CN103310492B - A kind of sensitivity calibration system and its calibration method - Google Patents
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Abstract
The present invention relates to intelligent transportation application field, especially a kind of sensitivity calibration system and its calibration method, the communication means of board units.This sensitivity calibration system, including calibration module, for exporting calibration command；Standard signal source on the outside of vehicle windscreen, the standard signal constant for output signal strength value；Board units on the inside of vehicle windscreen, for after the calibration command that calibration module is sent is received, it is connected with the standard signal source, according to the difference of the standard signal intensity level and actual signal intensity level, set it is corresponding with the difference, meet the board units into the threshold value of communications status requirement.The present invention also provides the board units communication means after the calibration method of this sensitivity calibration system, and calibration.The present invention can be made adjustment according to windshield to the attenuation degree of signal by calibrating the installations of the applicable different windshield of board units, solve the problems, such as to communicate because of signal attenuation not smooth.
Description
Technical Field
The invention relates to the field of intelligent traffic application, in particular to a system and a method for calibrating sensitivity of a vehicle-mounted unit.
Background
With the development of the automotive industry, automotive windshields with insulation designs are becoming more prevalent in vehicles. This glass is transparent to visible light but absorbs energy from other radiation spectra such as infrared and ultraviolet, with metal ion components added to the material.
When an automobile equipped with such a windshield passes through an ETC lane, the on-board unit may have difficulty in communication. Since microwaves are greatly attenuated by passing through such a metal insulating layer or film, the additional metal component absorbs the microwave energy. In China, the existing vehicle-mounted unit production standard generally specifies that the awakening sensitivity is less than or equal to minus 40dBm and the receiving and transmitting sensitivity is less than or equal to minus 50 dBm. According to public reports and field measurement, the signal attenuation of the windshield of the metal heat insulation layer or the film is as high as 20-40dB, which means that 99% of energy in microwave signals is absorbed by the front windshield, so that the problem that a vehicle cannot normally pass through an ETC lane is caused. Vehicles with insulating layer windshields cause ETC to have poor passage so that the vehicle-mounted unit cannot be installed, which is a problem for many years.
However, since the windshield of a vehicle has different properties and the attenuation degree of a signal is different, the vehicle cannot be generally adapted to different vehicle requirements. On the other hand, China does not have a mature system and method for calibrating the sensitivity of the vehicle-mounted unit and relevant parameters of the vehicle-mounted unit, so that the corresponding adjustment cannot be carried out according to the specific performance requirement of the mounted vehicle, and the sensitivity of the awakening or transceiving module cannot be automatically adapted according to the attenuation degree of the windshield to the signal. The production of the vehicle-mounted unit in the industry is still in a 'one-time cutting' state.
In recent years, with the development of economy, the customer group of high-grade vehicles in China is rapidly increased, and besides, ETC charging projects in China are continuously popularized, the problem that vehicle-mounted units cannot be installed or the success rate of passing after installation is low is particularly obvious. In view of the inconsistency of signal attenuation levels of various windshields, it is urgent to develop an on-board unit that can adjust and calibrate the sensitivity according to the characteristics of different windshields.
Disclosure of Invention
In order to solve the above problems, the present invention provides a calibration system for sensitivity of an on-board unit and a communication method of the on-board unit, which can adjust the communication sensitivity of the on-board unit according to the property of a windshield of an installed vehicle, and meet the requirement that different vehicles smoothly pass through an ETC.
The sensitivity calibration system, comprising:
the calibration module is used for outputting a calibration instruction;
the standard signal source is arranged on the outer side of the vehicle windshield and used for outputting a standard signal with a constant signal intensity value;
and the vehicle-mounted unit is arranged on the inner side of the vehicle windshield and used for being connected with the standard signal source after receiving a calibration instruction sent by the calibration module, and setting a threshold value corresponding to the difference value and meeting the requirement of the vehicle-mounted unit for entering a communication state according to the difference value between the standard signal intensity value and the actual signal intensity value.
The invention also provides a calibration method of the sensitivity calibration system, which comprises the following calibration steps:
step a: the calibration module sends a calibration instruction to a main control module of the vehicle-mounted unit to enable the vehicle-mounted unit to enter an automatic calibration mode;
step b: the vehicle-mounted unit receives a standard signal sent by the standard signal source;
step c: the main control module sets a threshold value corresponding to the difference value and meeting the requirement of the vehicle-mounted unit for entering a communication state according to the difference value between the standard signal intensity value and the actual signal intensity value;
step d: and after the calibration is finished, the on-board unit exits the automatic calibration mode.
The invention also provides a communication method of the vehicle-mounted unit calibrated by the sensitivity calibration system, which comprises the following communication steps:
step A: the vehicle-mounted unit receives the wake-up signal and enters a preparation state from a dormant state;
and B: the vehicle-mounted unit judges whether the received awakening signal strength value reaches a preset threshold value for starting the vehicle-mounted unit to enter a communication state from a preparation state;
and C: when the awakening signal strength value reaches the threshold value, the vehicle-mounted unit enters a communication state from a preparation state to perform information interaction; otherwise, the on-board unit returns from the stand-by state to the sleep state
The invention has the beneficial effects that:
a calibration system for the sensitivity of a vehicle-mounted unit is set, and a corresponding threshold value of the vehicle-mounted unit in the optimal communication state is found by judging the attenuation degree of a windshield of a mounted vehicle to a standard signal source, so that the problem that the sensitivity of the conventional vehicle-mounted unit cannot be correspondingly adjusted according to the characteristics of the mounted vehicle is solved.
In the communication process after the sensitivity of the vehicle-mounted unit is calibrated, the vehicle-mounted unit effectively avoids mistransaction caused by side road or vehicle following interference signals in the transaction process, avoids transaction failure caused by weak signal intensity, and further improves the transaction success rate of the electronic tag.
The vehicle-mounted unit improves the sensitivity range, effectively improves the application capability of the vehicle with serious signal attenuation caused by the windshield, and has flexibility, universality and wide application range.
Drawings
Fig. 1a is a schematic diagram of a sensitivity calibration system according to embodiment 1 of the present invention.
Fig. 1b is a schematic structural diagram of an on-board unit according to embodiment 1 of the present invention.
Fig. 1c is a schematic diagram of a structure of a vehicle-mounted unit wake-up module in embodiment 1 of the present invention.
Fig. 1d is a calibration flow chart of the sensitivity calibration system according to embodiment 1 of the present invention.
Fig. 1e is a communication diagram of embodiment 1 of the present invention.
Fig. 1f is a flowchart of a communication method of an on-board unit according to embodiment 1 of the present invention.
Fig. 2a is a schematic diagram of a sensitivity calibration system in embodiment 2 of the present invention.
Fig. 2b is a schematic diagram of an on-board unit according to embodiment 2 of the present invention.
Fig. 3a is a schematic diagram of a sensitivity calibration system according to embodiment 3 of the present invention.
Fig. 3b is a schematic diagram of an on-board unit according to embodiment 3 of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Example 1
As shown in fig. 1a, the present embodiment provides a sensitivity calibration system 100 for an on-board unit (hereinafter referred to as OBU110), wherein the calibration system 100 includes the OBU110 and a standard signal source 130 disposed on an outer surface of a vehicle windshield 120.
As shown in fig. 1b, the OBU110 is a monolithic vehicle-mounted unit, and includes a main control module 111, and a transceiver module 112, a wake-up module 115, and a calibration module 116 respectively connected to the main control module 111.
Wherein,
the transceiver module 112 has a signal strength value detecting unit 1121 for detecting the strength of the received microwave signal in the vehicle. In order to satisfy the requirement that the sensitivity of the transceiver module 112 is higher than the industry standard in normal use of the OBU110 (see fig. 1a) of a vehicle with severe signal attenuation caused by the windshield 120, the transceiver module establishes a wireless communication connection with the standard signal source 4 (see fig. 1a) or the road side unit (see fig. 1d, hereinafter referred to as RSU160) to perform data exchange, and is a channel for wireless data transmission between the OBU110 and the outside.
The main control module 111 is responsible for scheduling other modules to work according to instructions and is a central processing unit of the OBU 110. In this embodiment, the main control module 111 stores various windshield 120 attenuation performance parameters for the standard signal, that is, different differences exist between the actual signal strength and the standard signal strength when passing through different windshields 120, each difference has a corresponding lowest communication value, and the lowest communication value is a threshold value that can meet the requirement of the OBU110 for entering the communication state. The main control module 111 of the OBU110 receives the instruction to enter the calibration mode, controls the transceiver module 112 to detect the received actual signal strength value, compare the actual signal strength value with the standard signal strength value to obtain a difference value therebetween, automatically searches a threshold value corresponding to the current difference value from a list of the difference values between the actual signal strength value and the standard signal strength value, and sets the threshold value in the storage unit 1110. The storage unit 1110 of the main control module 111 is an EEPROM or FLASH memory, and data therein is not lost even if the main control module 111 is powered off. The master control module 111 also has other functions in the normal operating mode of the OBU 110. After the OBU110 is woken up, the main control module 111 enters a standby state, reads the strength value of the wake-up signal detected by the transceiver module 112 in the standby state, compares the strength value with a set threshold value, and controls the state of the OBU110 according to the comparison result.
The calibration module 116 stores a calibration program instruction, and is configured to send a calibration instruction to the main control module 111, start the OBU110 to automatically enter a calibration mode, and perform sensitivity calibration in cooperation with the standard signal source 130.
Referring to fig. 1c, the wake-up module 115 is responsible for receiving the square wave wake-up signal, which is a receiving channel for waking up other functional modules and making the application circuit of the OBU110 enter an operating state. The wake-up module 115 built by discrete components in the invention comprises a receiving antenna 1151, a diode detection unit 1152, an input buffer unit 1153, an amplifying circuit unit 1154, a diode envelope detection unit 1155 and a wake-up circuit 1156 which are connected in sequence.
The calibration procedure of the calibration device will be described in detail below with reference to fig. 1 d:
s111: the OBU110 and the standard signal source 130 are disposed on both the inside and outside of the windshield 120 of the vehicle, respectively.
S112: referring to fig. 1c, in this embodiment, the calibration module 116 is built in the OBU110, and when the initialization of the OBU110 is completed, the calibration module 116 immediately sends a calibration instruction to the main control module 111, so that the OBU110 executes the instruction and enters an automatic calibration mode. At this point the OBU110 establishes a communication connection with the standard signal source 130.
S113: a standard signal source 130 is arranged on the outside of the windshield 120 facing the OBU110, in close proximity to the windshield 120, and the standard signal source 130 transmits a standard signal with a fixed signal intensity value to the OBU110 via the windshield 120. Since the transmission power strength of the standard signal source 130 is calibrated when leaving the factory, the signal strength value received by the OBU110 is relatively fixed, and after the transceiver module 112 in the OBU110 receives the standard signal, the signal strength value detection unit 1121 detects the signal strength value and transmits the result to the main control module 111 for further processing. Due to the attenuation of the microwave signal by the windshield 120, the actual signal received by the OBU110 has a smaller intensity value than the standard signal, and the different intensity values of the windshields 120 with different performances are different due to the different attenuation capabilities. For example, some bulletproof glasses, which are coated with a heat insulating film or doped with metal ions, attenuate microwave signals much more than ordinary glasses.
The main control module 111 compares the difference between the standard signal strength values according to the received actual signal strength values, searches a mapping table between the signal strength difference preset in itself and the threshold value, finds out the threshold value corresponding to the current difference, and fixes the threshold value in the storage unit 1110 of the main control module 111. The threshold value mentioned in this embodiment is a minimum operating signal strength value for ensuring that the OBU110 operates under the optimum signal transmission condition by measuring the attenuation degree of the microwave signal by various windshields 120 and integrating the general communication distance between the OBU110 and the RSU 160. That is, the intensity value of the wake-up signal received by the OBU110 needs to reach an intensity sufficient to "cross" a predetermined threshold "in order for the OBU110 to enter a communication state and complete the data exchange process, so that the minimum communication intensity value solidified in the OBU110 in the calibration mode is defined as the threshold. For some windshields 120 that attenuate microwave signals more, the threshold of the OBU110 will be set smaller accordingly; for some windshields 120 that attenuate microwave signals less, the OBU110 threshold may be set higher accordingly. Only if the signal strength value is higher than the threshold value, the OBU110 enters a communication state, and if the signal strength value is lower than the other signal strength values of the threshold value, the OBU110 determines that the signal is an interference signal.
For example, when the standard signal intensity value is set to 40dBm, the signal intensity value received after the OBU110 detects that the windshield 120 having the heat insulating film has passed through is set to 20dBm, the communication distance between the OBU110 and the RSU160 is comprehensively analyzed, and the minimum communication value of the OBU110 is set to 10dBm in consideration of reducing the occurrence of the false transactions. When a standard signal is transmitted to the OBU110 through the common glass, a signal intensity value of 30dBm is detected, and the signal attenuation is small, the minimum communication value of the OBU110 can be set to 20dBm by using the above-mentioned reference method. The feature data is sorted into a "correspondence table between signal strength values and minimum communication values" and preset in the main control module 111, and when the OBU110 detects that the received signal strength value is 20dBm in the calibration mode, the minimum communication value of 10dBm can be automatically searched and solidified according to the correspondence table, and the minimum communication value is used as one of important parameters of the OBU110 in the normal working state. The OBU110 enters the communication state only if the received wake-up signal strength value is higher than the threshold value by 10dBm in the normal operating state.
S114: the threshold values set for the attenuation degree of the microwave signal by different windshields 120 can be obtained through limited experiments, and are in one-to-one correspondence with the signal strength value received by the OBU110, and are processed into a correspondence list and stored in the main control module 111 of the OBU 110. Thus, when the OBU110 enters the self-calibration operation mode, the threshold value corresponding to the signal strength value can be searched and called out in the main control module 111 through the self-calibration program, and the threshold value is solidified in the main control module 111, so that the threshold value cannot be lost even if the power is off, and is used as one of important parameters for normal operation of the OBU 110. At this time, the calibration is completed, the OBU110 exits the automatic calibration mode, the connection between the OBU110 and the standard signal source 130 is disconnected, and the OBU110 is started to enter a normal operating state.
The calibrated OBU110 communication method will be further described in detail with reference to fig. 1 f.
The operating state of the OBU110 of this implementation is divided into three types, which are respectively: a sleep state, a ready state, and a communication state. The communication steps are as follows:
s121: in conjunction with fig. 1e, A, B, C lanes are listed, wherein B, C lane is the same direction lane, and a lane is opposite to the B, C lane. To better illustrate the influence of the driving position of the vehicle on the operating state, fig. 1e illustrates the different positions of the vehicle passing through the toll station by using position No. 1, position No. 2, and position No. 3, which is helpful to illustrate the change of the operating state of the OBU 110.
When the vehicle 170 with the OBU110 installed enters the B lane of the ETC, which is outside the B communication area of the RSU160, i.e., the vehicle 170 is in position No. 1, a small amount of microwave signals from the RSU160 will still be transmitted to the OBU110 through the front windshield 120. When the wake-up module 115 of the OBU110 detects the microwave signal, it wakes up all the application circuit modules of the OBU110, so that the OBU110 enters the standby state from the sleep state.
S122: at this time, the transceiver module 112 enters an operating state and constantly detects the received microwave signal. In this embodiment, the signal strength value detecting unit 1121 of the transceiver module 112 detects the received wake-up signal strength value and sends the wake-up signal strength value to the main control module 111, and the main control module 111 compares the signal strength value with a preset threshold value and determines whether the wake-up signal strength value meets the communication requirement according to the comparison result. The threshold value is set to the lowest signal strength value that will initiate the OBU110 from the ready state to the communication state after the OBU110 has completed the calibration process.
S123: if the main control module 111 determines that the wake-up signal strength is lower than the threshold, the microwave signal is considered to be too weak or an interference signal from adjacent communication areas such as an a lane communication area and a C lane communication area, and the main control module 111 immediately instructs the OBU110 to return to the sleep state.
When the vehicle 170 enters the position No. 2, the OBU110 enters a normal communication range with the RSU160, that is, a communication area B in fig. 1d, the OBU110 detects and determines that the strength value of the wake-up signal is higher than the threshold value, and the main control module 111 instructs the OBU110 to enter a communication state to communicate with the RSU 160. The OBU110 returns to the sleep state from the communication state after the operation is completed.
The vehicle gradually moves away from the position 2, leaves the communication area B and enters the position 3. At this time, the OBU110 may receive the interference signal from the adjacent channel communication area again, and wake up the wake-up module 115 again, so that the OBU110 enters the standby state. The OBU110 determines that the wake-up signal strength value is lower than the threshold value and does not enter the communication state.
The OBU110 of the present embodiment adjusts the communication sensitivity for different vehicle windshield 120 performance by calibrating the system 100. The communication method can be applied to a plurality of intelligent traffic scenes, such as the fields of a multi-lane free flow electronic toll collection system, an ETC lane toll collection system and the like, can also be applied to different functional requirements of registration, transaction and the like, and greatly improves the success rate of the communication process.
Example 2
The calibration system 200 of the present embodiment also includes an OBU210 and a standard signal source 230 disposed outside the windshield 220, wherein the OBU210 is a monolithic onboard unit. Compared to example 1, the difference is: as shown in fig. 2a and 2b, the calibration system 200 further includes a handheld issuer 240, and the calibration module 216 is disposed in the handheld issuer 240; the OBU210 includes a main control module 211, and a transceiver module 212 and a wake-up module 215 respectively connected to the main control module 211, wherein the transceiver module 212 is provided with a signal strength value detection unit 2121. The handheld transponder 240 is coupled to the OBU210 via the transceiver module 212 such that the calibration module 216 is external to the OBU 210.
The handheld issuer 240 is generally used for OBU210 initialization, primary or secondary issuance, where the calibration module 216 may send calibration instructions to initiate OBU210 into calibration mode when OBU210 requires calibration. The step of S112 different from embodiment 1 is: after the initialization of the OBU210 is completed, the handheld transmitter 240 sends a calibration program instruction to the OBU210, the transceiver module 212 of the OBU210 receives a signal indicating calibration, transmits the signal to the main control module 211, and the main control module 211 instructs the OBU210 to execute the calibration instruction, so that the OBU210 automatically enters a calibration mode.
The rest of the calibration and communication steps are as in example 1.
Embodiment 2 separates the calibration module 216 from the OBU210, which not only enables a user to remotely control the calibration steps and procedures, but also reduces the number of parts of the OBU210 itself, thereby making the OBU210 circuit design more concise and efficient.
Example 3
The calibration system 300 of the present embodiment also includes an OBU310 and a standard signal source 330 disposed outside the windshield 320. Compared with the embodiment 1 and the embodiment 2, the embodiment is different in that: the OBU310 belongs to a two-piece vehicle-mounted unit series and is provided with a card slot, and the internal structure of the OBU comprises a main control module 311, a transceiving module 312, a wake-up module 315 and a card reading module 317 which are respectively connected with the main control module 311; the transceiver module 312 is provided with a signal strength value detection unit 3121. The calibration module 317 of the present embodiment is also externally disposed on the OBU310, but the external calibration module 317 is disposed in a calibration IC card 380. As shown in fig. 3a, the calibration system 300 further comprises a calibration IC card 380 connected to the OBU310, and the calibration program instructions are provided in the calibration IC card 380, and the IC card 3800 is connected to the OBU310 through the card reading module 317.
The card reading module 317 is a channel for the OBU110 to exchange information with the IC card. In the embodiment, the card reading module 317 may be used for reading a user transaction IC card, and may also be used for reading a calibration IC card 380 storing a calibration program. The IC card 380 conforms to the national standard ISO7816, and is inserted when the OBU310 needs to be calibrated, so as to start the OBU310 to enter a calibration mode.
The present embodiment differs from embodiment 1 in the step S112: when the OBU310 completes initialization and needs to calibrate the sensitivity, the calibration IC card 380 is inserted, the card reading module 317 reads a calibration instruction in the calibration IC card 380 and sends the calibration program instruction to the main control module 311 of the OBU310, and the main control module 311 instructs the OBU310 to execute the calibration instruction, so that the OBU310 automatically enters a calibration mode.
It should be added that after the calibration is completed, the calibration IC card 380 needs to be pulled out, inserted into the transaction IC card to connect with the two-piece OBU310, and then the OBU310 is normally started.
The rest of the calibration and communication steps are as in example 1.
Embodiment 3 provides the calibration module 316 in the calibration IC card 380, which enables the user to autonomously control the calibration procedure and program, and has good operability.
The OBU improves the sensitivity range of the awakening module and the transceiving module, and lays a foundation for vehicles with windshields made of special materials to smoothly pass through an ETC lane and a free flow lane; an OBU sensitive calibration system is set up, a corresponding threshold value in the best communication state of the OBU is found out by judging the attenuation degree of a windshield of a mounted vehicle to a standard signal source, and the threshold value is used as one of important parameters for normal operation of the OBU, so that the problem that the conventional OBU cannot make corresponding sensitivity adjustment aiming at the characteristics of the mounted vehicle is solved; through the calibration to the OBU, set for corresponding sensitivity, avoid the mistake transaction, further improve OBU's transaction efficiency. The OBU and the calibration and communication method thereof have the advantages of flexibility, universality, wide application range and wide application prospect.
While the present embodiments have been particularly shown and described with references to the point thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (7)
1. A sensitivity calibration system, comprising:
the calibration module is used for outputting a calibration instruction;
the standard signal source is closely attached to the outer side of the windshield of the vehicle and is used for outputting a standard signal with a constant signal intensity value;
the vehicle-mounted unit is arranged on the inner side of a vehicle windshield and used for being connected with the standard signal source after receiving a calibration instruction sent by the calibration module, searching a corresponding table of a received signal strength value preset in the vehicle-mounted unit and a threshold value according to the received actual signal strength value, and setting the threshold value corresponding to the actual signal strength value and meeting the requirement of the vehicle-mounted unit for entering a communication state; the threshold value is set according to the attenuation degree of different vehicle windshields to microwave signals obtained through limited experiments, the average communication distance between the vehicle-mounted unit and the road side unit is integrated, the lowest working signal intensity value of the vehicle-mounted unit working under the optimal signal transmission state is guaranteed, and the threshold value and the signal intensity value received by the vehicle-mounted unit are in one-to-one correspondence and processed into a corresponding table to be stored in the vehicle-mounted unit;
the vehicle-mounted unit comprises a wake-up module, wherein the wake-up module comprises a discrete component receiving antenna, a diode detection unit, an input buffer unit, an amplification circuit unit, a diode envelope detection unit and a wake-up circuit which are sequentially connected; the awakening module is used for receiving an awakening signal and awakening the vehicle-mounted unit to enter a preparation state;
the calibration module is arranged in the handheld issuer or the calibration IC card;
the intensity value of the wake-up signal received by the vehicle-mounted unit is higher than the threshold value, and the vehicle-mounted unit enters a communication state; and the intensity value of the wake-up signal received by the vehicle-mounted unit is lower than the threshold value, and the vehicle-mounted unit judges that the wake-up signal is an interference signal.
2. The sensitivity calibration system of claim 1, wherein the threshold value decreases as the difference between the signal strength value of the standard signal source and the signal strength value received by the on-board unit increases.
3. The sensitivity calibration system according to claim 1, wherein the on-board unit comprises a main control module and a transceiver module which are connected with each other;
the transceiver module is provided with a signal intensity value detection unit for detecting the actual signal intensity value of the received standard signal;
the main control module is used for controlling the transceiver module to detect the actual signal strength value; and searching and storing the threshold value corresponding to the actual signal intensity value according to the actual signal intensity value.
4. The sensitivity calibration system according to claim 3, wherein the main control module further comprises a storage unit for storing data that is not lost after power failure.
5. The sensitivity calibration system according to claim 4, wherein the on-board unit further comprises a card reading module for information interaction with an external memory.
6. A method of calibrating a sensitivity calibration system according to any one of claims 1 to 5, comprising the steps of:
step a: the method comprises the following steps that a vehicle-mounted unit and a standard signal source are respectively arranged on the inner side and the outer side of a vehicle windshield;
step b: the vehicle-mounted unit receives and executes a calibration instruction sent by the calibration module, and enters an automatic calibration mode; the vehicle-mounted unit receives a standard signal sent by the standard signal source;
step c: the vehicle-mounted unit sets a threshold value which corresponds to the actual signal intensity value and meets the requirement of the vehicle-mounted unit for entering a communication state according to the received actual signal intensity value, the threshold value is set according to the attenuation degree of microwave signals of different vehicle windshields obtained through limited experiments, the common communication distance between the vehicle-mounted unit and a road side unit is integrated, the minimum working signal intensity value of the vehicle-mounted unit working under the optimal signal transmission state is ensured, the threshold value and the signal intensity value received by the vehicle-mounted unit are in one-to-one correspondence and processed into a correspondence table to be stored in the vehicle-mounted unit, the intensity value of a wake-up signal received by the vehicle-mounted unit is higher than the threshold value, and the vehicle-mounted unit enters the communication state; the intensity value of the wake-up signal received by the vehicle-mounted unit is lower than the threshold value, and the vehicle-mounted unit judges the wake-up signal to be an interference signal;
step d: and after the calibration is finished, the on-board unit exits the automatic calibration mode.
7. The method according to claim 6, wherein the step c is performed in a main control module, and the actual signal strength value and the threshold value are stored in the main control module.
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| JP6500799B2 (en) * | 2016-02-11 | 2019-04-17 | 株式会社オートネットワーク技術研究所 | Vehicle communication system and portable device |
| CN107393033A (en) * | 2016-05-17 | 2017-11-24 | 上海搜林信息技术有限公司 | Board units wake up sensitivity adjustment method and its system |
| CN105846922A (en) * | 2016-05-20 | 2016-08-10 | 深圳市远望谷信息技术股份有限公司 | Method and device for RFID tag to determine master device in frequency division multiplexing system |
| CN108494506A (en) * | 2017-02-15 | 2018-09-04 | 北京聚利科技股份有限公司 | The sensitivity measuring method and device of mobile unit |
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| JP3698948B2 (en) * | 2000-03-28 | 2005-09-21 | 三菱電機株式会社 | DSRC OBE |
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| CN101431706A (en) * | 2007-11-08 | 2009-05-13 | 宏达国际电子股份有限公司 | Vehicular noise suppressing system and method |
| KR101016938B1 (en) * | 2008-03-05 | 2011-02-25 | (주)에프씨아이 | Electrical toll collection system with terminal limiting communication zone |
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| CN102157019B (en) * | 2011-01-24 | 2013-12-04 | 北京北大千方科技有限公司 | Communication method for on board unit and road side unit of ETC system |
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