JP2008298663A - Receiving device, radio controlled clock, and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve receiving sensitivity while miniaturizing a radio controlled clock and reducing power consumption and cost by simplifying switching of directional characteristics of an antenna of the radio controlled clock. <P>SOLUTION: The radio controlled clock 1 comprises the antenna 11 having directional characteristics corresponding to a case-grounded conductive part and receiving the input of a communication signal including time information which indicates a standard time; A directional characteristic changing section 12 changing the directional characteristic of the antenna by switching the conductive part; a receiving section 20 acquiring the time information from the communication signal input to the antenna 11; a time information output section 16 outputting the acquired time information; and a control section 14 instructing switching of the conductive part and re-receiving by the antenna whose directional characteristic is changed, when failing to acquire the time information from the communication signal input to the antenna 11 with one directional characteristic. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiving device, a radio timepiece, and a receiving method for receiving a communication signal including time information.

  A radio timepiece that receives a time signal transmitted by radio waves and displays accurate time information is a standard radio wave of a long wave band transmitted from a ground base station or a very high frequency wave transmitted from a GPS (Global Positioning System) satellite. In addition to a method for receiving a time signal in a band, in recent years, as described in Patent Document 1 below, for the purpose of mobile communication, radio waves in the ultra-high frequency band transmitted by CDMA (Code Division Multiple Access) modulation are transmitted. A timepiece device that receives a time signal included in the signal and obtains an accurate time has been proposed. Since such ultra-short-wave radio waves are relayed uniformly by various base stations, multiple radio waves are transmitted at the same time. Compared with long-wave standard radio waves and radio waves from GPS satellites, It is known that even various destinations such as these can receive well. In addition, as described in Patent Document 2 below, as a device for selecting a radio signal suitable for reception from radio signals transmitted from a plurality of base stations, a reflector is disposed in the vicinity of the antenna of the mobile phone device. There is known a mobile phone device that receives an optimal arrival radio wave from a base station by changing the directivity of an antenna in accordance with the received electric field strength or the like.

JP 2000-321383 A JP 2001-292017 A

  However, in the above-described mobile phone device, a reflector is disposed in the vicinity of the antenna, and in order to detect the received electric field strength and the like, an electric field strength detection means, a bit error rate (BER: Bit Error Rate) detection means, and the like are provided. Since it is necessary to add to the circuit of the device, the manufacturing cost, size and power consumption of the mobile phone device are increased.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The receiving device according to this application example has a directivity characteristic corresponding to a conductive part grounded in a housing, and switches the conductive part to an antenna to which a communication signal including time information indicating standard time is input. A directivity changing unit that changes the directivity of the antenna; a receiving unit that acquires the time information from the communication signal input to the antenna; and the switching of the conductive unit with respect to the directivity changing unit and the receiving unit. A control unit that instructs acquisition of time information, and when the control unit cannot acquire the time information from the communication signal input to the antenna having one directivity characteristic, The time information is instructed from the communication signal input to the antenna whose directivity characteristics have been changed. Characterized by instructions to acquire.

  According to such a configuration, when the time information cannot be acquired from the communication signal input to the antenna having one directivity characteristic, the directivity change unit is instructed to switch the conductive part grounded to the housing. Thus, the directivity of the antenna is changed, and the receiving unit is instructed to acquire time information from the communication signal input to the antenna having the changed directivity. Therefore, if the time information cannot be acquired from the communication signal without detecting the received signal strength of the input communication signal and determining the change in the antenna directivity, as in the past, the reception unit is switched to switch the conductive part. In addition to eliminating the need to detect the field strength, it is easy to change the antenna's directivity, so the configuration for switching the antenna's directivity can be simplified, resulting in smaller receivers, lower power consumption and manufacturing. Cost can be reduced.

[Application Example 2]
In the receiving apparatus according to the application example, the receiving unit includes a signal number information acquiring unit that acquires information on the number of signals of the communication signal input to the antenna, and the control unit has one directivity characteristic. When the number of signals of the communication signal input to the antenna is plural and the time information cannot be obtained from any of the plurality of communication signals, the conductive unit is switched with respect to the directivity changing unit. In addition to instructing, it is preferable to instruct the receiving unit to acquire the time information from the communication signal input to the antenna having the directional characteristic changed.

  According to such a configuration, when a plurality of communication signals are input to an antenna having one directivity and the time information cannot be acquired from any of these communication signals, the control unit Time information can be acquired from a communication signal input to an antenna whose directivity characteristics have been changed by instructing switching of the conductive portion.

[Application Example 3]
In the receiving apparatus according to the application example, the communication signal is transmitted for each base station by a CDMA system including a pilot channel signal, and the signal number information acquisition unit performs communication with the base station from the pilot channel signal. It is preferable to acquire information related to the number of communication signals based on a signal output when acquiring the synchronization timing.

According to such a configuration, since the signal number information acquisition unit can acquire the signal number of the communication signal from the signal output when acquiring the synchronization timing for communication with the base station, it detects the signal number. Therefore, the configuration of the apparatus can be further simplified without providing a new circuit.
[Application Example 4]
In the receiving device according to the application example described above, the directivity changing unit may switch the conductive unit using a switching diode.
[Application Example 5]
By applying the receiving apparatus according to the application example described above to a radio timepiece, it is possible to provide a radio timepiece having a reduced size, reduced power consumption, and reduced manufacturing cost due to a simplified configuration.
[Application Example 6]
In the radio timepiece according to the application example described above, it is preferable that one of the conductive portions is an exterior metal case.

According to such a configuration, the direction of the directivity can be changed efficiently by using the outer metal case of the radio timepiece as the conductive part of the antenna, and in addition, since the outer metal case of the radio timepiece is used, Since it is not necessary to add functional parts, it is possible to reduce the manufacturing cost and labor of the radio timepiece.
[Application Example 7]
The receiving method according to this application example includes a first step in which a communication signal including time information indicating a standard time is input to an antenna having directivity characteristics corresponding to a conductive part grounded in a housing, and the antenna is input to the antenna. In the second step of acquiring the time information from the communication signal, and in the second step, when the time information cannot be acquired from the communication signal input to the antenna having one directivity, And changing the directivity characteristic of the antenna by switching to obtain the time information from the communication signal input to the antenna with the changed directivity characteristic.

  According to such a method, when the time information cannot be obtained from the communication signal input to the antenna having one directivity characteristic, the directivity switching of the antenna is changed by instructing the switching of the conductive portion, and the change is made. It is instructed to acquire time information from a communication signal input to an antenna having the specified directivity. Therefore, if the time information cannot be acquired from the communication signal without detecting the received signal strength of the input communication signal and determining the change in the antenna directivity, as in the past, the reception unit is switched to switch the conductive part. In addition to eliminating the need to detect the electric field strength, the antenna directivity characteristics can be easily changed, so that the configuration for switching the antenna directivity characteristics can be simplified. , Low power consumption, and manufacturing cost reduction.

  Hereinafter, an embodiment of a radio timepiece will be described with reference to the drawings as an embodiment of a receiving apparatus.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of a radio timepiece 1 according to the first embodiment. FIG. 9 is a plan view showing a part of the inside of the radio timepiece 1. The radio timepiece 1 includes a receiving device that acquires time information of a standard time included in a radio wave of an ultra-high frequency band transmitted by CDMA modulation, and displays an accurate time corrected based on the standard time. That is, the radio timepiece 1 includes an antenna unit 10, a directivity changing unit 12, a control unit 14, a receiving unit 20, a time information output unit 16, a movement 17, and a metal housing 18. Among these, the antenna unit 10, the directivity changing unit 12, the control unit 14, the receiving unit 20, and the time information output unit 16 constitute a receiving device. In the first embodiment, the radio-controlled timepiece 1 is assumed to be a wristwatch, and the metal casing 18 is assumed to be an exterior metal case of the wristwatch. However, the metal casing 18 is not limited to the exterior metal case. As long as it is a metal member that constitutes, any component may be used.

  The antenna unit 10 has an antenna 11 in which the relationship between the radiation angle and the radiation intensity (directional characteristic) changes according to the conductive part to be grounded, and the time information indicating the standard time is CDMA-modulated and transmitted from the base station by radio waves. Received communication signal. In the first embodiment, the antenna 11 employs a chip antenna as shown in FIG. 9, and in a normal state, a metal member such as a GND portion of a substrate on which the antenna 11 is mounted is replaced with a pseudo member. It is used as ground (GND). Note that the shape of the antenna 11 is not limited to the chip antenna, and may be any shape as long as the directivity changes depending on the conductive part to be grounded.

  The directivity characteristic changing unit 12 changes the directivity characteristic of the antenna 11 by switching the conductive part grounded by the antenna unit 10 in accordance with an instruction from the control unit 14. In the first embodiment, the directivity changing unit 12 switches the ground destination by intermittently connecting the GND of the antenna 11 and the metal casing 18. Here, FIG. 2 is a diagram illustrating the directivity characteristics of the antenna 11. FIG. 2 (a) shows the directivity when the GND of the antenna 11 and the metal casing 18 are non-conductive, that is, when the GND of the antenna 11 is the GND portion of the substrate. The directivity characteristics when the GND of the antenna 11 and the metal casing 18 are conductive, that is, when the GND of the antenna 11 is the GND portion of the substrate and the metal casing 18 are shown. As shown in these two figures, in the first embodiment, by making the GND of the antenna 11 and the metal casing 18 conductive, the electric field characteristic of the antenna 11 is changed, and the chart showing the directivity characteristic is counterclockwise. Rotate about 30 degrees. In this case, since the metal casing 18 is a metal having a large capacity, such as an exterior metal case of a wristwatch, the directivity of the antenna 11 is increased by intermittently connecting the GND of the antenna 11 and the metal casing 18. Can change. In the first embodiment, the directional characteristics are switched by intermittently connecting the GND of the antenna 11 and the metal casing 18. However, the directional characteristic is switched to one metal portion such as the metal casing 18. Three or more directivity characteristics may be switched by switching a plurality of switches having different positions or switching a switch corresponding to each of the plurality of metal portions. Furthermore, the directivity may be changed by changing the impedance of the antenna 11 by intermittent connection with an electronic component such as a coil or a capacitor (not shown).

  Also, FIG. 3 shows that when radio waves transmitted from two base stations are receivable, one is a desired base station (base station A) and the other is a base station (base station B) where interference waves are transmitted. Is a graph showing a change in the error rate of data from the base station A due to a difference in radio wave intensity from the two base stations at a certain point. The horizontal axis of this graph indicates the received electric field intensity at a certain point, and the vertical axis indicates the BER. In this graph, in the case of “disturbance 0 dB (shown by a solid line)”, the intensity of the incoming radio wave from the base station A is substantially equal to the intensity of the incoming radio wave from the base station B. Even in a high state, an error floor occurs, and a BER below a certain value cannot be acquired. In such a state, even if the receiving unit 20 tries to acquire time multiple times, the possibility that time information can be acquired is reduced. On the other hand, as indicated by “jamming -5 dB (shown by a one-dot chain line)” and “jamming -10 dB (shown by a two-dot chain line)”, the intensity of the radio wave from the base station A and the radio wave from the base station B The BER can be greatly improved if the difference in intensity level can be several dB to 10 dB.

  In the above description, the radio wave from the base station A is the desired wave, and the radio wave from the base station B is the disturbing wave. However, since the same time information is transmitted from all the base stations, any radio wave is received. In the first embodiment, the radio wave having the stronger received electric field strength is received. Therefore, it is not necessary to change the directivity characteristics of the antenna 11 in a specific direction, and by slightly changing the directivity characteristics, the difference in intensity level between any one radio wave and other radio waves can be increased. BER is improved, and the success rate of demodulation / decoding processing of a communication signal, which will be described later, can be improved. Further, even when there is only one base station that can be received and sufficient reception field strength cannot be obtained due to the directivity characteristics of the antenna 11, the reception field strength is improved by slightly changing the directivity characteristics from the current state. Thus, the success rate of the demodulation / decoding processing of the communication signal can be improved. Furthermore, when other disturbing waves exist in the vicinity of the desired wave, there is a possibility that the interference is reduced by changing the directivity characteristics of the antenna 11 and the success rate of the demodulation / decoding process of the communication signal can be improved.

  Returning to FIG. 1, the reception unit 20 includes an RF (Radio Frequency) processing unit 22, a baseband processing unit 24, a time information extraction unit 26, and a data acquisition determination unit 27, and in response to an instruction from the control unit 14 Time information is acquired from the communication signal received by the unit 10. The RF processing unit 22 converts the high-frequency signal of the communication signal input to the antenna unit 10 into a baseband signal, and also performs AD conversion to convert it into a digital signal. The baseband processing unit 24 includes a synchronization unit 28 and a data acquisition unit 30. The baseband processing unit 24 performs CDMA demodulation processing on two digital signals (I signal and Q signal) whose phases are orthogonal to each other, and receives data including time information. Decrypt.

  Here, the function of the baseband processing unit 24 will be described in detail. The synchronization unit 28 acquires synchronization timing for synchronizing with the base station from the pilot channel signal included in the high-frequency signal. The data acquisition unit 30 has a function of acquiring sync channel signal data by demodulating the sync channel signal from the digital signal based on the acquired synchronization timing and decoding the demodulated sync channel signal. , A despreading unit 32, a modulation determining unit 34, and a decoding unit 36.

  In the first embodiment, the I signal and the Q signal are respectively input to the synchronization unit 28 and the despreading unit 32, and the synchronization unit 28 correlates the baseband signal and the short-period PN code to identify the base station. An operation is performed to notify the despreading unit 32 of the timing of the correlation peak. Based on the notified timing synchronization, the despreading unit 32 multiplies the I signal and the Q signal by a short-period PN code, and multiplies and integrates the 0th bit of the Walsh code that is a channelization code, thereby integrating the pilot channel The sync channel signal is demodulated by demodulating the signal and multiplying and integrating the Walsh code No. 32. The pilot channel signal is used to synchronize the base station and the receiver, and the sync channel signal is used to notify time information, system setting information, and the like from the base station. The modulation determination unit 34 excludes phase rotation from the pilot channel signal and determines binary phase shift keying (BPSK) data of the sync channel signal. The decoding unit 36 restores the rearrangement of the data order performed by the repeater and the interleaver at the time of data transmission from the base station to the original order by the deinterleaver and the delimiter. Further, the decoding unit 36 performs processing reverse to the convolutional encoding processing performed at the time of transmission by an error correction processing unit (not shown), thereby restoring data transmitted in 128-bit units to 32-bit units. To do. Of the data decoded by the data acquisition unit 30, the sync channel signal is sent to the time information extraction unit 26.

  The data acquisition determination unit 27 fails to acquire data when the data acquisition unit 30 cannot normally decode the sync channel signal due to insufficient received electric field strength of the received radio waves or the occurrence of mutual interference due to a plurality of radio waves. Information to that effect is sent to the control unit 14. On the other hand, when the sync channel signal is normally decoded, the time information extraction unit 26 extracts time-related information from the decoded sync channel signal data, and the extracted time-related information is the time information output unit 16. Sent to.

  The time information output unit 16 outputs the time information to other devices so that the time information is displayed or printed. In the radio timepiece 1 according to the first embodiment, time information is sent to the movement 17, and the display time is corrected based on the standard time. The movement 17 is a timepiece drive unit, and may be in any form of a digital timepiece or an analog timepiece. In addition, since the specific content of correcting the display time of the movement 17 based on the acquired time information is not the gist of the present invention, it is omitted (for example, this method is disclosed in Japanese Patent Application Laid-Open No. 2004-301712. See).

  The control unit 14 instructs the directivity changing unit 12 to switch between the antenna 11 and the conductive unit grounded to the housing, and the receiving unit 20 to acquire time information. Further, when information indicating that the sync channel signal decoding has failed is sent from the data acquisition determination unit 27, the directivity changing unit 12 is instructed to switch the conductive unit grounded to the case, and the change is made by this switching. The reception unit 20 is instructed to acquire time information from the communication signal input to the antenna 11 having the directional characteristics.

  Although not shown in the drawings, each of these functional units described above may be realized by an electric circuit, and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a memory card, and the like. These hardware and software may be realized in cooperation. Further, at least a part of these functional units may be mounted on an integrated circuit.

Next, the flow of processing in which the radio timepiece 1 receives a communication signal, extracts time information, and corrects the display time will be described with reference to FIG. When this process is started, first, a communication signal is input via the antenna 11 having a predetermined directivity (step S50). Next, the receiving unit 20 extracts time information from the communication signal received by the antenna 11 (step S52).
Subsequently, it is determined whether or not the reception unit 20 has been able to extract time information from the communication signal (step S54). If the time information has been extracted from the communication signal (Yes in step S54), the extracted time information is moved to the movement 17. (Step S60), the movement 17 corrects the display time based on the time information (Step S62), and ends the series of processes.

  On the other hand, when the time information cannot be extracted from the communication signal (No in step S54), the directivity changing unit 12 changes the directivity of the antenna 11 by switching between the antenna unit 10 and the conductive unit grounded to the housing ( Step S64). Subsequently, the process returns to the first step (step S50) so as to receive a communication signal by the antenna 11 having the directivity different from the previous time. In the first embodiment, since the time required for one reception is about 300 milliseconds, even if it is received a plurality of times, the user is hardly discomforted. When three or more directivity characteristics can be selected, the directivity characteristics may be sequentially switched and the process may return to the first step (step S50).

According to Embodiment 1 described above, there exist the following effects.
(1) When time information cannot be acquired from the received communication signal, the time information is acquired from the received communication signal again in order to receive the communication signal again after changing the directivity characteristics of the antenna 11 and acquire the time information. The possibility of being improved.
(2) Since the time required to receive the communication signal again and acquire the time information after changing the directivity characteristics of the antenna 11 is about 300 milliseconds, the user of the radio timepiece 1 does not feel uncomfortable. Time information can be acquired.

(Embodiment 2)
Next, Embodiment 2 will be described with reference to FIGS. In the following description, the same parts as those already described are denoted by the same reference numerals and description thereof is omitted. In the first embodiment described above, when the time information cannot be extracted from the communication signal, the control unit 14 instructs switching between the antenna unit 10 and the conductive unit grounded to the housing. In the second embodiment, as shown in the block diagram of FIG. 5, the baseband processing unit 24 further functions as a signal number information acquisition unit, and information on the number of base stations is transmitted from the baseband processing unit 24 to the control unit 14. It is done. As a result, when the time information cannot be extracted from any of the plurality of communication signals input to the antenna 11, the control unit 14 instructs the switching between the antenna unit 10 and the conductive unit grounded to the housing, and changes by this switching. The receiving unit 20 is instructed to acquire time information from one of the communication signals input to the antenna 11 having the directional characteristics.

  In the second embodiment, information regarding the number of base stations is acquired by the synchronization unit 28. Here, FIG. 6 is a diagram showing the output of the correlation peak obtained by the synchronization unit 28 performing the correlation calculation, and FIG. 6A shows the output when there is one receivable base station, FIG. 6B shows the output when there are two receivable base stations. As shown in FIG. 6B, after detecting the correlation peak of the output signal in the synchronization unit 28, the number of receivable base stations is detected by observing the output signal continuously for about 26.666 milliseconds. it can. Since the output signal for detecting the number of base stations is a signal that is output for the synchronization unit 28 to synchronize with the base station, the base station can be obtained simply by adding a circuit for outputting this signal to the synchronization unit 28. The number of stations can be detected.

  FIG. 7 shows a flow of processing in which the radio timepiece 1 receives a communication signal, extracts time information, and corrects the display time. In this process, if it is determined whether or not the reception unit 20 has extracted the time information from the communication signal (step S54) and the time information cannot be extracted from the communication signal (No in step S54), the reception unit 20 It is determined whether or not communication signals are received from a plurality of base stations from the correlation peak acquired when trying to acquire time information from the communication signal in S52 (step S58). In this case, the correlation peak of the output signal in the synchronization unit 28 may be observed again for at least about 26.666 milliseconds.

Here, when it is determined that communication signals are received from a plurality of base stations (Yes in step S58), the directivity changing unit 12 switches the antenna unit 10 and the conductive unit to be grounded to the antenna to change the antenna. 11 directivity characteristics are changed (step S64). Subsequently, the process returns to the first step (step S50) in order to receive a communication signal by the antenna 11 having the directivity different from the previous time.
On the other hand, when it is not determined that communication signals are received from a plurality of base stations (No in step S58), a series of processing ends. In this case, a series of processes may be executed from the beginning after a predetermined time has elapsed.

According to the second embodiment described above, in addition to the effects (1) and (2) described in the first embodiment, the following effects can be obtained.
(3) The number of base stations is acquired from information output by normal processing in the synchronization unit 28, and time information cannot be acquired from received communication signals, and communication signals from a plurality of base stations are received. Only in this case, the acquisition of time information is attempted by changing the directional characteristics of the antenna 11, so that re-reception can be performed efficiently by changing the directional characteristics of the antenna 11.

(Embodiment 3)
Next, Embodiment 3 will be described with reference to FIG. FIG. 8 is a block diagram showing the configuration of the radio timepiece 1 according to the third embodiment. In the first embodiment and the second embodiment described above, the directivity changing unit 12 switches the conductive unit that grounds the housing by intermittently connecting the GND of the antenna 11 and the metal housing 18 with a mechanical switch. However, in this Embodiment 3, it is intermittent by an electrical switch. In other words, the directivity changing unit 12 includes a diode 121, a capacitor 122, and a resistor 123, and controls conduction between the GND of the antenna 11 and the metal housing 18 using a DC control voltage and the diode 121. Moreover, it may replace with the diode 121 and may be switched by a relay.

According to the third embodiment described above, in addition to the effects (1), (2) and (3) described in the first and second embodiments, the following effects can be obtained.
(4) Since the antenna 11 switches the conductive portion grounded to the housing by an electrical switch, it is easy to control from the outside, and the drive portion is unnecessary, so that power saving can be achieved.

As described above, the description has been made based on the illustrated embodiments. However, the present invention is not limited to these embodiments, and modifications described below can be assumed.
(1) The receiving device is not limited to the mode of the radio timepiece 1, and may be applied to an information processing terminal or the like incorporating a clock function for correcting time by radio waves.

1 is a block diagram illustrating a configuration of a radio timepiece according to a first embodiment. The figure explaining the directional characteristic of an antenna. The figure which shows the change of the error rate which arises in the data of a desired base station by the intensity difference of the electromagnetic wave transmitted from two base stations. 6 is a flowchart illustrating a flow of processing in which the radio timepiece receives a communication signal, extracts time information, and corrects a display time in the first embodiment. FIG. 3 is a block diagram showing a configuration of a radio timepiece according to a second embodiment. (A) shows the output in the synchronization unit when there is one receivable base station, and (b) shows the output in the synchronization unit when there are two receivable base stations. 9 is a flowchart illustrating a flow of processing in which a radio timepiece receives a communication signal, extracts time information, and corrects a display time in the second embodiment. FIG. 5 is a block diagram showing a configuration of a radio timepiece according to a third embodiment. The top view which shows a part inside radio timepiece.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Radio clock, 10 ... Aerial part, 11 ... Antenna, 12 ... Directional characteristic change part, 14 ... Control part, 16 ... Time information output part, 17 ... Movement, 18 ... Metal housing, 20 ... Reception part, 22 ... RF processing unit, 24 ... baseband processing unit, 26 ... time information extraction unit, 27 ... data acquisition determination unit, 28 ... synchronization unit, 30 ... data acquisition unit, 32 ... despreading unit, 34 ... modulation determination unit, 36 ... Decoding section, 121 ... diode, 122 ... capacitor, 123 ... resistance.

Claims (7)

An antenna to which a communication signal including time information indicating standard time is input, having directivity characteristics according to the conductive portion grounded to the housing,
A directivity changing unit that changes the directivity of the antenna by switching the conductive unit;
A receiving unit that acquires the time information from the communication signal input to the antenna;
A control unit that instructs switching of the conductive unit with respect to the directivity changing unit and acquisition of the time information with respect to the receiving unit;
The controller is
When the time information cannot be acquired from the communication signal input to the antenna having one directivity characteristic,
The directivity changing unit is instructed to switch the conductive unit, and the receiving unit is instructed to acquire the time information from the communication signal input to the antenna whose directivity is changed. A receiving apparatus. The receiving device according to claim 1,
The reception unit includes a signal number information acquisition unit that acquires information regarding the number of signals of the communication signal input to the antenna;
When the control unit has a plurality of signals of the communication signal input to the antenna having one directivity characteristic and the time information cannot be obtained from any of the plurality of communication signals,
The directivity changing unit is instructed to switch the conductive unit, and the receiving unit is instructed to acquire the time information from the communication signal input to the antenna whose directivity is changed. A receiving apparatus. The receiving device according to claim 2,
The communication signal is transmitted for each base station by a CDMA system including a pilot channel signal,
The signal number information acquisition unit acquires information on the number of signals of the communication signal based on a signal output when acquiring synchronization timing for communication with the base station from the pilot channel signal. A receiving device. The receiving apparatus according to any one of claims 1 to 3,
The receiving device according to claim 1, wherein the directivity changing unit switches the conductive unit using a switching diode.   A radio timepiece to which the receiving apparatus according to claim 1 is applied. The radio timepiece according to claim 5,
One of the conductive parts is an exterior metal case. A first step in which a communication signal including time information indicating a standard time is input to an antenna having directivity according to a conductive portion grounded to the housing;
A second step of acquiring the time information from the communication signal input to the antenna;
In the second step, when the time information cannot be acquired from the communication signal input to the antenna having one directivity characteristic, the directivity characteristic of the antenna is changed by switching the conductive portion, And a third step of acquiring the time information from the communication signal input to the antenna whose directivity is changed.

Images