Application and Development of Flyaway Satellite Station in News Gathering System

1. Introduction

Building a video news gathering system which is comprehensive, three-dimensional and multi-echelon has been put on the construction schedule. The system can expand business in a maximum limit and improve real-time transmission capacity of audio and video business, secure a leading position in news gathering technology field. The construction goal of complete system is an integrated ground-space network. It makes full use of the advantage of on-orbit communication satellite coverage and combines the characteristics of ground cables broadband transmission. It develops diversified network terminal, such as fixed news gathering station in high-lighted areas and nationwide vehicle-mounted news gathering station and global flyaway moving news gathering station and 3G video live broadcast and so on. The paper mainly discusses the application and development of flyaway moving satellite station in the whole system.

2. Special needs for flyaway satellite station

Mature ground fiber network, fixed and mobile news gathering satellite station have been widely used in many years in the radio and television industry. When constructing diversified news gathering network terminal, it only needs to choose in the market according to the demand. And there is not much technical obstacles and difficulties. It is the first attempt to apply flyaway station in large-scale as news gathering terminal and safeguard of significant news event. Deep requirement analysis, strict technical investigation and decisive decision-making are all the indispensable conditions to ensure the success of project construction.

Because flyaway satellite station possesses the characteristics of fast deploy and convenient to transport, the system is usually applied in satellite communication business with 2Mbps low rate. Different from the demand of general flyaway satellite communication stationit needs the type of satellite communication system equipment of mobility, easy and simple operation, strong transmission capability, audio and video news real-time transmission, high-speed data rate transmission above the 6Mbps and high integration. It requires that it can carry equipment to arrive at news site through various traffic tools in harsh conditions and quickly establish satellite link and use frequently at a low failure rate. The existing flyaway satellite station can meet the special requirement. And it challenges the technical renovation ability of the equipment manufacturers.

3. Introduction of flyaway satellite stations news gathering system

3.1 Design and model selection principles of the system

Based on the existing application of flyaway satellite station system, combined with the actual situation of audio and video publicity, the scope and depth of technical products is further expanded. The systematic design principle is established from aspects of product price, appearance, techniques, performance and technology reforming.

Basis of main systematic design and model selection are as follows:

* Mobility: transport the equipment quickly to news site through vehicles, aircraft and even manpower.

* Adaptability to field: it can satisfy the requirements of jour work in field, of building communication link in adverse environment including temperature, humidity and air pressure.

*Easy operation: two or three people can operate the equipment after simple training.

* High real-time video transmission quality: it can satisfy video transmission requirement of broadcast studio.

* Standard interface and uniform transmission standard: device interface unified as standard SDI embedded audio type and broadcast by standard DVB.

* High integration: flyaway satellite station can be packed in two aviation cabinets. Audio and video code device use one aviation case. The whole equipment only consists of two or three aviation cabinets.

* Economy of purchase equipment: The whole equipment choice is to ensure transmission quality and to efficiently reduce purchase cost as well.

* The system with high flexibility which can support multiple transmission modes. It can support standard DVB-S mode and advanced transfer mode, such as DVB-S2, H.264 and so on. It efficiently reduces the bandwidth of satellite, and supports analog audio-video input interface.

* More importantly, based on the existing technology, it can be renovated technically for necessary according to the specific requirement of news gathering. Thus it realizes function of flyaway news gathering station in true sense. Flyaway satellite station, which is the important constituent of emergency communication system and news gathering network, is mainly applied in emergency coverage to improve the reaction speed. It offers a type of news gathering terminal based on satellite communication for audio-video report which possesses characteristics of mobility, easy to operate, strong transmission, high integration.

In actual report environment, it can transfer high data speed above 6Mbps and transmit live video content to satellite communication center in real-time by DVB. And it can transfer demodulated SDI signal to audio-video editing system and studio utilizing transmitted and optical fiber.

3.2 Antenna system of flyaway satellite station

Flyaway satellite antenna plays a vital role through the whole news gathering system of flyaway satellite station. Its portable performance and operation requirement will directly decide portability and operability of the whole system. After extensive market research, foreign flyaway satellite products can basically meet the need of news gathering in aspects of technology and performance. However, they are of high price, complex operation and low performance-price ratio. And the same kind of domestic products completely satisfying the demand is few in aspects of performance, technology, appearance or technological level. So based on the whole systematic design principle, it needs for domestic satellite antenna equipment to have necessary technical renovation in order to be suitable for the special need of news gathering.

Flyaway satellite communication antenna consists of reflector assembly, horn assembly, waveguide, rotation polarization joint, polarization adjusting assembly, antenna pedestal, drive assembly, electric motor, transducer, drive circuit, power, BUC, LNBantenna controllercarrier wave and beacon tracking receiver. All equipments and combination are integrated in antenna pedestal. They can operate in fully automatic mode including automatic deploy, pointing and store through precise pointing satellite procedure and connecting controller. When necessary, it also can adopt manual and semi-auto mode which can control antenna to point satellite quickly and establish communication link. The connection controller can be laptops or PDA installing a special software to achieve complete monitor and operation of antenna attitude. Non-professional can be proficient in operation after simple training to achieve one-key pointing satellite because of friendly man-machine interface and concise and easy operation.

The flyaway satellite system of is small diameter and light transmit amplifier configuration. Radio frequency connector mostly adopts flexible radio frequency cable of convenient fold and storage. Guaranteeing portability and meanwhile sacrificing transmission performance, it mostly applies communication business within 2Mbps data rate, not suitable for studio to broadcast high quality video content. In order to meet the special needs of news gathering, it is necessary for flyaway antenna system applied in communication to given technical reform. The main direction is to realize that the antenna system can transmit video business with 6Mbps~8Mbps data rate and keep enough system allowance to ensure that the system can apply normally in harsh environment. Implementing methods are summarized as follows:

Adopt special reflector design to realize total reflector structure and increase the reflector area on greatest degree to improve antenna gain.

All radio frequency connector adopts hardware waveguide and rotation joint parts to overcome high radio frequency cable loss and instability caused by long-term rotation of radio frequency cable and connectors.

Choose high-power BUC equipment and try to maximize transmission power ensuring the invariability of the equipment weight. At present the compression power of configuration BUC equipment 1dB can achieve above 40W.

To be suitable for the uncertainty of sudden news site, flyaway antenna device must meet the requirement that it can apply under the environment of -20~+55 temperature and above 5000m altitude.

All vulnerable parts must be modular design ensuring that non-professional can finish replacing spare parts within short time in an emergency.

Realizing the function of automatic pointing satellite, it must strengthen perfection of manual operation and simplicity of operation to fully guarantee reliability and real time of news gathering.

3.3 Coding and modulation system

Another important component of Flyaway satellite station news gathering system is base band DSNG system. It adopts DSNG system with compact structure and mature technology in aspects of code modulation. The emphasis of the system is of compact structure, advanced technology, low power consumption, light weight, high reliability and easy to carry and normal use in harsh environment such as in the open and high altitude place. The system needs to use together with L-band interface of flyaway satellite antenna system and try to save occupied space. To ensure portability, it must adopt audio and video coding and coding modulator with combination modulation.

Considering compatibility and expansibility of emergency communication network, DSNG especially emphasizes flexible use. Audio coding can support encoding mode of MPEG-2/4 and H.264. Video coding adopts 1st and 2nd layer of MPEG-2. The total compression coding ratio can be adjustable. There are two kinds of delay mode which can support and equip with BISS scrambling, one is normal delay mode and the other is low-latency delay mode. The system support multiple audio input way, that is PAL/NTSC embedded video signal including SDI digital signal, analog compound audio signal, analog balanced video signal and AES/EBU digital input signal. Meanwhile the system can also possess ASI code stream output, IP output and carrier multiplexing function conform to DVB-S/S2 standard. The modulator can adopt QPSK/8PSK mode, and possess obligate update ability which can achieve to 16APSK, 32APSK, HD high-definition programming code, and other function.

To realize the construction purpose of flyaway satellite news gathering system, to achieve real portability, the main principle of code and modulation system are as follows.

In order to ensure the convenience of system integration and the portable performance, the structure of coding modulation equipment must be 1RU.

Code format supports MPEG-2/4 and H.264.

For the convenience of field operation, the requirement for system display brightness and resolution rate can support full-screen 720576 pixel.

To fully ensure systematic compatibility, the system modulation mode must satisfy related standard about satellite modulator, such as DVB S/S2 standard, L-Band output which has 24DV output, L-Band output which has 10MHz reference clock output and so on.

The satellite station equipped with coding and modulation system has mature technology and large optional product. To coordinate the special requirement of portable use, it still needs to select carefully on technology and craft to use outdoors, except for volume and weight. It demands simple equipment operation, that is, once it is set up at the first time, It can do the communication after start-up. It can apply in harsh environment while possess enough seismic performance, ensuring the equipment safety in general transportation.

3.4 Configuration supporting system and system integration

To ensure the extensive application of flyaway satellite news gathering system, be unconstrained by region and environment, be convenient for personnel to establish communication link and ensure news timeliness, related corollary equipment and supporting system is also the essential component.

The supporting equipment including compass, altimeter equipment, and spectrum analyzer can strongly guarantee the accuracy of field operation. It includes systematic site search, target satellite search, correct use of distribution and systematic malfunction analysis, which ensure non-professionals establish satellite communication link in a few minutes.

A flyaway generator which ensures power supply in the process of various emergency news gathering is indispensable. Generally, its working time is more than 3 hours.

The monitoring system of local satellite video content can make local workers know themselves and the opponent. Local workers can fully understand the quality and various state of transmission content, especially the live broadcast situation. So they can find and solve problems timely, greatly guaranteeing the reliability of system. Therefore, flyaway satellite station is equipped with spectrum equipment, decoder equipment, small SDI display, which is used to watch live site recycling signal.

The saying small as the sparrow is, it possesses all its internal organs is the real reflection of flyaway satellite news gathering system. No matter how light the portable equipment design is, we still cannot call it portable type if there is large number and miscellaneous carrying.

The construction of flyaway satellite news gathering system, because of its special requirement, has no experience to abide. But we have to fall our way forward completely and design the appropriate systematic integration scheme. Yet there is some room for improvement. The whole system only consists of three aviation cases, which are antenna system case, accessory case and code modulation case. Each case equipped with antenna transportation seismic case, can be carried conveniently by one person. Thus it is convenient for flyaway satellite antenna system during long-distance transport.

4. Suggestions for flyaway antenna station applied in news gathering

The news gathering terminal of flyaway satellite station can quickly establish satellite link in the news site, realizing real-time report of mobile audio-video news information. After practical application in many important news reports, it has played a vital role and achieved good effect, which realize the construction goal basically.

In order to make flyaway satellite news gathering more suitable for news gathering, to make it play far important role, the paper puts forward four suggestions.

Firstly, with the development of new technology, we further increase antenna gain or improve systematic transmission power on the basis of keeping portability to meet the requirement of audio transmission with high definition.

Secondly, flyaway satellite news gathering system is convenient for person to take and it can also be used in vehicles. The system adopts transportable way in news site where vehicles can arrive at. Moreover, the system can be disassembled and taken by person to news site when vehicles can not pass some areas. In the way it reduces repeat construction of vehicle station and flyaway station and improves flexible application of the system.

Thirdly, under the premise of guaranteeing in domestic regions, we should gradually develop flyaway satellite products appropriate for oversea areas. Globalization strategy is inevitable as first-class modern communication agency.

Lastly, domestic satellite equipment, on par with foreign advanced products in aspects of function and performance, can not stand in aspects of equipment material and product technology. The equipment still needs to improve as soon as possible, especially on such harsh conditions, such as high temperature, arctic-alpine area and rain-fall and so on.

5. On-board experiment progress of flyaway satellite station

The manufacturers have made certain progress on on-board flyaway station recently through joint effort. Based on original equipment, the on-board flyaway station has following features.

1. Strong mobility. It can quickly carry equipment to news site by vehicles. Under the circumstances of road block, it can also be taken in the form of flyaway station by manpower and close to the core area of news at utmost.

2. Better adaptability to field. It can satisfy the requirement of field work within the range of possibilities. And it is applied in the form of on-board station in city areas which are not suitable for flyaway station to deploy.

3. High equipment integration. Flyaway satellite station equipment is assembled on rack inside the vehicle. And the antenna is assembled on the top of the vehicle, which is convenient for operation.

4. Convenient disassembly. The whole equipment is assembled on the car. If necessary, it is quite convenient to disassemble. It doesnt affect regular use of the vehicle. Moreover, the whole antenna can be assembled by adjusting the width of head frame, which meets assembled requirement of different vehicles to be convenient to change vehicles.

5. Low-cost modification. The important requirement of transportable flyaway station is low modifying cost. The standardized component and reasonable design make low-cost modification become possible.

Vehicle body design and modification should follow national standards, such as GB72581997 safety specifications for motor vehicles operating on roads, GB15892004 limitation of dimension, axle load and quality for road vehicles, GB125031995 general technical requirement for television car, GB937888 safety requirements for audio and pulse equipment of radio and television broadcasting system, GB/16127/GB50325-2001 environmental protection standard for interior decoration of vehicle, which provide basis for safe modification.

The vehicle modification process should comply with national standard, at the same time when you do the vehicle modification design; you also should lay emphasis on load balance weight and distribution safety design. Meanwhile, you should consider original load design and electrical need with union of equipment assembly and power safety.

The above photos are test prototype of video broadcast report during the opening of world exposition. Transportable flyaway satellite station, which avoids satellite signal block and scene accident caused by the crowd in urban regions, guarantees broadcast safety at large.

6. Conclusion

Flyaway satellite news gathering system is the first apply in emergency communication network. The systematic construction makes news gathering ability further expand. It can complete news broadcast task under the condition of poorer weather and environment, even limitation of small news site, which ensures effectiveness of the news and provides strong technical support to be invincible in competitive news industry.

Flyaway satellite news gathering system participates in the live coverage of many important events, including 60th anniversary parade, july5th Xinjiang event. The systematic flexibility and reliability is verified while totally satisfying task demand. The system will be gradually improved as the demand is deepen and technology is further developed. We should believe that systematic construction will become the light point in news gathering field.