In order to ensure the highest data communications security and reliability of the system. In the equipment selection, equipment configuration, system design have been carefully analyzed and considered in several aspects, and take the appropriate measures. American GE MDS Company The United States GE MDS company is recognized worldwide as the pioneer in providing wireless data acquisition systems, installed more than 700,000 MDS digital radio stations around the world. The performance of the GE MDS digital radio sets the standard for the wireless data communications industry. In March 2007, General Electric Corporation (GE) acquired MDS and changed its name to GE MDS. The GE MDS iNET300 is an industrial Ethernet radio with long transmission distances and high transmission rates. Through iNET300, users can directly transmit data from remote Ethernet or serial network to IP-based networks, such as oil wells, gas wells, pumping stations, pipelines, tanks, and instrumentation. It can also provide a mobile wireless access network for various applications based on on-board mobile. The advantages of the GE MDS iNET300 wireless solution Transmission distance is far: Industrial-grade products have the longest transmission distance of similar products. The iNET 300 radio supports multiple applications from multiple users and works simultaneously on the same radio station or network through multiple different protocols. Features ◆ The same device or network supports multiple protocols, multiple applications, and multiple users. 2.2 Selection of system frequency Taking into account the high altitude of the airship in the air and the weather conditions such as wind, wind, etc., we propose to adopt an ultra-short wave band with strong diffraction ability, and any frequency point between 336-344 MHz is in line with This requirement. 2.3.1 Calculation Analysis 1. Assume that the distance between the control center and the airship is 20km to calculate the system's weak reserve value Japanese Okumura did a lot of statistical work on the radio wave propagation problems of terrestrial mobile communications, and summed up an empirical formula for the propagation loss Lb applicable to a large city: Lb (dB) = 75 + 26Lgf + 45LgR - GT (dB) - GR (dB) - (14 + 6.5LgR) × LgHT - 3.2 [Lg (12HR)] 2 The iNET300 digital radio has a transmit power of 37dB and a receive sensitivity of -97dBm. The system depletion reserve = system gain - splice loss - cable loss - propagation loss = 134-1-2.298-94.3 2. Assume that the control center is 50km away from the airship According to the previous calculation and analysis, using the GE MDS iNET300 equipment, whether design margin or system hardware redundancy, data bandwidth redundancy, communication distance is very reasonable.
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Second, system design and related considerations
2.1 Equipment Selection
Founded in 1985, MDS Corporation is located in Rochester, New York, and specializes in the development and production of professional wireless data communications equipment. For 26 years, MDS has been leading the way in the field of industrial network communications and has become the largest manufacturer in this industry. MDS currently employs 280 people and occupies 70% of the same product market in the United States.
MDS has world-class factory buildings and automated production facilities. Its production management system uses flexible manufacturing. It has two production lines for surface welding technology. All parts, semi-finished products and finished products are tested and tested automatically. The factory produces according to the customer's order and can produce many different types of machines every day. The daily output can reach 1,000 units. The 56,000-square-foot factory building, ISO-9001 quality certification system and advanced management system have created first-class products and first-rate enterprises.
On the one hand, MDS continues to innovate and strengthen its technical reserves. On the other hand, MDS is making great efforts to maintain the compatibility of products, so that the installed products and new products can be compatible and upgraded. MDS has developed many special tools and software for the convenience of installation, debugging, use and maintenance of wireless data radio stations, and it is deeply loved by users. MDS radio has become the industry standard.
GE MDS iNET300 operating frequency is 336MHz-344MHz frequency band, because of its lower frequency, transmission distance is much larger than microwave equipment, in the sight distance case, the maximum transmission distance of up to 100 kilometers, the radio's air transmission rate up to 512Kbps.
High reliability:
The hot standby master station (implemented through P21) can provide high system reliability for some critical applications. The remote device can also adopt the hot standby mode.
Strong safety performance:
Wireless links provide multiple levels of protection, including 300MHz physical layer FM and 128-bit data encryption, AES-128, and RADIUS.
Good flexibility:
Strong compatibility:
iNET 300 uses an open interface standard that is backwards compatible.
Strong network management function:
Use NETview MS for remote management. NETview MS is based on a standalone Java application platform that can be integrated with other vendors' management software.
â—† The radio supports Ethernet port and serial port at the same time - it can be used as a gateway device for converting serial devices to Ethernet.
â—† Industrial grade equipment performance - can work in various harsh environments.
â—† Supports industrial Ethernet protocols.
â—† Transmission distance - up to 100KM.
â—† High transfer rate - up to 512Kbps
â—† Good security performance - Multi-level security measures to ensure that the device is not eavesdropped and illegally accessed.
â—† High reliability - Provides hot standby redundant configuration to ensure network reliability.
â—† Plug and Play - The device can be used simply by configuration.
â—† MDS network management system - advanced SNMP management system, easy to simplify equipment operation and maintenance and improve network operating performance.
2.3 System Calculation Analysis Regardless of the engineering formula used, the actual data may not be the same, but the conclusions will be the same. Only when the formulas used by the formulas are considered to be less important, the data will be more favorable, but the actual situation will be larger. The more comprehensive the factors considered in the formula, the closer to the actual situation. Here is the line-of-sight transmission, using the free-space transmission formula is closer to the actual value.
Known infrastructure raw data:
Airship height = 1000 meters The location of the control center is unknown. Assume that the control center is 20 kilometers away from the airship. Assume that the height of the receiving antenna is 50 meters.
Omnidirectional antenna for antenna, antenna gain is 8dB
In the formula, the receiving antenna height HR, the HT unit is m, f is 340MHz,
Then Lb(dB) = 75+26Lg340+45Lg20-8-8-(14+6.5Lg20)×Lg1000-3.2[Lg(12×50)]2
= 75 + 68.82 + 58.55 – 8 – 8 - 67.37 - 24.70
= 94.3dB
Fading reserve actual value = system gain - splice loss - cable loss - propagation loss where:
System Gain = Transmit Power of Digital Radio - Receiving Sensitivity of Digital Radio = 37-(-97) = 134 dBm
Splice loss = 8 x 0.25 = 1 dB (according to 8 connectors, including all connectors for feeders and jumpers)
Cable losses, different cable lengths for different installation positions, according to estimates, the length of the cable on the airship does not exceed 10m, and the ground does not exceed 50m.
Cable length = 10 meters (airship) + 50 meters (ground) = 60 meters Cable loss = 3.83dB x 60/100 = 2.298dB (using normal 1/2" cable, 3.83dB/100m)
= 36.40dB
At this time, the receiver's receiving field strength is about -60.60dB, leaving 36.40dB margin for the system.
Calculation of propagation loss between the airship and the ground:
Lb (dB) = 75 + 26Lgf + 45LgR - GT (dB) - GR (dB) - (14 + 6.5LgR) × LgHT - 3.2 [Lg (12HR)] 2
=75 + 68.82 + 76.45 – 8 – 8 – 75.12 - 24.70
=104.45 dB
The system depletion reserve = system gain - splice loss - cable loss - propagation loss = 134-1-2.298-104.45
=26.25dB
At this time, the receiving field strength of the receiver is about -70.75 dB, leaving a 26.25 dB margin for the system.
Considering that the airship is in the air, it is susceptible to wind and air currents, which can cause the antenna to swing, resulting in changes in the direction of gain and polarization in the transmission direction. The worst case scenario is that the gain of the antenna in the transmission direction is zero. The polarization direction is vertical (influencing the transmission maximum value 3dB), and the system can bring the insertion loss in the transmission path of maximum 19dB. The system debility reserve value of our iNET300 equipment design is much larger than the worst case.
Therefore, iNET300 digital radio can fully meet the design requirements here. 
First, the basic situation During the expo, the airship hovered over the air 1000 meters in the vicinity of the venue and collected CIF format video data for the conference. Now a wireless data transmission system needs to be installed. The system mainly completes the video surveillance video transmission of the airship equipment. In the event of an emergency, the ground control center may send control signals to the airship to control the airship to land after being away from the crowded area.