With the rapid development trend of social and economic development in my country and the acceleration of urbanization process, the total number of urban population has increased sharply, and the situation of traffic congestion is the most common in my country. It can be seen in all cities, and the construction of subways has an effect that cannot be ignored in improving the urban traffic and travel environment, which means that the subways in my country still have a large indoor space for the development trend. Most of today's big cities with populations of more than a million build subways to ease and improve traffic tensions. In the case of a large population in our country, it is more necessary to develop the subway project, and the subway in our country also has excellent development prospects. The subway opens up the underground space of the human body and relieves the congestion on the ground. The construction of the subway has become the key way of urban infrastructure construction and urban transportation in the 21st century in China. This is the selection of historical time and an inevitable result.
According to the ultra-long-distance wifi module wireless ad hoc network equipment to complete the vehicle-ground wireless two-way real-time transmission system software, the system software must be able to ensure that the train is running on a high-speed route or at a stop, with a reasonable bandwidth of not less than 5MBPS. The control center data information or control commands are transmitted in both directions, and can ensure a small delay time. In addition, it can ensure that the vehicle and ground equipment is fixed at the station to receive the machinery equipment and then to the main control room. When the data information switch is switched on, 0 packet loss is achieved, including in the depot And the wireless access points set along the road and track, the wireless equipment of the sub-control center, and the vehicle-ground wireless equipment, as well as the vehicle-ground wireless units and antennas, so as to achieve instant and seamless transmission of trains within the entire range of the incoming station. With the image and data information of the road surface, and complete the switch quickly. For the first time, the workers in the general control room can analyze and arrange the tasks after the subway stops according to the data information of the train and subway. There are more than 40 subway cars parked in this subway car lot. The parking lot is divided into upper and lower floors. About 20 cars are parked on each floor. The user stipulates that the subway will be transmitted to the center without delay when the subway enters the station.
According to the actual situation, the construction content of the ultra-long-distance wifi module includes the combination of wireless transmission and wired transmission. The on-board data in the subway parking lot is transmitted to the station receiving terminal by 2.4G wireless equipment, and the receiving terminal is transmitted to the main control room by wired optical fiber. According to the functional parameters of the mobile ad hoc network, it is tentatively set to have 20 vehicle-mounted transmitting terminals and 2 fixed receiving terminals per floor (one for each incoming station and one for the parking lot). Since the receiving port to the main control room is a closed building, it is not suitable for wireless transmission, so the receiving port on each floor collects the vehicle data to the main control room for optical fiber transmission.
The ultra-long-distance wifi module system adopts mature and reliable products, which are moisture-proof, dust-proof, anti-corrosion, suitable for the application environment of underground parking lot, and meet the needs of 24-hour wireless network transmission. Choose economical and practical products from the design and selection, the system meets the actual business needs, pays attention to practicality, and supports the anti-jamming transmission function of the parking station. The system adopts advanced software, hardware and network technology, with high cost performance, low error rate, strong compatibility, convenient capacity upgrade, avoiding repeated construction and wasting investment.
Provide convenience for future network expansion and upgrade, through functional, modular and hierarchical network structure design. During operation, the maintenance of the system should be as simple and easy as possible, the standard connection plug-in is convenient for the overall replacement of the equipment, and there is no need to use too many special maintenance tools during the maintenance process.
The subway wireless data transmission system is a data transmission channel system between the vehicle, the station and the control center. In order to realize the monitoring of train equipment and running status by subway operators, the on-board data is timely transmitted to subway management sites such as stations, depots, and parking lots during the parking or running process of the train. There are more than 40 subway cars in the subway depot to be implemented this time. The parking lot is divided into upper and lower floors, with about 20 cars on each floor. When the customer requests the subway to enter the station, the on-board data signal should be connected to the receiving end of the station, and the on-board data should be transmitted to the general control center without delay. According to the functional parameters of our company's mobile ad hoc network, each layer of the ultra-long-distance wifi module 2.4G wireless transmission equipment is configured as 20:2, that is, 20 transmitters and 2 receivers. The specific transmission method is that when the subway enters the station, the on-board data is first connected to the fixed-end receiving device at the entrance of the station. The equipment and the station receiver are connected, and the on-board data can be transmitted to the station equipment at the first time without delay. After the subway enters the station, the MESH ad hoc network is connected to the station equipment, and there is no need to delay the connection, so as to realize the uninterrupted transmission of the on-board data from the fast-forward station to the parking center from the fast-forward station to the master control center. Since the receiving end to the main control room is a closed building, it is not suitable for wireless transmission. Each receiving end is connected to a fiber optic transceiver through a network cable, and is connected to the wired channel and control center provided by 100M fiber. For the wireless communication environment of the underground subway parking lot, our company's ultra-long-distance wifi module ad hoc network equipment can be equipped and deployed with multiple wireless MESH nodes, and can also meet the needs of wireless data transmission from the parking lot to the maintenance workshop.
The wireless transmission antenna involved in the microwave communication system uses the common 2.4GHz frequency band in the industry for transmission, which has the advantages of long transmission distance and strong diffraction ability. However, 2.4GHz transmission equipment should not have too much blocking in the transmission. The transmitting antenna can maintain a line-of-sight path between the receiving antenna to ensure that the communication link transmits signals optimally. In addition, potential metal material machinery or other wireless devices will cause attenuation of electromagnetic wave transmission.
Ultra-long-distance wifi module wireless network transmission equipment is a kind of sophisticated communication equipment, which requires high power supply and is easily affected by other power supply equipment. The power supply of the equipment power supply should be separated from the power supply of other high-power equipment. When taking electricity in a unified location, UPS, regulated power supply or isolation transformer should be installed to filter the influence and interference of high-power equipment on the power supply during the working process. The power supply is 220V and the DC is 12-48V. If the voltage is lower or higher than this voltage, it will affect the normal operation of the device or cause abnormal damage to the power supply module.
At the same time, the equipment is equipped with a network lightning protection device to do a good job of lightning protection of the equipment. Secondly, according to the situation of the equipment being installed outdoors, it is necessary to customize the fixing bracket for the equipment, keep the equipment fixed, and do a good job of windproof protection for the equipment. According to the requirements of "Technical Specification for Electrical Equipment Installation", the installation of equipment is fixed, the transmission line is not limited, and the power supply wiring process.
