JPH0974589A - Cellular cordless master machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cellular cordless master machine which is capable of supplying stable service to a slave machine from the time when a power source is turned on. SOLUTION: In the cellular cordless master machine providing a cellular cordless slave machine with a service with a cellular base station, a decision means 28 deciding the significance/non-significance of a received signal and a reference frequency control means 24 calibrating the oscillation frequency of a reference oscillator 25 based on the frequency of the received signal are provided. The reference frequency control means 24 catches the time when the decision means 28 decides the non-significance of the received signal and receives the transmission signal of the cellular base station till the temperature rise of the reference oscillator 25 is saturated, and the calibration of the oscillation frequency of the reference oscillator 25 is repeated. Till the reference oscillator 25 performs a temperature saturation just after a power source is turned on, the transmission signal of the cellular base station is repeated and received, the oscillation frequency of the reference oscillator 25 is calibrated and the deviation of the oscillation frequency accompanying the temperature rise is corrected without stopping the service for the slave machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular cordless master unit in a digital cellular cordless system which can be used as a mobile unit of a portable telephone as a slave unit of a cordless telephone device, and more particularly to a frequency at the time of rising. It is designed to ensure stability.

[0002]

2. Description of the Related Art A digital cellular cordless system is a newly developed system which enables a mobile device of a portable telephone to be used as a slave device of a cordless telephone device.

In this system, as shown in FIG. 7, the cellular base station 1 forms a cellular service area 11 extending over a radius of several kilometers, and the cellular cordless base unit 2 forms a cellular cordless service area 12 in a narrow range. The cellular cordless cordless handset 3 walks through these service areas, and when it is located in the cellular service area 11, through the cellular base station 1,
When it is located in the cellular cordless service area 12, it can be connected to a wired line through the cellular cordless base unit 2. Also, in areas where those service areas overlap, the cellular cordless handset 3
Can be connected to both the cellular base station 1 and the cellular cordless base unit 2.

In order for the base station 1 and the base unit 2 to wirelessly connect to the cellular cordless handset 3, the carrier frequencies of the transmission signals to the handset 3 must be the same.
In this system, the 800 MHz band is used as a downlink frequency band for communication from the base station 1 or the master unit 2 to the slave unit 3, and as an uplink frequency band for communication from the slave unit 3 to the base station 1 or the master unit 2. , The 930 MHz band, which is 130 MHz higher than the downlink, is used.

Base station 1 equipped with a high-precision crystal oscillator
Can maintain the frequency 41 of the signal transmitted through the downlink constant, as shown in FIG. On the other hand, from the viewpoint of keeping the cost low, it is considered that the master unit has a rough reference oscillator, and therefore the oscillation frequency 42 fluctuates by about ± 4 ppm around the center frequency.
In order to match the reference frequency with that of the base station at startup, the master unit first receives the signal of the base station 1 and adjusts the oscillation frequency of the reference oscillator so as to follow the transmission frequency of the base station 1 (calibration). To do. Then, after the calibration is completed, the service is started.

Similarly to the master unit, the slave unit 3 having a coarse-accuracy reference oscillator receives a calibrated transmission signal from the master unit or a transmission signal from the base station and outputs a built-in low-precision reference oscillator. Calibrate the oscillation frequency. As a result, the child device 3 can receive the transmission signals from the base station 1 and the parent device 2,
Both services will be available.

As shown in FIG. 6, this digital cellular cordless master unit has a radio section 21 for frequency-converting a received wave into a baseband signal, and a radio section 21 for transmitting transmission data on a carrier wave and a radio section 21. Recovers a carrier with a single spectrum from the frequency-converted received signal, and
A demodulation unit 22 for demodulating data from the phase-modulated wave, and a demodulation unit 22
Frequency drift detection unit that detects the drift amount of the own frequency with respect to the base station transmission frequency from the carrier frequency obtained in
23, and a control voltage calculation unit 24 that generates a voltage that controls the reference oscillator according to the detected amount of detection and that performs switching control of the frequency accompanying the calibration operation of the reference frequency,
A reference oscillator 25 whose oscillation frequency is controllable by voltage, and a local oscillator which oscillates a signal phase-locked with the signal of the reference oscillator 25.
26 and a call control unit 27 that controls communication with the mobile device. The oscillation frequency accuracy of the local oscillator 26 depends on the frequency accuracy of the reference oscillator 25.

The signal received by the master unit is mixed with the signal oscillated by the local oscillator 26 in the radio unit 21, frequency-converted, and demodulated by the demodulation unit 22. The demodulation unit 22 demodulates the data and regenerates a carrier having a single spectrum from the frequency-converted reception signal, and the frequency drift detection unit 23 determines the frequency of the regenerated signal and the local oscillator 26.
The control voltage calculation unit 24 detects the deviation from the oscillation frequency of
A voltage according to the detected amount of deviation is calculated and output to the reference oscillator 25, and the reference oscillator 25 changes the oscillation frequency according to the voltage output from the control voltage calculation unit 24.

With this automatic control loop, the master unit can converge the frequency drift between its reference frequency and the reference frequency of the base station to an arbitrary value or less, and as a result, output from the radio unit 21 of the master unit. The frequency of the transmitted wave is also calibrated to match the cellular base station frequency.

The digital cellular cordless base unit is
The reference frequency is calibrated prior to the transmission of the downlink perch channel for notifying the information for the slave unit. Further, when adjusting the drift of the reference frequency due to aging, the control voltage calculation unit 24, by the information of the call control unit 27,
Check the time zone when there is no mobile station in the area, temporarily stop transmission of the downlink perch channel, switch to a frequency that can receive the downlink signal, receive the signal from the cellular base station, and receive the reference frequency. Calibrate.

When the master unit cannot receive the downlink signal of the cellular base station, the master unit starts the service by oscillating the reference oscillator 25 with an initial value preset at startup, and then the reference frequency due to a change with time. When adjusting the drift of, the transmission signal of the slave unit whose frequency is calibrated with the transmission frequency of the cellular base station as a reference is received under the control of the control voltage calculation unit 24, and the own frequency is adjusted to the frequency.

In this way, the master unit can supply the service to the slave unit by using an inexpensive oscillator without having a highly stable reference oscillator like the cellular base station.

[0013]

However, in the conventional digital cellular cordless base unit, the temperature of the base unit rises due to heat generation due to current consumption during continuous use after the power is turned on. The oscillation frequency of the reference oscillator continues to change until the saturation temperature is reached. Therefore, the reference frequency calibrated at startup changes with time, and the slave unit whose reference frequency is calibrated with the transmission frequency of the digital cellular cordless master unit immediately after the power is turned on has a lower reception rate for the master unit's transmission signal. In the worst case, the frequency drift of the base unit cannot be followed, and the service of the base unit cannot be received (the cellular cordless service area cannot be located, which is an out-of-range state).

FIG. 4 shows a change in the oscillation frequency of the oscillator with a change in temperature at this time. The oscillation frequency, which was Tn at the temperature when the initial power supply was started up, is lowered to Ts when the set temperature is saturated.

Such an adverse effect is a problem that occurs because a reference oscillator with coarse accuracy is used in the cellular cordless master unit. This is not a problem when using a high-grade reference oscillator, because it has a sufficient temperature compensation mechanism. Also, when starting the service after waiting for the master unit to reach the saturation temperature, there is no problem. However, if an inexpensive reference oscillator is used in order to reduce the cost of the cellular cordless master unit and the cellular cordless master unit is made to be usable immediately after the power is turned on, such a problem occurs.

Further, in the conventional digital cellular cordless master unit, when calibrating the change with time of the oscillation frequency of the reference oscillator after the start of operation, the transmission of the perch channel is stopped, the service is temporarily stopped, and then this calibration is performed. Are doing. Therefore, during that time, the service request of the child device cannot be met.

The present invention solves these problems, and even when an inexpensive reference oscillator is used, a stable service can be supplied to the slave unit (mobile unit) even after the power is turned on. The purpose is to provide a cellular cordless base unit.

[0018]

Therefore, in the present invention, in a cellular cordless master unit that provides a service to a cellular cordless slave unit together with a cellular base station, a determining unit that determines significance / insignificance of a received signal, Based on the frequency of the received signal, a reference frequency control means for calibrating the oscillation frequency of the reference oscillator is provided, and the reference frequency control means, until the temperature rise of the reference oscillator is saturated,
The determination unit is configured to capture the time when the reception signal is determined to be insignificant, receive the transmission signal of the cellular base station, and repeat the calibration of the oscillation frequency of the reference oscillator.

Further, when the reference frequency control means cannot receive the transmission signal of the cellular base station, the reference frequency control means receives the transmission signal of the slave unit whose oscillation frequency is calibrated based on the frequency of the transmission signal of the cellular base station and receives the reference oscillator. It is configured to repeat the calibration of the oscillation frequency.

Further, a temperature compensation parameter generating means for outputting a temperature compensation parameter for the oscillation frequency of the reference oscillator is provided to the reference frequency control means, and the reference frequency control means raises the temperature of the reference oscillator based on this temperature compensation parameter. It is configured so as to compensate for the accompanying fluctuation in the oscillation frequency.

Further, the temperature compensation parameter generating means is provided with a timer for measuring the elapsed time after the power is turned on, and a table describing the correspondence relationship between the elapsed time and the oscillation frequency. From the table to the present time, the amount of drift of the oscillation frequency is obtained from the table and output as a temperature compensation parameter.

[0022]

As a result, the oscillation frequency of the reference oscillator is calibrated by repeatedly receiving the transmission signal of the cellular base station from immediately after the power is turned on until the temperature of the reference oscillator is saturated. Is corrected. This reception is performed without stopping the service to the child device.

When the transmission signal of the cellular base station cannot be received, the transmission signal of the slave unit whose reference frequency is calibrated to the transmission frequency of the cellular base station is received to correct the deviation of the oscillation frequency due to the temperature rise. .

Further, in the master unit having the temperature compensation parameter generating means, the temperature compensation parameter generating means outputs the predicted value of the drift amount of the oscillation frequency due to the temperature rise, and the oscillation of the reference oscillator is based on this predicted value. The frequency is corrected. Therefore, even when the reception interval of the signal from the cellular base station or the handset is long, the deviation of the reference frequency can be suppressed low.

With such a configuration, even when an inexpensive reference oscillator is used for the cellular cordless master unit, stable service can be supplied to the slave unit.

[0026]

【Example】

(First Embodiment) As shown in FIG. 1, the digital cellular cordless base unit of the first embodiment is provided with a reception burst significant / insignificance determination unit 28 for determining significance / insignificance of a reception burst, and The control voltage calculation unit 24 controls the frequency switching associated with the reference frequency calibration operation based on the information of the reception burst significance / insensitivity determination unit 28 and the call control unit 27. Other configurations are the same as the conventional device.

After the power is turned on, this master unit receives the downlink signal of the cellular base station, and the radio unit 21, demodulation unit 22, frequency drift detection unit 23, control voltage calculation unit 24, reference oscillator 25, and local oscillator 26. The drift of the reference frequency output from the reference oscillator 25 is converged to an arbitrary value or less and the reference frequency is calibrated through the automatic control loop. It then sends the perch channel and starts the service.

At this time, since the main unit has just been powered on,
Since the temperature has not been saturated yet, the reference frequency output from the reference oscillator 25 drifts as the temperature of the reference oscillator 25 rises. In this temperature unsaturated state, the control voltage calculation unit 24 can receive the downlink of the cellular base station based on the information of the call control unit 27 and the reception burst significance / insensitivity determination unit 28 (cellular base station). If there is no call from the handset that interferes with the reception of the down line of the cellular phone, and if it can be judged that switching to this reception does not hinder the request of the handset, the signal of the down line of the cellular base station is received. The switching of the reception frequency is controlled so that the oscillation frequency of the reference oscillator 25 is calibrated. The control voltage calculation unit 24 intermittently performs this operation until the temperature of the parent device is saturated.

During this time, the call control unit 27 informs the control voltage calculation unit 24 when there is no slave unit in a call, and the reception burst significance / insensitivity judgment unit 28 makes random access from the slave unit. When no significant burst can be detected in a possible upstream control channel, it is determined that the control channel is not received, and the fact is notified to the control voltage calculation unit 24.

The control voltage calculator 24, as shown in FIG.
There is no cordless handset from the call control unit 27 (information channel (T
ch) is transmitted as an idle state), and the reception burst significant / intention determination unit 28 reports that there is no reception of the control channel, the slot time used for the Tch communication is used for the downlink reception of the cellular base station. Immediately switch the reception frequency to the downlink frequency so that it can be used,
The signal of the cellular base station is received and the reference frequency is calibrated. During this time, transmission continues normally.

As described above, the master unit according to the first embodiment receives many transmission signals from the cellular base station while continuing the frequency drift of the reference oscillator due to the temperature rise immediately after the power is turned on and continuing the service to the slave unit. This is solved by increasing the frequency of calibration of the reference frequency. By this calibration, the self-transmission frequency is calibrated, and the service to the child device can be stably supplied.

(Second Embodiment) In the second embodiment, the operation when the digital cellular cordless master unit of the first embodiment is in a position where the downlink signal of the cellular base station cannot be received will be described.

This master unit has a reference oscillator 25 after the power is turned on.
Attempts to receive the downlink signal of the cellular base station in order to calibrate At this time, the reception burst significance / insensitivity determination unit
When 28 cannot detect the reception of a significant burst and fails to receive the downlink signal of the cellular base station, the control voltage calculation unit 24 switches the reception frequency to the frequency for capturing the uplink, and the slave unit. Is received, and the reference oscillator 25 is calibrated based on the frequency of the transmission signal of the slave unit. This is because when the slave unit is in the service area of the cellular base station, the frequency is calibrated based on the reference frequency of the cellular base station.

The master unit thus starts the service after calibrating the oscillation frequency of the reference oscillator 25 based on the transmission frequency of the slave unit. At this time, since the base unit has just been powered on, the temperature is not yet saturated and the temperature rises with time, and the oscillation frequency of the reference oscillator 25 fluctuates accordingly. The master unit repeatedly receives the transmission signal of the slave unit until temperature saturation is reached, and each time the master unit calibrates the reference frequency based on the transmission frequency of the slave unit.

As described above, even when the master unit cannot receive the downlink signal of the cellular base station, the master unit receives the transmission signal of the slave unit and calibrates the oscillation frequency of the reference oscillator while continuing the service to the slave unit. By having many, the frequency drift of the reference frequency due to the temperature rise immediately after the power is turned on is eliminated. As a result, the parent device can provide a stable service to the child device while using an inexpensive reference oscillator.

(Third Embodiment) The digital signal of the third embodiment
As shown in FIG. 3, the cellular cordless master unit includes a temperature compensation parameter generation unit 29 that gives a temperature compensation control value to the control voltage calculation unit 24 that calculates the control voltage of the reference oscillator 25 in advance. Other configurations are the same as those of the base unit (FIG. 1) of the first embodiment.

This temperature compensation parameter generator 29 is shown in FIG.
It is provided with a table describing the correspondence between the elapsed time from the power supply startup and the oscillation frequency Tm at the elapsed time obtained from the characteristics of 1. and a timer for measuring the elapsed time from the power supply startup.

In this master unit, the control voltage calculation unit 24 controls the reception frequency so as to receive the downlink signal of the cellular base station when the power is turned on. A reference oscillator 25 is provided through an automatic control loop including a unit 21, a demodulator 22, a frequency drift detector 23, a control voltage calculator 24, a reference oscillator 25, and a local oscillator 26.
When calibrating the reference frequency of, the parameter generation unit 29 outputs the deviation expected due to the temperature rise to the control voltage calculation unit 24 as a drift amount to be corrected in advance, and the control voltage calculation unit 24 adds the correction amount to the reference voltage. Control the oscillator 25. The perch channel is then transmitted to start the service.

After that, until the master unit reaches the saturation temperature, the transmission signal of the cellular base station is intermittently received and the oscillation frequency of the reference oscillator 25 is set by the cellular base station by the same procedure as in the first embodiment. Also when calibrating based on the reference frequency, the parameter generator 29 outputs the deviation expected due to temperature rise to the control voltage calculator 24 as a drift amount to be corrected in advance, and the control voltage calculator 24 adds the correction amount. , Control the reference oscillator 25.

Therefore, in this master unit, the oscillation frequency of the reference oscillator 25 can be accurately compensated for the temperature change even if there is an interval in which the downlink signal of the cellular base station can be re-received. When the reference frequency is compensated by this temperature compensation control value, there is no need to increase the traffic and, of course, to stop the service.

If the downlink signal of the cellular base station is not successfully received at power-on, the oscillation frequency of the reference oscillator 25 is calibrated by the procedure of the second embodiment, and during the calibration, The oscillation frequency of the reference oscillator 25 is compensated based on the temperature compensation control value output by the temperature compensation parameter generator 29.

As described above, the digital cellular cordless master unit according to the third embodiment accurately compensates the fluctuation of the oscillating frequency due to the temperature change when the power is turned on, while using the inexpensive oscillator, to the slave unit. And stable service can be provided.

[0043]

As is apparent from the above description of the embodiments, the digital cellular cordless base unit of the present invention is
Even if the temperature rise that occurs immediately after the power is turned on induces fluctuations in the oscillation frequency of the reference oscillator, the reference frequency can be kept constant according to the reference frequency of the cellular base station, and this reference frequency must be calibrated. , Can be performed without interruption of service. Therefore, even when the parent device uses an inexpensive oscillator, it is possible to always provide a stable service to the child device.

Further, even when the base unit is in a position where the radio wave of the cellular base station cannot be received, its reference frequency can be adjusted to the reference frequency of the cellular base station via the handset unit, and the digital cellular cordless The system service can be stably supplied.

Further, in the master unit provided with the temperature compensation parameter generating section, it is possible to finely compensate the fluctuation of the oscillation frequency of the reference oscillator due to the temperature rise immediately after the power is turned on.
It is possible to provide more stable services.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital cellular cordless master unit according to a first embodiment of the present invention,

FIG. 2 is a diagram showing a timing at which a base unit of the first embodiment receives a signal of a cellular base station;

FIG. 3 is a block diagram showing a configuration of a digital cellular cordless master unit according to a third embodiment,

FIG. 4 is a characteristic diagram showing temperature dependence of an oscillation frequency in an oscillator,

FIG. 5 is an explanatory diagram showing frequency bands in a cellular cordless system,

FIG. 6 is a block diagram showing a configuration of a conventional digital cellular cordless base unit,

FIG. 7 is an explanatory diagram of a digital cellular cordless system.

[Explanation of symbols]

 1 Cellular base station 2 Cellular cordless master unit 3 Cellular cordless slave unit 11 Cellular service area 12 Cellular cordless service area 21 Radio section 22 Demodulation section 23 Frequency drift detection section 24 Control voltage calculation section 25 Reference oscillator 26 Local oscillator 27 Call control Part 28 Receive burst significance / insensitivity judgment part 29 Temperature compensation parameter generation part 41 Cellular base station reference frequency 42 Cellular cordless master unit oscillation frequency 43 Cellular cordless slave unit oscillation frequency

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akinori Tatsumi 4-3 Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd.

Claims (4)

[Claims] 1. A cellular cordless master unit that provides a service to a cellular cordless slave unit together with a cellular base station, and a criterion based on the frequency of the received signal and a determination unit that determines significance / insignificance of the received signal. Reference frequency control means for calibrating the oscillation frequency of the oscillator, the reference frequency control means, until the temperature rise of the reference oscillator is saturated, the determination means determines the time to determine the insignificance of the received signal. A cellular cordless master unit, which captures and receives a transmission signal of the cellular base station and repeats calibration of the oscillation frequency of the reference oscillator. 2. The reference frequency control means, when the transmission signal of the cellular base station cannot be received, receives the transmission signal of the slave unit whose oscillation frequency is calibrated based on the frequency of the transmission signal of the cellular base station, A cellular cordless master unit, wherein calibration of the oscillation frequency of the reference oscillator is repeated. 3. A temperature compensation parameter generation means for outputting a temperature compensation parameter of an oscillation frequency of the reference oscillator to the reference frequency control means, the reference frequency control means being based on the temperature compensation parameter. The cellular cordless master unit according to claim 1 or 2, which compensates for fluctuations in the oscillating frequency due to the temperature rise. 4. The temperature compensation parameter generating means comprises a timer for measuring an elapsed time after the power is turned on, and a table describing a correspondence relationship between the elapsed time and an oscillation frequency. The cellular cordless master unit according to claim 3, wherein a drift amount of the oscillation frequency from time to the current time is obtained from the table and is output as the temperature compensation parameter.