JPS60194841A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To prevent easily and surely radio interference with simple constitution by switching sequentially automatically a reception frequency to obtain an idle channel and exchanging the information between a master set and slave sets to fix a transmission and a reception frequency. CONSTITUTION:When an incoming call comes to a line T of the master set 1, it is detected by a CPU3, an incorporated programmable frequency divider is driven and the reception frequency is set to the 1st channel fR1. When the slave set 2 uses the fR1, it is received through an antenna 9 and no noise is detected. The CPU3 switches the reception frequency until noise is detected. When a channel fRn is detected to be an idle channel, this is stored and fixed. The transmission frequency is set to the 1st channel fT1 and the idle channel fRn is informed from the antenna 9 by a guard tone. The slave set 2 in standby on the 1st channel fT1 detects the fRn by using the reception 8 and the master set and the slave set start correspondence by using the fRn and fTn. The idle channel is obtained similarly when the slave set 2 makes a call to prevent radio interference.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention uses two radio waves of different frequencies,
The present invention relates to a cordless telephone device that is used for making and receiving calls, respectively.

Conventional configurations and their problems Cordless telephone devices are generally configured to send and receive signals between the base unit and handset using radio waves, so when multiple units are installed in close proximity, They very often interfere with each other.

Therefore, when multiple devices are used at the same time in close proximity to each other, different channels are used for each device. However, even in this case, it is impossible to determine whether the channel is free or not until it is actually used, and there is a problem in that interference occurs at least initially.

OBJECTS OF THE INVENTION The present invention is intended to eliminate the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide an excellent cordless telephone device that can automatically select an available channel and avoid interference. This is the purpose.

Structure of the Invention The present invention automatically switches reception frequencies in sequence to automatically search for an empty channel, and when an empty channel is detected, the information is transmitted to the base unit.

Exchange between slave units, and automatically switch between base units and base units based on that information.
The transmitting frequency and receiving frequency of the handset are fixed to the transmitting frequency and receiving frequency of the vacant channel, respectively.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a basic configuration diagram of an embodiment of the cordless telephone device of the present invention. In the figure, ▪ is a base unit connected to line T, and 2 is a slave unit. And 3゜4 are the base unit 1.
A controller 5, 6 is a transmitter, 7, 8 is a receiver, and 9.10 is an antenna. Receiving units 7 and 8 are respectively on the base unit 1 side,
Both handset 2 sides are constructed in the same way, and if the base unit 1 side is illustrated now, it is as shown in FIG.

In Fig. 2, 11 and 12 are the input sides, respectively.

a high frequency amplifier circuit whose output side is connected to the antenna 9;

13 is a frequency mixing circuit whose input is the output of the high frequency amplifier circuit 11; 14 is an intermediate frequency amplifier circuit; 15 is a detection circuit;
16 is a noise detection circuit, 17 is a guard tone detection circuit,
18 and 19 are reference oscillation circuits, 20 and 21 are frequency dividers that divide the outputs of the reference oscillation circuits 18 and 19, respectively;
22 and 23 are respective voltage controlled oscillation circuits, 24.25
is a frequency divider that divides the output of the voltage controlled oscillation circuits 22 and 23.

26 and 27 are respective programmable frequency dividers.

28, 29 are phase comparators that compare the outputs of the branchers 26, 27, 20, and 21, respectively; 30. '31 is a low-pass filter, and 32 is a guard tone generator.

In the above embodiment, it is assumed that there is an incoming call on line T now. When there is an incoming call on line T, this is detected by the control unit 3,
By the action of the control unit 3, the programmable frequency divider 26 is first driven, and the receiving frequency f is set to the receiving frequency fil of the first channel. Therefore, if the handset 2 is using the first channel in this state, the signal will not be received through the antenna 9, and no output will appear at the output terminal of the noise detection circuit 16. If no output appears at the output terminal of the noise detection circuit 16,
This is detected by the control unit 3 and operates to set the receiving frequency fR to the receiving frequency fR2 of the next channel.

If that channel is also in use, the receiving frequency fR is sequentially changed to the receiving frequency f of the next channel in the same manner.
Switch to ns+fR4...fnn.

Assume now that the first channel is an empty channel. In this case, even if the reception frequency 9 is set to fnn, no signal is input from the antenna 9, so a noise component larger than that of the noise detection circuit 16 appears. Therefore, this is detected by the control section 3, and the control section 3 itself stores the reception frequency fnn. And the reception frequency f
R is fixed at the reception frequency fRn, and in this state, the program frequency divider 27 is driven to set the reception frequency 17 to the oscillation frequency ft + of the first channel. At the same time, the guard 1-tone generator 32 is driven, and the generator 32 outputs data indicating how many empty channels there are.

FIG. 3 is a waveform diagram of data outputted from the guard tone generator 32. The data is weighted as bits by the 5 KHz guard tone, and is output as encoded data. ing. and,
As shown in FIG. 4(a), the first 4 bits represent information about which channel it is. Therefore, when representing the first channel, the third channel, and the sixth channel, FIGS. 4(b), (c), and d
) is output.

In this way, when the transmission frequency f is set to the first channel and the guard tone generator 32 outputs data indicating how many free channels there are, this is transmitted to the handset 2 via the antenna 9. transmitted to.

On the handset 2 side, the reception frequency during standby is always set to the reception frequency fT of the first channel (the transmission frequency of the first channel on the base unit L side), so the above data is received from the base unit L side. When this is transmitted, it is received by the receiving unit 8 on the side of the handset 2. When the above-mentioned data is received by the receiving section 8 on the handset 2 side and the above-mentioned data is outputted from the guard tone detection circuit of the handset 2, the control section detects this and
The transmission frequency fR+reception frequency fT on the side is set to the transmission frequency fnn and reception frequency frn of the n-th channel, which is an empty channel, respectively, based on the above data.

Then, the guard tone generator is driven and the base unit 1 is activated.
On the side, the transmitting frequency fn and receiving frequency fT of handset 2 are the transmitting frequency fnn of the empty channel, and the wave number fT for nn, respectively.
7+ (that is, the communication channel has been set).

When the data is transmitted from the handset 2, it is received by the receiver 7 on the base unit 1, and the guard tone detection circuit 17 on the base unit 1 outputs the data. therefore,
This drives the control unit 3, and the transmission frequency fT that has been set for the first channel is replaced by the frequency frn of the n-th channel, which is an empty channel. Therefore, in this state, the main unit 1. The transmission frequency fT (fR for handset 2) and reception frequency fR (fT for handset 2) of both handsets 2 and 2 are set to the n-th channel, which is an empty channel. Machine 2 allows you to talk to other parties.

Note that when the call ends and transmission is stopped on the handset 2 side, no signal is input to the receiver on the base unit 1 side, and large noises are input to the noise detection circuit 16 on the base unit 1 side. ingredients appear. Therefore, this causes the control unit 3 to
Return the side to its original state.

That is, in this state, base unit 1. The receiving frequency of both handsets 2 is switched to the first channel, and the handset 2 enters a so-called standby state.

Next, the case where the handset 2 side makes a call will be explained. If the call is made from handset 2, handset 2. The operation is the same as when a call is received on line T with base unit 1 being replaced by a base unit and a slave unit, respectively.

That is, in this case, the handset 2 side searches for an empty channel, and if an empty channel is found, it is transmitted to the base unit l, and the transmitting frequency and receiving frequency of the base unit 1 are set to the above-mentioned vacant channel. to switch to. When the switching is completed, the master unit 1 and the slave unit 2 are notified of this fact, and are operated to switch the transmitting frequency and receiving frequency of the slave units to the vacant channels, respectively.

Effects of the Invention As is clear from the embodiments, the cordless telephone device of the present invention is configured to automatically search for an empty channel, and when an empty channel is found, automatically tune to that channel. Therefore, there is an advantage that a channel in use is almost never erroneously selected, and interference can be easily and reliably prevented. Furthermore, the present invention has a very simple structure as a whole, which is extremely advantageous in practice.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of one embodiment of the cordless telephone device of the present invention, FIG. 2 is a schematic diagram of the main part of a main unit constituting the same embodiment, and FIGS. 3 and 4 are both the same embodiment. FIG. 3 is an output waveform diagram of a guard tone generation circuit that constitutes the circuit. 1... Master unit, 2... Child unit, 3, 4... Control unit, 5, 6
... Transmitter section, 7, 8... Receiving section, 9.10... Antenna, 11.12... High frequency amplification circuit, 13... Frequency mixing circuit, 14... Intermediate frequency amplification circuit, 15...・Detection circuit, 16... Noise detection circuit, 17... Guard tone detection circuit, 1'8.19... Reference oscillation circuit, 2
0,21゜24.25...Frequency divider, 22.23...Voltage controlled oscillator, 26.27...Programmable frequency divider, 28゜29...Phase comparison circuit, 30.31 Low-pass filter, 32 ...Guard tone generation circuit.

Claims (1)

[Claims] Each of the base unit and slave unit has an empty channel detecting means such as a noise detection circuit, a receiving unit having a guard tone detecting means, etc., a transmitting unit having a guard tone generating means, etc., the transmitting frequency of the transmitting unit, and the receiving unit, and the reception A switching means for switching the frequency is provided, and when an empty channel is detected by the empty channel detecting means, the guard tone generating means outputs the empty channel information, and the output of the guard tone detecting means causes the transmitting section and the receiving section to transmit. A cordless telephone device configured to automatically switch and set a reception frequency to the frequency of the empty channel.