JP2986232B2 - Wireless communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication device such as an automobile / portable radio telephone device and a cordless telephone device.
In particular, the present invention relates to a wireless communication device provided with a frequency synthesizer as a local oscillator.

[0002]

2. Description of the Related Art Generally, a radio telephone apparatus is provided with a PLL (Phase
A local oscillator frequency corresponding to the radio communication channel is generated from a frequency synthesizer using a locked loop circuit. The local oscillation frequency is converted into an intermediate frequency signal by mixing the local oscillation frequency with a received high frequency signal in a receiving circuit, and the intermediate frequency signal is amplified and then detected to reproduce a received baseband signal. Further, the transmission circuit modulates the transmission carrier signal with the transmission baseband signal, converts the modulated transmission carrier with the local oscillation frequency generated from the frequency synthesizer, converts it into a radio channel frequency, and transmits the radio channel frequency from the antenna. It is configured as follows.

The deviation between the reception and transmission local oscillation frequencies of this type of apparatus is determined by the frequency deviation of a reference oscillator provided to supply a reference signal to a frequency synthesizer. For this reason, a temperature-compensated crystal oscillator (TCXO) is generally used as the reference oscillator.
However, even when this TCXO is used, the frequency division number of the frequency divider that sets the oscillation frequency of the frequency synthesizer changes due to the effects of lightning surge and various noises generated in the vehicle, and the oscillation frequency of the frequency synthesizer changes. The channel may be set incorrectly. In some cases, the oscillation frequency of the frequency synthesizer shifts to the frequency band of another wireless communication system different from its own wireless communication system, whereby the PLL circuit of the frequency synthesizer is unlocked.

[0004] When such an oscillation frequency shift occurs, not only normal communication becomes impossible, but also other communication channels are disturbed and other radio communication systems are adversely affected. Very unfavorable. The interference to these other channels and to other wireless communication systems is caused by the recent wireless telephone systems in which the channel separation is becoming narrower and the bandwidth used between a plurality of wireless communication systems is approaching. Is a particularly big problem.

Therefore, conventionally, the oscillation frequency of the frequency synthesizer is reset arbitrarily or periodically during the transmission / reception period. The resetting of the oscillation frequency is performed, for example, by re-supplying the channel designating information from the control circuit to the voltage controlled oscillator (VCO) of the frequency synthesizer during the call period, thereby setting the oscillation frequency of the VCO to the radio communication channel in use. This is done by resetting to the corresponding frequency value.

[0006]

However, in such a conventional wireless communication device, the operation of resetting the oscillation frequency of the frequency synthesizer is performed during a call. For this reason, unnecessary modulation is added to the speech signal and the carrier signal due to the reset frequency component, and as a result, the S / N of the speech signal may be deteriorated. On the other hand, in order to prevent the deterioration of S / N, for example, it is considered that a shield structure is provided to the frequency synthesizer so that the frequency synthesizer is not affected by noise generated at the time of resetting the frequency. However, such a device has another problem that the size and cost of the frequency synthesizer circuit are increased due to the shield structure.

The present invention has been made in view of the above circumstances, and provides a wireless communication apparatus capable of performing channel resetting without using a frequency synthesizer having a special noise countermeasure and without affecting communication with noise. Aim.

[0008]

In order to achieve the above object, the present invention provides a radio communication apparatus used in a system employing a time-division multiple access system. Focus on the point that the communication operation is performed only during the slot and the communication operation is interrupted during the other periods.
A communication period determining unit and a frequency resetting unit are provided. Then, it is determined by the communication period determining means whether or not it is the period of the communication slot allocated to itself, and based on the determination result of the communication period determining means, the communication slot other than the communication slot allocated to itself by the frequency resetting means is determined. During the period, the oscillation frequency of the frequency synthesizer is reset to an accurate local oscillation frequency.

Further, according to the present invention, by means of frequency resetting means,
Resetting the oscillation frequency of the frequency synthesizer to a local oscillation frequency corresponding to a predetermined wireless communication channel within a period other than the communication slot assigned to itself and immediately before the next communication slot assigned to itself. Also features.

[0010]

As a result, according to the present invention, the operation of resetting the frequency for the frequency synthesizer is performed during an idle slot period other than the period of the communication slot allocated to the frequency synthesizer. There is no need to worry about unnecessary modulation added to the signal, thereby preventing the S / N of the communication signal from deteriorating. Therefore, high quality communication can be performed. Further, since it is not necessary to take any special measures such as a shield structure for the frequency synthesizer in order to prevent the deterioration of the S / N ratio, the frequency synthesizer circuit does not become large and the cost does not increase.

Further, since the radio channel frequency is reset within a period other than the communication slot allocated to itself and at a position immediately before the next communication slot allocated to itself, It is possible to clear all the frequency shifts that have occurred during the period, thereby making it possible to reduce the probability that communication will be performed in a state where a frequency shift has occurred in the next used slot.

[0012]

FIG. 1 shows the configuration of an automobile radio telephone apparatus for explaining an embodiment of the present invention. In FIG. 1, a radio communication signal transmitted from a base station (not shown) in a predetermined time slot of a radio communication channel being set is input to a receiving circuit (RX) 3 via an antenna 1 and a duplexer (DUP) 2. Here, the signal is combined with a local oscillation signal output from the receiving frequency synthesizer 41 of the frequency synthesizer circuit 4 and converted into an intermediate frequency signal. The received intermediate frequency signal is digitally demodulated after frame synchronization and bit synchronization are established by the digital code decoding circuit (MOD) 6. The synchronization signal obtained by the frame synchronization and the bit synchronization is supplied to a control circuit (CONT) 20. The digital demodulated signal output from the digital code decoding circuit 6 includes a digital communication signal and a digital control signal, and the digital control signal is supplied to the control circuit 20 and identified. On the other hand, the digital speech signal is supplied to an equalizer (EQL) 7, where the demodulated waveform is equalized, and then an error correction code decoding circuit (CH-CO
D) Error correction decoding is performed at 8. Then, after being decoded by an audio codec (SP-COD) 9 and returned to an analog communication signal, the signal is supplied to a speaker 10 as a receiver, and the speaker 10 outputs a sound.

On the other hand, a transmission signal output from a microphone 11 as a transmitter is input to a voice code decoding circuit 9, where it is coded. The digital transmission signal obtained by this encoding is error-correction-coded by the error-correction code decoding circuit 8 together with the digital control signal output from the control circuit 20, and then input to the digital code decoding circuit 6. In the digital code decoding circuit 6, a modulation signal of an intermediate frequency corresponding to the digital transmission signal supplied from the error correction code decoding circuit 8 is generated and input to the transmission circuit (TX) 5. In the transmission circuit 5, the modulated signal is combined with a local oscillation signal output from the transmission frequency synthesizer 42 and converted into a high-frequency signal. The high-frequency signal is amplified by the high-frequency signal from the antenna 1 via the duplexer 2. Sent to the base station. Reference numeral 12 denotes an input display unit having switches such as a dial key and a transmission switch and a display.

The control circuit 20 includes, for example, a microcomputer as a main control unit. The control circuit 20 includes a connection control unit for setting a radio communication channel with a base station in connection with an outgoing call and an incoming call. In addition to the timing control means for controlling transmission / reception timing according to the positions of the transmission slot and the reception slot allocated to itself, a communication period determination means 21 and a channel reset control means 22 are newly provided. doing.

The communication period determination means 21 detects a period of an idle slot other than a period of a transmission slot and a reception slot to which it is assigned during a call. Further, while the idle period is detected by the communication period determining unit 21, the channel resetting control unit 22 performs channel designation corresponding to the currently set reception radio channel frequency and transmission radio channel frequency. The information is supplied to the frequency synthesizers 41 and 42, and thereby the radio channel frequencies are reset for the frequency synthesizers 41 and 42.

Next, the operation of the above-configured apparatus will be described according to the control procedure of the control circuit 20. Here, fR is set as the radio channel frequency for reception, and fT is set as the radio channel frequency for transmission, and these radio channel frequencies are set as shown in FIG.
R, fT (6 time slots TS1
To TS6), it is assumed that communication data is transmitted / received to / from a base station (not shown) using the time slot TS1.

In this call state, the control circuit 20 monitors the end of the call in step 2a as shown in FIG.
Monitoring of the start timing. In this state, when the call is ended and the call end operation is performed, the control circuit 20 shifts to step 21 to execute the call end control, and returns to the standby state.

On the other hand, at the start timing of the transmission slot TS1, the control circuit 20 shifts from step 2b to step 2c, where the transmission circuit 5 is first set to the transmission operation state. Is performed. Then, while performing the transmission control, the end timing of the transmission slot TS1 is monitored in step 2e, and when the end timing of the transmission slot TS1 is reached, the operation of the transmission circuit 5 is stopped in step 2f. When the transmission operation in one frame is completed, the control circuit 20 monitors the start timing of the reception slot TS1 in step 2g. And
At the start timing of the receiving slot TS1, the receiving circuit 3 is set to the operation state in step 2h, and then in step 2i, receiving control of the received data coming from the base station is executed. The control circuit 20 monitors the end timing of the reception slot TS1 in step 2j during the reception control, and when the end timing comes, stops the operation of the reception circuit 3 in step 2k, thereby ending the reception operation in one frame. I do.

When the period of the transmission slot and the period of the reception slot have passed and the period of the idle slot has elapsed, the control circuit 20 proceeds to step 3a as shown in FIG. Monitor whether it has been done. Then, when the predetermined time T1 has elapsed, the control circuit 20 supplies channel designation data for resetting the transmission radio channel frequency fT to the transmission frequency synthesizer 42 in step 3b. Therefore, the transmission frequency synthesizer 42 refreshes the wireless channel frequency that has been set up to the reset wireless channel frequency fT. Therefore, even if the oscillation frequency of the frequency synthesizer 42 is shifted due to external noise before the refresh, the fluctuation is cleared by the refresh.
The length of the fixed time T1 is set to be shorter by about one slot than the period up to the start timing of the transmission slot TS1 of the next frame. Therefore, the resetting of the radio channel frequency fT is performed one slot before the transmission slot TS1 of the next frame. Therefore, all the frequency shifts occurring in the period up to two slots before the transmission slot TS1 of the next frame are cleared.

Next, the control circuit 20 monitors whether or not a predetermined time T1 has elapsed since the operation stop timing of the receiving circuit 3 in step 3c. The channel designation data for resetting fR is supplied to the frequency synthesizer 41 for reception. For this reason, the frequency synthesizer 41 for reception replaces the previously set radio channel frequency with the reset radio channel frequency fR.
Refresh. Therefore, even if the oscillation frequency of the frequency synthesizer 41 is shifted by the external noise before the refresh, the fluctuation is cleared by the refresh. The length of the fixed time T1 is also set shorter by one slot than the period until the start timing of the reception slot TS1 of the next frame, as in the case of resetting the transmission radio channel frequency fT.

As described above, according to the present embodiment, the radio channel frequency fT for transmission and the radio channel frequency fR for reception are reset using the idle slot period of one frame. Even if noise is generated at the time of resetting, there is no fear that the transmitted data and the received data are adversely affected by the noise, thereby enabling a high quality communication. Further, since it is not necessary to use a frequency synthesizer having a special countermeasure such as a shield structure, there is no problem that the circuit scale of the frequency synthesizer becomes large or expensive.

Further, according to the present embodiment, the radio channel frequency is reset at a position relatively close to the position immediately before the used slot of the next frame. All of the frequency shifts can be cleared, so that the probability of performing communication in the state where the frequency shift has occurred in the next used slot can be extremely reduced.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where separate frequency synthesizers 41 and 42 are provided for reception and transmission has been described. However, the present invention can be similarly applied to an apparatus provided with a frequency synthesizer for both transmission and reception. In this case, as shown in FIG. 5, during the idle slot period from the end of the reception slot to the start of the transmission slot of the next frame, the frequency synthesizer may reset the locked radio channel frequency. Good. Note that the resetting timing may be any time during the idle slot period, but for the same reason as described in the above embodiment, at the position immediately before the start timing of the next transmission slot, that is, as shown in FIG. It is best to set the time T2 after the end of the receiving slot.

The gist of the present invention also relates to the control procedure and control contents of the idle period determination means and the channel reset control means, the reset timing, the configuration of the radio communication apparatus, the type of radio communication system to be applied, and the like. Various modifications can be made without departing from the scope of the present invention.

[0025]

As described above in detail, according to the present invention, it is determined by the communication period determining means whether or not it is the period of the communication slot allocated to itself, and based on the determination result of the communication period determining means, By resetting the oscillation frequency of the frequency synthesizer to the correct local oscillation frequency during periods other than the communication slot allocated to itself by the frequency resetting means, without using a frequency synthesizer with special noise suppression measures In addition, it is possible to provide a wireless communication apparatus capable of performing channel resetting without affecting communication with noise.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating a configuration of a wireless communication device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure and control contents of a control circuit shown in FIG. 1;

FIG. 3 is a flowchart showing a control procedure and control contents of the control circuit shown in FIG. 1;

FIG. 4 is a timing chart used to explain the operation of the device shown in FIG. 1;

FIG. 5 is a timing chart for explaining another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Duplexer (DUP), 3 ... Receiving circuit (RX), 4 ... Frequency synthesizer circuit, 41 ... Frequency synthesizer for reception (SYNR), 5 ... Frequency synthesizer for transmission (SYNT), 6 ... Digital code decoding circuit (MOD), 7 equalizer (EQL), 8 error correction code decoding circuit (CH-COD), 9 voice code decoding circuit (SP-COD), 10 speaker, 11 microphone 12: input display unit, 20: control circuit (CONT),
21: communication period determination means, 22: channel reset control means.

Claims (2)

(57) [Claims] 1. A frequency synthesizer for generating a local oscillation frequency corresponding to a predetermined radio communication channel during a communication slot allocated to itself, which is used in a system employing a time division multiple access system. A wireless communication device that performs wireless communication using a wireless communication channel set in accordance with a period determination means for determining whether or not a communication slot is allocated to itself, and a determination result of the period determination means. And a frequency resetting means for resetting the oscillation frequency of the frequency synthesizer to a local oscillation frequency corresponding to the predetermined wireless communication channel during a period other than the communication slot assigned to the self. A wireless communication device characterized by the following. 2. The frequency resetting means sets the oscillation frequency of the frequency synthesizer to a predetermined wireless communication channel within a period other than the communication slot allocated to itself and immediately before the next communication slot allocated to itself. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is reset to a corresponding local oscillation frequency.