JPH09149011A - Data communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid continuity of a state that synchronization data as to a data signal to be received are not properly recovered due to fading even under effect of fading attended with movement of mobile stations. SOLUTION: A control unit 15 that causes a state of a data signal from a transmission section 17 is sent through an antenna 19 or 21 for a data transmission period and that causes a state of a data signal through the antenna 19 or 21 is received by a reception section 22 for a data reception period discriminates a recovery state of synchronization data based on a synchronization data part included in the data signal through either of the antennas 19, 21 received by the reception section 22. When it is discriminated that the recovery state of the synchronization data is not proper, the data signal through the other of the antenna 19 or 21 is received by the reception section 22.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to performing data communication with a selected one of a plurality of distributed base stations using wireless communication means, for example, forming an on-vehicle mobile station. The present invention relates to a data communication device.

[0002]

2. Description of the Related Art In a digital cellular telephone system which is one of digital cordless telephone systems, each service area is called a "cell".
l) ”and divide into a plurality of divisions, one base station is installed in each“ cell ”, and the communication between telephones in the service area is the bases arranged in each“ cell ”. Therefore, each telephone in the service area transmits / receives a data signal to / from a base station. Forming a data communication device which is supposed to form a mobile station.

FIG. 3 shows an example of the relationship between the service area in the digital cellular telephone system and the data communication device (telephone) in the service area. In the example shown in FIG. 3, one service area is provided. Is 7 "cells" CA, CB, CC, CD, CE, CF and CG
The base stations Sa, Sb, Sc, Sd, Se, Sf and Sg are arranged in the "cells" CA to CG, respectively. Each of the base stations Sa to Sg has a mobile station switching station (MTSO: Mo-bile T) commonly installed for them.
elephone Switching Office). And within a service area, eg, within a “cell” CA,
The data communication device MS forming the mobile station uses the base station Sa arranged in the "cell" CA to which it belongs as a specific base station, and transmits / receives data signals to / from the specific base station.

Transmission and reception of a data signal between each data communication device in the service area and the base station are performed by, for example, TD.
This is performed under the adoption of a time division multiplex communication system such as a so-called MA (Time Division Multiple Access) system. Each data communication device has two antennas, one of which is used for both transmission and reception, because it is mounted on a vehicle to form a mobile station. In addition, at the time of reception, it is proposed to adopt an antenna diversity method in which one of the two antennas having a better reception condition for the data signal through it is selected and used by the antenna selection unit. There is.

In this way, the TDMA method is adopted, and the data signal is transmitted and received between the data communication device and the base station under the antenna diversity method for the reception in each data communication device. At this time, for example, a unit period called a frame period is set, and the frame period is repeated. FIG.
Shows an example of the frame period (FP). In the example of the frame period shown in FIG. 4, the whole (1FP) is 20
5. ms, of which the data transmission segmentation period T is 6.67 ms, the antenna selection operation segmentation period LM is 1 ms, and the data reception segmentation period R is 6.67 ms. It is divided into base station monitoring division periods I of 66 ms.

When each of the data communication devices in the service area is used, the "cell" to which the data communication device belongs in the divided period T for data transmission for each frame period when the data communication device is used (see FIG. In the case of the data communication device MS in 3, the operating state is taken for transmitting the data signal through one of the two antennas to the particular base station, which is the base station located in the "cell" CA). In the data reception division period R, a data signal from a specific base station (that is, a base station arranged in a "cell" to which the data communication device belongs) is selected from two antennas. The operation state of receiving through the one selected by the unit is taken, and the reception of the data signal through the one of the two antennas in the antenna selection operation division period LM. The antenna selector selects the one having the better state, and in the base station monitoring section period I, the "cell" adjacent to the cell to which it belongs (the data communication device in FIG. 3). In the case of MS, it is either "cell" CB to CG)
When a data signal from a base station other than a specific base station, which is regarded as the base station of the above, is received through one of the two antennas selected by the antenna selection unit, an operation state in which the reception state is detected is To be A data signal from a specific base station and a data signal from a base station other than the specific base station received by the data communication device have carrier frequencies different from each other.

A base station other than a specific base station obtained in the base station monitoring division period I (that is, a "cell" base station adjacent to a "cell" to which the data communication device belongs)
The detection result of the reception state of the data signal transmitted from the device is specified by the state included in the data signal in the data transmission section period T in the next frame period following the frame period including the base station monitoring section period I. Base station, that is, the "cell" to which the data communication device belongs
To the base station.

[0008]

As described above, a data communication apparatus that transmits and receives a data signal to and from a base station in a service area under the TDMA system and uses an antenna diversity method for reception. In this case, antenna selection is performed according to the antenna diversity method in the antenna selection operation division period LM included in each frame period, and two antenna selection operation division periods LM in each frame period are performed. One of the antennas that is considered to be in a good reception state for a data signal through the antenna is selected, and then the selected antenna is used to receive data following the segment period LM for antenna selection operation in the frame period. Reception of a data signal from a specific base station in the segmentation period R for The reception state of the data signal from the base station other than the specific base station in the base station monitoring division period I is detected, and further, the data signal is transmitted in the data transmission division period T in the next frame period. . That is, the selected state of the antenna selected in the antenna selection operation division period LM in a certain frame period is maintained at least until the antenna selection operation division period LM in the next data transmission division period T. Of.

When such a data communication device is mounted on an automobile and used to form an on-vehicle mobile station, a so-called fading phenomenon occurs in association with the selected antenna as the automobile moves at a relatively high speed. When a fading phenomenon related to the selected antenna occurs, the influence may affect the reception state of the data signal from the base station in the data reception division period R in each frame period. Become.

The data reception division period R in each frame period is, for example, as shown in FIG.
A preamble period P, a previous data period DTA in which the information data portion included in the data signal from the base station is received,
It includes a synchronous data period SW in which the synchronous data portion included in the data signal from the base station is received, a late data period DTB in which the information data portion included in the data signal from the base station is received, and the like. And under such circumstances,
When a fading phenomenon related to the selected antenna occurs due to the relatively high speed movement of the vehicle, the data signal in the data reception section period R in each frame period,
In particular, there is a possibility that the reception state of the sync data portion included in it and received in the sync data period SW may be affected.

As described above, the frame period is 20 ms in total, and each frame period is continuous. Therefore, the period of the synchronous data period SW in the data reception division period R in each frame period is, for example, 20 ms. On the other hand, regarding the fading phenomenon associated with the selected antenna, which occurs when the vehicle equipped with the data communication device is traveling, the fading frequency is Ff, the vehicle speed is Vv,
If the wavelength of the carrier component of the data signal is λ, then Ff =
The relationship of Vv / λ is established. Therefore, if the frequency of the carrier component is 800 MHz and therefore the wavelength λ of the carrier component is approximately 375 mm, the vehicle speed Vv of the automobile is approximately 67.
At Km / h (approximately 67 km per hour), and when the frequency of the carrier component is 1.5 GHz, and therefore the wavelength λ of the carrier component is approximately 200 mm, the vehicle speed Vv of the automobile is approximately 3
At 6 km / h (approximately 36 km / h), the fading frequency Ff is 50 Hz, and the fading cycle is 20.
ms.

That is, when the frequency of the carrier component of the received data signal is 800 MHz, the fading phenomenon associated with the selected antenna that occurs when the vehicle is traveling at about 67 km / h causes the fading period to be 20 ms. Further, when the frequency of the carrier component of the received data signal is 1.5 GHz, the fading phenomenon associated with the selected antenna that occurs when the vehicle travels at approximately 36 km / h,
The fading cycle is set to 20 ms, which coincides with the cycle of the synchronous data period SW in the data reception section period R in each frame period.

When the fading period in the fading phenomenon associated with the selected antenna is brought into a state in which it coincides with the period of the synchronous data period SW in the data reception division period R in each frame period, both phases are When they are substantially aligned, there is a situation in which the synchronization data portion included in the data signal from the base station, which is the portion corresponding to the synchronization data period SW in the data signal from the base station arriving at the selected antenna, is not properly received. It will continue. That is, due to the fading phenomenon associated with the selected antenna, which occurs with the running of the automobile, the synchronous data portion in the data signal from the base station arriving at the selected antenna is not properly received,
As a result, a situation may occur in which the synchronization data based on the data signal from the base station is not properly reproduced.

Moreover, such a situation cannot be eliminated even if the antenna selection in the antenna selection operation division period LM in each frame period is appropriately performed. Then, in such a situation that the synchronous data based on the data signal from the base station is not properly reproduced in the data reception division period R in each frame period, each data reception division is performed. Information data reproduced based on the information data portion received in the first data period DTA and the second data period DTB in the period R cannot be properly obtained.

In view of such a point, the present invention adopts the TDMA method for transmitting and receiving a data signal to and from a base station within a service area such as that set under a digital cordless telephone system. Data signal that should be received even when affected by the fading phenomenon caused by the movement of the mobile station when the antenna diversity method is used for reception. The situation in which the sync data based on the sync data part included in is not properly reproduced due to the fading phenomenon,
A data communication device that can be effectively avoided.

[0016]

A data communication apparatus according to the present invention includes a first and a second antenna, an antenna selecting section for selecting one of the first and second antennas, and an antenna selecting section. A transmitting unit which forms a data signal to be transmitted through one of the first and second antennas, and an external data signal through one of the first and second antennas selected by the antenna selecting unit. A receiving unit that receives and processes, performs a repetitive operation in units of a frame period including a data transmission segment period and a data reception segment period, and in the data transmission segment period,
In the state in which the data signal from the transmitter is transmitted through either the first or second antenna, or during the data reception segment period, the data signal from the outside through either the first or second antenna is And a motion control unit that causes a state to be received by the reception unit, and the motion control unit,
In the data reception division period, the reproduction state of the synchronization data based on the synchronization data portion included in the data signal from the outside through one of the first and second antennas received by the reception unit is determined, When it is determined that the reproduction state of the synchronization data is not proper, the antenna selection unit is made to be in a state of selecting the other of the first and second antennas.

In addition, in an example of the data communication device according to the present invention, the operation control unit includes a data transmission section period and a data reception section period in addition to the operation in the data reception section period described above. In the period between, the first level detection signal corresponding to the level of the data signal from the outside through the first antenna received by the receiver and the data from the outside through the second antenna received by the receiver. The second level detection signal corresponding to the signal level is compared, and the antenna selection unit obtains the larger one of the first and second level detection signals.
One of the antennas is selected.

The data communication apparatus according to the present invention is used as a mobile station in a service area such as that set under a digital cordless telephone system. In the case of being affected by a fading phenomenon caused by movement, that is, when one of the first and second antennas is selected by the antenna selection unit, a fading phenomenon associated with the selected antenna occurs and the fading phenomenon occurs. Due to a phenomenon, when the synchronization data portion included in the data signal arriving at the selected antenna is not properly received by the reception unit, and thus the synchronization data is not properly reproduced, the synchronization data by the operation control unit It is determined that the playback state of is not appropriate, and the operation control unit
The antenna selection unit is moved from a state of selecting one of the first and second antennas to a state of selecting the other of the first and second antennas.

As a result, the data signal, which was previously received through one of the first and second antennas, is placed in a state where it is received through the other of the first and second antennas. . At this time, the other of the first and second antennas newly selected by the antenna selection unit is affected by a fading phenomenon similar to the fading phenomenon associated with one of the first and second antennas. Is very low probability, and the reception condition for the synchronous data part included in the data signal is improved by using the other of the newly selected first and second antennas. . as a result,
After the antenna selector selects the other of the first and second antennas, the synchronization data part included in the data signal received through the other of the first and second antennas. The synchronous data is properly reproduced based on the above, and the state in which the synchronous data is not properly reproduced is prevented from continuing.

Therefore, according to the data communication apparatus of the present invention, the data signal to be received is used even if it is used as a constituent of a mobile station and affected by the fading phenomenon caused by the movement. It is possible to effectively avoid a situation where the sync data based on the included sync data portion is not properly reproduced due to the fading phenomenon.

[0021]

FIG. 1 shows an example of a data communication apparatus according to the present invention, which is used in a digital cellular telephone system to transmit and receive data signals to and from a base station. At this time, the TDMA system is adopted, and at the time of reception, a telephone is formed in which an antenna diversity method is adopted. An example of the data communication device according to the present invention that forms such a telephone is, for example, an automobile in a service area set under the digital cordless telephone system as shown in FIG. It is mounted and used for forming an on-vehicle mobile station.

In the example shown in FIG. 1, a voice signal QA obtained from a microphone 11 in response to a voice input thereto is supplied to an analog / digital (A / D) conversion section 12, digitized, and converted into A / A. D converter 12
The digital audio signal DA sent from is supplied to the encoding / decoding unit 13. In the encoding / decoding unit 13, the digital audio signal DA from the A / D conversion unit 12
On the basis of the above, the encoded voice information data DCA is obtained and the synchronization data DSA is obtained, and these are supplied to the time division multiplexing processing unit 14.

In the example shown in FIG. 1, a control unit 15 forming an operation control unit for controlling the operation of each unit is provided, and the time division multiplex processing unit 14 outputs from the control unit 15. Data DOD is also provided. And
In the time division multiplexing processing unit 14, under the control of the operation mode control signal CMS sent from the control unit 15, the audio information data DC from the encoding / decoding unit 13 is controlled.
A, the synchronous data DSA, the output data DOD from the control unit 15, and other data are time-division multiplexed to form multiplex combined data DTX, and the multiplex combined data DTX is supplied to the QPSK modulator 16.

In the QPSK modulator 16, four-phase phase modulation (Quadra phase modulation) using the multiplex combined data DTX as the modulation data is performed.
(ture phase shift keying: QPSK) modulation is performed, and the QPSK modulator 16 outputs multiple combined data DT.
A digital phase modulation signal SXM having a predetermined carrier frequency based on X is obtained and supplied to the transmitter 17. In the transmitter 17, under the control of the operation mode control signal CMS sent from the control unit 15,
Frequency conversion and other processing are performed on the digital phase modulation signal SXM to obtain the data signal SDT for transmission.
Is formed and is delivered to the selective contact 18a of the switch 18.

An operation mode control signal CMS sent from the control unit 15 is supplied to the switch 18, and the switch 18 is in a state in which the movable contact 18c is connected to the selection contact 18a by the operation mode control signal CMS. The data signal SDT for transmission from the transmitter 17 is transmitted via the switch 18 and the antenna 19 connected to the movable contact 18c of the switch 18 under the condition. At that time, the example shown in FIG. 1 is, for example, as a telephone mounted on an automobile, for example, in a service area formed by including seven “cells” CA to CG as shown in FIG. Or, for example, in a "cell" CA,
The data signal SDT transmitted from the antenna 19 is received by the base station Sa installed in the "cell" CA.

On the other hand, when the switch 18 is placed in a state in which the movable contact 18c is connected to the selection contact 18b by the operation mode control signal CMS sent from the control unit 15, for example, As shown in FIG. 3, the data signal transmitted from the base station Sa or the like installed in the “cell” CA included in the service area and reaching the antenna 19 passes through the switch 18 and the switch 18
Is supplied to the selection contact 20a of the switch 20 connected to the selection contact 18b. Further, an antenna 21 is connected to the selective contact 20b of the switch 20, and, for example, as shown in FIG. 3, a "cell" CA included in the service area.
The antenna 2 is transmitted from the base station Sa etc. installed inside
The data signal arriving at 0 is the selection contact 2 of the switch 20.
0b is supplied.

An antenna selection control signal CAS sent from the control unit 15 is supplied to the switch 20, and the switch 20 is brought into a state in which its movable contact 20c is connected to the selection contact 20a by the antenna selection control signal CAS. When placed, the data signal through the antenna 19 and the switch 18 is transferred to the movable contact 20c as the data signal SD.
When the switch 20 is derived from R and its movable contact 20c is connected to the selection contact 20b by the antenna selection control signal CAS, the antenna 2
The data signal through 1 is derived as the data signal SDR to the movable contact 20c. The data signal SDR derived from the movable contact 20c of the switch 20 is received by the receiving unit 2
2 is supplied.

The operation mode control signal CMS and the frequency switching control signal CFS sent from the control unit 15 are supplied to the receiver 22. In the receiver 22, under the control of the operation mode control signal CMS, the reception frequency is, for example, as shown in FIG. 3 according to the frequency switching control signal CFS.
“Cell” CA included in the service area as shown in
It is set to one corresponding to the carrier frequency of the data signal transmitted from any of the base stations Sa to Sg respectively installed in the CG.

Then, the receiving section 22 receives the data signal SDR having the carrier frequency corresponding to the receiving frequency set according to the frequency switching control signal CFS, and under the control of the operation mode control signal CMS, Frequency conversion and other processing are performed on the received data signal SDR to form a digital phase modulation signal SXD, which is supplied to the QPSK demodulation unit 23. QPS
In the K demodulator 23, the digital phase modulation signal SX
Demodulation according to the QPSK method for D is performed, and QP
From the SK demodulation unit 23, reception multiplex combined data DRX based on the digital phase modulation signal SXD is obtained, and this is supplied to the time division multiplex processing unit 14. Further, in the receiving unit 22, the level of the received data signal SDR is detected, and the detected data signal SDR obtained thereby is detected.
Of the detection signal SV representing the level of the control unit 15
Supplied to

In the time division multiplex processing unit 14, under the control of the operation mode control signal CMS sent from the control unit 15, the reproduction multiplex data DSB and the reproduction synchronous data DSB are reproduced from the reception multiplex combined data DRX from the QPSK demodulation unit 23. The voice information data DCB and the control information data DID are obtained separately. Then, the reproduction synchronization data DSB and the reproduction audio information data DCB are supplied to the encoding / decoding unit 13, and the reproduction synchronization data DSB and the control information data DID are supplied to the control unit 15.

In the encoding / decoding unit 13, the decoding of the reproduced audio information data DCB from the time division multiplexing processing unit 14 is referred to the reproduction synchronization data DSB from the time division multiplexing processing unit 14. Is performed to obtain a reproduced digital audio signal DB based on the reproduced audio information data DCB, which is the digital / analog (D / A) converter 2.
4 is supplied. Then, in the D / A converter 24, the reproduced digital audio signal DB is converted into an analog signal,
A reproduced audio signal QB is obtained, supplied to the speaker 25, and an audio output is emitted from the speaker 25.

An input operation section 26 and a display section 27 are connected to the control unit 15. The input operation unit 26 inputs various control data DK to the control unit 15 under the key switch operation, and
The display unit 27 displays the display control signal D from the control unit 15.
In accordance with P, a display indicating the operation control state and the like by the control unit 15 is displayed.

Under the circumstances, in the control unit 15, the time division multiplex processing unit 14, the transmission unit 17, the switch 18 are provided.
And 20, the receiving unit 22, and the like, when performing operation control on each unit, a frame period that is a unit period is set, and the frame period is repeated. The frame period set in the control unit 15 is, for example, as shown in FIG. 2 and described above. That is, the whole (1 FP) is set to 20 ms, of which 6.6 is
The data transmission division period T is set to 7 ms, the antenna selection operation division period LM is set to 1 ms, the data reception division period R is set to 6.67 ms, and the base station monitoring division period I is set to 5.66 ms. The divided period R for data reception is divided into the guard period G, the preamble period P, and the previous data period in which the information data portion included in the data signal from the base station is received, as shown in FIG. DTA, a synchronous data period SW in which the synchronous data part included in the data signal from the base station is received, a late data period DTB in which the information data part included in the data signal from the base station is received, etc. .

Then, as shown in FIG. 1, the control unit 15 performs the following operations in each frame period under the continuous arrival of the frame periods as shown in FIG. Is set to.

In the data transmission section period (T), which is the beginning of each frame period, the control unit 1
The operation mode control signal CMS, which is set to a high level, is transmitted from the signal transmission unit 5, and the time division multiplexing processing unit 14 and the transmission unit 1
The output data DOD from the control unit 15 is supplied to the time division multiplex processing unit 14 while being supplied to the switch 7, the switch 18, and the receiving unit 22. Thereby, in the time division multiplexing processing unit 14, the audio information data DCA and the synchronization data DS from the encoding / decoding unit 13
A, the output data DOD from the control unit 15, and further other data are time-division multiplexed to form multiplexed combined data DTX.
Frequency conversion and other processing are performed on the digital phase modulation signal SXM from the SK modulator 16 to form a data signal SDT for transmission. Further, the switch 18 is set so that the movable contact 18c is connected to the selection contact 18a, and the antenna 19 is selected. As a result, the data signal SDT for transmission from the transmission unit 17 is transmitted.
Is transmitted through the switch 18 and the antenna 19.

In this case, the receiving section 22 is placed in the non-operating state according to the operation mode control signal CMS which is set to the high level, but the receiving frequency in the receiving section 22 is At a time point before the start of the transmission division period T, for example, the example shown in FIG. 1 is installed such as the base station Sa installed in the “cell” CA included in the service area as shown in FIG. It is set to a frequency corresponding to the carrier frequency of the data signal transmitted from the base station (hereinafter referred to as the corresponding base station) installed in the opened "cell".

Next, in the antenna selecting operation division period LM, which is a period between the data transmission division period T and the data reception division period R, first, the control unit 15 is set to the low level. Operation mode control signal CMS
Is transmitted to the time division multiplexing processing unit 14, the transmission unit 17, the switch 18, and the reception unit 22, and at the same time, the control unit 15 outputs the antenna selection control signal CAS that is set to a high level. It is supplied to the switch 20. As a result, the switch 18 has its movable contact 1
8c is connected to the selection contact 18b, and the movable contact 20c of the switch 20 is connected to the selection contact 2b.
0a is connected.

At this time, the operation section control signal CMS, which is set to the low level, causes the transmitter section 17 to be inoperative and the receiver section 22 to be in operation. At this time, the reception frequency in the reception unit 22 is set to the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station.

As a result, the antenna 19 is selected by the switches 18 and 20 and is connected to the receiving section 22, and as a result, the data signal transmitted from the corresponding base station and arriving at the antenna 19 is switched. And 20
After that, the data signal SDR is supplied to the receiving unit 22, and is received by the receiving unit 22. And the receiver 2
2, the level of the data signal SDR from the corresponding base station received through the antenna 19 is detected, and the detection signal SV that is the first level detection signal SV1 corresponding to the level of the data signal SDR is the control unit. 15 are supplied. The control unit 15 supplied with the detection signal SV
In that case, the detection signal SV, that is, the first level detection signal SV1 is held.

Subsequently, the antenna selection control signal CAS, which has a low level, is sent from the control unit 15 and supplied to the switch 20. As a result, the switch 20 is brought into a state in which the movable contact 20c is connected to the selection contact 20b, the antenna 21 is selected by the switch 20, and the antenna 21 is connected to the reception unit 22. The antenna 21 is transmitted from the base station.
The data signal arriving at is supplied to the receiving unit 22 as a data signal SDR via the switch 20.

In this case, the receiving section 22 detects the level of the data signal SDR received from the corresponding base station through the antenna 21, and outputs the second level detection signal corresponding to the level of the data signal SDR. The detection signal SV that is SV2 is supplied to the control unit 15. In the control unit 15 to which the detection signal SV is supplied, the detection signal SV, that is, the second level detection signal SV2 is held.

Then, in the control unit 15, the first
Level detection signal SV1 and second level detection signal SV2
And the first level detection signal SV1 is greater than the second level detection signal SV2, the control unit 1
The antenna selection control signal CAS which is set to the high level from 5 is supplied to the switch 20 so that the movable contact 20c is connected to the selection contact 20a. That is, the switches 18 and 20
Thus, the antenna 19 is selected and connected to the receiving unit 22. When the first level detection signal SV1 is equal to or lower than the second level detection signal SV2, the control unit 15 sends the antenna selection control signal CAS which is set to the low level to the switch 20.
And the switch 20 is in a state in which the movable contact 20c is connected to the selection contact 20b. That is, the antenna 21 is selected by the switch 20 and connected to the receiving unit 22.

As described above, in the first antenna selection operation division period LM, the reception frequency of the reception unit 22 is set to the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station. Then, antenna selection is performed in which one of the antenna 19 and the antenna 21 is selected to be connected to the receiving unit 22.

In the data reception division period R following the antenna selection operation division period LM, the operation mode control signal CM which is set to the low level from the control unit 15
S is transmitted, and the time division multiplexing processing unit 14, the transmission unit 17,
While the state of being supplied to the switch 18 and the receiving unit 22 is maintained, the antenna selection control signal CAS sent from the control unit 15 and supplied to the switch 20 is sent at the end of the antenna selecting operation division period LM. Be maintained in a closed state. Therefore, the switch 18 is brought into a state in which the movable contact 18c is connected to the selection contact 18b, and the switch 20 is kept in the state taken at the end of the first antenna selection operation division period LM. It

At this time, the reception frequency in the reception unit 22 is maintained at the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station. Therefore, the data signal from the corresponding base station through the antenna 19 or the antenna 21 selected to be connected to the reception unit 22 in the antenna selection operation division period LM is supplied to the reception unit 22 as the data signal SDR and received. It is received by the unit 22.

Then, the receiving section 22 obtains a digital phase modulation signal SXD based on the received data signal SDR from the corresponding base station and supplies it to the QPSK demodulating section 23. Further, at this time, in the time division multiplexing processing unit 14, in accordance with the operation mode control signal CMS which is set to the low level, from the reception multiplex combined data DRX from the QPSK demodulating unit 23 to the reproduction synchronization data DS.
B, reproduced voice data DCB, control information data DID, etc. are separated and obtained. Then, the reproduction synchronization data DSB and the reproduction audio data DCB are supplied to the encoding / decoding unit 13, and as a result, from the speaker 25,
An audio output based on the reproduced audio data DCB is issued.
In addition, reproduction synchronization data DSB and control information data DID
Are supplied to the control unit 15.

At this time, in the control unit 15,
The display control signal DP corresponding to the control information data DID is formed and supplied to the display unit 27, and the data signal SDR from the corresponding base station received by the receiving unit 22 is received based on the reproduction synchronization data DSB. The reproduction state of the sync data is determined based on the included sync data portion.

Here, under the condition that one of the antennas 19 and 21 is selected by the switches 18 and 20, the example shown in FIG. 1 is moved by the traveling of the automobile in which the antenna is mounted, and the movement thereof is performed. Suppose that a fading phenomenon associated with one of the selected antennas 19 and 21 is generated. Then, as described above, the fading cycle in the fading phenomenon matches the cycle of the synchronous data period SW in the data receiving section period R in each frame period according to the traveling speed of the vehicle, Moreover, when the phases of both are substantially the same, the detection signal SV obtained from the receiving unit 22 and representing the level of the data signal SDR received through one of the selected antennas 19 and 21.
2 changes as represented by the solid line in FIG. 2, and the level of the received data signal SDR sharply decreases for each synchronous data period SW in the data reception division period R within each frame period. Will show that. That is, the received data signal SD
The level of the synchronous data portion included in R becomes extremely low, whereby the time division multiplexing processing unit 14
The reproduction synchronization data DSB from is not obtained properly.

Further, in this case, the selected antenna 19
, 21, and the unselected antennas 19 and 2 under the fading phenomenon associated with one of
Since it is extremely unlikely that the fading phenomenon associated with the other one of 1 will occur at the same time, it is generally considered that the fading phenomenon associated with the other of the unselected antennas 19 and 21 does not occur. Therefore, temporarily, at this time, the other of the antennas 19 and 21 is selected, and the antennas 19 and 21 in the receiving unit 22 are selected.
Assuming that the data signal is received through the other of the two, the detection signal obtained from the receiving unit 22 based on such an assumption and representing the level of the data signal SDR received through the other of the antennas 19 and 21. The SV changes, for example, as represented by a broken line as SVN in FIG. 2, and the level of the received data signal SDR in the synchronous data period SW in the data reception division period R in each frame period is relatively high. Will be shown. That is, the received data signal S
The level of the synchronous data portion included in the DR is set to a relatively high level, so that the reproduced synchronous data DSB from the time division multiplexing processing unit 14 is properly obtained.

The control unit 15 determines the reproduction state of the synchronization data based on the reproduction synchronization data DSB sequentially for each data reception division period R in each frame period, and as a result, the reproduction synchronization data DSB is properly obtained. If the situation in which the reproduction output of the synchronous data is not properly obtained is repeated a plurality of times, for example, seven times in succession, the control unit 15 determines that the reproduction state of the synchronous data is not appropriate. judge. Then, the control unit 15 that determines that the reproduction state of the synchronization data is not appropriate
Immediately before the synchronous data period SW in the data reception divided period R in the frame period that comes after that, for example, at the time point ta shown in FIG. 2, the antenna selection control signal CAS having a high level or a low level is sent to the switch 20. Switch 18 and 20 so that one of the antennas 19 and 21 is selected by switch 18 and 20.
Switch to the state in which the other one of 1 is selected.

As a result, in the data reception division period R in which such switching is performed, after the time point ta, the other of the antennas 19 and 21 is selected, and the antennas 19 and 21 are selected. The data signal SDR from the corresponding base station through the other of the two is received by the receiving unit 22. As a result, the synchronization data portion included in the data signal SDR is received by the reception unit 22 at a relatively high level, and the reproduction synchronization data DSB from the time division multiplexing processing unit 14 is properly obtained. It is possible to avoid a situation in which the reproduction synchronization data DSB cannot be properly obtained from the time division multiplexing processing unit 14.

Next, in the base station monitoring division period I following the data reception division period R, first, the control unit 1
From the control unit 15, the operation mode control signal CMS having a low level is transmitted from the control unit 5 and the state of being supplied to the time division multiplexing processing unit 14, the transmission unit 17, the switch 18, and the reception unit 22 is maintained. First, the reception frequency of the reception unit 22 is set to correspond to one of the base stations Sb to Sg installed in the "cells" CB to CG included in the service area as shown in FIG. 3, for example. A frequency switching control signal CFS for switching to a frequency corresponding to the carrier frequency of the data signal transmitted from a base station other than the base station is transmitted and supplied to the receiving unit 22. As a result, the reception frequency of the receiving unit 22 becomes a frequency corresponding to the carrier frequency of the data signal transmitted from the base station other than the corresponding base station.

Then, the data signal from the base station other than the corresponding base station through the antenna 19 or the antenna 21 selected to be connected to the receiving unit 22 in the terminal portion of the data reception division period R is the data signal SDR.
Is supplied to the receiving unit 22 and is received by the receiving unit 22.

At this time, the receiving unit 22 detects the level of the received data signal SDR from the base station other than the corresponding base station, and the receiving unit 22 receives the data signal SDR from the base station other than the corresponding base station. A detection signal SV representing the reception state of the signal is formed and is supplied to the control unit 15. In this way, the control unit 15 to which the detection signal SV representing the reception state of the data signal SDR from the base station other than the corresponding base station in the receiving unit 22 is supplied.
In, in accordance with the detection signal SV, the reception state of the data signal SDR from the base station other than the corresponding base station by the receiving unit 22 is detected, the output data DOD representing the result of the detection is formed, It is supplied to the time division multiplexing processing unit 14. The output data DOD supplied to the time division multiplex processing unit 14 is held by the time division multiplex processing unit 14.

After the output data DOD representing the detection result of the reception state of the data signal SDR from the base station other than the corresponding base station by the receiving unit 22 is supplied from the control unit 15 to the time division multiplexing processing unit 14, the control is performed. Unit 1
5, the frequency switching control signal CFS for switching the reception frequency in the receiving unit 22 to the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station is transmitted and supplied to the receiving unit 22. To be done. As a result, the receiving unit 22 performs an operation of returning the reception frequency to the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station, according to the frequency switching control signal CFS,
The reception frequency in the reception unit 22 is returned to the frequency corresponding to the carrier frequency of the data signal transmitted from the corresponding base station within the base station monitoring division period I.

In this way, one frame period is completed, and the receiving unit 22 from the base station other than the corresponding base station held by the time division multiplex processing unit 14 in the base station monitoring division period I. The output data DOD representing the detection result of the reception state of the data signal SDR is, in the data transmission division period T included in the next frame period,
With the voice information data DCA and the synchronization data DSA from the encoding / decoding unit 13, and other data,
It is supposed to form the multiple composite data DTX. Therefore, the output data DOD representing the detection result of the reception state of the data signal SDR from the base station other than the corresponding base station, which is obtained in the base station monitoring division period I included in a certain frame period, is In the data transmission division period T included in the next frame period, the transmission data signal SDT is formed, and is transmitted to the corresponding base station through the switch 18 and the antenna 19. Thereby, the reception state of the data signal from the base station other than the corresponding base station is monitored, and the result is reported to the corresponding base station.

[0057]

As is apparent from the above description, the data communication apparatus according to the present invention is used, for example, as a constituent of a mobile station and is affected by a fading phenomenon caused by the movement. That is, when one of the first and second antennas is selected by the antenna selection unit, a fading phenomenon associated with the selected antenna occurs, and the fading phenomenon causes a data signal to arrive at the selected antenna. The synchronous data part contained in is not properly received by the receiving unit, and
When the synchronization data is not properly reproduced, the operation control unit determines that the reproduction state of the synchronization data is not proper, and the antenna selection unit selects one of the first and second antennas. Since the state of selecting is changed to the state of selecting the other, and the data signal that has been received through one of the first and second antennas until then is received through the other, , The synchronization data is properly reproduced based on the synchronization data portion included in the data signal received through the other of the first and second antennas, and the state where the synchronization data is not properly reproduced does not continue. To be done.

Therefore, according to the data communication apparatus of the present invention, a data signal to be received is used even if it is used as a constituent of a mobile station and is affected by a fading phenomenon caused by the movement. It is possible to effectively avoid a situation in which the state in which the sync data based on the included sync data portion is not properly reproduced due to the fading phenomenon continues.

[Brief description of the drawings]

FIG. 1 is a block connection diagram showing an example of a data communication device according to the present invention.

FIG. 2 is a conceptual diagram provided for explaining an operation in each frame period in the example shown in FIG.

FIG. 3 is a conceptual diagram showing an example of a relationship between a service area and a data communication device (telephone) in a digital cellular telephone system.

FIG. 4 is a conceptual diagram for explaining a frame period set in the data communication device.

5 is a conceptual diagram for explaining a data reception division period in the frame period shown in FIG. 4;

[Explanation of Codes] 11 Microphone 12 A / D Converter 13 Encoding / Decoding Section 14 Time Division Multiplexing Section 15 Control Unit 16 QPSK Modulation Section 17 Transmitting Section 18, 20 Switch 19, 21 Antenna 22 Receiving Section 23 QPSK Demodulation Section 24 D / A conversion section 25 speaker 26 input operation section 27 display section

Claims (4)

[Claims] 1. A first and a second antenna, an antenna selection section for selecting one of the first and second antennas, and a first antenna for the first and second antennas selected by the antenna selection section. A transmitter that forms a data signal to be transmitted through any one of the first and second antennas selected by the antenna selector,
A receiving unit that receives and processes a data signal from the outside through any of the antennas of (1) and (2) performs a repeating operation in units of frame periods including a data transmission segment period and a data reception segment period, and A state in which the data signal from the transmitter is transmitted through either the first or second antenna in the transmission division period, or a state in which the data signal from the first or second antenna is transmitted in the data reception division period. An operation control unit that causes a state in which a data signal from the outside through any of them is received by the reception unit, and the operation control unit is received by the reception unit in the data reception division period. In the reproduction state of the synchronization data based on the synchronization data portion included in the data signal from the outside through one of the first and second antennas. Performs discrimination of stomach, when the playback state of the synchronous data is determined not to be appropriate, in the antenna selector, the first
And a data communication device characterized by causing the other of the second antenna to be selected. 2. When the operation control section determines that the reproduction state of the synchronous data is not proper, the operation of the synchronous data portion included in the external data signal in the incoming data reception division period is determined. 2. The data communication device according to claim 1, wherein immediately before, the antenna selection unit is brought into a state of selecting the other of the first and second antennas. 3. The operation control unit sequentially determines the reproduction state of the synchronization data based on the synchronization data portion included in the external data signal in each data reception division period, and as a result, the reproduction output of the synchronization data is obtained. 3. The data communication apparatus according to claim 1, wherein when a situation where the synchronization data has not been properly obtained continues a plurality of times, it is determined that the reproduction state of the synchronization data is not proper. 4. The operation control unit responds to the level of a data signal from the outside through the first antenna, which is received by the receiving unit, in the period between the data transmitting segment period and the data receiving segment period. The first level detection signal and the second level detection signal corresponding to the level of the data signal from the outside through the second antenna received by the reception unit are compared, and the antenna selection unit is configured to detect the first and second signals. 4. The state is set such that one of the first and second antennas, which is the larger one of the second level detection signals, is selected. The described data communication device.