JP5034128B2 - Wireless communication apparatus, wireless communication method, and wireless tag reader / writer - Google Patents

Description

  The present invention relates to a wireless communication apparatus, a wireless communication method, and a wireless tag reader / writer in which a transmission unit and a reception unit share an antenna.

A wireless communication apparatus in which a transmission unit and a reception unit share an antenna is known.
For example, in the wireless tag reader / writer 100 shown in FIG. 7, the transmission unit 103, the reception unit 104, and the antenna 105 are connected via a circulator (directional coupler) 102 of the front end circuit 101.
The antenna 105 is shared by the reception unit 104 receiving a signal while synchronizing with the transmission unit 103.

By the way, in such a wireless communication apparatus, sneak signals 106 and 107 from the transmission unit 103 to the reception unit 104 are generated, which may adversely affect the processing of the reception unit 104.
That is, when the transmission unit 103, the reception unit 104, and the antenna 105 are connected via the circulator 102, the transmission signal wraps around due to the isolation characteristics of the circulator 102 (wraparound signal 106) and the transmission signal due to the return loss characteristics of the antenna 105 A sneak (a sneak signal 107) is generated, and the synthesized signal 108 is input to the mixer 109 of the receiving unit 104.
For this reason, the analog waveform input to the A / D converter 110 of the receiving unit 104 may be disturbed, and the processing in the decoding unit 111 may fail.

In view of this, a wireless communication device that suppresses the sneak in the signal from the transmission unit to the reception unit has been proposed.
For example, in the wireless communication devices disclosed in Patent Documents 1 and 2, the influence of the sneak signal in the receiving unit is reduced by generating a cancel signal having a phase opposite to that of the sneak signal and canceling the sneak signal with this cancel signal. .

JP 2006-203469 A JP 2008-028450 A

However, in the wireless communication devices shown in Patent Documents 1 and 2, in order to cancel the sneak signal from the transmission unit to the reception unit with a cancel signal, a distributor, an attenuator, a phase shifter, a combiner, a reception intensity detection circuit, etc. Many parts needed to be added.
For this reason, there is a problem that not only the circuit configuration becomes complicated, but also the manufacturing cost increases.

In addition, if a distributor is provided on the transmission side of the front end circuit as in the wireless communication devices disclosed in Patent Documents 1 and 2, the loss generated here must be compensated by the gain of the amplifier, and power consumption is reduced. There was a problem of getting bigger.
Furthermore, when a synthesizer is provided on the reception side of the front-end circuit as in the wireless communication devices disclosed in Patent Documents 1 and 2, there has been a problem that the SN ratio of the received signal deteriorates.

  An object of the present invention is to reduce the sneak signal from the transmission unit to the reception unit, which is the above-described problem, at a low cost, and to avoid an increase in power consumption and a decrease in SN ratio by eliminating a distributor and a combiner. An object of the present invention is to provide a wireless communication device, a wireless communication method, and a wireless tag reader / writer.

  In order to achieve the above object, a wireless communication apparatus of the present invention includes a transmitter that modulates and transmits a baseband signal, a receiver that receives a signal while synchronizing with the transmitter, and the transmitter via a circulator And an antenna that is connected to the receiving unit and is used for transmission / reception, a control unit that controls transmission / reception by the transmitting unit and the receiving unit, and a transmission unit that is provided between the transmitting unit and the circulator. A sneak signal for detecting a voltage level of a sneak signal that sneaks from the transmitter to the receiver using a component of the receiver. A configuration comprising level detection means, and automatic phase adjustment means for automatically adjusting the phase of the signal transmitted from the transmission unit in accordance with the voltage level of the sneak signal. And Aru.

  The wireless communication method of the present invention includes a transmitter that modulates and transmits a baseband signal, a receiver that receives a signal while synchronizing with the transmitter, and the transmitter and the receiver via a circulator. A phase shifter that changes the phase of a signal transmitted from the transmission unit to a wireless communication device that is connected to the antenna and includes a control unit that controls transmission / reception by the transmission unit and the reception unit The control unit is configured to detect a voltage level of a sneak signal that sneaks from the transmitter to the receiver using a component of the receiver, and a voltage level of the sneak signal. Accordingly, a phase automatic adjustment procedure for automatically adjusting the phase of the signal transmitted from the transmission unit is executed.

  The wireless tag reader / writer according to the present invention includes a transmitter that modulates and transmits a baseband signal when performing wireless communication with a wireless tag, a receiver that receives a signal while synchronizing with the transmitter, and a circulator. Connected to the transmission unit and the reception unit via, and used for transmission and reception, a control unit for controlling transmission and reception by the transmission unit and the reception unit, and provided between the transmission unit and the circulator, A phase shifter that changes a phase of a signal transmitted from the transmission unit, and the control unit uses a component of the reception unit to determine a voltage level of a sneak signal that wraps around from the transmission unit to the reception unit. Sneak signal level detecting means for detecting the sneak current, and phase auto-adjustment for automatically adjusting the phase of the signal transmitted from the transmitter according to the voltage level of the sneak signal It is constituted and a settling unit.

  According to the present invention, not only can a sneak signal from a transmission unit to a reception unit be reduced at a low cost, but also an increase in power consumption and a decrease in SN ratio can be avoided by eliminating the need for a distributor and a combiner.

It is a block diagram which shows the structure of the radio | wireless communication apparatus which concerns on 1st embodiment of this invention. It is a flowchart which shows the operation | movement procedure of the radio | wireless communication apparatus which concerns on 1st embodiment of this invention. It is a flowchart which shows the process sequence of the wraparound suppression process of the radio | wireless communication apparatus which concerns on 1st embodiment of this invention. It is explanatory drawing which shows the phase adjustment table of the radio | wireless communication apparatus which concerns on 1st embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication apparatus which concerns on 2nd embodiment of this invention. It is a flowchart which shows the operation | movement procedure of the radio | wireless communication apparatus which concerns on 2nd embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication apparatus which concerns on a reference example.

Embodiments of a wireless communication device, a wireless communication method, and a wireless tag reader / writer according to the present invention will be described below with reference to the drawings.
[First embodiment]
FIG. 1 is a block diagram showing a configuration of a wireless communication apparatus according to the first embodiment of the present invention.
As shown in this figure, the wireless communication device 1A according to the first embodiment of the present invention is a wireless tag reader / writer that performs wireless communication with a wireless tag (RFID), and includes a transmission unit 2, a reception unit 3, and a front end. The circuit 4, the antenna 5, and the control unit 6 are provided.

The transmitter 2 modulates the baseband signal input from the controller 6 and transmits this as a carrier wave.
Moreover, the transmission part 2 has a filter (not shown), and attenuates the signal of an unnecessary band.
The clock signal of the transmission unit 2 is supplied from the oscillator 7.

The receiving unit 3 includes a mixer 31, a bandpass filter 32, an amplifier 33, an A / D converter 34, and a decoding unit 35.
The mixer 31 receives a signal while synchronizing with the transmission unit 2.
The band pass filter 32 passes only a necessary band of the mixer output.
The amplifier 33 amplifies the bandpass filter output.
The A / D converter 34 converts the voltage level of the amplifier output into a digital value.
The decoding unit 35 decodes the A / D converter output.

The front end circuit 4 includes an amplifier 41 and a circulator 42.
The amplifier 41 amplifies the signal transmitted from the transmission unit 2.
The circulator 42 is connected to the transmission unit 2, the reception unit 3, and the antenna 5, and allows the transmission unit 2 and the reception unit 3 to share the antenna 5.

The control unit 6 has a function of transmitting and receiving baseband signals, and transmits baseband signals to the transmission unit 2.
Further, the control unit 6 controls the transmission and stop of the carrier by sending a carrier wave transmission command and a carrier wave stop command to the transmission unit 2.

In the wireless communication device 1A configured as described above, transmission signal wraparound due to the isolation characteristic of the circulator 42 (wraparound signal 8) and transmission signal wraparound due to the return loss characteristic of the antenna 5 (wraparound signal 9) occur. The synthesized signal 10 may be input to the mixer 31 of the receiving unit 3.
Since these sneak signals 8 and 9 may disturb the analog waveform input to the A / D converter 34 of the receiving unit 3 and cause the processing in the decoding unit 35 to fail, suppress them as much as possible. Is desired.

  In the wireless communication device 1A according to the present embodiment, in order to suppress the sneak signals 8 and 9, the D / A converter 61, the voltage variable phase shifter (phase shifter) 43, the bypass path 36, the switch 37, 38, a sneak signal level detecting means 62, and an automatic phase adjusting means 63 are added.

The D / A converter 61 is hardware added to the control unit 6 in order to control the voltage variable phase shifter 43.
The voltage variable phase shifter 43 is hardware added between the amplifier 41 and the circulator 42 of the front end circuit 4, and changes the phase of the signal transmitted from the transmission unit 2.
The bypass path 36 and the switches 37 and 38 are hardware added to the receiving unit 3. The bypass path 36 can directly input the mixer output to the A / D converter 34. The switches 37 and 38 are bypass paths. 36 selectively switches between valid / invalid.

The wraparound signal level detection means 62 and the phase automatic adjustment means 63 are software added to the control unit 6.
The sneak signal level detection means 62 detects the voltage level of the sneak signals 8 and 9 (synthesized signal 10) sneaking from the transmission unit 2 to the reception unit 3 by using the A / D converter 34 which is a component of the reception unit 3. To do.
Specifically, when the voltage levels of the sneak signals 8 and 9 are detected, the mixer output is directly input to the A / D converter 34 based on the switching control of the switches 37 and 38, and the A / D converter output is obtained. Input to the control unit 6.

The automatic phase adjustment unit 63 automatically adjusts the phase of the signal transmitted from the transmission unit 2 in accordance with the voltage level of the wraparound signals 8 and 9.
Specifically, the voltage levels of the sneak signals 8 and 9 detected when the transmission unit 2 is transmitting signals, and the voltages of the sneak signals 8 and 9 detected when the transmission unit 2 is not transmitting signals. The phase of the signal transmitted from the transmission unit 2 is automatically adjusted so that the difference from the level is not more than a predetermined threshold.

Next, an operation procedure of the wireless communication device 1A according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a flowchart showing an operation procedure of the wireless communication apparatus according to the first embodiment of the present invention. FIG. 3 is a flowchart showing a processing procedure of a wraparound suppression process of the wireless communication apparatus according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing a phase adjustment table of the wireless communication apparatus according to the first embodiment of the present invention.

As shown in FIG. 2, the control unit 6 of the wireless communication device 1A according to the first embodiment of the present invention determines the start of a command transmission process (S103) that is an actual transmission / reception operation (S101). The wraparound suppression process (S102) is executed before the start of.
The sneak suppression processing is processing including detection of the sneak signal level by the sneak signal level detection unit 62 and automatic phase adjustment by the phase automatic adjustment unit 63, and a specific processing procedure will be described with reference to FIG. .
In the present embodiment, the mixer 31 and the A / D converter 34 are bypassed, and the voltage level of the mixer output detected in a state where no carrier wave is output and a phase adjustment table to be described later are held in the control unit 6 in advance. ing.

As shown in FIG. 3, in the wraparound suppression process, first, the switches 37 and 38 are turned on to bypass the mixer 31 and the A / D converter 34 (S201).
Next, in the phase adjustment table held by the control unit 6 (see FIG. 4), the first set value of the entry is used as the input value of the D / A converter 61 (S202), and the phase of the voltage variable phase shifter 43 is changed. (S203).
The elements of the phase adjustment table are the angle of the voltage variable phase shifter 43 and the corresponding input value (set value) of the D / A converter 61 as shown in FIG.

Next, the control unit 6 instructs the transmission unit 2 to output a carrier wave, and the transmission unit 2 outputs the carrier wave (S204).
When the carrier wave is output, transmission signal wraparound due to the isolation characteristic of the circulator 42 (wraparound signal 8) and transmission signal wraparound due to the return loss characteristic of the antenna 5 (wraparound signal 9) occur on the receiving unit 3 side. The synthesized signal 10 is input to the mixer 31.
The A / D converter 34 converts the output voltage level of the mixer 31 into a digital value and inputs the digital value to the decoding unit 35. The decoding unit 35 holds this digital value.

The control unit 6 waits until the output of the carrier wave becomes constant (S205), acquires the output value of the A / D converter 34 from the decoding unit 35 (S206), and stores the carrier-free data held by the control unit 6 The difference from the mixer output voltage level in the output state is calculated (S207).
If the difference is equal to or smaller than the predetermined threshold value (S208), the switches 37 and 38 are turned off (S209), and the wraparound suppression process ends.
Note that the threshold used in step S208 is set in advance based on the measured values at the time of design and verification.

On the other hand, if it is not below the threshold value, the next entry in the phase adjustment table is acquired (S210).
The set value of the D / A converter 61 in the acquired entry is set, and the phase of the voltage variable phase shifter 43 of the front end circuit 4 is changed (S211).
And the control part 6 acquires the output value of the A / D converter 34 from the decoding part 35 again (S206), and performs the process of step S207 and step S208. These processes are repeated until it is determined in step S208 that the difference is equal to or less than a predetermined threshold value.

  As described above, according to the wireless communication device 1A of the present embodiment, the transmission unit 2 that modulates and transmits a baseband signal, the reception unit 3 that receives a signal while synchronizing with the transmission unit 2, and the circulator 42 is connected to the transmission unit 2 and the reception unit 3 via 42, and is also used for transmission / reception, the control unit 6 that controls transmission / reception by the transmission unit 2 and the reception unit 3, and between the transmission unit 2 and the circulator 42 And a voltage variable phase shifter 43 that changes the phase of the signal transmitted from the transmission unit 2, and the control unit 6 determines the voltage levels of the sneak signals 8 and 9 that wrap around from the transmission unit 2 to the reception unit 3. A sneak signal level detection unit 62 that detects the components of the receiving unit 3 and a phase automatic adjustment unit 6 that automatically adjusts the phase of the signal transmitted from the transmission unit 2 in accordance with the voltage level of the sneak signal. Because comprising the door, it is possible to reduce the echo signal from the transmission unit 2 to the receiver 3 at a low cost.

That is, the wireless communication device 1A according to the present embodiment not only detects the voltage level of the sneak signals 8 and 9 using the components of the receiver 3, but also sneak signal 8 based on the phase adjustment of the transmission signal. 9 is reduced, the number of necessary parts can be greatly reduced and the cost can be reduced as compared with the case of canceling the sneak signal.
In addition, since a distributor and a combiner are not necessary, an increase in power consumption and a decrease in the SN ratio can be avoided.

The receiving unit 3 includes a mixer 31 that receives a signal in synchronization with the transmitting unit 2, a bandpass filter 32 that passes only a necessary band of the mixer output, an amplifier 33 that amplifies the bandpass filter output, An A / D converter 34 that converts the voltage level of the amplifier output into a digital value, a decoding unit 35 that decodes the A / D converter output, a bypass path 36 that can directly input the mixer output to the A / D converter 34, and a bypass And switches 37 and 38 that selectively switch the validity / invalidity of the path 36. When the sneak signal level detection means 62 detects the voltage level of the sneak signals 8 and 9, the switch 37 and 38 are switched. First, the mixer output is directly input to the A / D converter 34 and the A / D converter output is input to the control unit 6. The voltage level of the interrupt signal 8,9 can be accurately detected.
The reason is that in detecting the voltage level of the sneak signals 8 and 9 using the A / D converter 34 which is a component of the receiving unit 3, the responsiveness of the bandpass filter 32 and the disturbance of the analog waveform by the amplifier 33 are detected. This is because the influence can be eliminated.

Moreover, the phase automatic adjustment means 63 detects the voltage levels of the sneak signals 8 and 9 detected when the transmission unit 2 is transmitting signals, and the sneak signal 8 detected when the transmission unit 2 is not transmitting signals. Since the phase of the signal transmitted from the transmission unit 2 is automatically adjusted so that the difference from the voltage level of 9 is equal to or less than a predetermined threshold value, the fluctuation of the voltage level caused by other than the wraparound signals 8 and 9 Can be canceled and highly accurate phase adjustment can be performed.
Further, the control unit 6 performs the detection of the sneak signal level by the sneak signal level detection unit 62 and the automatic phase adjustment by the phase automatic adjustment unit 63 before performing the actual transmission / reception operation. The sneak signals 8 and 9 in the operation can be reliably suppressed.

[Second Embodiment]
Next, a wireless communication device 1B according to a second embodiment of the present invention will be described with reference to FIGS. However, about the part which is common with the said embodiment, description of the said embodiment is used by attaching | subjecting the same code | symbol as the said embodiment.
FIG. 5 is a block diagram showing a configuration of a wireless communication apparatus according to the second embodiment of the present invention, and FIG. 6 is a flowchart showing an operation procedure of the wireless communication apparatus according to the second embodiment of the present invention.

As shown in these drawings, the wireless communication device 1B according to the second embodiment of the present invention includes a plurality of antennas 5-1 to 5-n and a switch 11 for switching the antennas 5-1 to 5-n to be used. And the control unit 6 detects the sneak signal level by the sneak signal level detection unit 62 after the antennas 5-1 to 5-n are switched, and the automatic phase adjustment by the phase automatic adjustment unit 63. The point which performs is different from the said embodiment.
Specifically, as shown in FIG. 6, the switching of the antennas 5-1 to 5-n is determined (S301), and the wraparound suppression process (S302) is executed after the switching of the antennas 5-1 to 5-n. .
The wraparound suppression process of the second embodiment is a process having the same content as the wraparound suppression process of the first embodiment shown in FIG.

  According to the second embodiment configured as described above, the control unit 6 includes the plurality of antennas 5-1 to 5-n and the switch 11 that switches the antennas 5-1 to 5-n to be used. After the antennas 5-1 to 5-n are switched, the detection of the sneak signal level by the sneak signal level detection unit 62 and the automatic phase adjustment by the phase automatic adjustment unit 63 are executed. Even if a change occurs in the wraparound of the transmission signal due to the return loss characteristics of the antennas 5-1 to 5-n by switching from 1 to 5-n, the wraparound signal 9 can be reliably suppressed.

  The wireless communication device, the wireless communication method, and the wireless tag reader / writer according to the present invention have been described with reference to the embodiments. However, the wireless communication device, the wireless communication method, and the wireless tag reader / writer according to the present invention are limited to the above-described embodiments. It goes without saying that various modifications are possible within the scope of the claims.

  The present invention can be applied to a wireless communication apparatus, a wireless communication method, and a wireless tag reader / writer in which a transmission unit and a reception unit share an antenna.

1A wireless communication device 1B wireless communication device 2 transmitter 3 receiver 4 front end circuit 5 antenna 6 controller 7 oscillator 8 sneak signal 9 sneak signal 10 composite signal 11 switch 31 mixer 32 bandpass filter 33 amplifier 34 A / D converter 35 Decoding unit 36 Bypass path 37 Switch 38 Switch 41 Amplifier 42 Circulator 43 Voltage variable phase shifter 61 D / A converter 62 Signal level detection means 63 Phase automatic adjustment means

Claims (6)

A transmitter that modulates and transmits a baseband signal;
A receiving unit for receiving a signal in synchronization with the transmitting unit;
An antenna that is connected to the transmission unit and the reception unit via a circulator and is also used for transmission and reception;
A control unit for controlling transmission and reception by the transmission unit and the reception unit;
A phase shifter provided between the transmission unit and the circulator, and changing a phase of a signal transmitted from the transmission unit;
The control unit is
A sneak signal level detection means for detecting a voltage level of a sneak signal that wraps around from the transmission unit to the reception unit, using components of the reception unit;
In accordance with the voltage level of the sneak signal, phase automatic adjustment means for automatically adjusting the phase of the signal transmitted from the transmission unit ,
The receiver is
A mixer that receives a signal while synchronizing with the transmitter;
A bandpass filter that passes only the required band of the mixer output;
An amplifier that amplifies the bandpass filter output;
An A / D converter that converts the voltage level of the amplifier output into a digital value;
A decoding unit for decoding the output of the A / D converter;
A bypass path capable of directly inputting a mixer output to the A / D converter;
A switch that selectively switches between valid / invalid of the bypass path,
The wraparound signal level detection means is
When detecting the voltage level of the echo signal, on the basis of the switching control of the switch, the mixer output is directly input to the A / D converter, a Rukoto to enter the A / D converter output to the control unit A wireless communication device. The phase automatic adjustment means is
The difference between the voltage level of the sneak signal detected when the transmitter is transmitting a signal and the voltage level of the sneak signal detected when the transmitter is not transmitting a signal is equal to or less than a predetermined threshold value. become such, the wireless communication apparatus according to claim 1 wherein automatically adjusting the phase of the signal transmitted from the transmitting unit. The control unit is
3. The wireless communication apparatus according to claim 1, wherein detection of a sneak signal level by said sneak signal level detection means and automatic phase adjustment by said phase automatic adjustment means are executed before performing an actual transmission / reception operation. Multiple antennas,
A switch for switching the antenna to be used,
The control unit is
After switching of the antenna is performed, the detection of the echo signal level by the echo signal level detection means, according to any one of claims 1 to 3 for executing the automatic phase adjustment by the automatic phase adjusting means Wireless communication device. A transmitter that modulates and transmits a baseband signal;
A receiving unit for receiving a signal in synchronization with the transmitting unit;
An antenna that is connected to the transmission unit and the reception unit via a circulator and is also used for transmission and reception;
A wireless communication apparatus comprising: a control unit that controls transmission and reception by the transmission unit and the reception unit;
A phase shifter for changing a phase of a signal transmitted from the transmission unit;
In the control unit,
A sneak signal level detection procedure for detecting a voltage level of a sneak signal that wraps around from the transmission unit to the reception unit using components of the reception unit;
A phase automatic adjustment procedure for automatically adjusting the phase of the signal transmitted from the transmitter according to the voltage level of the sneak signal , and
A mixer that receives a signal while synchronizing with the transmitter;
A bandpass filter that passes only the required band of the mixer output;
An amplifier that amplifies the bandpass filter output;
An A / D converter that converts the voltage level of the amplifier output into a digital value;
A decoding unit that decodes the output of the A / D converter;
A bypass path capable of directly inputting a mixer output to the A / D converter;
A switch for selectively switching between valid / invalid of the bypass path,
The sneak signal level detection procedure includes:
When detecting the voltage level of the sneak signal, the mixer output is directly input to the A / D converter and the A / D converter output is input to the control unit based on the switching control of the switch. A wireless communication method. In performing wireless communication with the wireless tag,
A transmitter that modulates and transmits a baseband signal;
A receiving unit for receiving a signal in synchronization with the transmitting unit;
An antenna that is connected to the transmission unit and the reception unit via a circulator and is also used for transmission and reception;
A control unit for controlling transmission and reception by the transmission unit and the reception unit;
A phase shifter provided between the transmission unit and the circulator, and changing a phase of a signal transmitted from the transmission unit;
The control unit is
A sneak signal level detection means for detecting a voltage level of a sneak signal that wraps around from the transmission unit to the reception unit, using components of the reception unit;
In accordance with the voltage level of the sneak signal, phase automatic adjustment means for automatically adjusting the phase of the signal transmitted from the transmission unit ,
The receiver is
A mixer that receives a signal while synchronizing with the transmitter;
A bandpass filter that passes only the required band of the mixer output;
An amplifier that amplifies the bandpass filter output;
An A / D converter that converts the voltage level of the amplifier output into a digital value;
A decoding unit for decoding the output of the A / D converter;
A bypass path capable of directly inputting a mixer output to the A / D converter;
A switch that selectively switches between valid / invalid of the bypass path,
The wraparound signal level detection means is
When detecting the voltage level of the echo signal, on the basis of the switching control of the switch, the mixer output is directly input to the A / D converter, a Rukoto to enter the A / D converter output to the control unit A featured wireless tag reader / writer.

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