2015 AOSWA @Fukuoka

Cheol-Oh Jeong 1 (e-mail : cojeong@etri.re.kr), Jin-Ho Jo1
1 Electronics and Telecommunications Research InstituteMa rc h 02- 05, 2015

Contents
1.

Background2.

Outline of Ionos onde in Kore a3.

De ve lopme nt Flow4.

Tra c e Extra c tion

5.

Tra c e Conve rs ion from O to V

6.

Ele c tron De ns ity & Pa ra me te r Extra c tion

7.

Summa ry2

Background (1/2)□ Korean Space Weather Center(KSWC) of Radio Research Agency (RRA)
has function to forecast the space weather like space weather indicators inradio range.
□ KSWC is performing routine observation of ionosphere using 2 digisonde
systems deployed at Jeju site & Ichon site.
- Delivers daily ionosphere status information through homepage, e-mail, etc. to users.
□ As a part of KSWC’s plan, ionosphere measuring and analysis project wasstarted since January 2013.
- to checkup and verify oblique sound mesearing function between two digisondes- to make conversion technology from oblique ionogram data to converted verticalparameters at mid point of between two digisondes

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Background (2/2)□ The project was performed by ETRI funded by KSWC for Developing
Ionosphere Measuring and Analysis Technology- The purposes of this project were as follows ; to re-check & verify oblique function of existing Digisonde systems
 to develop SW for extracting ionogram data from raw data (RSF file) to develop algorithm for extracting ionogram trace data from ionogram data to develop algorithm for converting ionogram trace data from Oblique toVertical to develop algorithm for extracting ionospheric N-profile & parametersfrom converted vertical ionogram trace data to implement SW4

Outline of Ionosonde in Korea (1/2)• Ionosonde deployed at KSWC in Korea– Fully digital ionosonde made by LDI, model DPS-4D* LDI : Lowell Digisonde International• Ionosonde sites in Korea– North site at Icheon (37.1°N, 127.5°E)– South site at Jeju (33.4°N, 126.3°E)※ distance between two site : 480Km• Oblique sounding in Korea– Frequency range– Frequency step
– Sounding intervalIcheon
nn480Km

1MHz ~ 16MHz
25kHz
30 minutemidpointJeju5

Outline of Ionosonde System in Korea (2/2)• Measurement schedule– Vertical sounding measurement : 8 minutes interval– Oblique sounding measurement : 30 minutes interval• Total 4 oblique ionogram are produced every hour

- JJ : Jeju
- IC : Icheon- TX : Transmission- RX : Receive- VS : Vertical Sounding- OS : Oblique Sounding
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Development Flow (1/2)• ETRI divided this project into 5 tasks as follows;□– Generation oblique ionogram data from RSF data file of Digisonde※ RSF : Routine Scientific Format– Oblique trace data extraction from the oblique sounding ionogram– Trace conversion from oblique to vertical– Get electron density profile from the converted vertical ionogram– Extraction ionospheric parameters from electron density• This project was performed by ETRI with IPS & LDI and SELab support7

Development Flow (2/2)
 Concept of O2V Ionogram Conversion Procedure
Oblique Ionogram (measured)

Extract Oblique Ionogram Trace

Trace extraction

O to V conversion

N-profile & Parameter
extraction

Ionosperic N-profile & parameter

Vertical Ionogram Trace (converted)8

Trace Extraction (1/2)
sum0

sum315• Vector tacking algorithm

sum45– is for trace extraction from the scattered data in the ionogram
sum270– calculate 8 direction amplitude sum of echo signal up to 4 echoes in eachdirections (T1)

sum90

– Move trace coordination to direction of maximum amplitude sum (T2, T3, T4)
sum225sum135sum180• 3 steps of trace extraction– Find maximum amplitude echo signal in the ionogram, that will be T1– Trace extraction of right part of ionogram from the maximum amplitude point by the vector
tracking algorithm (T2, T3)– Trace extraction of left part of ionogram from the maximum amplitude point by the vector
tracking algorithm (T4)sum0Start Point

sum45
jkdeabsum0

sum315lmf

ngoijhgr
qidcphcogbn

f

sum90
c

sum315hpiq

sum270klraefbml

sum270sum225sum135

Find maximum amplitude echo (T1)
in ionogram

Trace extraction in T2 zone

Trace extraction in T3 zone

aedkj

sum180Trace extraction in T4 zone
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Trace Extraction (2/2)• Validation Process of trace extraction– 3 steps development were performed• Algorithm verify using Excel  Algorithm verify using Matlab  S/W programusing programwith C language• Trend of extraction trace is seemed to be similar to oblique ionogram
GUI program10Trace Conversion from O to V (1/2)• Equivalent conversion theory was applied to trace conversion from O to V
• The vertical frequency (fv) and virtual height (h’v) can be derived from theoblique frequency (fob) and virtual path (P’ob)• Validation of Trace Conversion– Compare vertical ionogram between measured and converted was impossible
because there was no digisonde at mid point and there was not available
vertical measured ionogram– Alternative validation method was considered that is compare converted
vertical ionogram to measured vertical ionogram before and after oblique
sounding measurement• Converted vertical ionogram at midpoint can be compared with measured
vertical ionograms at TX and RX station for the validation• If converted vertical ionogram at midpoint is located between the vertical
ionograms of TX and RX station, conversion algorithm seems to be Breit-Tuve [1926], Martyn’s equivalent path theorem [1935]
validated Smith [1970], Rao [1973], Reilly [1985, 1989], Kotovich [2006]11

Trace Conversion from O to V (2/2)
 Ionogram Trace Conversion verification
 O to V conversion verification method•

Compare converted vertical ionogram to measured vertical ionogram ofJeju and Ichon site digisonde (450Km apart between 2 sites) O to V conversion verification (using 13 ionograms @Ichon site, 2013.05.27)

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Electron Density & Parameter Extraction• POLAN algorithm has adopted to extract electron density and ionosphericparameters• Validation of POLAN algorithm– By comparing with ARTIST of Digisonde for same measured vertical ionogram
data13

Summary• This project had been completed end of 2013
– Oblique sounding measurement data between Jeju and Icheon stations was used
– To build sw program on server in KSWC was completed• Trace extraction from the oblique measured ionogram data
• Conversion from oblique to vertical ionogram trace• Extraction of electron density & ionospheric parameters from converted
vertical ionogram data

• Future Works– KSWC has a plan to perform 2nd phase of ionosphere measuring and analysis
project from this year with domestic institute and company• to upgrade the O2V conversion SW algorithm developed in 2013 and the SW
to be user friendly more
• to perform long distance (around 1,000Km) O2V conversion algorithm
development to measure ionosphere status information above sea between
NICT and KSWC
• to install new ionosonde receiving system only for receiving the signal from
NICT’s new ionosonde14

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