JPH06177795A - Cordless telephone set - Google Patents

Abstract

PURPOSE:To enable communication between mobile stations without through a base station by providing a BPF passing signals in the transmission and reception frequency bands of the mobile station, switching means switching the transmission and the reception states, reception signal demodulation means, and wide-band VCO on mobile stations. CONSTITUTION:When the communication between mobile stations is started, the signal passes an antenna 11 and a shared device 12 in an arrow A and inputted to a BPF 25 which passes the only frequency of 254MHz and sent through a switch 32 to a 1st MIX16. In a wide-band VCO31, a control circuit 22 is operated by the control of ten keys 28 to switch the oscillation from 359MHz to 276MHz, starting the communication between mobile stations. On the other hand, in the case of transmission, both the transmission frequency and the reception frequency are 254 MHz. As the route of an arrow B, ten keys 28 are operated to turn a switch 32 from 1st MIX 16-BPF25 to R and AMP 24-BPF 25. Thus, the press-to-talk system communication is used only when the transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone device for making a call between mobile stations without going through a base station.

[0002]

2. Description of the Related Art In a mobile station of a low power cordless telephone, a reception frequency from a base station is limited to a 380 MHz band and a transmission frequency to a base station is limited to a 254 MHz band. Therefore, in the conventional cordless telephone device, since the reception frequency band and the transmission frequency band are different as described above, it is impossible to make a call between mobile stations. Therefore,
In a conventional cordless telephone device, two radio units are provided on the base station side, and one radio unit connects to one mobile station and another radio unit connects to another mobile station through different channels. The configuration allows mobile stations to communicate with each other via the base station.

FIG. 3 is a schematic block diagram of a mobile station of a conventional cordless telephone system, and FIG. 4 is a connection diagram of a master unit and a slave unit of the cordless telephone system.

In the mobile station 10 shown in FIG. 3, 11 is an antenna, 12 is a duplexer connected to a transmission system and a reception system, and 1
3 is a BPF that allows only signals in the 380 MHz band to pass (first
Band pass filter), 14 RFAMP (high frequency amplifier), and 15 receiving VCO (Voltage Contorolled Osci)
16-16 are reception signal demodulating means, of which 16 is a 1ST mixer for combining the input signal of the antenna 11 with the output signal of the reception VCO 15, and 17 is a BP.
F and 18 are IFAMP (intermediate frequency amplifier), 19 is 2
A demodulation circuit composed of an ND mixer, a limiter AMP and a quadrature detection circuit, 20 is an emphasis circuit,
A baseband circuit provided with a secret circuit, a compander circuit, a modem, etc., 21 is a PLL (Phase Locked Loo) composed of a phase detector and a programmable divider.
p), 22 is a control circuit for setting the channel of the PLL 21, etc., 23 is a frequency synthesizer together with the receiving VCO 15 and the PLL 21, and a transmitting VCO oscillating a frequency according to the set channel, 24 is an RFAM
P and 25 are BPFs that pass only signals in the 254 MHz band
(Second bandpass filter), 26 is receiver, 27
Is a microphone, and 28 is a ten-key operation unit.

Next, the operation of the above conventional example will be described.
3 and 4, in the mobile station 10, a signal in the 254 MHz band is oscillated by the transmission VCO 23 and transmitted to one radio unit of the base station 50 through the antenna 11.
When being received by another mobile station from another radio unit of the base station 50, the internal configuration of this mobile station is the same as that of the mobile station 10, and the 380 MHz band signal received by the antenna 11 is received by the 1ST mixer 16. The VCO 15 is mixed (synthesized) with the 359 MHz band signal oscillated, and converted into a signal having a frequency of 21.7 MHz. Further, the converted signal is converted into 455 KHz by the demodulation circuit 19, and the voice signal is demodulated.

[0006]

However, in the conventional cordless telephone apparatus, the base station must always be interposed in order to realize a call between mobile stations.

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a cordless telephone device that enables telephone calls between mobile stations without going through a base station.

[0008]

In order to achieve this object, a cordless telephone apparatus of the present invention is a cordless telephone apparatus provided with a base station and a mobile station wirelessly connected to the mobile station. A bandpass filter for passing signals in the transmission and reception frequency bands of the station, a switching means connected to this bandpass filter for switching between the transmission state and the reception state, and the bandpass filter when the switching means is in the reception state. The receiving signal demodulating means for inputting the signal from the above and the wide band receiving VCO for outputting the signals of a plurality of frequency bands to the receiving signal demodulating means are provided.

[0009]

Therefore, according to the present invention, the frequency of the transmission signal from the mobile station is input to the reception signal demodulation means via the bandpass filter, and the signals of a plurality of frequency bands are input from the wideband reception VCO to the reception signal demodulation means. However, the reception signal demodulation means can output the audio signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of the first embodiment of the present invention. Mobile station 30 of the cordless telephone system shown in FIG.
3, a wideband reception VCO 31 capable of oscillating from the 276 MHz band to the 359 MHz band is provided in place of the reception VCO 15 of the mobile station 10 of FIG.
A switch 32 for switching the connection between 25 (transmission system) and 1STMIX16-BPF25 (reception system) is added.

Next, the operation of the above embodiment will be described. When starting a call between mobile stations, arrow A in FIG.
, The reception frequency of the signal received from another mobile station is 254 MHz, so that signal is transmitted to the antenna 11,
It is input to the BPF 25 that passes only the frequency of 254 MHz band through the duplexer 12 and 1 STM through the switch 32.
Sent to IX16. In the wide band VCO 31, the control circuit 22 operates by operating the ten-key unit 28 and 359 MHz.
The band is switched to the oscillation of the 276 MHz band. The frequency synthesizer including the frequency signals used in the wide band VCO 31 and the PLL 21 performs carrier sense of the selected channel. If it is in use, switch to another channel and set the two mobile stations to the same channel. The signal input to 1STMIX16 (received signal demodulation means) is converted to 21.7 MHz and converted to 455 KHz by the demodulation circuit (received signal demodulation means) to start communication between mobile stations.

On the other hand, when transmitting, since both the transmission frequency and the reception frequency are 254 MHz, the numeric keypad section 28 is operated as shown by the path of arrow B, and the switch 32 is operated.
From the receiving system to the transmitting system, that is, 1STMIX16-B
Switch from PF25 to RFAMP24-BPF25. As a result, a press talk type call is required in which the ten-key unit 28 needs to be operated only during transmission.

FIG. 2 shows the configuration of the second embodiment of the present invention. In the cordless telephone device 40 shown in FIG.
Wideband reception VCO 31 of the cordless telephone device 30 of FIG.
Instead of the VCO 41 and 2 for 359MHz band oscillation
The receiver VCO 42 for 76 MHz band oscillation is provided.
In the same manner as in the first embodiment, when the mobile station 40 and the base station call each other, the receiving VCO 41 is selected, and when the mobile stations call each other, the receiving VCO 42 is selected.
A press talk system between mobile stations is realized.

Therefore, according to the present invention, a wide band receiving VC
The reception frequency of the mobile stations can be switched from 380 MHz to 254 MHz by the O31 or the reception VCOs 41 and 42, and the mobile stations can communicate with each other without going through the base station.

[0015]

As is apparent from the above embodiment, the present invention inputs the frequency of the transmission signal from the mobile station into the reception signal demodulation means via the bandpass filter to obtain the wide band reception VC.
Since signals of a plurality of frequency bands are input from O to the reception signal demodulation means and the reception signal demodulation means outputs a voice signal, it is possible to make a call between mobile stations without going through the base station.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of a cordless telephone device according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram showing the configuration of a cordless telephone device according to a second embodiment of the present invention.

FIG. 3 is a schematic block diagram showing the configuration of a conventional cordless telephone device.

FIG. 4 is a connection diagram of a base unit and a handset of a cordless telephone device.

[Explanation of symbols]

 13, 17, 25 BPF 14, 24 RFAMP 16 1STMIX 18 IFAMP 19 demodulation circuit 22 control circuit 31 wideband reception VCO 32 switch

Claims (2)

[Claims] 1. A cordless telephone apparatus provided with a mobile station wirelessly connected to a base station, and a bandpass filter for allowing the mobile station to pass signals in the transmission and reception frequency bands of the mobile station and the bandpass filter. A switching means connected to the filter for switching between a transmission state and a reception state, a reception signal demodulation means for inputting a signal from the band pass filter when the switching means is in a reception state, and a plurality of reception signal demodulation means. Wideband receiving VCO that outputs signals in the frequency band
A cordless telephone device comprising: and a reception signal demodulating means which outputs voice signals so that mobile stations can transmit and receive the same. 2. Two reception Vs instead of a wideband reception VCO which outputs signals in a plurality of frequency bands to the reception signal demodulation means.
The cordless telephone device according to claim 1, comprising a CO.