JPH09116455A - Radio data communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the communication efficiency by avoiding an interference radio wave due to an electronic range or the like and minimizing the loss of a transmission opportunity at the time of detecting the interference radio wave. SOLUTION: This radio data communication equipment is provided with a carrier detection circuit 33b, which detects a radio wave to output a carrier detection signal CS, and a channel monitor signal generation circuit 35 which outputs radio channel monitor signals WCS1 to WCS4 in accordance with the signal CS. The monitor signal generation circuit outputs the signal WCS1 when the signal CS continues for a time t1 or longer, and it outputs the signal WCS2 when the signal WCS1 continues for a time t3 or longer. It outputs the signal WCS3 when the signal WCS1 is turned on, and it turns off the signal WCS3 after a time t4 when the signal WCS2 is turned on and the signal WCS1 is turned off, and it outputs the signal WCS4 when the signal CS is outputted continuously for a time t5 or longer. The reception operation is started when the signal WCS4 is turned on, and the reception operation is stopped when the signal WCS4 is turned off, and transmission of the local station is inhibited when the output of the signal WCS3 is turned on.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to CSMA (Carrie
The present invention relates to a wireless data communication device using an r Sense Multiple Access (ESR) method, and in particular, ISM (Industrial Scientific
and Medical) band, such as a microwave data communication device for use in a frequency band in which electromagnetic wave interference is strong.

[0002]

2. Description of the Related Art A CS that avoids collision of radio waves transmitted by radio stations by observing whether radio waves are transmitted to a specific radio communication channel and controlling the transmission opportunity of its own station.
In the MA method, each wireless station determines the usage status of a wireless communication channel based on the strength of the electric field strength of a received radio wave in the channel. That is, if the electric field strength in the channel is larger than the preset value, it is determined that the carrier is being detected, and another station recognizes that the transmission is in progress and does not send the radio wave to the channel. ing. By performing such communication control,
Avoiding collision of transmitted radio waves between wireless stations,
It is often used in a so-called simplex communication wireless data communication system in which the transmission wireless channel and the reception wireless channel are the same.

By the way, the communication protocol in wireless communication is basically transmission of information (data) and commands (commands), so-called command transmission, whereas a receiving station that receives this normally receives information and commands. It sends a response indicating that it has done, that is, returns a response. Therefore, assuming a case where multiple wireless stations transmit commands almost at the same time, after one wireless station finishes command transmission, the receiving station that receives this sends a response to the transmitting station, and then another It is desirable that the communication control be performed such that the command transmission and the response transmission always form a pair such that the wireless station of 1 transmits the next command.

Therefore, conventionally, the carrier detection signal indicating that the electric field strength of the received radio wave detected in the wireless communication channel to be communicated is larger than a preset value is monitored, and the carrier detection signal is detected. Is turned on as soon as it indicates a carrier present state, and a non-reception time delay signal is generated which is turned off when this carrier detection signal indicates a state without a carrier continuously for a preset time or longer. The non-reception time delay signal is monitored by the transmission control means, and when this signal is in the ON state, command transmission of the own station is prohibited, while only the response transmission can be transmitted regardless of the state of the non reception time delay signal. I am trying.

FIG. 10 is a block diagram showing the configuration of a conventional wireless data communication apparatus, which includes a CPU (Central Processing Unit) 1 and R.
It is composed of an OM (read only memory) 2, a RAM (random access memory) 3, a wireless circuit section 4, a non-reception time delay circuit 5 and an antenna 6. The wireless circuit unit 4 creates a transmission message for command transmission and response transmission according to a command from the CPU 1, and a modulation for modulating the transmission message from this transmission unit 4a at a predetermined frequency and wirelessly transmitting it from the antenna 6. Section 4b, demodulation section 4c for demodulating a radio signal received by the antenna 6, this demodulation section 4c
The reception state of the carrier by the antenna 6 is monitored from the output signals of the reception unit 4d and the demodulation unit 4c which take in the reception signal demodulated in step S1 and notify the CPU 1, and the content of this monitoring is used as a carrier detection signal CS of a binary signal at the non-reception time delay circuit 5 and a carrier sense section 4e which outputs the signal to the carrier.

Although not shown, the switching between the modulator 4b and the demodulator 4c and the antenna 6 is performed in order to stop the operation of the reception function unit to save power when the local station is transmitting. A switch is inserted to normally connect the antenna 6 and the demodulation unit 4c and disconnect the modulation unit 4b from the antenna 6 to put it in a reception standby state. At the time of transmission, the antenna 6 and the modulation unit 4b are connected and the demodulation unit 4c is connected to the antenna. 6
I try to separate it from.

The non-reception time delay circuit 5 monitors the carrier detection signal CS from the carrier sense unit 4c and, when detecting the presence of carrier reception, sets the carrier sense delay signal CST output to the CPU 1 to the carrier reception present state. Further, when no carrier reception is detected in the carrier detection signal CS, and this state continues for a preset time, the carrier sense delay signal CST is set to no carrier reception.

The CPU 1 is programmed to control command transmission and response transmission according to the transmission algorithm shown in FIG. That is, in the case of command transmission for transmitting information (data), commands (commands), etc. to other stations, the carrier sense delay signal CST from the non-reception time delay circuit 5 is checked and no carrier reception state (for example, low level signal) Command is sent when
When the carrier is being received (for example, a high level signal), command transmission is prohibited and postponed. The response transmission of the response to the command reception is performed regardless of the state of the carrier sense delay signal CST.

The operation state of the wireless device when communication is performed by the wireless data communication device having such a configuration will be described with reference to the timing chart of FIG. For example, it is assumed that there are three wireless devices A, B, and C in one wireless area and they can communicate with each other. Radio A to Radio B
To the carrier sense unit 4 of each of the radios.
The wireless devices B and C output the carrier detection signal CS during the transmission period TCM of the command CM1 from the wireless device A. Note that the wireless device A does not receive the radio wave while the station A is transmitting the command CM1 because the receiving function unit is separated by the changeover switch, and the carrier sense unit 4e outputs the carrier detection signal CS. There is no output.

Of the radios B and C that have received the command CM1, only the radio B returns the response RP1. At this time, the wireless device B transmits the response RP1 regardless of the state of the carrier sense delay signal CST. Further, the carrier sense delay signal CST of the radio devices B and C falls by a time TST after the fall of the carrier detection signal CS due to the function of the non-reception time delay circuit 5. Since the receiving function unit of the wireless device B is separated by the changeover switch while the local station is transmitting the response RP1, the length of time that the carrier sense delay signal CST is output is TCM + TST.

On the other hand, since the wireless device C does not return a response and the receiving function unit is connected by the changeover switch, the carrier detection signal CS is the command CM1.
And the response RP1 is output, and a TST time delay occurs for each. Therefore, the carrier sense delay signal CST in the radio device C has a continuous delay and continues for TCM + 2 · TST time.

In the wireless data communication apparatus having such a configuration, while the carrier sense delay signal CST continues, no new command is sent from another wireless device, so that command transmission and response transmission are paired. Therefore, the response transmission is promptly performed in response to the command transmission, and stable wireless communication can be performed. That is, by prohibiting the command transmission of the wireless device C from interrupting the command transmission CM1 of the wireless device A and the response transmission RP1 of the wireless device B, a pair of the command transmission CM1 and the response transmission RP1 is formed, A response is promptly sent to the command.

Further, Japanese Unexamined Patent Publication No. 6-140966 discloses a wireless communication device for reducing the influence of interference by radio waves radiated from other electronic equipment, especially a microwave oven. That is, as shown in FIG. 13, the receiving section high-frequency circuit 8 is connected to the antenna 7 to form the receiving section 9, and the signal received by the receiving section 9 is demodulated by the demodulation circuit 10 and stored in the memory 11 as data. It is supposed to do. In addition, the data held in the memory 11 is modulated by the modulation circuit 12 and wirelessly transmitted from the transmission unit 15 configured by connecting the transmission unit high frequency circuit 14 to the antenna 13. Each of the above units forms a relay unit 16 and supplies power from the power unit 17 to the relay unit 16 and also provides a solar cell 18, which receives indoor lighting such as a fluorescent lamp that is not an inverter type. The light reception signal is supplied to the output timing control circuit 19 provided in the relay section 16. Since the output of the solar cell 18 is synchronized with unnecessary radiation from a microwave oven or the like, the output timing control circuit 1
Reference numeral 9 divides a period in which unnecessary radiation is output from the output of the solar cell 18 and a 0 level period, and the transmission unit 15
The transmission section high frequency circuit 14 and the memory 11 are controlled to perform data transmission, thereby preventing interference due to unnecessary radiation from a microwave oven or the like.

That is, according to this publication, unnecessary radiation emitted from a microwave oven or the like repeatedly outputs and pauses at a fixed time interval, and the repetition cycle is a power source supplied from a power company. The property of being synchronized with the AC current cycle of is used. In the case of a microwave oven having a transformer type oscillation circuit, the period during which radio waves are emitted is half the power supply cycle. Whether the radio wave is emitted when the AC power source of the power supply is positive or the radio wave is emitted when the AC power source of the AC power source is negative cannot be specified because it changes depending on the insertion direction of the power plug of the microwave oven, but in either case. However, the time when the radio wave is emitted from the microwave oven and the time when it is not emitted are alternately ½ each, and it corresponds to the cycle of the power supply.

On the other hand, the non-inverter type fluorescent lamp luminaire also oscillates in synchronization with the frequency of the alternating current of the power source. Therefore, if an optical sensor such as a solar cell is installed in an environment where indoor lighting is dominant, the cycle and phase of the AC power supply can be detected by a signal that indicates the intensity of light obtained from the optical sensor. Therefore, in the publication, the information on the cycle and phase of the power source obtained from the solar cell 18
The period in which the microwave oven emits a radio wave is predicted, and the wireless transmission / reception operation is prohibited during the period in which the microwave oven emits a radio wave, and the wireless transmission / reception operation is controlled during the period in which the microwave oven does not emit a radio wave.

[0016]

However, FIG. 10 to FIG.
The conventional device shown in FIG. 2 has a problem that it interferes with communication because it detects radio waves emitted from electronic devices other than the wireless device. For example, when a wireless data communication system is constructed by using a spread spectrum system of 2.4 GHz band, interference radio waves radiated from a microwave oven or the like are included in the used band, which hinders communication. As shown in FIG. 12, in the wireless device, the electric field strength of the interfering radio waves is
If it is greater than or equal to the comparison reference value of c, it is detected, and the carrier detection signal CS of each of the wireless devices A, B, and C is turned on. When the duration of the carrier detection signal CS is Ti, the carrier sense delay signal CST becomes longer than this by TST time.
The time during which T is in the ON state is Ti + TST, and during this period, the wireless devices A, B, and C cannot transmit commands.
As described above, there is a problem in that the command transmission cannot be performed for a time TST longer than the time Ti in which the interference wave due to the microwave oven actually exists, and the transmission opportunity is reduced accordingly and the communication efficiency is reduced.

Further, in the publication shown in FIG. 13, since the carrier sense delay signal CST is not generated and the transmission control is not performed as in the former case, there is a case where the response transmission cannot be promptly returned in response to the command transmission. Even when an interference radio wave from a microwave oven or the like is received, the communication prohibition time does not become longer than necessary, and the communication efficiency does not deteriorate. However, in recent years, an inverter type is increasing in the oscillation system of the fluorescent lamp lighting equipment, and the blinking cycle of the fluorescent lamp is not coincident with the AC power cycle. In addition, there is also an inverter system for oscillating the magnetron of a microwave oven, and the cycle of electromagnetic waves emitted from the microwave oven may not match the cycle of the AC power supply. Therefore, as in this publication, in the control of predicting the period in which the microwave oven emits a radio wave based on the information of the cycle and phase of the AC power supply and prohibiting the wireless transmission / reception operation, an environment using an inverter type fluorescent lamp lighting fixture is used. For a microwave oven using a magnetron that oscillates in the bottom or an inverter system, there is a problem that it is not possible to avoid interference radio waves radiated from the microwave oven and perform wireless communication.

Therefore, the inventions according to claims 1 and 3 are
In an environment where wireless communication is performed using a frequency band in which electromagnetic waves such as microwave ovens have strong interference such as the SM band, it is possible to reliably avoid interfering radio waves and perform wireless communication, and to quickly send a response to command transmission. (EN) Provided is a wireless data communication device capable of performing the above-mentioned operation, controlling the loss of transmission opportunity when interference radio waves are detected to a minimum, and improving communication efficiency.

The inventions according to claims 2 and 3 are IS
In an environment where wireless communication is performed using a frequency band where electromagnetic waves such as microwave ovens have strong interference such as the M band, it is possible to reliably avoid interfering radio waves and perform wireless communication, and quickly send a response to command transmission. (EN) Provided is a wireless data communication device capable of improving communication efficiency by minimizing loss of transmission opportunity when an interference radio wave is detected and a response is received.

[0020]

According to the first aspect of the present invention,
The electric field strength of the received radio wave detected in the wireless channel to be communicated is compared with the set value, and if the electric field strength of the received radio wave exceeds the set value, it indicates that the radio wave is being sent out in this wireless channel. Carrier detecting means for outputting a carrier detecting signal, and outputting a first radio channel monitoring signal,
When the output of the first radio channel monitoring signal is in the off state, the carrier detection means sets the carrier detection signal to a time shorter than the existence time Ti of the interference radio wave, the first time t.
If the output of the first radio channel supervisory signal is turned on when continuously output for 1 or more, and the output of the first radio channel supervisory signal is in the on state, the carrier detection means presets the output of the carrier detection signal. The first channel monitoring means for turning off the output of the first wireless channel monitoring signal when continuously stopped for the second time t2 or more, and the second wireless channel monitoring signal for outputting the second wireless channel monitoring signal. When the output of the supervisory signal is in the off state, the output of the first radio channel supervisory signal from the first channel supervisory means continues to be in the on state for the preset third time t3 or longer and the second radio channel is supervised. When the output of the signal is turned on and the output of the second radio channel monitoring signal is in the on state, the output of the first radio channel monitoring signal from the first channel monitoring means is turned off. And a second channel monitoring means for turning off the output of the second wireless channel monitoring signal, and a third wireless channel monitoring signal for outputting the third wireless channel monitoring signal when the output of the third wireless channel monitoring signal is in the off state. When the output of the first wireless channel monitoring signal from the first channel monitoring means is turned on, the output of the third wireless channel monitoring signal is turned on, and the output of the third wireless channel monitoring signal is on, It is preset that the output of the first wireless channel monitoring signal from the first channel monitoring means is turned off when the output of the second wireless channel monitoring signal from the second channel monitoring means is on. The output of the third radio channel supervisory signal is turned off after the lapse of the fourth time t4,
Further, when the output of the third wireless channel monitoring signal is in the ON state and the output of the second wireless channel monitoring signal from the second channel monitoring means is in the OFF state, the first channel monitoring means outputs the first wireless channel monitoring signal. The third channel monitoring means for turning off the output of the third wireless channel monitoring signal at the same time that the output of the first wireless channel monitoring signal is turned off, and the fourth wireless channel monitoring signal are output. When the output of the radio channel monitoring signal is in the off state, the carrier detection means continuously outputs the carrier detection signal for a fifth time t5 or longer set to a time longer than the existence time Ti of the interference radio wave, thereby outputting the fourth radio channel. When the output of the supervisory signal is turned on and the output of the fourth radio channel supervisory signal is in the on state, the carrier detection unit presets the output of the carrier detect signal for the sixth time t. If you continue to stop for more than 6 fourth
And a fourth channel monitoring means for turning off the output of the wireless channel monitoring signal from the second channel monitoring means. When the output of the fourth wireless channel monitoring signal from the fourth channel monitoring means is turned on, the reception operation is performed. The reception operation is stopped when the output of the fourth wireless channel monitoring signal is turned off, and the output of the third wireless channel monitoring signal from the third channel monitoring means is turned on. In this case, the own station's transmission is prohibited.

According to the first aspect of the invention, when the carrier detecting means detects a carrier, it outputs a carrier detection signal. Then, the carrier detection signal outputs the first to fourth radio channel monitoring signals. While the carrier detection signal flutters within the first time t1 or the second time t2, the first radio channel supervisory signal does not react and the first radio channel supervisory signal removes noise from the carrier detect signal. Obtained as a signal. Then, the second radio channel supervisory signal rises after a delay of the third time t3 from the rise of the first radio channel supervisory signal, and the fall of the second radio channel supervisory signal is the fall of the first radio channel supervisory signal. It coincides with the fall. When the ON time of the first radio channel supervisory signal does not reach the third time t3, the second radio channel supervisory signal does not rise. That is, it does not turn on.

The third radio channel supervisory signal turns on at the same time as the first radio channel supervisory signal, but the timing of turning off is divided into two cases. That is, when the second radio channel supervisory signal remains off,
The third radio channel supervisory signal turns off at the same time as the first radio channel supervisory signal, but when the second radio channel supervisory signal is on, the third radio channel supervisory signal indicates the second radio channel supervisory signal. It turns off after the delay time of the fourth time t4 has elapsed from the timing when the signal turned off. Then, the wireless reception operation is performed while the carrier detection signal is on, and the wireless transmission operation is prohibited when the third wireless channel monitoring signal is on.

On the other hand, the fourth radio channel supervisory signal is generated by the carrier detection signal similarly to the first radio channel supervisory signal, but at this time, the carrier detection signal continues at the rising and falling points of the carrier detection signal. Unlike the case of the first radio channel supervisory signal, the time for monitoring the time is the fifth time t5 and the sixth time t6, respectively. Then, the reception operation is performed when the fourth wireless channel monitoring signal is on, and the wireless transmission operation is prohibited when the third wireless channel monitoring signal is on.

According to a second aspect of the present invention, the electric field strength of the received radio wave detected in the radio channel to be communicated is compared with a set value, and when the electric field strength of the received radio wave exceeds the set value, this radio channel is detected. Carrier detection means for outputting a carrier detection signal indicating that radio waves are being transmitted within,
The first radio channel supervisory signal is output, and when the output of the first radio channel supervisory signal is in the off state, the carrier detection means sets the carrier detection signal to a time shorter than the existence time Ti of the interference radio wave. When the output of the first radio channel supervisory signal is turned on when the output is continued for a time t1 of 1 or more, the carrier detection means outputs the carrier detection signal when the output of the first radio channel supervisory signal is in the on state. Is stopped for more than a preset second time t2, the output of the first radio channel supervisory signal is turned off.
And the second radio channel supervisory signal is output, and when the output of the second radio channel supervisory signal is in the off state, the first radio channel supervisory signal is output from the first channel supervisor The third time t3 set in advance
When the output of the second radio channel supervisory signal is turned on when the ON state continues for the above, and when the output of the second radio channel supervisory signal is in the ON state, the first channel monitoring means outputs the first A second channel monitoring means for turning off the output of the second wireless channel monitoring signal when the output of the wireless channel monitoring signal is turned off, and a third wireless channel monitoring signal for outputting the third wireless channel monitoring signal. The first from the first channel monitoring means when the output of the signal is in the off state
When the output of the wireless channel monitoring signal of
Turn on the output of the wireless channel monitoring signal of the
The output of the wireless channel supervisory signal of the
When the output of the first wireless channel monitoring signal from the first channel monitoring means is turned off while the output of the second wireless channel monitoring signal from the second channel monitoring means is on, the fourth preset After the lapse of time t4, the output of the third radio channel supervisory signal is turned off, the output of the third radio channel supervisory signal is in the on state, and the second radio channel supervisory signal from the second channel supervisory means. Third channel monitoring in which the output of the first wireless channel monitoring signal from the first channel monitoring means is turned off and the output of the third wireless channel monitoring signal is turned off when the output of Means for outputting a fourth radio channel supervisory signal, and when the output of the fourth radio channel supervisory signal is in an off state, the carrier detecting means outputs the carrier detect signal to the presence of the interference radio wave. When the output continues for more than the fifth time t5 set to a time longer than the interval Ti, the output of the fourth wireless channel supervisory signal is turned on, and when the output of the fourth wireless channel supervisory signal is in the on state. In addition, when the carrier detection means continuously stops the output of the carrier detection signal for the preset sixth time t6 or more, the fourth channel monitoring means for turning off the output of the fourth radio channel monitoring signal is transmitted to the own station. Response reception means for transmitting a response whose transmission time is shorter than the third time t3 in response to the reception of the signal, and the output of the fourth radio channel monitoring signal from the fourth channel monitoring means is turned on. The receiving operation is started at the time point, the receiving operation is stopped at the time point when the output of the fourth wireless channel monitoring signal is turned off, and the third wireless channel monitoring unit monitors the third wireless channel. When the output signal is in the ON state is intended to prohibit the transmission of the local station.

According to the second aspect of the present invention, the transmission time for transmitting the response to the reception to the own station is set to a time shorter than the third time t3. The radio channel supervisory signal is never turned on, and the third radio channel supervisory signal is the first radio channel supervisory signal.
The signal turns off at the same time as the wireless channel monitoring signal of, and does not turn off after the lapse of the delay time of the fourth time t4.

According to a third aspect of the present invention, in the wireless data communication apparatus according to the first or second aspect, the fifth time t5 is set to about 100 μsec.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, three wireless devices, that is, a wireless device A, a wireless device B, and a wireless device C are arranged as wireless data communication devices in one wireless area and are in a state where they can communicate with each other. As shown in FIG. 2, each of the wireless devices A, B, and C has a transmission / reception antenna 31, an antenna duplexer (DPX) 32, a wireless reception unit 33, a wireless transmission unit 34, a channel monitoring signal generation circuit 35, and a communication controller 36. , 37, direct memory access controller (DMAC) 38, interrupt controller 39, microprocessor (MPU) 40, E ² PROM 41, R
OM42, RAM43 and wired interface (I /
F) The circuit 44 is used. The wireless receiver 3
3 is composed of a demodulation circuit 33a and a carrier detection circuit 33b, and the wireless transmission section 34 is composed of a modulation circuit.

The antenna / duplexer 32 is for sharing one antenna 31 between the transmitting circuit and the receiving circuit. The carrier detection circuit 33b compares the electric field strength of the received radio wave received by the antenna 31 with a preset value, and turns on if the received electric field strength is larger,
If it is smaller, the carrier detection signal CS that is turned off is output. Then, the carrier detection circuit 33
The carrier detection signal CS from b is supplied to the channel supervisory signal generation circuit 35.

As shown in FIG. 3, the channel supervisory signal generation circuit 35 includes a first channel supervisory signal generator circuit (first channel supervisory means) 351 for generating a first radio channel supervisory signal WCS1, and a first channel supervisory signal generator circuit 351. 2 wireless channel monitoring signal WC
A second channel supervisory signal generation circuit (second channel supervisory means) 352 for generating S2, and a third channel supervisory signal generator circuit (third channel supervisory means) for generating a third radio channel supervisory signal WCS3 353 and a fourth channel monitoring signal generation circuit (fourth channel monitoring means) 354 that generates a fourth wireless channel monitoring signal WCS4.

The first channel supervisory signal generation circuit 35
1 indicates the first time t1 when the carrier detection circuit 33b sets the carrier detection signal CS to a time shorter than the existence time Ti of the interference radio wave when the output of the first radio channel monitoring signal WCS1 is in the off state. If you continue to output above, the first
Turn on the output of the wireless channel monitoring signal WCS1 of
When the output of the first wireless channel monitoring signal WCS1 is in the ON state, if the carrier detection circuit 33b continuously stops the output of the carrier detection signal CS for a preset second time t2 or more, the first wireless channel monitoring is performed. The control to turn off the output of the signal WCS1 is performed.

The second channel supervisory signal generation circuit 35
2 indicates that when the output of the second wireless channel monitoring signal WCS2 is in the off state, the output of the first wireless channel monitoring signal WCS1 from the first channel monitoring means 351 is the preset third time t3 or more. When it is continuously turned on, the output of the second wireless channel monitoring signal WCS2 is turned on, and the second wireless channel monitoring signal WCS2 is turned on.
If the output of the first wireless channel monitoring signal WCS1 from the first channel monitoring means 351 is turned off while the output of the wireless channel monitoring signal WCS2 of
The control of turning off the output of the wireless channel monitoring signal WCS2 of is performed.

The third channel supervisory signal generation circuit 35
3 indicates a third wireless channel when the output of the first wireless channel monitoring signal WCS1 from the first channel monitoring means 351 is turned on when the output of the third wireless channel monitoring signal WCS3 is in the off state. The output of the monitoring signal WCS3 is turned on, the output of the third wireless channel monitoring signal WCS3 is on, and the output of the second wireless channel monitoring signal WCS2 from the second channel monitoring means 352 is on. , The first channel from the first channel monitoring means 351
When the output of the wireless channel monitoring signal WCS1 is turned off, the output of the third wireless channel monitoring signal WCS3 is turned off after the preset fourth time t4. Further, when the output of the third wireless channel monitoring signal WCS3 is in the ON state and the output of the second wireless channel monitoring signal WCS2 from the second channel monitoring means 352 is in the OFF state, the first channel When the output of the first wireless channel monitoring signal WCS1 from the monitoring means 351 is turned off, at the same time, the output of the third wireless channel monitoring signal WCS3 is turned off.

The fourth channel supervisory signal generation circuit 35
Reference numeral 4 denotes a fifth time t5 when the carrier detection circuit 33b sets the carrier detection signal CS to a time longer than the existence time Ti of the interference radio wave when the output of the fourth wireless channel monitoring signal WCS4 is in the off state. When the output is continued, the output of the fourth wireless channel monitoring signal WCS4 is turned on, and when the output of the fourth wireless channel monitoring signal WCS4 is in the on state, the carrier detection circuit 33b causes the carrier detection signal CS When the output of the fourth wireless channel monitor signal WCS4 is continuously stopped for a preset sixth time t6 or longer, the output of the fourth wireless channel monitoring signal WCS4 is turned off.

Each channel supervisory signal generation circuit 351 to
Wireless channel monitoring signals WCS1, WCS2, WCS3, W from 354
CS4 is supplied to the interrupt controller 39 and the microprocessor 40, respectively. The interrupt controller 39 uses the wireless channel monitoring signals WCS1, WCS2, WCS3, WCS
When 4 is taken in, it interrupts the microprocessor 40. When a command transmission such as information (data) or a command (command) is received from the antenna 31, the received data is demodulated by the demodulation circuit 33a and the demodulated data RXD is obtained by the communication controller 3
Transferred to 6. The communication controller 36 is provided with a receiving section and a transmitting section, and when the receiving section receives the demodulated data RXD, it performs serial / parallel conversion. Then, the demodulated data obtained by parallel conversion is stored in the RAM 43 by the DMA controller 38.

The data stored in the RAM 43 is the D
The MA controller 38 reads out the data and transfers it to the transmission unit of the communication controller 37.
Then, serial / parallel conversion is performed and transferred as transmission data TXD to the wired interface 44. The wired interface 44 uses the transmission data TX.
D is transmitted to the information communication terminal (not shown) via the wired communication line 45. Also, when the wired interface 44 receives data from the information communication terminal via the wired communication line 45, the wired interface 44 transfers the received data RXD to the receiving unit of the communication controller 37. The communication controller 37 serially receives the received data RXD.
Convert to parallel and output. The DMA controller 3
8 is the RA received data received from the communication controller 37
It is designed to be stored in M43.

The microprocessor 40 has a RAM 4
A command transmission or a response transmission is determined from the content of the data stored in No. 3, and the received data once stored in the RAM 43 is wirelessly transmitted. At this time, the microprocessor 40 causes the wireless channel monitoring signals WCS1, WCS2,
WCS3 and WCS4 are used as transmission control judgment criteria. When transmitting data wirelessly, the microprocessor 40 sets the DMA controller 38, reads the data once stored in the RAM 43, and transfers it to the transmitting unit of the communication controller 36. The communication controller 36 controls the data such as a communication protocol and then performs parallel / serial conversion and transfers the data as transmission data TXD to the wireless transmission unit 34. The wireless transmission unit 34 modulates the transmission data TXD and then wirelessly transmits the data through the antenna duplexer 32 and the antenna 31.

The microprocessor 40 is programmed to control the command transmission and the response transmission according to the communication algorithm shown in FIG. 4 and perform the receiving operation. First, in S1, the fourth wireless channel monitoring signal WC from the fourth channel monitoring signal generation circuit 354 is output.
It is checked whether or not S4 is on, and if it is on, wireless reception processing is performed in S2. In this way, the determination as to whether or not to perform the wireless reception process is performed by the fourth wireless channel monitoring signal WCS4.

Subsequently, in S3, it is determined whether or not there is a transmission request. Here, if the wireless device is in a state in which command transmission or response transmission should be performed, the process proceeds to wireless transmission processing. If there is no message to be transmitted, this wireless transmission process ends. If it is determined in S3 that there is a message to be transmitted, subsequently in S4, it is determined whether the content of the transmission request is a command transmission or a response transmission or the like. Here, in the case of transmission other than command transmission, in S5, each channel supervisory signal generation circuit 351
To 354 wireless channel monitoring signals WCS1, WCS2, WCS
Wireless transmission processing is performed regardless of the state of WCS4. In other words, the transmission of responses other than command transmission is always performed after the command is received and then in pairs with the received command.
CS2, WCS3, WCS4 are not checked.

If it is determined in S4 that the command is transmitted, then in S6, the third wireless channel monitoring signal WCS3 from the third channel monitoring signal generation circuit 353 is sent.
It is determined whether or not is on. Then, if the third wireless channel monitoring signal WCS3 is on, it is determined that another station is performing wireless transmission, and in S7, the command transmission is postponed. If the third wireless channel monitoring signal WCS3 is off, it is determined that another station is not using the same wireless communication channel, and in step S5, wireless transmission processing, that is, command transmission is performed.

In such a configuration, each radio A,
FIG. 5 is a timing diagram showing the operation state of each radio when B and C perform radio transmission / reception control. In FIG. 5, the wireless device A transmits the command CM1 to the wireless device B, and the wireless device B responds to the command R1.
The case where P1 is returned is shown. At this time, the wireless device C can receive messages such as commands and responses transmitted by the wireless devices A and B, but since the destination of the message is not its own station, it responds to these messages. do not do.

When the command CM1 is transmitted from the wireless device A, the carrier detection circuit 33b of each of the wireless devices A to C detects the carrier and outputs the carrier detection signal CS from the carrier detection circuit 33b. That is, the carrier detection signal CS is turned on. This carrier detection signal CS
Is a signal that is turned on when the electric field strength of the received radio wave detected in the wireless communication channel is compared with a preset value and the received electric field strength becomes larger than the set value. Therefore, the time TCM during which the carrier detection signal CS is on
Is almost the same as the time during which the wireless device A is transmitting the command CM1.

When the carrier detection signal CS is output from the carrier detection circuit 33b, the channel supervisory signal generation circuit 35 is generated.
Then, from the first channel supervisory signal generation circuit 351 to the first
The wireless channel monitoring signal WCS1 of is output. The first radio channel supervisory signal WCS1 rises with a delay of a first time t1 with respect to the rise of the carrier detection signal CS, and with a second time t2 with respect to the fall of the carrier detection signal CS. Get down. The first time t1 and the second time t2 may be the same.

That is, the first radio channel supervisory signal WC
S1 is not turned on unless the carrier detection signal CS is in the ON state continuously for the first time t1 or more, and once turned on, the carrier detection signal CS is turned on for the second time t.
It is a signal that does not turn off unless it is turned off continuously for 2 or more times. As a result, even if noise having a time width of less than time t1 when the carrier detection signal CS is in the off state and less than time t2 when the carrier detection signal CS is in the on state can be eliminated.

Then, the first radio channel supervisory signal WCS1
If the ON state continues for the third time t3 or more, the third time t has passed from the rise of the first wireless channel supervisory signal WCS1.
The second wireless channel monitoring signal WCS2 is turned on after a delay of three. Then, at the same time that the first wireless channel monitoring signal WCS1 is turned off, the second wireless channel monitoring signal WCS2 is also turned off. That is, when a long message like the command CM1 is transmitted and the first wireless channel monitoring signal WCS1 is continuously turned on for the third time t3 or longer, the second wireless channel monitoring signal WCS2 is turned on. However, as when receiving a response or an interference radio wave, the first wireless channel monitoring signal WC
When S1 does not continue for the third time t3 or longer, the second wireless channel supervisory signal WCS2 remains off.

The first channel supervisory signal generation circuit 3
51 to the first wireless channel monitoring signal WCS1 and the second channel monitoring signal generation circuit 352 to the second wireless channel monitoring signal WCS2 are the third channel monitoring signal generation circuit 353.
Then, the third channel monitoring signal generation circuit 353 turns on the third wireless channel monitoring signal WCS3 in synchronization with the rising of the first wireless channel monitoring signal WCS1. And
The third radio channel supervisory signal WCS3 falls with a delay of a fourth time t4 from the fall of the second radio channel supervisory signal WCS2.

When the received signal is short and the duration of the first wireless channel monitoring signal WCS1 does not reach the third time t3 and the second wireless channel monitoring signal WCS2 is not output, the third wireless channel The falling timing of the monitoring signal WCS3 is the same as the falling timing of the first wireless channel monitoring signal WCS1. Further, when the first radio channel supervisory signal WCS1 rises again within the fourth time t4, the first radio channel supervisory signal WCS1 and the second radio channel at the time when the fourth time t4 elapses. The fall timing of the third wireless channel supervisory signal WCS3 is determined by the state of the supervisory signal WCS2. In FIG. 5, since the second wireless channel monitoring signal WCS2 is off and only the first wireless channel monitoring signal WCS1 is on at the time when the fourth time t4 has elapsed, the fourth time t4 has elapsed. After that, the first wireless channel monitoring signal WCS1 turns off, and at the same time, the third wireless channel monitoring signal WCS3 turns off.

The fourth radio channel supervisory signal WCS4 is the first
Is generated by the carrier detection signal CS similarly to the wireless channel monitoring signal WCS1 of
The continuous monitoring time of the carrier detection signal CS is different from that of WCS1. That is, the fourth wireless channel monitoring signal WCS4 is not turned on unless the carrier detection signal CS is in the on state continuously for the fifth time t5 or more, and once turned on, the carrier detection signal CS is turned on this time. This signal does not turn off unless it remains off for a sixth time t6 or longer.

Therefore, when the wireless device A transmits the command CM1 to the wireless device B, not only the wireless device B but also the wireless device C turns on the fourth wireless channel monitoring signal WCS4. C will first perform a wireless reception process. As a result, it is found that the content of the wireless message is a command message to the wireless device B, and the wireless device B is requested to send a response. On the other hand, even if the same command message is received, since the wireless device C is not a message addressed to its own station, no response is made to this.

Radio B for which a response transmission request has been issued
Enters a response message transmission operation. That is, the third
The wireless channel monitoring signal WCS3 of is turned on during the delay of the fourth time t4, but since the response transmission is not a command transmission, a response message transmission operation is immediately performed.
As a result, it is possible to quickly send a response to the command. When the wireless device B transmits the response RP1, the wireless channel monitoring signals WCS1 to WCS4 of the wireless devices A to C are as follows.

Similar to the case of transmitting the command CM1 described above, the timing at which the carrier detection signal CS is turned on substantially coincides with the timing at which the radio device B sends the response RP1. Here, each numerical value is set so that the relationship of t5 <TRP <t3 is established between the transmission time TRP of the response RP1 and the third time t3 and the fifth time t5. In this way, the response R is sent for the third time t3.
By setting it longer than the transmission time TRP of P1, the second wireless channel monitoring signal WCS2 is not sent out when the response signal is received, and the fall of the third wireless channel monitoring signal WCS3 is delayed. None, the first wireless channel supervisory signal WCS1 falls at the same timing as the fall. This prevents the fall of the third wireless channel monitoring signal WCS3 from being delayed by the fourth time t4 when the response message is received. Therefore, when the response message is received, the wireless transmission is prohibited. The time is shortened, which can minimize the loss of the transmission opportunity when the response is received, and improve the communication efficiency.

Also, the third radio channel supervisory signal WCS3
Is continuously turned on after the first time t1 has elapsed since the wireless device A started transmitting the command CM1 and until the second time t2 has elapsed since the wireless device B has finished transmitting the response RP1. Therefore, the wireless device C cannot transmit a command while the third wireless channel monitoring signal WCS3 is in the ON state. This ensures the transmission of the radio wave from the wireless device C until the transmission of the response from the wireless device B to the transmission of the command CM1 from the wireless device A is completed, that is, until the pair of communication is completed. It can be prevented. The fourth time t4 for controlling the fall delay of the third wireless channel monitoring signal WCS3 is the processing time required from the completion of the command reception by the microprocessor 40 of the wireless device to the start of the response transmission. You just have to anticipate.

Further, the response RP1 is sent at the fifth time t5.
Of the fourth wireless channel monitoring signal WCS4 when the response RP1 is transmitted
Can be reliably turned on. In other words, the wireless devices A to C can reliably detect the response signal. In addition,
Since the fifth time t5 is the operation delay time until the reception operation is started, the data to be transmitted cannot be actually put in the response message RP1 from the beginning of the message to time t5. A response message packet is formed and transmitted by adding dummy data to the original transmission data. Therefore, the actual length of the response message is TRP-t
5, That is, the shaded portion of the response message TRP in the figure is the actual response message. Also, when transmitting a command for exactly the same reason, dummy data having a length of time t5 is added before the actual transmission message and transmitted. Therefore, the actual length of the command transmission message is TCM-t5. That is, the shaded portion of the command transmission message CM1 in the figure is the actual command transmission message. As described above, since the dummy data is added, the communication efficiency is somewhat deteriorated by the amount of the added data, but since the length of the dummy data in the entire communication is small, the deterioration of the communication efficiency is hardly a problem.

Further, FIG. 6 shows the timing when the wireless device A transmits the command CM1 to the wireless device B, and then no wireless device returns a response and receives an interference radio wave with a time width Ti. . The relationship between the time width Ti of the interference radio wave and the first time t1 and the fifth time t5 is t1 <Ti <t
5 is set. Due to this interference radio wave Ti, the first wireless channel monitoring signal WCS1 and the third wireless channel monitoring signal WCS3 are output at the timings shown in the figure, but the second wireless channel monitoring signal WCS2 and the fourth wireless channel monitoring signal WCS4 are output. Do not output. As described above, the fourth radio channel monitoring signal WCS4 is not turned on even when the interference radio wave Ti is received, so that the radio device does not perform the radio reception process. Therefore, even if the interference radio wave Ti exists in the wireless area, the interference radio wave Ti is not erroneously received, the reception processing is not started, and the wireless reception processing can be realized without waste.

Since the second wireless channel monitoring signal WCS2 is not turned on even when the interference radio wave Ti is received, the fourth time t4 is set at the fall of the third wireless channel monitoring signal WCS3.
No delay occurs, and the third wireless channel monitoring signal WCS3 falls at the same time as the falling of the first wireless channel monitoring signal WCS1. Therefore, when the interference radio wave Ti is received, the time during which the radio transmission is prohibited due to the ON state of the third radio channel monitoring signal WCS3 is shortened, and the loss of the transmission opportunity when the interference radio wave Ti is received is minimized. Can be controlled to improve communication efficiency. In particular, the first time t1
If the second time t2 is made as small as possible within the range allowed by the system design, the time during which transmission by the interference radio wave becomes impossible can be made as close as possible to the time when the interference radio wave exists.

By the way, in recent years, the ISM (Indu) has come to be used as a frequency band for wireless LAN.
In the strial Scientific and Medical band, there are radio waves radiated from various devices, and depending on the wireless data communication device, the radio environment is not very good. Above all, the leakage electromagnetic wave radiated from the microwave oven is the 2.4 GHz IS
It is radiated fairly strongly in the M band, and this becomes a strong interference radio wave for the wireless data communication device. FIG. 7 shows a result of actually measuring how the carrier detection signal CS is affected by the electromagnetic wave of the microwave oven radiated in the 2.4 GHz band that can be used for the spread spectrum communication wireless data communication. ~ Shown in FIG.

FIG. 7 shows 2472 MHz (2.472 GH).
z), FIG. 8 shows 2484 MHz (2.48 MHz).
496 MHz), and FIG. 9 shows 2496 MHz.
It is a measurement result at the time of measuring at (2.496 GHz). In any case, the horizontal axis represents the pulse signal width generated in the carrier detection signal CS by the interference radio wave from the microwave oven. That is, the horizontal axis represents the time width T of the interference radio wave shown in FIG.
It is equivalent to i. The vertical axis represents the number of samples, and the total number of samples measured was 10 ⁵ . From this, it was investigated how many time width pulses were generated and how often.

From the measurement results, it can be seen that most of the width of the CS noise pulse generated by the interference radio wave radiated from the microwave oven is less than 100 μsec. From this measurement result, if the fifth time t5 is set to about 100 μsec, the fourth radio channel monitoring signal WCS4 is not accidentally turned on by the interference radio wave from the microwave oven, and the reception malfunction due to the interference radio wave from the microwave oven is prevented. Can be prevented. That is, in an environment in which wireless communication is performed using a frequency band in which electromagnetic waves from a microwave oven have strong interference, it is possible to reliably avoid interfering radio waves and perform wireless communication.

[0058]

As described above, according to the first and third aspects of the present invention, it is possible to reliably perform the wireless communication in an environment using a frequency band such as an ISM band in which electromagnetic wave interference due to a microwave oven or the like is strong. Wireless communication can be performed while avoiding interference radio waves, and response transmission can be performed promptly in response to command transmission. Further, loss of transmission opportunity when interference radio waves are detected can be controlled to a minimum, and communication efficiency can be improved.

According to the second and third aspects of the present invention, the interference radio wave can be reliably received in an environment where wireless communication is performed using a frequency band such as an ISM band in which electromagnetic waves are strongly interfered by a microwave oven or the like. The wireless communication can be avoided and the response can be promptly transmitted in response to the command transmission. In addition, the loss of the transmission opportunity when the interference radio wave is detected and the response is received can be controlled to the minimum, and the communication efficiency can be improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wireless communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a wireless device according to the same embodiment.

FIG. 3 is a block diagram showing a configuration of a channel monitoring signal generation circuit of the wireless device according to the same embodiment.

FIG. 4 is a flowchart showing a wireless communication process of the microprocessor of the wireless device in the embodiment.

FIG. 5 is a timing chart showing an example of communication control of each wireless device in the wireless communication system according to the first embodiment.

FIG. 6 is a timing diagram showing an example of communication control of each wireless device when an interference radio wave is received in the wireless communication system according to the same embodiment.

FIG. 7 is a graph showing the result of measurement at 2472 MHz as to how the electromagnetic wave of the microwave oven affects the carrier detection signal, as a relationship between the pulse signal width generated in the carrier detection signal and the number of samples.

FIG. 8 is a graph showing the result of measurement at 2484 MHz as to what effect the electromagnetic wave of the microwave oven has on the carrier detection signal, as a relationship between the pulse signal width generated in the carrier detection signal and the number of samples.

FIG. 9 is a graph showing the result of measurement at 2496 MHz as to how the electromagnetic wave of the microwave oven affects the carrier detection signal, as a relationship between the pulse signal width generated in the carrier detection signal and the number of samples.

FIG. 10 is a block diagram showing a conventional example.

FIG. 11 is a flowchart showing a transmission process of the conventional example.

FIG. 12 is a timing chart showing an example of communication control of each wireless device when a plurality of wireless devices are arranged in the conventional example.

FIG. 13 is a block diagram showing another conventional example.

[Explanation of symbols]

 33 ... Radio receiver 33b ... Carrier detection circuit 34 ... Radio transmitter 35 ... Channel monitoring signal generation circuit 36, 37 ... Communication controller 40 ... Microprocessor (MPU)

Claims (3)

[Claims] 1. Comparing the electric field strength of a received radio wave detected in a wireless channel to communicate with a set value, and when the electric field strength of the received radio wave exceeds the set value, the electric wave is sent out in this radio channel. Carrier detection means for outputting a carrier detection signal indicating that the first wireless channel monitoring signal is output, and the carrier detection means detects the carrier when the output of the first wireless channel monitoring signal is in an off state. Signal is the existence time T of the interfering radio wave
When the output is continued for the first time t1 or more set to a time shorter than i, the output of the first wireless channel supervisory signal is turned on, and when the output of the first wireless channel supervisory signal is in the on state. A first channel monitoring means for turning off the output of the first radio channel monitoring signal when the carrier detecting means continues to stop the output of the carrier detection signal for a preset second time t2 or more; Outputting a radio channel supervisory signal, and when the output of the second radio channel supervisory signal is in the off state, the output of the first radio channel supervisory signal from the first channel supervisory means is a preset third time. When the output of the second radio channel supervisory signal is turned on when continuously turned on for t3 or more, and when the output of the second radio channel supervisory signal is in the on state, the first channel monitor means is provided. A second channel monitoring means for turning off the output of the second wireless channel monitoring signal when the output of the first wireless channel monitoring signal is turned off, and a third wireless channel monitoring signal for outputting the third wireless channel monitoring signal. When the output of the first wireless channel monitoring signal from the first channel monitoring means is turned on while the output of the third wireless channel monitoring signal is in the off state, the output of the third wireless channel monitoring signal is turned on, Further, when the output of the third wireless channel monitoring signal is in the on state and the output of the second wireless channel monitoring signal from the second channel monitoring means is in the on state, the first channel monitoring means outputs When the output of the first wireless channel monitoring signal of the third wireless channel monitoring signal is turned off, the output of the third wireless channel monitoring signal is turned off after the preset fourth time t4 has elapsed, and the third wireless channel monitoring signal is turned off. First wireless channel from the first channel monitoring means when the output of the channel monitoring signal is on and the output of the second wireless channel monitoring signal from the second channel monitoring means is off. Third channel monitoring means for turning off the output of the third radio channel supervisory signal at the same time when the output of the supervisory signal is turned off, and outputting the fourth radio channel supervisory signal, and the fourth radio channel supervisory signal When the output of the carrier is off, the carrier detecting means outputs the carrier detecting signal to the existence time T of the interference radio wave.
When the output continues for a fifth time t5 or longer set to a time longer than i, the output of the fourth wireless channel supervisory signal is turned on, and when the output of the fourth wireless channel supervisory signal is in the on state. A fourth channel monitoring means for turning off the output of the fourth radio channel monitoring signal when the carrier detecting means continuously stops the output of the carrier detecting signal for a preset sixth time t6 or more, When the output of the fourth wireless channel monitoring signal from the fourth channel monitoring means is turned on, the receiving operation is started, and when the output of the fourth wireless channel monitoring signal is turned off, the reception operation is started. A wireless data communication device, characterized in that, when the reception operation is stopped and the output of the third wireless channel monitoring signal from the third channel monitoring means is in the ON state, transmission of the own station is prohibited. 2. The electric field strength of the received radio wave detected in the radio channel with which communication is attempted is compared with a set value, and when the electric field strength of the received radio wave exceeds the set value, the radio wave is transmitted in this radio channel. Carrier detection means for outputting a carrier detection signal indicating that the first wireless channel monitoring signal is output, and the carrier detection means detects the carrier when the output of the first wireless channel monitoring signal is in an off state. Signal is the existence time T of the interfering radio wave
When the output is continued for the first time t1 or more set to a time shorter than i, the output of the first wireless channel supervisory signal is turned on, and when the output of the first wireless channel supervisory signal is in the on state. A first channel monitoring means for turning off the output of the first radio channel monitoring signal when the carrier detecting means continues to stop the output of the carrier detection signal for a preset second time t2 or more; Outputting a radio channel supervisory signal, and when the output of the second radio channel supervisory signal is in the off state, the output of the first radio channel supervisory signal from the first channel supervisory means is a preset third time. When the output of the second radio channel supervisory signal is turned on when continuously turned on for t3 or more, and when the output of the second radio channel supervisory signal is in the on state, the first channel monitor means is provided. A second channel monitoring means for turning off the output of the second wireless channel monitoring signal when the output of the first wireless channel monitoring signal is turned off, and a third wireless channel monitoring signal for outputting the third wireless channel monitoring signal. When the output of the first wireless channel monitoring signal from the first channel monitoring means is turned on while the output of the third wireless channel monitoring signal is in the off state, the output of the third wireless channel monitoring signal is turned on, Further, when the output of the third wireless channel monitoring signal is in the on state and the output of the second wireless channel monitoring signal from the second channel monitoring means is in the on state, the first channel monitoring means outputs When the output of the first wireless channel monitoring signal of the third wireless channel monitoring signal is turned off, the output of the third wireless channel monitoring signal is turned off after the preset fourth time t4 has elapsed, and the third wireless channel monitoring signal is turned off. First wireless channel from the first channel monitoring means when the output of the channel monitoring signal is on and the output of the second wireless channel monitoring signal from the second channel monitoring means is off. Third channel monitoring means for turning off the output of the third radio channel supervisory signal at the same time when the output of the supervisory signal is turned off, and outputting the fourth radio channel supervisory signal, and the fourth radio channel supervisory signal When the output of the carrier is off, the carrier detecting means outputs the carrier detecting signal to the existence time T of the interference radio wave.
When the output continues for a fifth time t5 or longer set to a time longer than i, the output of the fourth wireless channel supervisory signal is turned on, and when the output of the fourth wireless channel supervisory signal is in the on state. , The fourth channel monitoring means for turning off the output of the fourth radio channel monitoring signal when the carrier detecting means continuously stops the output of the carrier detecting signal for a preset sixth time t6 or more, and to the own station Response reception means for transmitting a response whose transmission time is shorter than the third time t3 in response to the reception of the signal, and the output of the fourth radio channel monitoring signal from the fourth channel monitoring means is in the ON state. When the output of the fourth wireless channel monitoring signal is turned off, the receiving operation is stopped and the third wireless channel from the third channel monitoring means is started. A wireless data communication device characterized in that transmission of its own station is prohibited when an output of a channel monitoring signal is in an ON state. 3. The wireless data communication apparatus according to claim 1, wherein the fifth time t5 is set to about 100 μsec.