135KATO Hisao

5 Information service

5-1 Ionospheric observation and observationinformation processing system

KATO Hisao

The CRL has been making ionospheric observations for about 70 years. Recently, wehave updated the ionospheric sounder and have expanded the observation information pro-cessing system. The new ionospheric sounder gathers various observational data by auto-matic control / remote control. The new observation information processing system ensuresthe reliability / safety of data. The system also provides the data service quickly and conve-niently to users.

Keywords Ionosphere, Ionogram, Data service

1 Introduction

For approximately 70 years, the CRL(including the Radio Research Laboratory ofthe former Ministry of Posts and Telecommu-nications and the Radio Physics Laboratory ofthe former Ministry of Education) has carriedout ionospheric observations in which a vari-ety of ionospheric data has been acquired andanalyzed. Made available to researchers, thisdata has been used as an important source ofinformation for HF radio communication andalso as basic data useful in monitoring long-range variations of the global environment.Over the years, there have been many changesin the methods of ionospheric observation andthe ways in which the observation data istreated[1]; and the current system, whichbegan in fiscal 2001, is the natural successorto these past methods[2][3], responding to cur-rent trends in information communicationtechnology and attempting to answer theneeds of diverse groups. This paper will givean outline of the system configurations and themain methods of treating ionospheric observa-tion data.

2 Outline of Systems

An outline of the hardware configurationis shown in Fig.1.

A newly developed 10C-type ionosphericsounder (hereinafter referred to as the "10C")and a primary processing system (primary sys-tem) are arranged at each of the four observa-tion points (Wakkanai, Kokubunji, Yamagawa,and Ogimi) set up in Japan to enhance opera-tional functions, improve classification ofobservation data, and allow for better load dis-

Outline of system hardware configura-tion

Fig.1

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tribution in terms of processing. Moreover, asecondary processing system (secondary sys-tem) with a duplicate database and a data-pub-lication system with an exclusive databasehave been established at the head office(Kokubunji) to manage safe, quick serviceswhile ensuring the reliability of data. In addi-tion, all facilities are connected via TCP/IPcommunication, allowing them to function asa whole.

3 10C-type Ionospheric Sounder

The outline of a hardware configurationfor the 10C ionospheric sounder is shown inFig.2.

The 10C is equipped with the basic func-tions of a conventional ionospheric sounder, iscapable of acquiring a wide variety of obser-vation data, and is highly accessible, highlyfunctional, and easy to use, without the needfor an attendant operator. The main new func-tions of the 10C are described below.

3.1 Observations Including IntensityInformation

Conventional ionospheric sounders outputobservation data that was essentially made upa black-and-white (2-level gradation) iono-grams, in which received intensity informationwas digitized relative to a certain threshold.However, in view of the current cost perform-ance of external computer storage, improvedreliability, and advances in network environ-ments, we have decided that observation data

output from the 10C should consist of color(256-level gradation) ionograms with 8-bitintensity information.

Observations that include intensity infor-mation allow for the recording of faint echoes.Prior to the Leonid meteor shower in Novem-ber 2001, the ionospheric sounder recorded agreat number of sudden faint echoes, whichwere considered to be related to this event. Itis hoped that in the future the new ionosphericsounder will enable us to investigate phenom-ena that might previously have gone unno-ticed.

3.2 Polarization Split ObservationIn normal operation, the 10C acquires

ionograms in which an ordinary wave and anextraordinary wave are intermixed on a one-sheet-per-observation basis; in addition, twobuilt-in receivers (featuring the same perform-ance) enable research observations in whichthe ordinary wave and the extraordinary waveare received separately, through polarizationsplit observaion. Through ionograms obtainedusing polarization split observation on a two-sheet-per-observation basis, automatic readingand processing of factor values and the likebecomes relatively easy; it is thus hoped thatmore accurate values may be obtained.

Moreover, since one of the two receivers isalways on stands-by during normal operation,this configuration improves reliability.

3.3 Oblique Incidence ObservationThe 10C is configured to be capable of

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10C-type ionospheric sounderFig.2

Example of a color ionogramFig.3

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oblique incidence observation on its own, sup-planting the now-obsolete dedicated sounderfor oblique incidence. The vertical-observa-tion transmission waves of all stations areobserved by each of the 10Cs at the fourobservation points, all of which have clockscalibrated to high precision using GPS. Byperforming conversion processing of theobserved data into a pseudo vertical ionogramthat takes propagation distance into account,six pseudo vertical observation points may beadded. Moreover, the sounder is providedwith a function for observing the error rate ofdigital communication (at a fixed frequency)at the time of the propagation of oblique inci-dence.

3.4 Programmable Automatic Obser-vation

The signal-processing component is modi-fied to allow for DSP (Digital Signal Process-ing), thus enabling reduced dependence onhardware relative to its predecessor, and isalso configured so that almost all observationsetup information (date and time, classification,detailed parameters for each classification, etc.)can be input into the application program. Bysetting basic observation information and vari-able information beforehand, including suchitems as observation-point data and data on sea-sonal variation, the new sounder allows forautomatic observations that do not requirehuman labor in normal operation.

3.5 Unattended OperationThe operating state of each circuitry block

of the hardware constituting the 10C is regu-lated through multipoint monitoring, whileauxiliary information collected at the time ofobservation (such as various electric powervalues and self-diagnostic values) enablesfaults to be located at the earliest stages.Through the automatic evaluation of such aux-iliary information, early detection of problemsand the issuance of corresponding alertsbecome possible. Moreover, the new sounderis prepared for emergencies, with a remoteshutdown function in the event of power fail-

ure as well as an automatic recovery functionupon restoration of power.

3.6 Networking CapabilityBy making the 10C's control computer

capable of networking, nearly completeremote control and remote monitoring via net-work are realized, making it possible to trans-mit observation data in real time and enablingquick response to a variety of unexpectedevents. In addition, the new sounder is con-figured to allow for remote maintenance,including upgrading the firmware/applicationsoftware of the 10C itself, leading to improvedease of maintenance and greater modularity.

In addition, the 10C is provided with alocal database for storing observed raw datafor a certain period, which is useful, for exam-ple, in the event of a failure halting operationsin the primary, or any other following systemincluding the secondary system.

4 Primary System

The main data streams of the primary sys-tem are shown in Fig.4.

The primary system, deployed at eachobservation point, performs, for each observa-tory, distributed processing of the dataobtained from the 10C and manages relay pro-cessing of control-system informationbetween the 10C and the head office, as wellas a variety of local processing tasks. Themain functions of the primary system aredescribed below.

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Main data streams of primary systemFig.4

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4.1 Vertical-Observation Color Iono-gram Data

A vertical observation color ionogramobtained from the 10C is subjected to trim-ming, reduction, noise removal, summary plotformation, automatic reading, etc., and theoutput thus obtained is stored in the local data-base. This data is used for a variety of localprocessing tasks and is transferred to the sec-ondary system as well, so that the sequentialreal-time nature of the data is preserved.Moreover, the data is subject to the processingrequired for color ionogram noise removal,summary plot formation, and the like, toimprove overall data quality.

4.2 Conventional Database Compati-bility

In order to maintain compatibility withexisting conventional databases, the vertical-observation color ionogram obtained from the10C is subject to trimming, black-and-whitebinarization, and conventional format process-ing. Subsequently, the processed data is subjectto compatibility processing (equivalent to theprocessing of observation data obtained fromthe earlier ionospheric sounder), thereby ensur-ing continuity and consistency with past data.

4.3 Control-system information relayThe auxiliary information obtained from

the 10C at the time of observation (includingvarious electric power values, self-diagnosticvalues, remote-control information from thesystem at the head office, etc.) is relayed inreal time within the CRL system, allowing theprimary system to perform both collectiveremote monitoring and collective remote con-trol. Moreover, the primary system enablesoperational and control details from the localstation's ionospheric sounder to be confirmedwith reference to past data, and provides abasis for evaluation of the transition betweenthe different operational modes of the 10C,together with evaluation of the observationdata itself.

In addition, by performing distributed pro-cessing of the relatively large load presented

by observed raw data (involving conversion ofthe oblique incidence observation data to apseudo vertical ionogram, for example), loadis prevented from concentrating in the second-ary system. Moreover, the storage of maindata for a certain period in a local databaseenables not only response to a network or sec-ondary-system failure that halts operations butalso recovery of lost data through re-transmis-sion thereof.

5 Secondary System

The main data streams of the secondarysystem are shown in Fig.5.

The secondary system, established in thehead office, collects and manages the dataobtained from the primary system at eachobservation point and from the data-publica-tion system, and also functions as a data serverand a server for various internal functions.Moreover, the secondary system handles data-base multiplexing. The main functions of thesecondary system are described below.

5.1 Observation Data Collection andManagement

The secondary system collects and man-ages observation data obtained from both theprimary system (at each observation point)and from the data-publication system, and alsoperforms sequential storage of the data in cor-responding locations on the main database. Interms of this data storage, user convenience isenhanced through connection processing for

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Main data streams of secondary sys-tem

Fig.5

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each observatory, secondary conversion pro-cessing for each period, and so on; at the sametime, storage and data-access efficiency areimproved through archive processing for eachdata classification.

5.2 Various Internal ServicesVarious internal services, such as display

output and printouts (including publication ofthe Ionospheric Data in Japan) and data-fileoutput for specified data classifications forselected periods, are enriched, thereby offer-ing greater user convenience.

5.3 Data MultiplexingVarious files on the main database and

their contents are automatically evaluated bymirror processing, and complete duplicationof the data is implemented through sequentialreplication in the sub database, resulting inimproved reliability of both the system and thedata it holds. Moreover, all data that must beexternally accessible is subjected to mirrorprocessing in an exclusive database within thedata-publication system, to ensure independ-ent multiplexing, thus ensuring system safetyand integrity of data.

5.4 Control-System Information RelayThe auxiliary information obtained from

the primary system at each observation pointat the time of observation (such as variouselectric power values and self-diagnostic val-ues) is collected for all observation points andis relayed to the data-publication system inreal time, and remote control information andthe like obtained from the data-publicationsystem is distributed to the primary systems atthe various observation points in real time.

Since the primary system relieves the sec-ondary system from the relatively large loadrequired to process observed raw data, andsince the secondary system is also protectedfrom the load resulting from general publicaccess to the external services of the data-pub-lication system, the secondary system can con-centrate on data management and internalservices; therefore it will be capable of

expanding in response to the larger anticipatedprocessing loads of the future, without theneed for local enlargement of the system.

6 Data-publication system

The main data streams of a data-publica-tion system are shown in Fig.6.

The data-publication system, establishedin the head office, performs data publicationservices for outside users (mainly via theInternet), and manages collection and relay ofdata received from outside of the system. Themain functions of the data-publication systemare described below.

6.1 Dedicated Publication Database;External Data Publication

Data for publication that is transferred tothe data-publication system by mirror process-ing in the secondary system is sequentiallystored in a corresponding location on the dedi-cated publication database for each classifica-tion. The data stored in the database exclusivefor publication immediately becomes avail-able for various services intended for externaluse. As a result, although available data islimited by physical storage size, popular serv-ices nearly equivalent to the various internalservices are available through the worldwideweb, thus offering greater overall user conven-ience.

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Main data streams in a data-publica-tion system

Fig.6

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6.2 External Observation Data Collec-tion and Relay

Observation data obtained from observa-tion points other than those of the CRL issequentially stored in the relay database inlocations corresponding to each classification.The data stored in the relay database issequentially collected within the secondarysystem, thus preserving the sequential real-time characteristics of the data.

6.3 Collective Remote Monitoring andControl

Information obtained from the 10C at eachobservation point (such as various electricpower values and self-diagnostic values) iscollected and managed within the data-publi-cation system and may be reviewed via theworldwide web. Moreover, control informa-tion for the 10C at each observation point is

also controlled collectively within the data-publication system and may be operatedthrough the worldwide web.

This configuration has allowed for collec-tive remote monitoring and for the collectiveremote control of 10Cs at all observationpoints, from anywhere, subject only to sus-tained Internet connection.

In addition, we have implemented homeprocessing of manual scaling operations bydeveloping a Windows-version manual scalingsystem and installing an exclusive interfacefor the data-publication system.

Moreover, rapid and safe services are pos-sible through the provision of a data-publica-tion system with an exclusive database andconfiguring it independently; further, outsideusers can still use the services even whenoperation of the secondary system is halted.In addition, a special firewall is installed for

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External data publication through the worldwide webFig.7

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the data-publication system to block outunnecessary logical communication ports,thereby further ensuring the safety of the sys-tem.

7 Conclusions

This system has been constructed torequire virtually no attendant intervention withrespect to basic operations, from data acquisi-tion to the distribution and use thereof. More-

over, this system has the following advantagescompared with its predecessor.

(1) This system has paved the way for thetransition to color ionograms featuringintensity information, offering the pos-sibility of the investigation of previ-ously unobservable phenomena.

(2) The ability to perform polarizationsplit observation allows for unprece-dented high precision in calculations.

(3) With oblique incidence observationperformed among all four observationpoints, we will see an increase in thenumber of pseudo vertical observationpoints.

(4) Enriched programmable automaticobservation, remote monitoring, andremote control all support unattendedoperation of the sounder and alsoenable quick response in the event ofunexpected events.

(5) Data reliability has been improved byproviding a storage buffer on each datapath and by multiplexing the respectivedatabases.

(6) Quick and safe external services have

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Remote control of 10C through the worldwide webFig.8

Manual scaling systemFig.9

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been realized by making the data-pub-lication system independent.

(7) Expansion is possible to accommodatefuture load increases.

The focus of this paper is on the main han-dling of ionospheric observation data. Thesystem in question operates as a comprehen-sive ionospheric information system and dealssimultaneously with multiple items of ionos-

pheric observation data. We hope that withthe effective use of this system, ionosphericphenomena will be grasped more precisely;accordingly, we intend to investigate the waysin which analytical values having higher pre-cision may be automatically acquired, and topursue service techniques that will meet theneeds of future data users.

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References1 Radio research laboratory,"The history of ionospheric sounder in Japan",1984.(In Japanese)

2 H.Takahashi,I.Kuriki,"Development of automatic ionogram processing system",Review of the communica-

tions research laboratory,35,174,pp.1-3,1989.(In Japanese)

3 S.Igi,K.Nozaki,M.Nagayama,A.Ohtani,H.Kato, and K.Igarashi,"Automatic Ionogram processing systems in

Japan",UAG report on Ionosonde network and stations,1994.

KATO Hisao

Senior Researcher, Ionosphere andRadio Propagation Group, AppliedResearch and Standards Division

Ionospheric Observation