the handset and the base unit, an extension call between the handset units, and an extension call between another handset and the base unit while one handset is an outside line call. A call path such as a three-way call between both handsets and an outside line, and a four-way call including the master unit are appropriately formed.

At this time, in the transmission to the slave unit, the signal input from the AF unit 35 is modulated by the transmission units A ₁ and A ₂ , and the transmission signal is guided to the antenna 1 via the coupler 30 and the antenna duplexer 2, Antenna 1
To send from.

FIG. 2 shows a more specific structure of each of the receivers B ₁ and B ₂ in the cordless telephone having the above structure.

In the figure, 4,5 are bandpass filters, 6 and 7 are RF amplifiers, 8 and 9 are bandpass filters, 10 and 20 are first mixers,
13,23 is a second mixer, 16 and 26 are second IF amplifiers, 18 and 28 are audio output terminals, and 19 and 29 are data output terminals. Since these configurations are the same as the configurations of the conventional circuit described above, Here, the same reference numerals are given and duplicate description is omitted.

Further, 50 and 53 are first local oscillators, 51 is a first IF ₁ bandpass filter, 54 is a first IF ₂ bandpass filter, 52 and 55 are second local oscillators, 56 and 57 are second IF bandpass filters, and 5
Reference numerals 8 and 59 denote FM demodulators, and their configurations are substantially the same as those of the conventional circuit described above, but the oscillation frequency bands of the first local oscillator 50 and the first local oscillator 53 are different,
Also, the first IF ₁ bandpass filter 51 and the first IF ₂ bandpass filter 54 have different pass bands due to the difference in the oscillation frequency band between the first local oscillator 50 and the first local oscillator 53, which is different from the conventional circuit. It has a different configuration. Also,
When the second intermediate frequency is the same, the oscillation frequencies of the second local oscillator 52 and the second local oscillator 55 are different, and when the oscillation frequencies of the second local oscillators 52 and 55 are the same, the second IF bandpass The filter 56 and the second IF bandpass filter 57 have different pass bands, and the corresponding FM demodulators 58 and 59 also have different demodulation frequency bands accordingly, which is different from the conventional circuit.

Next, the operation of the cordless telephone having the above configuration will be described.

Now, it is assumed that the parent device 39 uses the call channel (for example, the transmission radio wave f _T1 , the reception radio wave f _R1 ) corresponding to the one child device 40 to transmit the transmission unit A ₁ and the reception unit B ₁ corresponding thereto. It is assumed that wireless communication is performed by operating the and corresponding to each other.

In this state, the received radio wave f _R1 input to the antenna 1
Is distributed to the receiving section B ₁ through the antenna duplexer 2 and the distributor 3.

The received radio wave f _R1 input to the receiving unit B ₁ passes through the bandpass filter 4 that passes the frequency band allocated for reception, is high-frequency amplified by the RF amplifier 6, and further passes through the bandpass filter 8 to generate the first signal. Input to the mixer 10. And where it is mixed with first local oscillation signal f _L1 made by the first local oscillator 50, the difference signal f _L1 -f _R1 = f
_IF1 is created. Then, the difference signal f _IF1 passes through the first IF ₁ band pass filter 51 that passes only the first intermediate frequency (f _IF1 ) and is input to the second mixer 13. Then, the second local oscillator signal f generated by the second local oscillator 52 is generated here.
It is mixed with _2L1, the difference signal f _IF1 -f _2L1 = f _2IF is created. Then, the difference signal f _2IF passes through the second IF bandpass filter 56 that passes only the second intermediate frequency (f _2IF ) and is input to the second IF amplifier 16. This second IF amplifier
The signal whose intermediate frequency has been amplified in 16 is demodulated in the next FM demodulator 58 and becomes an AF signal. And this AF signal is
The audio signal and the transmission / reception data are branched, and the audio signal is input to the audio output terminal 18 and the transmission / reception data is input to the data output terminal 19. Such operation is performed by the receiving unit B ₂
The same is true for.

In such an operating state, the master device 39 has the call channel (for example, the transmission radio wave f) corresponding to the other one slave device 41.
Consider a case where a transmitter A ₂ and a receiver B ₂ corresponding to the receiver _{T 2} and the received radio wave f _R2 ) are respectively operated to make a wireless call.

In this case, the first local oscillator signal f _L2 of the first local oscillator 53 of the receiver B ₂ becomes a radio wave and jumps directly into the first local oscillator 50 or the first mixer 10 of the receiver B ₁ , or the reception input path. To the receiving section B ₂ , that is, the first mixer 20, the bandpass filter 9, the RF amplifier 7, the bandpass filter 5, and the distributor 3
Attenuating the bandpass filter 4, the RF amplifier 6, and the bandpass filter 8 of the receiving unit B ₁ via the signal passing through and inputting to the first mixer 10. Therefore, receiving unit B in the first mixer 10 of _1, the receiving section B first receiving portion B ₂ together with the first station oscillation signal f _L1 and receiving radio waves f _R1 of ₁
The local signal f _L2 and the received radio wave f _R2 are also mixed, and as a difference signal f _L1 −f _R1 = f _IF1 f _L2 −f _R2 = f _IF2 f _L1 −f _R2 = f _IF3 f _L2 −f _R1 = f _IF4 etc. To occur. However, since all of these first intermediate frequencies have different frequencies and the levels except f _IF1 are small, it is unnecessary by the next first IF ₁ band pass filter 51.
f _IF2 , f _IF3 , and f _IF4 are greatly attenuated and their passage is blocked. In this way, only the signal of the desired channel is
It can be amplified by the 2IF amplifier 16 and demodulated by the FM demodulator 58. Such an operation is the same as when the receiving unit B ₁ makes a wireless call with the child device 40 while the receiving unit B ₂ makes a wireless call with the child device 41.

By the way, as described above, the first local oscillator of the receiver B ₁
By making the transmission frequency bands of 50 and the first local oscillator 53 of the receiving unit B ₂ different frequency bands, unnecessary signals are significantly attenuated in the _first IF ₁ bandpass filter 51 and the first IF ₂ bandpass filter 54. However, some leakage signal is still the second
It is possible that it flows into the mixers 13 and 23.

In this case, the oscillation frequencies of the second local oscillator 52 and the second local oscillator 55 are also set to different frequencies, or the second IF band pass filter 56 and the second IF band pass filter 57 also have different pass bands depending on the case. It may be set to.

That is, the oscillation frequency of the second local oscillator 52 of the receiver B ₁ and f _2L1, the oscillation frequency of the second local oscillator 55 of the receiver B ₂ and f _2L2.

As a result, the first intermediate frequency f _IF1 input to the second mixer 13 through the _first IF ₁ band pass filter 51 and the attenuated other first intermediate frequencies f _IF2 , f _IF3 , f _IF4 are _generated by the second mixer. At 13, the signal is mixed with the second local oscillator f _2L11 from the second local oscillator 52, and as a difference signal, f _IF1 −f _2L1 = f _2IF1 f _IF2 −f _2L1 = f _2IF2 f _IF3 −f _2L1 = f _2IF3 f _IF4 − _Generates f _2L1 = f _2IF4, etc. However, all of these second intermediate frequencies have different frequencies, and f _2IF2 other than f _2IF1 ,
Since the levels of f _2IF3 and f _2IF4 are small, the unnecessary second f / _IF2 , f _2IF3 , and f _2IF4 are further attenuated by the second IF bandpass filter 56, and their passage is blocked. In this way, only the signal of the desired channel is output to the second IF amplifier 1
It can be amplified by 6 and demodulated by the FM demodulator 58. Such an operation is the same as when the receiving unit B ₁ makes a wireless call with the child device 40 while the receiving unit B ₂ makes a wireless call with the child device 41.

(Effect of the invention) A cordless telephone according to the present invention includes at least a first mixture, a first intermediate frequency filter, a second mixing section, and a second intermediate frequency filter, and is produced by the first mixing section. Since the one intermediate frequency is set to a different frequency for each receiving unit, the first local oscillator signal of an arbitrary receiving unit is set to the first frequency of another receiving unit.
Even if input to the mixing unit, the first intermediate frequency is different, so only the first intermediate frequency corresponding to the receiving unit is selected, and interference occurs even when communication with a plurality of slave units is performed at the same time. It has the effect of never happening.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a master unit of a cordless telephone according to the present invention, FIG. 2 is a block diagram showing a more specific configuration of each receiving unit in the cordless telephone, and FIG. It is a block diagram which shows the electric constitution of each receiving part of the conventional cordless telephone with a plurality of cordless handsets. 1 …… antenna 2 …… antenna duplexer 3 …… divider 4,5 …… bandpass filter 6,7 …… RF amplifier 8,9 …… bandpass filter 10,20 …… first mixer 11,21… … First local oscillator 13,23 …… Second mixer 14,24 …… Second local oscillator 15,25 …… Second IF bandpass filter 16,26 …… Second IF amplifier 17,27 …… FM demodulator 50, 53 …… First local oscillator 51 …… First IF ₁ bandpass filter 54 …… First IF ₂ bandpass filter 52,55 …… Second local oscillator 56,57 …… Second IF bandpass filter 58,59 …… FM Demodulator

Claims (3)

(57) [Claims] 1. A master unit connected to a telephone line, and a plurality of slave units connected to the master unit by non-turning lines of different frequency channels. The master unit is a slave unit. A cordless telephone having a configuration in which a plurality of receiving units corresponding to the number of devices are provided, wherein each of the receiving units mixes at least a received radio wave and a first local oscillator signal of a first local oscillator. A first mixing section for producing a signal of an intermediate frequency, a first intermediate frequency filter for passing the produced signal of the first intermediate frequency, an output of the first intermediate frequency filter and a second station oscillation of a second local oscillator. And a second mixing section for mixing the signal with the second intermediate frequency signal to generate a signal of the second intermediate frequency, and a second mixing section for passing the generated signal of the second intermediate frequency.
A cordless telephone, wherein an intermediate frequency filter is provided, and at least a first intermediate frequency created by the first mixing unit is set to a different frequency for each receiving unit. 2. The cordless telephone according to claim 1, wherein the oscillation frequency of the second local oscillator is further set to be different for each receiving section. 3. The second intermediate frequency is further set so as to have a different frequency for each receiving section.
Cordless telephone described in.