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This article discusses the National MODIS Data Sharing Platform in China and its application in providing satellite data to users. It also covers the data reception and collecting system, data broadcast and uplink station, DVB-S user station, and various applications of MODIS data.
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National MODIS Data Sharing Platform and its Application YANG Zhongdong zhdyang@nsmc.cma.gov.cn ZHAO Licheng National Satellite Meteorological Center (NSMC) China Meteorological Administration (CMA) Beijing 100081, P. R. China
Outline 1. Why do we need the DVB-S 2. Data reception and collecting 3. Data Broadcast and uplink station 4. DVB-S user station 5. MODIS Data Application 6. Summary
1. Why do we need the DVB-S ? What’s DVB-S? DVB-S is a Digital Video Broadcast by Satellite system used to distribute satellite data Broadcast China Star-1 1B Data and Products NSMC DVB UPLINK USERS
System Architecture Data Reception User Station Data Broadcast Data Archiving
It’s initially purpose is to provide EOS-MODIS data sharing for national users. Now it become a environmental satellite data sharing platform. May 2004: start of the trial through China Star-1 communication satellite with 2Mb.China Star-1 is positioned above 87.5E. June 2004: start of operations with 6Mb to distribute MODIS data. Sep 2004: added NOAA HRPT, FY-1D CHRPT data. 2005: distributed image data and numerical products。 History & plan
EOS-MODIS system installed in Chinese Mainland after 2000 三亚
Operational EOS-MODIS Ground Stations Operational EOS-MODIS Ground Stations and developing Ground Stations
Why so many MODIS system in China? • MODIS data is very useful for user. • Data network in China is still in development. The bandwidth of network is not wide enough for data transfer. • Users have to install EOS-MODIS system to receive data from EOS/AM and PM directly. • Problems for MODIS user who setup directly reception system? • It cost too much for users to setup MODIS system • It cost too much for system maintains and data arching • It need specialist to operate and maintains system
Why does the DVB come out? In order to provide satellite data to users, NSMC try to seek many ways. Under support of China MOST (Ministry Of Science and Technology) NSMC setup a data sharing platform. This platform consists of Digital Video Broadcast and Web server. Since this system get into operation in the middle of 2004, over 70 users installed DVB-S user station and more than 200 users opened a network account from NSMC for satellite data downloading.
Geographic locations: • 6 ground stations. Four of them belongs to NSMC(National Satellite Meteorological Center), they located in Beijing, Guangzhou, Urumuqi, Lasha; the rest two belongs to NSOC, they located in Bejing and Sanya. • Satellites: 5 satellites including FY-1D,NOAA-16/17,Terra/Aqua Beijing Guangzhou
Data Availability: Two stations in Beijing backup each other, Guangzhou and Sanya backup each other. • 北京 • 广州
National MODIS Data Center • We build up a data center in Beijing. It located in NSMC’s building. The main function of data center are follows: • Data collecting • Data Processing • Data distribution • Data archiving • The MODIS data center consists of three IBM UNIX servers and a SAN storage system, a IBM tape library. The capacity of SAN is 3TB. It can store MODIS data online for one month. The data are migrate to tape library after month.
Data flow: Data are relayed to NSMC in real time or slightly delay Guangzhou (NSMC) Wrumuqi (NSOC) Lasha Beijing (NSMC) Sanya (NSOC) NSOC Data Collecting Overlay delete & preprocess Beijing (NSOC) Catalogue and Archiving Media Deliver Download Broadcast
Data communication bandwidth upgrade • Sanya => NSOC:VSAT => SDH,8Mb. Jun.2005 • Wrumuqi => NSMC:ATM, 4Mb => 10Mb Mar. 2004 • Guangzhou => NSMC:ATM,4Mb => 10Mb Mar.2004 • NSOC => NSMC:Set up LAN、100Mb (Sep. 2004) • Lasha => NSMC:Set up SDH WAN、4Mb (AUG 2004) • File Transfer programming for PDS file transfer • Overlay data delete
Site:Beijing(116.91°,39.90°) Uplink Antenna: 4.5M Amplify:16W@Max Carrier: Single Band:6MHz Uplink Central Frequency :14175MHZ Rate: 5920KHz(Char Rate ,4340KHz) Code:QPSK,3/4FEC,188/204RS Availability: 99.97% Parameters for Uplink
DVB Satellite Reception / Receiver Unit 4.DVB-S user station DVB Standard Hardware LNB Ku-band Satellite Dish DVB PCI Card DVB Multicast Client software PC, Hard disk, Ethernet
5. MODIS Data Application • MODIS L1 Data • MODIS Cloud Mask • MODIS temperature profile • MODIS moisture profile • MODIS NDVI • MODIS Image Product • ……
Cloud Mask RGB Image Land Cloud Possible Land Possible Cloud
Chinese Mainland Terra-MODIS NDVI First 10 days of Sep. 2005
Tibet 3D Perspective image from MODIS data ---From south to north
Tibet 3D Perspective image from MODIS data ---From west to east
Multi-data distribution: currently broadcast MODIS, HRPT and CHRPT. More High level data will be broadcast in 2005. Flexible:configurable bandwidth, multicast. Supports more 8192 users. Fast distribution capability: 6Mb bandwidth. Priority: Data to be uplinked could be arrange priority. Large coverage: China and surrounding china, Totally more 19 Asia countries are under it’s footprint. Low cost: Client device is very cheap. 6. Summary