JP3306177B2 - Digital frequency modulation cordless telephone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital frequency modulation type cordless telephone capable of wireless communication with little bit error between a base unit and a slave unit without being largely influenced by high-level noise in a carrier frequency band. It concerns the device.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable development of a cordless telephone apparatus of a digital frequency modulation system. The digital frequency modulation type cordless telephone is constituted by a combination of a master unit and a slave unit. Hereinafter, the configuration of a conventional digital frequency modulation type cordless telephone unit will be described with reference to the drawings.

FIG. 14 is a block diagram showing the structure of a conventional digital frequency modulation cordless telephone. 1
Reference numeral 00 denotes a base unit of the cordless telephone apparatus of the digital frequency modulation system (hereinafter, simply referred to as base unit), and reference numeral 200 denotes a slave unit of the cordless telephone apparatus of the digital frequency modulation system (hereinafter, simply referred to as slave unit). In base unit 100,
Reference numeral 101 denotes digital control data for performing incoming call control and the like of the child device 200 (hereinafter referred to as child device control data), and digital control data for performing a call control and the like of the parent device 100 from the child device 200. (Hereinafter, referred to as master unit control data), and a control unit for controlling the entire master unit 100 as a whole, 102 as a station line connecting the master unit 100 to a central office exchange (not shown), and 103 as a station line. 102 and parent device 100
A modular jack 104, which is a connection portion with the terminal, detects a bell signal transmitted from the central office exchange and connects / connects the office line 102.
Release, multi-frequency selection signal (hereinafter referred to as DTMF signal)
, Transmission line termination, detection of an end signal from the station line 102, etc.
02, a transmission line processing unit for digitally frequency-modulating a voice band signal and slave unit control data, up-converting the signal to a cordless frequency band signal, and increasing the power; 106, a received cordless frequency band A reception processing unit for converting a signal into an analog voice band signal and master unit control data, an antenna unit 107 for transmitting and receiving radio waves to and from the slave unit 200, and a transmission / reception unit 108 for separating a transmission wave and a reception wave which are cordless frequency band signals Wave splitter.

[0004] The reception processing unit 106 has the following configuration. 1
09 is a power amplifying unit for amplifying the received cordless frequency band signal, 110 is a down-converting unit for down-converting the amplified cordless frequency band signal into a voice frequency signal and a digital frequency modulation signal of master device control data, 1
Reference numeral 11 denotes a band-pass filter unit (hereinafter, referred to as a BPF unit) that limits the band of the digital frequency modulation signal. Reference numeral 112 denotes a reference carrier reproduction unit that reproduces a reference carrier for demodulating the digital frequency modulation signal. A detection and demodulation unit that demodulates the frequency-modulated signal with reference to the carrier reproduced by the reference carrier reproduction unit 112. A detection and demodulation unit 114 intercepts a signal having a frequency equal to or higher than the carrier frequency among the digital frequency modulation signals demodulated by the detection and demodulation unit 113. A low-pass filter unit (hereinafter, referred to as an LPF unit) 115 that outputs a voice band signal and master unit control data, and 115 is an LPF unit 1
A digital / analog conversion unit (hereinafter, referred to as a D / A conversion unit) that converts a digital voice band signal output from 14 into an analog voice band signal.

FIG. 15 is a block diagram showing a configuration of the slave unit 200. As shown in FIG. In the slave unit 200, 201 is a control unit that controls the entire slave unit of the digital frequency modulation type cordless telephone device, 202 is a transmission unit that converts voice into a voice signal, 203 is a reception unit that converts a voice signal into voice, 204
Is a voice interface unit for adjusting the gain of the input / output of the voice signal, 205 is a transmission processing unit for converting and up-converting the voice signal, and 206 is a reception processing unit for converting the received signal into an analog voice signal or digital control data. And 207, an antenna unit for transmitting and receiving radio waves to and from the master unit 100, and 208, a transmission / reception wave demultiplexing unit for separating transmission waves and reception waves.

In the reception processing section 206, 209 is a power amplification section for amplifying a reception signal, 210 is a down-converter section for down-converting the reception signal, 211 is a BPF section for band-limiting the reception signal, and 212 is a demodulation of the reception signal. A reference carrier recovery unit for recovering a reference carrier for
A detection demodulation unit 213 demodulates the received signal subjected to digital frequency modulation with reference to the carrier reproduced by the reference carrier reproduction unit 212. A detection unit 215 cuts off a signal having a carrier frequency or higher among the reception signals demodulated by the detection demodulation unit 213. LP
An F / 215 is a D / A converter for converting a digital reception signal output from the LPF 214 into an analog audio signal.

The operation of the conventional digital frequency modulation type cordless telephone having the above configuration will be described below. In this case, however, the modulation method is a binary digital frequency modulation method of "0" and "1", and the channels used are two channels for transmission and two reception channels for both audio data and control data, for a total of eight channels.

First, the transmission processing operation from the master unit 100 to the slave unit 200 will be described with reference to FIG. The analog voice band signal transmitted from the central office via the central office line 102 and the modular jack 103 is converted into a digital audio band signal by the transmission processing unit 105 via the central office interface unit 104, and then converted into a digital frequency modulation signal. The signal is then up-converted into a cordless frequency band signal and power-amplified. The amplified transmission signal is mixed with the reception signal in the transmission / reception demultiplexing unit 108 and the antenna unit 10
7, and is transmitted to the slave unit 200 as a transmission radio wave. Also, the slave unit control data such as the incoming call output from the control unit 101 is processed in the same manner as the voice band signal in the transmission processing unit 105, mixed with the reception signal in the transmission / reception demultiplexing unit 108, and transmitted through the antenna unit 107, It is transmitted to slave unit 200 as a transmission radio wave.

Next, the reception process of the slave unit 200 will be described with reference to FIG. The transmission radio wave transmitted from base unit 100 is received by antenna unit 207 of handset 200, and is separated into a reception signal and a transmission signal by transmission / reception wave separation unit 208. The separated received signal is amplified by the power amplifying unit 209, down-converted by the down-converter unit 210, band-limited to the carrier band by the BPF unit 211, and the out-of-band noise is removed. The reference carrier recovery unit 212
A carrier component is reproduced from the reception signal band-limited by the F section 211, and a detection demodulation section 213 detects and demodulates the reception signal using the reproduced carrier as a reference signal. LPF section 214 blocks components having a frequency equal to or higher than the carrier frequency in the reception signal detected and demodulated by detection and demodulation section 213. The received signal whose high frequency is cut off by the LPF unit 214 is transmitted to the D / A conversion unit 2.
At 15, the audio signal is converted into an analog audio signal, the audio interface unit 204 adjusts the gain of the audio signal, and the receiving unit 203 converts the audio signal into audio. Similarly, the control data that has been received and output from the LPF unit 214 is input to the control unit 201.

[0010] Next, the transmission processing operation from the slave unit 200 to the master unit 100 will be described. The voice converted to the voice signal by the transmitting unit 202 is converted to a digital transmission signal by the transmission processing unit 205 via the voice interface unit 204, and this transmission signal is digitally frequency-modulated. It is up-converted, power-amplified, and mixed with the reception signal in the transmission / reception branching unit 208,
A transmission radio wave is transmitted to base unit 100 via antenna unit 207. The control data output from the control unit 201 is also processed in the same manner as the audio data in the transmission processing unit 205, mixed with the received signal in the transmission / reception demultiplexing unit 208, and
Is transmitted to master device 100 via

[0011] In FIG. 14, the voice band signal transmitted from handset 200 is received by antenna unit 107 of base unit 100, and separated from the transmission signal by transmission / reception branching unit 108. The separated received signal is amplified by power amplifying section 109 and down-converted by down-converting section 110 to a digital frequency modulation signal of a voice band signal. This digital frequency modulation signal is band-limited to the carrier band by the BPF unit 111, and out-of-band noise is removed. The reference carrier reproduction unit 112 reproduces a carrier component from the digital frequency modulation signal of the audio band signal band-limited by the BPF unit 111, and the demodulation unit 113 detects and demodulates the audio band signal using the reproduced carrier as a reference signal. I do. LP
The F section 114 cuts off a component equal to or higher than the carrier frequency in the digital audio band signal detected and demodulated by the detection and demodulation section 113. The digital voice band signal whose high band has been cut off by the LPF unit 114 is converted into an analog voice band signal by the D / A conversion unit 115, and the local line interface unit 1
04, the modular jack 103 and the central office 102 to the central office. The base unit control data transmitted from the slave unit 200 is also subjected to reception processing in the same manner as the voice band data in the reception processing unit 106, and the digital base unit control data output from the LPF unit 114 is input to the control unit 101. , Outgoing calls and the like.

As described above, the parent device 100 and the child device 200 of the conventional digital frequency modulation type cordless telephone device are
The reception processing units 106 and 206 have the same configuration, and perform reception processing in a similar manner.

[0013]

However, in the above-mentioned conventional digital frequency modulation type cordless telephone apparatus, when high-level noise is added to the carrier frequency band, the BPF section in the reception processing section cannot remove the noise. The carrier used as the reference to be reproduced by the reference carrier reproduction unit cannot be distorted greatly due to the noise, and the demodulation unit detects and demodulates the audio band signal or the master unit control data based on the distorted reproduced carrier. Produces an error,
As a result of an increase in the number of retransmissions, there has been a problem that the communicable range between the parent device and the child device becomes extremely narrow.

[0014] The present invention solves the above-mentioned problems, and realizes a digital frequency capable of performing stable wireless communication between a master unit and a slave unit over a wide range with little bit error even when high-level noise is added to a carrier frequency band. An object of the present invention is to provide a modulation system cordless telephone device.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides two oscillation frequencies of a digital frequency modulation signal by a received signal in a data window which is time-shifted by one symbol length per sampling time. A power spectrum calculation unit that calculates only a nearby power spectrum, a power spectrum storage unit that temporarily stores the maximum power spectrum calculated by the power spectrum calculation unit up to several sampling times, and two power spectra calculated by the power spectrum calculation unit. The average value of the power spectrum near the oscillation frequency and the power spectrum stored in the power spectrum storage unit up to several sampling times before is calculated and compared for each oscillation frequency, and the information symbol for the dominant oscillation frequency is calculated. Output information system in the data window It is obtained by a power spectrum comparison unit performs demodulation by the Bol.

[0016]

The power spectrum in the data window is calculated only in the vicinity of two oscillation frequencies based on the sampling data of the received signal in the data window while shifting the data window by one sampling time. The maximum value in the vicinity is defined as the maximum power spectrum, the maximum power spectrum is averaged for each oscillation frequency until several sampling times, the average power spectrum of the two oscillation frequencies is compared, and the information symbol for the dominant oscillation frequency is obtained. Since demodulation is performed by using the output information symbol at the time at the center of the data window, even if high-level noise is added to the carrier frequency band, bit errors hardly occur, and a stable and stable communication between the master and slave units is possible. Wireless communication is possible It made.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a cordless telephone apparatus of the digital frequency modulation system in one embodiment of the present invention, wherein 1 is a master unit and 2 is a slave unit. In the base unit 1, the base unit 3 outputs base unit control data for performing incoming call control and the like of the base unit 2, and inputs base unit control data for performing call control and the like of the base unit 1 from the base unit 2. A control unit for controlling the whole of the base unit 1; a line 4 for connecting the base unit 1 to the central office;
5 is a modular jack which is a connection between the office line 4 and the base unit 1, 6 is detection of a bell signal transmitted from the central office exchange, connection / release of the office line 4, transmission of a DTMF signal, termination from the office line 4. A transmission line processing unit for digitally frequency-modulating a voice band signal and slave unit control data, up-converting the signal to a cordless frequency band signal, and increasing the power; ,
Reference numeral 8 denotes a reception processing unit which converts the received cordless frequency band signal into an analog voice band signal and master device control data.
Denotes an antenna unit for transmitting and receiving radio waves to and from the slave unit 2, and 10 denotes a transmission / reception wave demultiplexing unit for separating a transmission wave and a reception wave, which are cordless frequency band signals.

The reception processing unit 8 has the following configuration. 11 is a power amplifying unit for amplifying the received cordless frequency band signal, 12 is a down-converting unit for down-converting the amplified cordless frequency band signal to a voice frequency signal and a digital frequency modulation signal of master unit control data, 13 is a digital frequency modulation The power spectrum of the received signal in the data window is calculated only in the vicinity of two oscillation frequencies based on the received digital frequency modulation signal in the data window which is time-shifted by one sampling time with one symbol length of the signal, and each oscillation is calculated. A power spectrum calculation unit for setting the maximum value near the frequency to be the maximum power spectrum; a power spectrum storage unit for temporarily storing the maximum power spectrum calculated by the power spectrum calculation unit 13 up to several sampling times before; Is pa -The maximum value of the maximum power spectrum in the vicinity of the two oscillation frequencies calculated by the spectrum calculation unit 13 is stored in the power spectrum storage unit 14 until several sampling times before, and the average value of the maximum power spectrum is calculated and compared for each oscillation frequency. The power spectrum comparing unit 16 that demodulates the information symbol for the dominant oscillation frequency as the output information symbol at the center of the data window and outputs the digital voice band signal and the base station control data, 16 D for converting a digital voice band signal into an analog voice band signal
/ A conversion unit.

FIG. 2 is a block diagram showing the configuration of the slave unit 2 in one embodiment of the present invention. In the handset 2, reference numeral 21 denotes the handset 2 of the digital frequency modulation type cordless telephone.
A control unit for integrally controlling the whole; a transmitting unit for converting a voice into a voice signal; a receiving unit for converting a voice signal into a voice; a voice interface unit for adjusting a gain of input and output of the voice signal; Is a transmission processing unit for converting and up-converting an audio signal; 26 is a reception processing unit for converting a received signal into an analog audio signal or digital control data; 27 is an antenna unit for transmitting and receiving radio waves to and from the base unit 1; Is a transmission / reception wave splitter for separating a transmission wave and a reception wave.

The reception processing unit 26 has the same configuration as the reception processing unit 8 of the master unit 1 shown in FIG. 1, 29 is a power amplification unit for amplifying the reception signal, and 30 is a down-conversion unit for down-converting the reception signal. , 31 are 2 according to the received signal in the data window which is time-shifted every pulling time.
A power spectrum calculator for calculating only the power spectrum in the vicinity of one oscillation frequency; 32, a power spectrum storage for temporarily storing the maximum power spectrum calculated by the power spectrum calculator 31 until several sampling times before; The power spectrum in the vicinity of the two oscillation frequencies calculated by the arithmetic unit 31 and the power spectrum stored in the power spectrum storage unit 32 up to several sampling times before are calculated and compared for each oscillation frequency with the average value of the power spectrum. A power spectrum comparing unit that uses information symbols corresponding to a typical oscillation frequency as output information symbols in the data window, and converts a digital received signal into an analog voice signal by using a D signal.
/ A conversion unit.

The operation of the cordless telephone apparatus of the digital frequency modulation system configured as described above will be described below with reference to FIGS. However, as in the conventional example, the modulation method is a binary digital frequency modulation method of “0” and “1”, and the channel to be used is audio data,
It is assumed that the control data is two channels for transmission and two channels for reception, for a total of eight channels.

In the cordless telephone apparatus of the digital frequency modulation system according to the present embodiment, the transmission processing from the base unit 1 to the base unit 2 and from the base unit 2 to the base unit 1 are completely the same as those in the conventional example, and the description is omitted. In addition, since the reception processing operation from the parent device 1 in the child device 2 and the reception processing operation from the child device 2 in the parent device 1 according to the present embodiment are the same, the reception processing operation from the child device 2 in the parent device 1 is performed here. Will be described only. The audio band signal transmitted as the transmission radio wave of the cordless frequency band signal by the slave unit 2 is received by the antenna unit 9 of the master unit 1 and separated from the transmission signal by the transmission / reception wave separation unit 10. The separated received signal is supplied to the power amplifier 11
, And down-converted by the down-converting section 12 into a digital frequency modulation signal of the audio band signal.
The power spectrum calculator 13 calculates the power spectrum of the received signal in the data window based on the sampling data of the received digital frequency modulation signal in the data window of one symbol length only in the vicinity of two oscillation frequencies. For one of the oscillation frequencies, the maximum value among the power spectra near the oscillation frequency is set as the maximum power spectrum for the oscillation frequency in the data window, and stored in the power spectrum storage unit 14. Then, an average of the maximum power spectrum and the maximum power spectrum up to several sampling times before stored in the power spectrum storage unit 14 is obtained, and the average power spectrum for the oscillation frequency in the data window is obtained. The average power spectrum is calculated for the other oscillation frequency in the same manner. From the calculated average power spectrum, the dominant oscillation frequency is found in the power spectrum comparing unit 15, that is, which oscillation frequency the average power spectrum is larger is found, and the information symbol for the dominant oscillation frequency is placed at the center of the data window. Demodulation is performed by using output information symbols at the time. D / A converter 1
6 converts the digital voice band signal demodulated by the power spectrum comparison unit 15 into an analog voice band signal,
The data is transmitted to the central office via the central office interface unit 6, modular jack 5, and central office line 4. Master device control data that has been subjected to reception processing in the same manner as the voice band data and output from power spectrum comparison unit 15 is input to control unit 3 and controls calling and the like.

Next, the operations of the power spectrum calculation unit 13, the power spectrum storage unit 14, and the power spectrum comparison unit 15 will be described in detail with reference to FIGS. FIG. 3 is a diagram showing the relationship between the digital frequency modulation signal received by the power spectrum calculation unit 13, the data window at each sampling time, and the demodulated signal.
8 are diagrams showing the relationship between the power spectrum and the data window in the vicinity of the oscillation frequency in the power spectrum comparison unit 15 in the case of normal noise, and FIGS. 9 to 12 show that a large noise is added to the carrier band. FIG. 9 is a diagram showing the relationship between the maximum power spectrum near the oscillation frequency and its time change in the power spectrum comparing unit 15 in the case.

First, for a normal noise level,
3 and 4 to 7, the information symbol is "1".
The demodulation operation will be described by taking as an example the case of changing from "0" to "0". In FIG. 3, f _C is the carrier frequency, f ₁ is the oscillation frequency for the information symbol “1”, f ₀ is the oscillation frequency for the information symbol “0”, and Δf is the frequency deviation from the carrier frequency f _C. . That is, f ₀ = f _C − △ f, f
₁ = f _C + Δf. Indicates the data window at the current sampling time K = 0, N / 4, N / 2, 3N / 4, N, the right end of each data window is the current sampling time, and the data window width is 1
Let the symbol length be N, and the number of samples in one symbol be N. K _C is the time at the center of the data window, and K _L is the oldest time in the data window. To calculate the power spectrum, the maximum entropy method (M
EM). Also, FIG.
5 corresponds to FIG. 5, FIG. 6 corresponds to FIG. 7, and FIG.

FIG. 4 (current sampling time K = 0)
Powers from sampling time in data window
When the spectrum is obtained, this sampling data contains f₀
Since the frequency component of f is not included, f₁Only when
It has a strong power spectrum. In practice, f₀And f₁Is already
Since the frequency is a known frequency, the power spectrum calculation unit 13
Therefore, it is necessary to obtain a power spectrum in a wide frequency range.
No need, f₀And f₁Only need to find the neighborhood of
No. To find the neighborhood is the instantaneous circumference of the carrier due to noise.
This is because the micro frequency deviation of the wave number was considered, and
Targeting only the vicinity of the wave number itself is a narrow band bandpass.
It has the same function as a filter. Shown by arrows in FIG.
In the enlarged view, f₀And f₁Maximum power spectrum near
PS for each₀(F₀) And PS₀(F₁)
You. Further, it is stored in the power spectrum storage unit 14.
F before n-1 sampling time₀And f₁Neighborhood of
The maximum power spectrum of ｛PS₁(F₀), PS_Two
(F₀),…, PS_n-1(F₀ )｝ And ｛PS
₁(F₁), PS_Two(F₁),…, PS_n-1(F₁)｝
And Then, for each oscillation frequency,
The average of the torques is PS (f₀) = ｛PS₀
(F₀) + PS₁(F₀) + ... + PS_n-1(F₀)｝ ／
n and PS (f₁) = ｛PS₀(F₁) + PS₁(F₁)
+ ... + PS_n-1(F₁)｝ / N. Average power spec
Kutor PS (f₀) And PS (f₁Dominant lap comparing)
Find the wave number. Usually, the power spectrum of the dominant oscillation frequency
The vector level is higher than the noise power spectrum level.
Because it is much higher, the power spectrum
Even if the average is not taken, it is not affected by noise. As a result,
In the case of 4, the dominant frequency is the oscillation frequency f₁Is
I understand. From this, the data at the current sampling time K = 0
Output information for the time K = -N / 2 at the center of the data window
The information symbol is "1". This average power spectrum
FIG. 13 shows the relationship between the symbol and the output information symbol.

When the same processing is repeated at each sampling time for the digital frequency modulation signal shown in FIG.
In the case of the data windows, power spectra are respectively shown in FIGS. 5 to 8, and a dominant oscillation frequency is obtained from the average power spectrum as in the case of FIG.
When the output information symbol for the time at the center of each data window is determined, demodulation can be performed as in the demodulated signal of FIG.

Next, high-level noise is applied to the carrier frequency band.
Will be described with reference to FIGS. 9 to 12.
You. Here, for the sake of simplicity,
To take the average of the power spectrum before
I do. 9 to 11 show high-level noise in the carrier frequency band.
Current sampling time K = K when sound is added₀, K
₀-1, K₀-2 power spectrum
This is for the vicinity of a number. Maximum at each time
Each power spectrum is ｛PS₀(F₀), PS₁
(F₀), PS_Two(F₀)｝, ｛PS₀(F₁), PS
₁(F₁), PS _Two(F₁)｝. 2 sampling
Taking the average before the time, the power spectrum due to noise is
Figure 1
2, this average power spectrum PS
(F₀) = ｛PS₀(F₀) + PS₁(F ₀) + PS_Two
(F₀)｝ / 3 and PS (f₁) = ｛PS₀(F₁) + P
S₁(F₁) + PS_Two(F₁) If you compare や / 3,
Beam oscillation frequency f₁Dominates the average power spectrum of
It is a target. As a result, f₁Information symbol "1" for
Is the current sampling time K = K₀Data window in
Central time K of_C= K₀Output information thin at -N / 2
It is demodulated by setting it to a vol.

In this manner, even when high-level noise is added to the carrier frequency band, demodulation can be performed without being affected by noise.

In the present embodiment, the information symbols to be transmitted and received are binary, "0" and "1". However, even when the information symbols are multi-valued, the effect of the present invention is not affected at all.
Further, the reception processing unit is the same for the parent device 1 and the child device 2, but the reception processing unit of the present invention may be provided in one of the parent device 1 and the child device 2, and the region may be the same as the conventional one.

[0030]

As is apparent from the above embodiment, the present invention provides a stable master system which causes almost no bit error even when high-level noise is added to the carrier frequency band and has no waste such as retransmission over a wide range. This has the effect of enabling wireless communication between the handset units.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a base unit of a digital frequency modulation type cordless telephone according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a slave unit according to one embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a digital frequency modulation signal received by a reception processing unit, a data window at each sampling time, and a demodulated signal in one embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a power spectrum and a data window near an oscillation frequency in the case of normal noise in a power spectrum comparison unit according to one embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a power spectrum and a data window near an oscillation frequency in the case of normal noise in a power spectrum comparison unit according to one embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relation between a power spectrum and a data window near an oscillation frequency in the case of normal noise in a power spectrum comparison unit according to one embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a relationship between a power spectrum and a data window near an oscillation frequency in the case of normal noise in a power spectrum comparison unit according to one embodiment of the present invention.

FIG. 8 is a characteristic diagram showing a relationship between a power spectrum and a data window near an oscillation frequency in the case of normal noise in a power spectrum comparison unit according to one embodiment of the present invention.

FIG. 9 is a characteristic diagram showing the relationship between the maximum power spectrum near the oscillation frequency and its time change when a large noise is added to the carrier frequency band in the power spectrum comparison unit according to one embodiment of the present invention.

FIG. 10 is a characteristic diagram showing the relationship between the maximum power spectrum near the oscillation frequency and its time change when a large noise is added to the carrier frequency band in the power spectrum comparison unit according to one embodiment of the present invention.

FIG. 11 is a characteristic diagram showing the relationship between the maximum power spectrum near the oscillation frequency and its time change when a large noise is added to the carrier frequency band in the power spectrum comparison unit according to one embodiment of the present invention.

FIG. 12 is a characteristic diagram showing the relationship between the maximum power spectrum near the oscillation frequency and its time change when a large noise is added to the carrier frequency band in the power spectrum comparison unit according to one embodiment of the present invention.

FIG. 13 is a list showing a relationship between an average power spectrum and output information symbols in one embodiment of the present invention.

FIG. 14 is a block diagram showing the configuration of a base unit of a conventional digital frequency modulation type cordless telephone device.

FIG. 15 is a block diagram showing a configuration of a slave unit of a conventional digital frequency modulation type cordless telephone device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 digital frequency modulation cordless telephone base unit 2 digital frequency modulation cordless telephone handset 3 control unit 4 local line 5 modular jack 6 local line interface unit 7 transmission processing unit 8 reception processing unit 9 antenna unit 10 transmission / reception division unit 11 power Amplifying unit 12 down-converting unit 13 power spectrum calculating unit 14 power spectrum storing unit 15 power spectrum comparing unit 16 D / A converting unit 21 control unit 22 transmitting unit 23 receiving unit 24 voice interface unit 25 transmission processing unit 26 reception processing unit 27 Antenna unit 28 Transmission / reception wave demultiplexing unit 29 Power amplification unit 30 Down converter unit 31 Power spectrum calculation unit 32 Power spectrum storage unit 33 Power spectrum comparison unit 34 D / A conversion unit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 27/00-27/38

Claims (3)

(57) [Claims] 1. A wireless telephone device for performing cordless communication between a master unit and a slave unit using a digital frequency modulation method, wherein a reception signal in a data window which is time-shifted every sampling time by one symbol length of a transmission signal. A power spectrum calculation unit that calculates only a power spectrum near two transmission frequencies, a power spectrum storage unit that temporarily stores the power spectrum calculated by the power spectrum calculation unit until several sampling times, and a power spectrum calculation unit. The average value of the power spectrum near the two oscillation frequencies calculated in the section and the power spectrum stored up to several sampling times before in the power spectrum storage section is calculated and compared for each oscillation frequency, and The information symbol for the oscillation frequency is A digital frequency modulation type cordless telephone device comprising: a power spectrum comparison unit that performs demodulation by using output information symbols in a data window. 2. A digital frequency modulation type cordless telephone device provided with the configuration according to claim 1 in a base unit. 3. A cordless telephone apparatus having a digital frequency modulation system provided with the configuration according to claim 1.