JPH02150129A - Cordless telephone system - Google Patents

Abstract

PURPOSE:To eliminate harmful interference between sets and the disturbance of privacy by guiding and deciding the frequencies of carriers to be used in a fixed machine and a portable machine from proper identification codes set at every cordless telephone system. CONSTITUTION:The frequencies of carriers to be used in the fixed machine and the portable machine are guided and decided from the identification codes proper to each cordless telephone system. Since all the identification codes at each cordless telephone system differ from each other, for example, frequency synthesizers 6 and 9 by PLL(Phase locked loop) are used to generate the carriers of the fixed machine and the portable machine. and by guiding and deciding the frequency division ratio of a digital frequency divider 15 from the the identification codes, the frequency of the carrier can be set differently from each other at each cordless telephone system. In such a way, even when an area where the carriers of the fixed machines of two sets of cordless telephone systems are superimposed occurs, the speech of the set on another side can be prevented from being heard by the set on one side in that area, which eliminates the harmful interference and the disturbance of the privacy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cordless telephone device that uses weak radio waves.

[Prior Art] Cordless telephone devices include a fixed unit that is connected to a telephone line (hereinafter referred to as a base unit), and a portable unit that can be freely moved over a range (hereinafter referred to as a slave unit). Among them, a weak radio wave type that combines so-called weak radio waves is recognized, and it is becoming widespread because it is cheaper than the other method, the low power type.

In a cordless telephone device, for example, the operation of a handset unit will be explained based on a highly simplified configuration diagram as shown in FIG. 4, which is an example of the configuration of a cordless telephone device. The carrier wave fI is mixed with the oscillation wave f, I from the local oscillator 52, and the carrier wave f,
and oscillation wave f.

After being converted to an IF (intermediate frequency) with a difference frequency of
The audio signal is output from the speaker 54. In addition to voice, the carrier wave f contains an identification code unique to this cordless telephone device (hereinafter referred to as an ID code) and other digital signals, which are input into the microcomputer 55 after demodulation. , the necessary processing is added. Incidentally, the microcomputer 55 is connected to an ID code storage means (hereinafter referred to as ID-ROM) 56 that stores the above-mentioned unique ID code.

On the other hand, when audio is input through the microphone 57, the audio signal is inputted from the carrier wave oscillator 59 and modulated by the carrier wave f2 of the slave unit in the modulator 58. Also, this carrier wave f
2 is the microcomputer 5 from the ID-ROM 56.
The antenna 51 is also modulated by the ID code and other digital signals applied via the antenna 51.
The message is sent to the base unit.

The base unit basically has the same configuration as the slave unit, and when it receives the carrier wave f2 from the slave unit, it performs the same processing as the slave unit, and outputs the demodulated audio signal as an output unique to the base unit. output to the telephone line through the device.

This allows a mobile handset to make calls to the outside.

In weak radio wave type cordless telephone devices, the frequency of the carrier waves f+ and f2 of the base unit and handset can be freely selected for each cordless telephone device as long as the electric field strength at the specified distance is less than the specified value. can do.

In addition, for cordless telephone devices that use weak radio waves, it is mandatory to set a unique ID code of 19 bits or more, and the base unit and handset communicate with each other while confirming this ID code. It looks like this.

[Problem to be solved by the invention]

By the way, there is one cordless telephone device set A, that is, a fixed device A-1 and a portable device A-2, and another cordless telephone device set B, that is, a fixed device B-1 and a portable device B.
-2 is relatively close, as shown in Figure 5,
There is a region C (shaded area) in which the carrier waves of both fixed devices A-1 and B-1 have the same frequency and overlap, and when one portable device B-2 is in this region C, A If -1 and A-2 are talking first, B-2 has a carrier wave detection function according to the regulations, and this function is activated.
B-2 itself cannot make a call, but there is a problem in that B-2 can hear calls made by A-1.

Furthermore, in the manufacture of cordless telephone devices, in order to predetermine the frequency for each cent, several crystal oscillators with different transmission frequencies are provided, or a PLL (Phas
e Locked Lo.

In the case of generating a carrier wave using a frequency synthesizer according to p), it is necessary to set the division ratio of the programmable frequency divider, set the ID code for each set, and input data twice, which reduces manufacturing efficiency. There is also a problem that the situation is not good.

[Failure to solve the problem]

In order to solve the above problems, the present invention provides a cordless telephone device consisting of a fixed device connected to a telephone line and a movable portable device wirelessly connected to the fixed device. It is characterized in that the frequency of the carrier wave to be used is determined by being derived from the unique identification code of each cordless telephone device.

[For production]

According to the above configuration, since the identification code for each cordless telephone device is different, for example, a frequency synthesizer using a PLL is used to generate a carrier wave for a fixed device and a portable device, and a frequency synthesizer using a digital frequency divider is used to generate a carrier wave for a fixed device and a portable device. If the frequency ratio is determined by deriving the frequency ratio from the identification code, the frequency of the carrier wave will be determined because the carrier frequencies for each cordless telephone device are different, so there will be an area where the carrier waves of the fixed devices of the two sets of cordless telephone devices overlap. However, within that area, one set of mobile devices will no longer be able to hear calls from the other set.

In addition, in a PLL-based frequency synthesizer, there is no need to predetermine the frequency division ratio of the frequency divider, and it is derived from the identification code by calculations in the microcomputer installed in the fixed and portable cordless telephone devices. Since it is determined, there is no need to input two pieces of data, the identification code and the frequency division ratio, at the manufacturing stage, and it is sufficient to input only the identification code, which can improve manufacturing efficiency.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 3.

A weak radio wave type cordless telephone device consists of a fixed device (hereinafter referred to as a base device) and a portable device (hereinafter referred to as a slave device). Showing the configuration of the handset, as shown in Figure 1, an antenna 1 is connected to a mixer 2, and an IF (intermediate frequency) amplifier 3, demodulator 4, and speaker 5 form a receiving path for audio analog signals. ing. Note that a PLL 6 as a local oscillator is connected to the mixer 2. In addition, the weak radio wave type cordless telephone device includes an identification code of 19 bits or more (hereinafter referred to as an ID code) unique to each set and other digital data, and the demodulator 4
The output side of the demodulator 4 is also connected to the microcomputer 7 as a path for the digital data signal outputted from the demodulator 4.

This microcomputer 7 is connected to ID code storage means (hereinafter referred to as ID-ROM) 8 which stores the above-mentioned 10 codes.

Further, as a signal path when oscillating from the slave unit, the output of a PLL 9 as a carrier wave oscillator is connected to a modulator 10, and a microphone 11 and a microcomputer 7 are connected to the modulator 10. In addition,
Microcomputer 7 is also connected to PLL6 and PLL9. The output side of the modulator 10 is connected to the antenna 1. Note that the base unit basically has the same configuration as the slave unit, but has a unique output device that outputs audio signals to the telephone line.

The PLL 6 as a local oscillator and the PLL 9 as a carrier wave oscillator in FIG. 1 have the same configuration as shown within the chain line in FIG. 2. That is, a phase comparator 12 to which a reference oscillator 16 using a crystal oscillator is connected, a low-pass filter 13, and a VCO (voltage control
The loop of the led frequency divider 14 and the digital frequency divider 15 forms a so-called frequency synthesizer, the output of the VCO 14 being connected to the modulator 10 . Further, the microcomputer 7 is also connected to the digital frequency divider 15.

The operation of the cordless telephone device configured as described above during a call is as follows.

When a carrier wave of frequency f transmitted from the base unit is input to the antenna 1 of the slave unit in FIG. 1, this carrier wave f is mixed with the local oscillation wave f, L from the PLL 6 in the mixer 2. is converted into a specified intermediate frequency of the difference frequency of the carrier wave f and the local oscillation wave (L), amplified by the IF amplifier 3, demodulated by the demodulator 4, and an audio analog signal is output from the speaker 5. At the same time, digital components such as ID codes are input to the microcomputer 7 and processed.

In addition, in the case of a call from a handset, the frequency f is sent from the PLL9.
2 carrier waves are applied to the modulator 10 and the microphone 11
After being modulated by the voice signal from the microcomputer 7 and the ID code and other digital data signals from the microcomputer 7, the signal is transmitted from the antenna 1 to the base unit.

The lt device receives the carrier wave f2 and demodulates it by performing the same processing as in the case of the slave device, while outputting the audio signal to the telephone line via an output device unique to the base device.

Here, the local oscillation wave of the slave unit (, L is the VCO1 of PLL6
From 4, the carrier wave f2 oscillated by the slave unit is the VCO of PLL9.
As shown in FIG. The output of this phase comparator 12 passes through a low-pass filter 13 to control the output frequency of the VCO 14, and maintains a stable state with the following relationship.

fl　’　　　fz　　　”’Na　’’ f.

Here, f,' fl = output oscillation frequency of vco (r,'
: local oscillation wave frequency of the slave unit f2: carrier wave frequency of the slave unit) f, = output frequency of the reference oscillator Nd = division ratio of the digital frequency divider Therefore, the output oscillation frequency of the VCO 14, that is, the local oscillation frequency of the slave unit [1 ' or the carrier wave frequency f2 of the slave device is centrally determined only by the division ratio Nd of the digital frequency divider 15. This division ratio N.

In determining the value of , the present invention uses a unique ID code for each cordless telephone device, and the procedure will be explained using the flowchart of FIG.

First, the microcomputer 7 reads the ID code stored in the ID-ROM (Sl). The microcomputer 7 performs calculations on the read ID code using a predetermined program to create a frequency division ratio N (S2
). In this case, only the part of the ID code that is always different for each cordless telephone device may be extracted and used. Next, based on the frequency division ratio N obtained in the above (S2), a frequency division ratio N6 is set in the digital frequency divider (S3). Thereafter, the digital frequency divider 15 generates an output of the frequency fv based on the oscillation frequency of the VCO 14 and the frequency division ratio N4 (S4), and the frequency comparator 12 generates the reference frequency fv output from the reference oscillator 16. ,
(S5). If frequency fv and reference frequency f
, and match, PLL9 is locked and ■C0
14 continues to stably oscillate carrier wave frequency f2 (S6)
. When it is detected that the frequency fv and the reference frequency f do not match, the phase comparator 12 generates a voltage proportional to the difference between the frequency f and the reference frequency f, S7).
In the low-pass filter 13, it is converted into a DC control signal (S8), and in the VCOI 4, an output with a frequency proportional to this control signal is oscillated (S9), and then the digital frequency divider 1
5 to generate an output frequency fv (S4). Then, the above operation is repeated until the output frequency fv and the reference frequency f, .

The carrier wave ft etc. of the slave unit is determined as described above, but
In the case of the base unit, the carrier wave f is obtained using the same procedure.

etc. can be determined.

The frequencies of fl' and rz are different, but this is due to PLL6,
If the values of the output frequencies f, of the reference oscillator 16 in 9 are made different, or if f is the same, the microcomputer 7 sets two different frequency division ratios N, , N2 based on the ID code. create these,
By inputting to P I-L6 and 9 respectively, f
The frequencies of l' and f2 can be different.

Note that in this embodiment, an example of a telephone device is shown in which a call is made between a base unit and a slave unit using one carrier frequency generated using a PLL, but it is also possible to use a plurality of carrier frequencies using the same circuit configuration. You can also do that.

That is, the PLL digital frequency divider 1 having the configuration shown in FIG.
5. Increase the number of variables input in step 5 and create several carrier frequencies. These variables are also determined by the calculations of the microcomputer 7 based on the ID code, as described above, and the output frequency f2 of the VCO 14 in the PLL 9 is thereby determined.

〔Effect of the invention〕

As described above, the cordless telephone device according to the present invention includes a fixed device connected to a telephone line, and a movable portable device wirelessly connected to the fixed device. The configuration is such that the frequency of the carrier wave used by the telephone is determined by being derived from the unique identification code of each cordless telephone device.

Therefore, the frequency of the carrier wave for each cordless telephone device is different, and a region where the carrier waves of the two sets of cordless telephone devices overlap occurs, and in that region,
harmful interference between sets, such that one set can no longer hear calls from the other set, or
Invasion of privacy can be eliminated.

In addition, there is no need to determine the frequency division ratio of the digital frequency divider of the PLL frequency synthesizer in advance, and there is no need to input two data, the identification code and the frequency division ratio, at the manufacturing stage of the cordless telephone device. , you only need to enter the identification code. In addition, since it uses PLL, there is no need to provide a plurality of crystal oscillators for selecting the carrier frequency for each set, which improves manufacturing efficiency and reduces costs.

[Brief explanation of the drawing]

1 to 3 are detailed explanations of the present invention, in which FIG. 1 is a block diagram showing a schematic configuration of a portable device of a cordless telephone device, and FIG. 2 is a schematic diagram of the PLL frequency synthesizer shown in FIG. 1. FIG. 3 is a block diagram showing the configuration and a flowchart showing the procedure for determining the frequency division ratio of the digital frequency divider of the PLL frequency synthesizer. 4 and 5 explain conventional examples, FIG. 4 is a block diagram showing a schematic configuration of a portable device of a cordless telephone device, and FIG. 5 is a diagram showing a case where carrier waves of two sets of cordless telephone devices are superimposed. FIG. 2 is a mixer, 7 is a microcomputer, 8 is an ID code storage means (ID-ROM), 6.9 is a PLL frequency synthesizer, 10 is a modulator, 12 is a phase comparator, 14 is CO
515 is a digital frequency divider.

Claims (1)

[Claims] 1. A cordless telephone device comprising a fixed device connected to a telephone line and a movable portable device wirelessly connected to the fixed device, wherein a carrier wave used by the fixed device and the portable device is A cordless telephone device characterized in that the frequency is determined by being derived from an identification code unique to each cordless telephone device.