Low Latitude Ionospheric Tomographic Network


TIn the spring of 1992 BC,NCU set up Low Latitude Ionospheric Tomographic Network , LITN This network scanning From north to south , there are six observation station in mainland China in Shanghai, Wenzhou, in Chungli in Taiwan, Kaohsiung, the Philippines Baguio and Manila by using Naval Navigation Satellite System , NNSS and receiver JMR –1 By CT scan technology to do for ionospheric electron concentration of the two-dimensional distribution (Tsai et al . , 2000 ; Huang et al . , 1997 ; 黃啟瑞 , 1997 ) ,but now some NNSS satellite systems were failure In order to be able to continue to study over the Taiwan area near the ionosphere we must rebuild the ionosphere tomography Network。Now in July 2003 NCU has to the beginning to bought ITS-system form NWRA(NorthWest Research Associates , Inc . ) and receive signals from Formosa 3 satellite to set up low-latitude ionospheric observation network ( LITN )

Formosa 3 satellite for the use of irregular observations(Note 1)




An antenna to receive flowchart

The first part useing two line element(TLE) to estimate when flying satellite

The second part useing ground station antenna to Pre-Amp conveyed to the receiving system




ITS30 receiver

ITS30 (Ionospheric tomography system 30),receiver frequency is 150MHz、400MHz and 1066.67MHz (beacon signal)之OSCAR/NNSS satellite set up receiving station at the NCU,and then set up ITS30 station in Nantou and Kenting,To the re-establishment of Low-latitude Ionosphere Tomography Network,LITN For the low-latitude ionospheric research。
The system receive satellite radio signals,apply for slant Total Electron Content ,By CT scan technology,For use in the ionosphere tomography study.

Receiving System:cross-coupling antenna (turnstile-type),Tri-band(UHF, VHF,L-band),At wide1.4m、1.4 m long metal platform,In addition 30 dB preamplifier 、signal combiner 、Antenna connection cable、PC。
Cross-coupling antenna: Divided into three parts include VHF、UHF and L-BAND

150MHz diameter: 95 cm 400MHz diameter: 2 6.5cm 1067 MHz diameter: 14 cm
red : VHF top 4cross-coupling
blue : UHF middle 4cross-coupling
yellow: L-BAND down下 4cross-coupling
30 dB Above the device signal preamplifier:
4 holes were then to VHF signal line、UHF signal line、Cable、L-BAND signal line
Receiver:for the internalis ADC conversion devices 、30db Amplifier、Joint receiver signal devices OSCAR/COSMIC 150MHz (VHF)and400 MHz (UHF),1066.67MHz(L-band) (Frequency range offset) from -200 ppm to +110 ppm
Antenna connection cable: About 40 meters long
User interface: windows xp


Receive satellite parameters (LEO Satellites and their Beacon Frequencies for NWRA ITS Receivers)

Sattellite Inclination VHF Freq.(MHz) UHF Freq(MHz)
OSCAR27 90.3070 149.988 399.968
OSCAR29 90.3134 149.988 399.968
OSCAR23 90.3668 149.988 399.968
OSCAR3232 90.3642 149.988 399.968
OSCAR2525 89.8024 149.988 399.968
OSCAR31 89.0024 149.900 399.968
NADEZHDA3 82.9208 150.000 400.000
COSMOS2184 82.9302 149.910 399.760
RADCAL 89.8562 150.012 400.032
COSMOS2266 82.9506 149.970 399.920
TSIKADA 82.9284 150.000 400.000
COSMOS2310 82.9417 149.910 399.760
COSMOS2315 82.9033 150.000 400.000
COSMOS2334 82.9348 150.030 400.080
COSMOS2336 82.9423 149.970 399.920
COSMOS2341 82.9190 149.910 399.760
COSMOS2346 82.9223 150.030 400.080
GEOSAT FO 108.0470 150.012 400.032
NADEZHDA5 82.9505 150.000 400.000
COSMOS2361 82.9350 150.030 400.080
ARGOS 98.7944 150.012 400.032
COSMOS2366 82.9248 149.940 399.840


ITS-System station

Taiwan: Taoyuan NCU
ITS Station
hight: 182 m
Tauwan: Chiayi NCCU
ITS Station
hight:114 m
Taiwan: Pingtung Checheng
ITS Station
latitude: 22.050
hight: 32 m
Philippines: Manila-> Canlubany
ITS Station
hight: 112 m
Indonesia: Pontianak
ITS Station
hight:10 m
Taiwan:Linkou HWC(Test)
ITS Station
hight: x m
Taiwan: Khinmen
ITS Station
hight: 112
Taiwan: Itu Aba Island
ITS Station
hight: 10 m



The following chart station after receiving the results of the analysis of information

F-layer (350km) ionospheric penetration points



At the Central University in Chungli ITS30 station set up by the proceeds of the projection to 350 kilometers of track changes Figure S4. Showing its location map longitude coordinates of the horizontal axis for the longitudinal axis of latitude coordinates, and red multi-display its longitudinal axis magnetic latitude coordinates, and the upper left of Figure show its satellite orbit from its north-south running, with a satellite OSCAR 32 flight path projection to 350 kilometers of track map, and use color changes show its strength S4 changes in circumstances.20080506 00:32UT OSCAR32












Satellite signals azimuth and elevation relative TEC

Central University in Chungli ITS30 station set up by the proceeds of elevation, azimuth, the relative variation of the TEC with the passage of time. Top-down order of elevation, azimuth, the TEC relative value received by the horizontal axis for the time sampling frequency of 50Hz..







The satellite VHF UHF L-Band and Strength


Central University in Chungli established by the ITS30 station, as well as through the phase variation of the signal strength. One received by the horizontal axis for the time, the phase is divided into longitudinal axis values from -180 to 180 degrees, as well as units dB signal strength down phase followed by VHF, UHF phase, L-band phase, power signal strength , red for VHF signals, blue for the UHF signals, green for the L-band signals, and signals of change in the use of judgement.













Earlier in communications, found a strange phenomenon, when the satellite communications, signals will be flashing (scintillation) situation, when VHF signals from the satellite launch out in the vicinity of the station, and sometimes even to get a signal, This phenomenon has aroused the interest of scientists. This phenomenon is due to irregularities in the ionosphere in the F layer instability, which we call spread F. In this study, the scientists used a variety of instruments for observing this phenomenon and analysis, radar echo signal measurements, satellite and the rocket in-situ measurements, as well as theory and numerical simulation method allows us to the formation of spread F mechanism is a more clear。


Contact us

Telephone:  +886-3-4227151 ext 57621 , 57647
Address: R3-413Center for Space and Remote Sensing Research No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.)