Transcript P2(03)_Zhang_China.pps

Development and application of CDMA and OFC communication technology in ground based GPS sensor network in Northeast China
Zhang Jingjiang Zhang Chaolin
Institute of Urban Meteorology (IUM), CMA, Beijing, China
Abstract
GPRS/CDMA Data Transfer Topology Network
GPRS/CDMA
Internet
Permanent IP
GPRS/CDMA
Data Processing
GPRS/CDMA
Wireless Unit
LAN of BMB
Catalyst 3900
GPRS/CDMA
online Watch
Catalyst 3900
Catalyst 3900
GPS Receiver
Up to the 1st quarter of this year, there are 48 ground-based GPS observation stations in Northeast China,
they belong to Beijing Meteorological Bureau(BMB), Beijing Municipal Government and China
Meteorological Administration (CMA), respectively. The Bernese GPS software is used to do the postprocessing work. By the cooperation with NCAR/UCAR, BMB can calculate GPS-derived precipitable water
vapor of Northeast China almost in real time (less than 2 hours delay). The operational GPS-Met products
include the PWV variation charts in Northeast China (every 30 minutes), meteorological elements (air pressure,
temperature and relative humid ) variation at each stations and (every 30 minutes) and GPS water-vapor
topography at Fangshan area in Beijing (2 days delay). Data assimilation of GPS PWV has been put into the
MM5 NWP and LAPS system successfully.
By support of Beijing Municipal Science and Technology Commission, BMB has set up 14 stations at the
end of 2004. These 14 stations are divided into two group , one group is located in Fangshan county which
includes 8 stations , the other group is in Huairou county which includes 6 stations. BMB has developed a GPS
data communication system based on the CDMA wireless telecommunication technology. Therefore, the
observation data can be transmitted to BMB in every 30 minutes with no more than 10 minutes delay. The
bandwidth is about 100kbps. The Beijing Municipal Government has invested to build 16 GPS stations in each
county of Beijing area for civilian use, most of them are built in local weather station. Optical fiber cables
(OFC, 2M ) connect to the stations so observation data can be get in real time.
Both of CDMA and OFC can be used to reliably transfer data in real-time. CDMA does meet the
requirement of operational demand, though its bandwidth is narrower than OFC. Since it takes less money and
time to set up data transferring links by CDMA than by OFC, it is more suitable for those stations in remote
area, where stations are not man-operated.
Data Transfer System based on PSTN
Modem
Location of GPS site in North China
PSTN
Tianjin
BMB
CDMA Instrument
Optical fiber cables instrument
CMA
Beijing Government
The operational GPS-Met products