JPH0474028A - Cordless telephone system - Google Patents

Abstract

PURPOSE:To reduce power consumption and to make the size and the weight small by using a local frequency obtained from an exclusive crystal oscillation circuit in a frequency synthesizer circuit so as to implement a reception opera tion in the standby state. CONSTITUTION:A high frequency changeover switch 22 and a power supply changeover switch 23 are thrown respectively to the position (a) in the standby operation to supply power to a 1st local oscillation circuit 20 and a crystal vibrator 21, from which a 1st local frequency is oscillated. The input of a recep tion frequency is awaited by a mixer circuit 6 and an intermediate frequency BPF 7 by using the frequency so as to be tuned to the control channel. When a radio wave is inputted from an antenna 1, a high frequency signal tuned by the 1st local frequency is demodulated by a detection circuit 12 to be a low frequency signal, a control data is demodulated and outputted, and a discrim ination output of the presence of a carrier is informed to a control circuit. When talking is finished and the standby operation is transited again, the change over switches 22, 23 are thrown to the position (a) to stop power supply of a frequency synthesizer circuit 17 so as to reduce the current consumption of the reception circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cordless telephone device comprising a base station connected to a telephone line and a mobile station wirelessly connected to the base station, and particularly relates to a wireless This relates to the configuration of a receiving circuit.

BACKGROUND OF THE INVENTION FIG. 2 shows the configuration of a radio receiving circuit in a mobile station of a conventional cordless telephone device. In Figure 2, 1 is an antenna, 2 is a DPX (antenna duplexer) for distinguishing between transmitting and receiving frequencies, 3.5 is a bandpass filter that passes only the receiving frequency, and 4.8.10 is a high-frequency amplification 6 is a mixer circuit for the 10th Cull frequency and reception frequency, 7 is a first intermediate frequency band pass filter, 9 is a mixer circuit for the 20th Cull frequency and intermediate frequency, 11
is a second intermediate frequency band pass filter, 12 is a detection circuit,
13 is a low frequency amplifier circuit, 14 is a VCO (voltage controlled oscillation circuit) that oscillates the 10th-cal frequency, and 15 is a 10th-
16 is a reference crystal oscillation circuit including a crystal oscillator for obtaining the reference frequency of the PLL 15; 17 is a reference crystal oscillation circuit including these VCOs 14, PPLI
5 and a reference crystal oscillation circuit 16; 18 is a second frequency synthesizer circuit for obtaining the 20th-cal frequency;
0-Cal oscillation circuit, 19 is a crystal resonator.

Next, the operation of the conventional example will be explained. If the cordless phone is unused and in standby mode, the second
The receiving circuit shown in the figure generally turns on and off the power intermittently to reduce power consumption. When the power is intermittently turned on, the frequency synthesizer circuit 17 consisting of the Vco 14, PLL 15 and reference crystal oscillation circuit 16
The base station performs reception on the control channel and waits for an incoming call from the base station. At this time, when a transmission wave from the base station is received, this receiving circuit is switched to continuous power supply, demodulates the control data for the incoming call operation, and shifts to the designated communication channel.

Setting of the channel is performed by a frequency synthesizer 17 which generates the 10th-cal frequency.

Problems to be Solved by the Invention However, in the conventional cordless telephone device, the entire receiving circuit including the frequency synthesizer circuit 7 is intermittently supplied with power during the reception standby operation, so that its power consumption is Compared to a single channel receiving circuit, the number of frequency synthesizer circuits is larger (therefore, there is a problem that the effective power during standby, which is determined by the intermittent period and the power consumption of all receiving circuits, cannot be reduced very much. There was a limit to the standby time determined by the capacity of the rechargeable battery that was the built-in power source, and there was a limit to how long standby operation could be achieved.

Means for Solving the Problems In order to achieve the above object, the present invention provides a system that can operate with less current consumption without operating a frequency synthesizer circuit in order to set the 10th-cal frequency on a control channel. By providing a dedicated crystal oscillation circuit, the power required during standby can be kept to a minimum.

Effects The present invention has the above-mentioned configuration, and provides a first method for setting a channel during an intermittent reception operation on a control channel during standby.
By obtaining the 0-cal frequency from a dedicated crystal oscillator circuit, the receiver circuit can operate with less power without running the frequency synthesizer circuit, and with the same capacity battery, a longer standby time can be achieved. can do. Also, in order to obtain the same standby time,
Since this can be achieved using a battery with a smaller capacity, the device can be made smaller and lighter.

Embodiment FIG. 1 is a block diagram of a radio reception circuit in a mobile station of a cordless telephone device showing an embodiment of the present invention.
Elements similar to those of the conventional example shown in the figure are given the same reference numerals. In other words, in Fig. 1, 1 is an antenna, 2 is a DPX (antenna duplexer) for distinguishing between transmitting and receiving frequencies, 3.5 is a bandpass filter that passes only the receiving frequency, and 4.8.10 is a high frequency. Amplification circuit, 6 is the first
0 - mixer circuit for the cull frequency and reception frequency, 7 is the first
9 is a mixer circuit for the 20th-cal frequency and intermediate frequency; 11 is the second intermediate frequency band-pass filter; 12 is a detection circuit; 13 is a low-frequency amplification circuit; 14 is a 10th-cal frequency mixer circuit; A VCO (voltage controlled oscillation circuit) for oscillating, 15 a PLL (phase locked loop) for controlling the 10th-cal frequency, 16 a reference crystal oscillation circuit including a crystal oscillator for obtaining a reference frequency of the PLL 15,
17 is a frequency synthesizer circuit consisting of these VCo 14, PPL 15 and reference crystal oscillation circuit 16;
18 is a 20th-Cull oscillation circuit for obtaining the 20th-Cull frequency, and 19 is a crystal oscillator.

Further, 20 is a 10th-Cull oscillation circuit for the control channel, and 21 is a crystal oscillator, which supplies the 10th-Cull frequency to the first mixer circuit 16 instead of the frequency synthesizer circuit 17 during standby. Reference numeral 22 denotes a high frequency switch, which is connected to side a during standby operation by a control circuit built into the mobile station to obtain a fixed local frequency sufficient to receive the control channel. 23
is a power supply changeover switch that switches in synchronization with the high frequency switch 22, and is connected to the a side during standby, and the first
A power supply is connected to the 0-cal oscillation circuit 20, and the power supply on the frequency synthesizer circuit 17 side is cut off.

Next, the operation of the above embodiment will be explained. During standby operation, the high frequency switch 22 and the power selector switch 2
3 to the a side, connect the power supply to the 10th-cal oscillation circuit 20 and the crystal resonator 21, and
oscillates the cull frequency. The mixer circuit 6 and the intermediate frequency bandpass filter 7 are tuned to the control channel using this 10th-cal frequency, and are waiting for input of the reception frequency.

When a control channel radio wave is input from the antenna 1, the high-frequency signal tuned by the 10th Cal frequency is demodulated by the detection circuit 12 through the subsequent stages and becomes a low-frequency signal, and the control data is transmitted. It demodulates and outputs the signal, and notifies a control circuit (not shown) of the carrier presence determination output.

When reception is completed on the control channel and the connection operation is to be started, each of the switches 22 and 23 is switched to the b side and the frequency synthesizer circuit 17 is operated.
A 10th-Cull frequency corresponding to the channel set to L15 is generated.

Thereafter, the transition to the communication channel is performed by rewriting the channel data set in the PLL 15, as in the conventional cordless telephone device.

When the call ends and the system returns to standby mode, the switches 22 and 23 are switched to the a side to stop the power supply to the frequency synthesizer circuit 17 and reduce the current consumption of the receiving circuit.

Effects of the Invention As is clear from the embodiments described above, the present invention allows the 10th-cal frequency of the receiving circuit during standby to be converted to the 10th-cal frequency exclusively used for control channel reception without operating the frequency synthesizer circuit.
- Since the power is obtained from the Cull oscillator circuit and the crystal oscillator, the power consumption can be significantly reduced. Therefore, it is possible to extend the standby time, eliminate the need for the user to charge the battery frequently, and eliminate the need for the user to charge the battery frequently. In addition, in order to obtain the same continuous standby time, the mobile station can be configured with a smaller capacity and weight battery, making it possible to make the mobile station smaller and lighter. This has the effect of improving usability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a wireless receiving circuit of a cordless telephone device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a wireless receiving circuit of a conventional cordless telephone device. 1... Antenna, 2... D that discriminates between transmitting and receiving frequencies
PX (antenna duplexer), 3.5... Reception frequency band pass filter, 4, 8.10... High frequency amplification circuit, 6... First mixer circuit, 7... First intermediate frequency band Pass filter, 9...Second mixer circuit, 11.
...Second intermediate frequency band pass filter, 12...Detection circuit, 13...Low frequency amplification circuit, 14...VcO (
voltage controlled oscillation circuit), 15... PLL (phase locked loop), 16... reference crystal oscillation circuit, 17... frequency synthesizer circuit, 18... 20th-cal oscillation circuit, 2
0...10th-Cal oscillation circuit (for control channel), 2
1... Crystal resonator, 22... High frequency switch, 23
...Power selector switch.

Claims (1)

[Claims] It consists of a base station connected to a telephone line and a mobile station wirelessly connected to this base station, and uses a multi-channel radio receiving circuit that uses a frequency synthesizer method to enable transmission and reception on multiple radio channels. The cordless telephone device is characterized in that reception operation on a control channel during standby is performed using a local frequency obtained by a dedicated crystal oscillation circuit, without using a local frequency obtained by a frequency synthesizer circuit. Cordless telephone equipment.