JP2003069488A - Mobile device, and reception frequency automatic control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and stably attain automatic frequency control while narrowing an AFC pull-in range without the need for using an expensive highly stable local oscillator. SOLUTION: The method of this invention comprises reading an initial reference control voltage from a storage circuit 156 or other reference control voltage as required, giving the read voltage to a digital/analog converter 158 via an addition/ subtraction circuit 157, converting the voltage into a control voltage, applying the control voltage to a voltage-controlled crystal oscillator 141, which oscillates a local oscillation signal with a corresponding frequency. A detection circuit 152 detects the received signal after frequency conversion, restores a phase modulation signal to detect phase information, an angle difference detection circuit 153 detects a deviation in the reception frequency from the angle difference and an addition/subtraction circuit corrects the reference control voltage so as to eliminate the deviation. When the reception is performed, the output reference control voltage information from the adder/subtraction circuit corresponding to the base station identification information detected by a base station ID detection circuit 155 is registered to the storage circuit as the reference control voltage information particular to the base station. The AFC operation at reception next time can be quickened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile station and a receiving automatic frequency control method for the same, and more particularly to a mobile station for transmitting and receiving radio signals to and from each of a plurality of base stations of a mobile communication system. The present invention relates to a mobile device that performs automatic frequency control of an oscillation frequency of a local oscillation signal for frequency conversion of a reception signal into an input frequency band of a detection unit when receiving a radio signal from a base station, and a reception automatic frequency control method thereof.

[0002]

2. Description of the Related Art Mobile stations (mobile units) of mobile communication systems
Transmits and receives radio signals to and from a plurality of base stations. When receiving a radio signal from each base station, the local oscillation signal is applied to the received signal, and the frequency is converted to a frequency band that the detection means can easily process, but in order to accurately match the received frequency to the transmission frequency of the base station, Usually, the local oscillator is composed of a voltage-controlled oscillator, and the frequency of the local oscillation signal is made variable by changing the voltage value according to the reception situation.
C: Automatic Frequency Con
troll).

[0003]

This AFC system is generally based on the SCPC (Single Channel Per).
When receiving using a signal with a narrow required bandwidth such as Carrier: 1 channel / 1 carrier, another signal exists in the vicinity of the frequency of that signal, so the pull-in range (frequency that can be pulled in) of AFC If the width is set large, unless a highly stable local oscillator is selected as the transmitter / receiver local oscillator, the signal is received outside the planned AFC pull-in range, and desired communication cannot be performed. That is, there is a problem that an expensive local oscillator must be used.

FIG. 7 shows an example of a conventional system. Each of the mobile devices (mobile stations) 4-1 to 4-4 stores only one initial reference voltage value as the value of the control voltage supplied to the voltage controlled local oscillator. Wireless area 3 of each base station 2-1 and 2-2
The downlink transmission frequencies (f1, f2) in 1, 3-2 are
The mobile units 4-1, 4-2, 4-3, 4-4 are within the AFC pull-in range (see FIG. 4). However, the downlink transmission frequency f3 of the emergency transmission type base station 2-3 and the reception frequency of the backup mobile station 4-5, which are not normally used, are frequency-shifted due to the secular change of the local oscillators used. Then, the mobile station 4-2 moves and the base station 2-3
, Or when the backup mobile station 4-5 is activated and receives the signal of the base station 2-1, it cannot be received if the downlink transmission frequency of the base station is outside the AFC pull-in range of the mobile device, It takes time to pull in even within the AFC pull-in range.

An object of the present invention is to provide a mobile station and its automatic reception frequency control which enable quick and stable automatic frequency control while narrowing the AFC pull-in range without using an expensive and highly stable local oscillator. To provide a method.

[0006]

A mobile device according to the present invention is used as a mobile station for transmitting and receiving radio signals to and from each of a plurality of base stations of a mobile communication system, and a radio signal from each of the base stations is transmitted. In a mobile station that performs automatic frequency control on the oscillation frequency of a local oscillation signal for frequency conversion of a received signal into the input frequency band of the detection means at the time of reception, the local unit oscillates at a frequency according to the value of the supplied control voltage. Voltage control oscillation means for outputting as an oscillation signal, and a plurality of reference control voltage value information including a preset initial value are stored, and a unique reference control voltage value obtained when a signal is received from each base station. Storage means capable of storing information in association with base station identification information of the base station, and detection by the detection means for a reception signal frequency-converted by the local oscillation signal Corresponding to the control voltage correction means for correcting the value of the reference control voltage value information read from the storage means based on the force, and the corrected reference control voltage value information output from the control voltage correction means. A control voltage generation means for generating a control voltage of a value and supplying it to the voltage controlled oscillation means and a signal transmission / reception with each of the base stations are controlled. By sequentially inputting any one of the stored plurality of reference control voltage value information to the control voltage correcting means, reception by automatic frequency control through the control voltage generating means and the voltage controlled oscillating means becomes possible. Together with the base station identification information extracted from the received signal of the base station that can be received, and the corrected reference control voltage value information output from the control voltage correction means at that time in association with each other. For the base station which is stored in the storage means and is received after the second time, the reference control voltage value information unique to the base station stored in the storage means at the time of the first reception is input to the control voltage correction means. By doing so, a control means that enables quicker and more stable automatic frequency control than during the first reception is provided.

Further, in the above structure, the received electric field strength detecting means for measuring the electric field strength of the received signal frequency-converted by the local oscillation signal to detect the presence of the received signal, and the detected electric field strength of the frequency-converted received signal. Detection means for recovering the phase-modulated and transmitted information symbol sequence,
The difference between the phase shift amount between the information symbols and the reference phase shift amount that is the closest to the corresponding phase shift amount among the reference unit phase shift amounts and multiples thereof. Angle difference detection means for detecting a certain angle difference, and base station identification information for synchronizing the data demodulated from the information symbol sequence and extracting the base station identification information of the base station when the signal is from the base station When the detection means and the reference control voltage value information read from the storage means are input to the control voltage generation means, and the presence of a reception signal is detected by the reception electric field strength detection means, the angle difference detection is performed. Means for correcting the increase or decrease of the value of the reference control voltage value information in a direction in which the angle difference detected by the means becomes “0”, and the storage means stores the angle by the angle difference detecting means. Difference “0” is detected And the modified reference control voltage value information output from the adding / subtracting means corresponding to the base station identification information extracted by the base station identification information detecting means may be newly stored or updated. .

Further, means for directly transmitting / receiving a radio signal to / from another mobile station without passing through a base station, reference control voltage value information unique to the base station stored in the storage means of the mobile station itself, and Of the means for transmitting the base station identification information to the other mobile device and the reference control voltage value information and the base station identification information unique to the base station stored in the other mobile device, which is received from the other mobile device, It may be configured to have a means for storing the reference control voltage value information and the base station identification information unique to the base station, which are not stored in the storage means of the own mobile device, in the storage means of the own mobile device.

The mobile communication system of the present invention comprises a plurality of base stations having different radio areas, and a plurality of mobile units having the above-mentioned configuration which move between the radio areas.

The automatic frequency control method of the present invention detects a received signal from each base station in a mobile station used as a mobile station for transmitting and receiving radio signals to and from each of a plurality of base stations of a mobile communication system. In the automatic frequency control method for the oscillation frequency of the local oscillation signal for frequency conversion into the input frequency band of the means, at the time of starting the reception to the base station immediately after the power is turned on, the initial reference control voltage value preset from the storage means Information is read out, a corresponding control voltage is generated and supplied to the voltage controlled oscillation means to oscillate a local oscillation signal having a frequency corresponding to the value of the control voltage, and the reference control voltage value information of the reference control voltage value information is generated based on the detection output of the detection means. By changing the receivable frequency while correcting the value, the signal reception from the base station is tried, and the initial reference control voltage value information is obtained. If the signal cannot be received at, the base station-specific reference control voltage value information or other preset reference control voltage value information is read out instead from the storage means, and similarly, the corresponding control voltage is generated. Frequency control signal is supplied to the voltage control oscillating means to oscillate a local oscillation signal having a frequency corresponding to the value of the control voltage, and the receivable frequency while correcting the value of the reference control voltage value information based on the detection output of the detecting means. When the signal reception from the base station is attempted by changing the signal, and the signal reception from the base station is possible, the base station is identified by the base station identification information in the received signal, and the corrected standard at that time is identified. There is a step of registering the control voltage value information in the storage means as reference control voltage value information unique to the base station.

In the above step, a radio signal is directly transmitted / received between the first mobile station and the second mobile station without passing through a base station, and the first mobile station stores the memory of its own mobile station. The base station which transmits the reference control voltage value information and the base station identification information unique to the base station registered in the means to the second mobile device, and which is received by the second mobile device from the first mobile device. Among the unique reference control voltage value information and the base station identification information, the reference control voltage value information and the base station identification information unique to the base station which are not registered in the storage means of the own mobile device are stored in the storage means of the own mobile device. The step of registering can be included.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the present invention will be described.
The present invention is based on an SCPC (Single Channel)
Per Carrier: In a mobile communication system in which a signal having a narrow required frequency bandwidth such as 1 channel / 1 carrier) is used and one wave is commonly assigned to a plurality of base stations, When performing communication between base stations, automatic reception frequency control to absorb frequency fluctuations that appear due to some factors such as secular change of the local oscillator of the base station transmitter, temperature change, Doppler effect, etc. (AFC: Automatic Frequ
With regard to (energy control), when the AFC pull-in range (pull-in frequency bandwidth) is narrowed in order to prevent reception of signals other than the desired wave, the frequency deviation of the desired wave and the oscillation frequency deviation of the local oscillating means of the receiving unit cause
Provided are means and methods capable of receiving signals even when there is a signal outside the FC pull-in range (pull-in frequency bandwidth).

Specifically, the reference voltage value of the local oscillator is stored at a frequency step width other than the initial value and a value corresponding to the base station which has been pulled in once, and is pulled in by the AFC pull-in range of the initial value. Even if it is not present, the stored value is used and the pull-in range of the AFC is varied to absorb a large shift in the transmission frequency or a shift in the reception frequency caused by aging. As a result, it is possible to quickly pull in the same base station from the second time.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a mobile device of the present invention, and shows only a portion related to the present invention. This mobile device is used as a mobile station of the mobile communication system shown in FIG. In FIG. 1, a mobile device (mobile station) 1 of this example includes a wireless unit 11 that transmits and receives wireless signals to and from a base station, a wireless unit 11 and an operation unit (not shown).
It has the control part 15 which controls the whole including a display part. In addition, the transmission / reception signal with the base station is π / 4QPSK
Use modulation method.

The radio section 11 controls the control section 1 according to the frequency of the local oscillation signal (local oscillation frequency, local frequency).
5, a mixer 121 and a mixer 12 for determining the transmission frequency by frequency conversion of the transmission signal (baseband signal) from
The transmission system 12 including the antenna 122 that transmits the frequency-converted transmission signal as a radio signal (after power amplification by an amplifier (not shown)), the antenna 131 that receives the radio signal, and the antenna 1 according to the local oscillation frequency.
The mixer 132 that performs frequency conversion of the signal received by 31 to determine the reception frequency, and the RSSI (reception electric field strength) of the reception signal (baseband signal) frequency-converted by the mixer 132 is measured to detect the presence of the reception signal. RSSI
It has a reception system 13 including a detection circuit 133, and a local oscillation circuit 14 that oscillates a local oscillation frequency supplied to the transmission system 12 and the reception system 13 according to the value of the control voltage from the control unit 15.

The local oscillator circuit 14 includes a voltage controlled crystal oscillator 141 that oscillates a reference frequency according to a control voltage value.
And a PLL circuit 142 that generates a higher local oscillation frequency based on the reference frequency.

The control unit 15 performs analog-to-digital conversion of the received signal (baseband signal) from the wireless unit 11 A
The D converter 151, a detection circuit 152 that detects the output of the AD converter 151 and restores the transmitted information symbol sequence by phase modulation (π / 4QPSK modulation), and the phase deviation between the information symbols of the output of the detection circuit 122. An angle difference that detects an angle difference that is a difference value between the shift amount and the reference phase shift amount that is the closest to the corresponding phase shift amount among the reference phase shift amount that is a predetermined unit phase shift amount and a multiple thereof. Detection circuit 153
And a data demodulation circuit 154 that demodulates the data sequence transmitted from the information symbol sequence that has passed through the angle difference detection circuit 153.
And a synchronization detection / base station ID detection circuit that detects the synchronization of the wireless line with the base station based on the output data of the data demodulation circuit 154 and extracts the base station identification information (base station ID) for identifying the base station. 155, a storage circuit 156 that stores a plurality of reference control voltage value information including a preset initial value and reference control voltage value information (digital value) unique to each base station, and a reference read from the storage circuit 156. The control voltage value information remains unchanged until the reception signal is detected by the RSSI detection circuit. When the reception signal is detected, reference control is performed in the direction in which the angle difference detected by the angle difference detection circuit 153 becomes “0”. The addition / subtraction circuit 157 which corrects the increase or decrease of the value of the voltage value information and outputs it, and the control voltage of the value (analog value) corresponding to the reference control voltage value information output from the addition / subtraction circuit 157 Conversion to and a DA converter 158 supplied to the voltage controlled crystal oscillator 141.

FIG. 2 shows a mobile communication system using the mobile device of the present invention as a mobile station. This system is based on the premise that channels of the same frequency are used in adjacent areas (radio areas corresponding to base stations), and the base stations 2-1 and 2-2 are base stations for constant transmission. , The base station 2-3 is an emergency transmission base station. Emergency transmission base stations usually do not transmit because they follow the boundaries of the area. The downlink transmission frequencies of the base stations 2-1, 2-2 and 2-3 and the base station identification information are (f1, ID1),
Let (f2, ID2) and (f3, ID3). Mobile station 1
-1, 1-3 are operating only in the respective areas 3-1 and 3-2 of the base stations 2-1, 2-3, and the mobile station 1-4 is of the base station 2-1. Area 3-1 to base station 2
-2 is a mobile station that has moved to area 3-2. The mobile station 1-2 is an emergency transmission base station 2 from the area of the base station 2-1.
-3 is a mobile station that has moved to the area. The spare mobile station 1-5 is a spare mobile station that is normally powered off,
It is assumed that the local oscillator, etc. has changed over time (deviation in control voltage vs. oscillation frequency characteristic).

FIG. 3 is a diagram showing an operation flow for performing AFC (automatic frequency control) of each mobile unit (mobile station) 1. FIG. 4 is a diagram showing the relationship between the AFC pull-in range in the mobile device and the downlink transmission frequency of each base station 2 (2-1 to 2-3). FIG. 5 is a diagram showing an example of setting the reference voltage value by the frequency band of the channel and the AFC pull-in range in the mobile device, and also shows a situation where the control voltage-oscillation frequency characteristic shifts due to aging. ing.

Next, the operation of the present invention will be described with reference to FIGS.

First, each mobile unit 1 (mobile stations 1-1 to 1-
The operation of 5) AFC will be described. In the initial state immediately after the power is turned on, the DA converter 158 converts the initial reference voltage value data read from the storage circuit 156 of the control unit 15 into an analog signal and controls the voltage of the wireless unit 11 as the frequency control voltage (reference control voltage value V0). It is applied to the crystal oscillator 141. The voltage controlled crystal oscillator 141 creates a reference frequency according to the applied control voltage, raises the frequency to the local frequency by the PLL 142, and determines the transmission frequency and the reception frequency by the mixers 121 and 132.

If there is downlink transmission (frequency f1, f2) of the base station within the AFC pull-in range, the RSSI detection circuit 133 senses the reception and performs the AFC operation.
When RSSI cannot be detected within the AFC pull-in range, reference voltage value data (corresponding to control voltage values V1 to V4) that covers the outside of the pull-in range is stored in the storage circuit 156 in advance as shown in FIG. 5, and changes to that value. By doing so, the AFC pull-in range is changed, and the transmission of the base station (frequency f3) is searched for.

The AD converter 151 of the control unit 15 performs analog-to-digital conversion on the received transmission signal of the base station, performs detection by the detection circuit 152, and receives the received signal (information symbol).
The frequency phase information of is detected. The angle difference detection circuit 153 detects the frequency phase difference (angle difference) with respect to the reference, and the addition / subtraction circuit 157 adds or subtracts the reference voltage value data,
DA converter 1 for the voltage value for correcting the frequency difference
Analog conversion is performed at 58, and the reference frequency and local frequency of the local oscillator circuit 14 are changed by the value. This series of operations is performed until the detected angle difference of the angle difference detection circuit 153 becomes "0", and the frequency error can be absorbed.

At this time, the transmission data of the base station is demodulated by the data demodulation circuit 154, and the synchronization detection / base station ID detection circuit 1
At 55, a sync signal is detected, and then base station identification information (base station ID) of the base station is detected. With the base station ID as a key, the output reference voltage value data of the addition / subtraction circuit 157 when the angle difference detected by the angle difference detection circuit 153 is “0” is stored as reference voltage value data unique to the base station in the storage circuit. It is stored (registered) in 156. If reference voltage value data has already been recorded for a certain base station ID and reference voltage value data having a different value is newly obtained, the recording is updated to the new reference voltage value data.

Next, the operation of the mobile device (mobile station) in each situation in the mobile communication system of FIG. 2 will be described with reference to the flowchart of FIG.

When the power is turned on, each mobile station 1 (1-1 to 1-5) determines the transmission / reception frequency based on the initial reference voltage value data read from the storage circuit 156 (step S1).

In the mobile station 1-1, since the transmission frequency (f1) of the base station 2-1 is within the AFC pull-in range of the initial reference voltage value, RSSI is detected (step S2) and synchronization detection is performed. (Step S3), the base station ID (ID1) is detected (step S4), and the base station 2-
The reference voltage value corresponding to 1 is stored (step S5).
This is the same for the mobile station 1-3 and the base station 2-2 (ID
The reference voltage value corresponding to 2) is stored.

In the mobile station 1-2, since the transmission frequency (f3) of the base station 2-3 is outside the AFC pull-in range, the process of step S2 shifts to the process of step S6. In the process of step S6, the mobile station 1-
Since No. 2 was in the area of the base station 2-1 until then, it has the reference voltage value corresponding to the base station 2-1 (ID1), and therefore the process proceeds to step S7. RSSI in the AFC pull-in range of the reception frequency corresponding to the base station 2-1
(Step S8), the RSSI cannot be detected because the frequency of the base station 2-2 is further deviated. Therefore, the process returns to step S6, but since there is no reference voltage value other than that of the base station 2-1, the process proceeds to step S12.

Here, as shown in FIG. 5, a preset reference voltage value in the memory circuit is varied (V1 to V4, usually selected from V1 to V2) to vary the AFC pull-in range. As a result of the change, since RSSI is detected (step S13), synchronization detection is performed (step S14), base station ID is detected (step S15), and AFC at that time is detected.
The reference voltage value drawn in is stored as the reference voltage value of the base station 2-3 (ID3) (step S16). As a result, since the mobile station 1-2 has the reference voltage of the base station 2-3, the mobile station 1-2 can be pulled into the transmission of the base station 2-3 sooner.

The mobile station 1-4, like the mobile station 1-3, operates when it moves from the area of the base station 2-1 to the area of the base station 2-2. After pulling in the AFC, the reference voltage value of the base station 2-2 (ID2) is stored.

In the spare mobile station 1-5, the power is not normally turned on and the local oscillator is aged, and at the reception frequency of the initial reference voltage value of the process of step S1, RSSI cannot be detected by the process of step S2. Then, the process proceeds to step S6. However, since it does not have the reference voltage value corresponding to the base station ID, the process proceeds to step S12,
The preset reference voltage value in the memory circuit is varied (selected from V1 to V4) to vary the AFC pull-in range. As shown in FIG. 5, when there is no secular change, the frequency band for one channel can be covered by three reference voltages V0, V1, and V2. If the control voltage-oscillation frequency characteristic shifts, V3 or V4
Is required.

As a result of changing the reference voltage value, RSSI will be detected (step S13), so synchronization detection is performed (step S14), base station ID is detected (step S15), and the AFC at that time is pulled in. The reference voltage value is stored as the reference voltage value of the base station 2-3 (step S16). After that, since the reference voltage value corresponding to the base station 2-1 is provided, it can be used as an AFC quickly and stably by using it.

As described above, even if the transmission frequency of the base station is received outside the pull-in range of AFC and AFC cannot be applied and demodulation cannot be performed, the reference voltage value set in the storage device is By variably (selecting) and searching outside the pull-in range of the AFC of the initial reference voltage value, AFC is applied and demodulation is possible. Further, in the system using the same frequency, by storing the reference voltage value corresponding to the base station ID, the AFC can be pulled in earlier in the second communication with the same base station.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 6, the basic operation is as described in the above-mentioned embodiment, but in the direct communication between mobile stations, the data of the base station IDs stored in the storage device are exchanged with each other, and the base station which the user does not own is exchanged. If there is a station ID, the data is used for the next communication. That is, each mobile device (mobile station) can directly transmit / receive a radio signal to / from another mobile device by the transmission system 12 and the reception system 13 of the radio unit 11 without using a base station. The control unit 15 of each mobile unit transmits the base station-specific reference control voltage value data and the base station ID stored in the storage circuit 156 to the other mobile unit via the radio unit 11, and the other mobile unit is moved. From the device, the reference control voltage value data unique to the base station and the base station ID stored in the mobile device are received, and the reference control voltage value data corresponding to the base station ID not stored in the storage circuit 156 is stored. It is stored in the circuit 156.

As a result, for example, even a mobile station (mobile station 1-4) that has never (or just arrived) visited the area 3-2 of the base station 2-2 will still be in the area of the base station 2-2. By communicating with a mobile station (mobile station 1-3) that has been (or is currently), the reference voltage value corresponding to the downlink transmission frequency of the base station 2-2 can be obtained, so that the base station 2- It is possible to quickly pull in even for the first reception from 2. Strictly speaking, the reference voltage value for the same base station is slightly different for each mobile station, but it is possible to surely pull in earlier than the case of sequentially selecting from preset reference voltage values and trying to pull in the AFC. . In addition, after pulling in once, the contents of the memory circuit are rewritten with the reference voltage value at that time, so it is the same as when pulling in with the reference voltage value only for the own station from the beginning, and it is even faster from the second reception. You will be able to pull in.

[0037]

According to the present invention, if the transmission frequency of the base station is received outside the pull-in range of AFC, A
Even if FC cannot be applied and demodulation is not possible, AFC can be applied and demodulated by varying the reference voltage value set in the storage device and searching outside the AFC pull-in range of the initial reference voltage value. Becomes Further, in the system using the same frequency, by storing the reference voltage value corresponding to the base station ID, the AFC can be pulled in earlier in the second communication with the same base station.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of a mobile device of the present invention.

FIG. 2 is a system schematic diagram for explaining the operation of the embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the present invention.

FIG. 4 is a diagram showing an example of a relationship between an AFC pull-in range in a mobile device and a transmission frequency from a base station.

FIG. 5 is a diagram showing an example of setting a reference voltage value based on a frequency band of a channel and an AFC pull-in range.

FIG. 6 is a system schematic diagram for explaining the operation of another embodiment of the present invention.

FIG. 7 is a system schematic diagram for explaining a conventional technique.

[Explanation of symbols]

1 (1-1 to 1-5) mobile station 2 (2-1 to 2-3) Base station 121,132 mixer 141 Voltage controlled crystal oscillator 152 Detection circuit 153 Angle difference detection circuit 154 Data demodulation circuit 155 Synchronization detection / base station ID detection circuit 156 memory circuit 157 Addition / subtraction circuit 158 DA converter

Claims (6)

[Claims] 1. A mobile station used for transmitting and receiving radio signals to and from each of a plurality of base stations of a mobile communication system,
When receiving a radio signal from each of the base stations, in a mobile device that performs automatic frequency control for the oscillation frequency of the local oscillation signal for frequency conversion of the reception signal into the input frequency band of the detection means, the value of the control voltage supplied Voltage control oscillating means for oscillating at a frequency according to the above and outputting as the local oscillation signal, and storing a plurality of reference control voltage value information including a preset initial value, and receiving a signal from each base station. Based on the detection output of the detection means for the received signal frequency-converted by the local oscillation signal, a storage means capable of storing the unique reference control voltage value information obtained at the time in association with the base station identification information of the base station. The control voltage correction means for correcting the value of the reference control voltage value information read from the storage means, and output from the control voltage correction means. The control voltage generation means for generating a control voltage having a value corresponding to the corrected reference control voltage value information and supplying it to the voltage controlled oscillation means and the signal transmission / reception with each of the base stations are controlled to be the first reception. For the base station, the control voltage generating means and the voltage controlled oscillator means are sequentially input to the control voltage correcting means by sequentially inputting one of the plurality of pieces of reference control voltage value information stored in advance in the storage means. It is possible to receive by automatic frequency control through, the base station identification information extracted from the received signal of the base station that can be received, and the corrected reference control voltage value output from the control voltage correction means at that time. The reference control voltage unique to the base station, which is stored in the storage unit at the time of the first reception, is stored in the storage unit in association with information and stored in the storage unit. A mobile unit comprising: a control unit that enables faster and more stable automatic frequency control than the first reception by inputting value information to the control voltage correction unit. 2. A reception electric field strength detecting means for measuring the electric field strength of the reception signal frequency-converted by the local oscillation signal to detect the presence of the reception signal, and the reception electric field strength detecting means for detecting the frequency conversion reception signal and phase-modulating the reception signal. Detecting means for recovering the transmitted information symbol sequence, the phase shift amount between the information symbols, and the corresponding phase shift of the reference phase shift amount consisting of a predetermined unit phase shift amount and its multiples. Angle difference detecting means for detecting an angle difference that is a difference value with the reference phase shift amount closest to the amount, and when the signal from the base station is synchronized with the data demodulated from the information symbol sequence, Base station identification information detecting means for extracting base station identification information of a base station, inputting reference control voltage value information read from the storage means to the control voltage generating means, and detecting the received electric field strength When it is detected that there is a received signal in the stage, the addition / subtraction means for correcting the increase or decrease of the value of the reference control voltage value information in the direction in which the angle difference detected by the angle difference detection means becomes "0". The storage means outputs, when the angle difference “0” is detected by the angle difference detection means, the addition / subtraction means corresponding to the base station identification information extracted by the base station identification information detection means. The mobile device according to claim 1, wherein the corrected reference control voltage value information is newly stored or updated. 3. A means for directly transmitting / receiving a radio signal to / from another mobile device without going through a base station, reference control voltage value information unique to the base station stored in the storage means of the mobile device itself, Means for transmitting the base station identification information to the other mobile device, among the base station-specific reference control voltage value information and the base station identification information received from the other mobile device and stored in the other mobile device The base station specific reference control voltage value information and the base station identification information, which are not stored in the storage means of the mobile station, are stored in the storage means of the mobile station. The mobile device described in 2. 4. A plurality of base stations having different wireless areas, and a plurality of mobile stations moving between the wireless areas.
Alternatively, the mobile communication system according to the third aspect is provided. 5. A mobile station used as a mobile station for transmitting and receiving radio signals to and from each of a plurality of base stations of a mobile communication system, a received signal from each of the base stations having a frequency in an input frequency band of a detection means. In an automatic frequency control method for the oscillation frequency of a local oscillation signal for conversion, at the time of starting reception to the base station immediately after power is turned on, preset reference control voltage value information for initialization is read from the storage means, and corresponding control is performed. A voltage is generated and supplied to the voltage controlled oscillating means to oscillate a local oscillating signal having a frequency corresponding to the value of the control voltage, and the value of the reference control voltage value information is corrected based on the detection output of the detecting means and received. When the signal reception from the base station is tried by changing the possible frequency, and the signal cannot be received with the initial reference control voltage value information. , The reference control voltage value information peculiar to the base station or other preset reference control voltage value information is sequentially read from the storage means instead, and similarly, a corresponding control voltage is generated and supplied to the voltage controlled oscillation means. By oscillating a local oscillation signal having a frequency corresponding to the value of the control voltage, and changing the receivable frequency while modifying the value of the reference control voltage value information based on the detection output of the detection means. From the base station, if the signal can be received from the base station, the base station is identified by the base station identification information in the received signal, and the corrected reference control voltage value information at that time is applied to the base station. A reception automatic frequency control method, characterized in that it is registered in the storage means as unique reference control voltage value information. 6. A radio signal is directly transmitted / received between the first mobile device and the second mobile device without passing through a base station, and is registered in the storage means of the mobile device itself from the first mobile device. The base station specific reference control voltage value information and the base station identification information that are transmitted to the second mobile station, and the second mobile station receives the base station specific reference control received from the first mobile station. Of the voltage value information and the base station identification information, the reference control voltage value information and the base station identification information unique to the base station that are not registered in the storage means of the mobile station are registered in the storage means of the mobile station. Claim 5 characterized by the above-mentioned.
The automatic reception frequency control method described.