Introduction to ETC basic principles and technical advantages

According to the requirements of the Ministry of Transport, it is necessary to ensure that the speed of non-stopping will reach over 90% by the end of this year to ensure smooth operation of the entire road network. Under the premise of vigorously promoting ETC in the country, I believe that many car owners have already installed ETC equipment on their cars. Today, let's find out what ETC is!

What is ETC

ETC (Electronic Toll Collection) is a non-stop electronic toll collection system. ETC-dedicated lanes are used for vehicles equipped with ETC vehicle-mounted devices.

ETC system composition and working principle

The ETC system performs wireless communication and information exchange between an in-vehicle device mounted on a vehicle and an antenna mounted on a toll booth lane. It is mainly composed of automatic vehicle identification system, central management system and other auxiliary facilities. Among them, the vehicle automatic identification system has an onboard unit (OBU), also known as a transponder or an electronic tag (Tag), a roadside unit (RSU), a loop sensor, and the like. The OBU contains the identification information of the vehicle, which is generally installed on the windshield in front of the vehicle. The RSU is installed next to the toll booth, and the loop sensor is installed under the lane floor. The central management system has a large database that stores information on a large number of registered vehicles and users.

When the vehicle passes through the toll gate, the loop sensor senses the vehicle, the RSU sends an inquiry signal, the OBU responds, and performs two-way communication and data exchange; the central management system acquires vehicle identification information such as the car ID number, the model, and the like. The corresponding information in the database is compared and judged, and the management system generates different actions according to different situations. For example, the computer charging management system deducts the toll fee payable from the prepaid account of the vehicle, or sends instructions to other auxiliary facilities. . Other auxiliary facilities such as: illegal vehicle camera system, automatic control of railings or other obstacles, traffic display equipment (red, yellow, green light and other equipment) to indicate vehicle travel.

1. Vehicle automatic identification technology

The automatic identification technology of vehicles in ETC system is the most important technology, which directly affects the performance and application promotion of the system, and is also the main indicator of distinguishing different ETC systems. At present, the identification technologies used mainly include: 1 infrared scanning recognition technology; 2 CCD camera recognition technology; 3 laser scanning recognition technology; 4 IC card recognition technology. However, due to the characteristics of transportation itself, there is a system that can be applied in all weather and harsh environments, with long-distance function (about 10m), high safety and reliability, high speed and long service life. These systems cannot fully meet the above requirements due to their own defects, and cannot be effectively promoted and applied. Microwave contactless ID card recognition technology is developed to meet this need. Due to its strong microwave penetration, it can penetrate dense fog, raindrops, sand and so on. It has a long working distance and is suitable for all-weather and harsh environmental conditions. It has a long working distance and small volume, and it can be used for active emission. For more than 10 years, it can also work in passive reflection mode (no life limit). It can be active or passive, and the vehicle passes through the toll station at a normal speed of 50-120km/h. The working band mainly has 900MlHz, 2.45GHz and 5.8GHz frequency bands.

The microwave non-contact ID card (ie, OBU) receives the inquiry signal sent by the RSU, and is sent to the control unit for processing through the data demodulation. After the identity verification and password verification, the control unit reads and writes the data to the EEPROID and encodes it. After modulation, the antenna is sent out. The processing control unit is mainly used for password verification, programming mode checking, data encryption and decryption, and controlling read and write operations on EEPROID. The EEPROID contains the vehicle ID number, license plate number, model, driver and other related information. The RSU performs corresponding operations according to the received ID number and the like, thereby achieving identification of the vehicle.

2. Communication between OBU and RSU

In the ETC system, a dedicated short-range communication standard protocol (DSRC) is used between the OBU and the RSU for half-duplex communication. Since the 900IDHz and 2.45GHz bands are close to the mobile communication band and the background noise is large, the international trend is 5.8GHz. The system is used as a standard ETC system. For example, the United States adopts 900MHz or 5.8GHz, and Japan and Europe both 5.8GHz as the frequency band of ETC. The ISO/TC204 Technical Committee of China has proposed to allocate the 5.8 GHz band to short-range communications in the ITS field, including the ETC system, and to approve the test of the ETC system in the 5.8 GHz band with a communication distance of 10 m. The 5.8 GHz microwave band is consistent with the Chinese ISID industrial band and is not affected by mobile communication. At present, the frequency bands of ETC systems used in China are mostly 900 IDHz and 2.5 GHz bands.

ETC technology equipment: electronic tag + microwave antenna

Electronic tags: According to different working modes of tags, they can be divided into read-only (single-chip) and read-write (two-chip) systems; depending on the electronic tag response mode, they can be divided into active and passive.

Monolithic electronic tag - it consists of an integrated circuit chip with vehicle properties (identification code, etc.) and a small microwave transmitter. Attribute data can only be written once and cannot be changed;

The two-piece electronic tag, also known as the smart card type electronic tag, consists of an IC card and a car microwave transceiver. The IC card contains a micro CPU with certain computing, processing and storage data capabilities. Therefore, it has more functions than a one-piece tag. It can be used not only as an electronic tag, but also as a credit card and a financial card. When making an electronic tag, insert it into the in-vehicle device, and the in-vehicle device completes the two-way communication between the tag and the DSRC, and displays the information in the card.

The read-write active electronic tag is based on a read-only type, and adds a readable and writable data memory and a small microwave receiver, which can transmit data such as a vehicle identification code in the tag to the DSRC, and can also receive and store. Information about the DSRC.

The passive tag is to modulate and reflect the microwave emitted by the DSRC in some way to transmit the information in the tag to the DSRC.

ETC has 6 advantages

Advantage 1: 3 seconds through the toll booth is much faster than the artificial lane

Advantage 2: discount on tolls, real money and silver benefits

Advantage three: take the high-speed can "pay", online can also recharge

Advantage 4: Introducing non-cash payment services for trucks, and discounts

Advantage 5: ETC lanes continue to increase, and some toll stations will be dominated by ETC lanes.

Advantage 6: parking, shopping, refueling... ETC will expand multi-domain applications