TECHNICAL DEVELOPMENT CENTER NEWS No.8
International Earth Rotation Service - VLBI Technical Development Center News

published by

Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184, Japan
June, 1996

CONTENTS
Overview of the Eighth TDC Meeting : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2

GSI Activity : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3
Reorganization of the IERS VLBI : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3
Format of the VLBI Data Publication : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4
Data Format of the Key Stone Project VLBI Analysis Results : : : : : : : : : : : : : : : : : : : : : : : : : : : 5

Technical Reports
Current Status of the Key Stone Project:::::::::::::::::::::::::::::::::::::::::::::::: 9

VLBI Data Analysis System for the Key Stone Project : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 10
Correlation Processing System for the Key Stone Project : : : : : : : : : : : : : : : : : : : : : : : : : : : : 17
Pulsar VLBI Experiment with Kashima (Japan) - Kalyazin (Russia)
Baseline : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 21
The Examination of Selenodesy and Planetodesy Using VLBI andCounter VLBI : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 23
A Plan of Interferometric Observations of Jovian Radio Wave
Emissions at Low Frequencies (25-35 MHz) : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 24

News-News-News
Letter of Thanks from National Institute of Polar Research : : : : : : : : : : : : : : : : : : : : : : : : : : 25
First Step Toward Geodetic Real-Time VLBI : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 26

1

2

IERS TDC News No.8

Overview of the Eighth TDC Meeting ment, Maritime Safety Agency), Kazuo Shibuya(National Institute of Polar Research), Yoshimitsu
Okada( National Research Institute for Science andDisaster Prevention), Teruyuki Kato (Earthquake
The Eighth meeting of the Technical Develop- Research Institute, University of Tokyo),ment Center was held on March 8, 1996 at the conFollowing special members could not attend:
ference room of Kashima Space Research Center of Nobuyuki Kawano (National Astronomical ObserCommunications Research Laboratory.
vatory), Noriyuki Kawaguchi (National Astronomical Observatory), Hisashi Hirabayashi (Institute of
AttendanceSpace and Astronautical Science),
CRL members

Fujinobu Takahashi, Taizoh Yoshino, Michito
Imae, Hiroo Kunimori, Shin'ichi Hama, Chihiro
Miki, Jun Amagai, Akihiro Kaneko, Toshimichi
Otsubo, Hideyuki Nojiri, Mizuhiko Hosokawa,
Hitoshi Kiuchi, Kohichi Sebata, Yuko Hanado,
Shingo Ohmori (KSRC: Kashima Space ResearchCenter), Yukio Takahashi (KSRC), Takahiro
Iwata (KSRC), Noriyuki Kurihara (KSRC),
Ryuichi Ichikawa (KSRC), Yasuhiro Koyama(KSRC), Mamoru Sekido (KSRC), Junichi Nakajima (KSRC), Tadahiro Gotoh (KSRC), Tetsuro
Kondo (KSRC)
Special members

Kosuke Heki (National Astronomical Observatory), Takashi Saito (Geographical Survey Institute), Teruo Kanazawa( Hydrographic Depart-

Agenda

1. Opening address by Fujinobu Takahashi, director of the Standards andMeasurements Division, CRL
2. Reorganization of the IERS VLBI
3. Activity reports by the special members
4. Antarctica VLBI and Asia Pasi c
VLBI
5. Data publication format and coordinate system
6. Technical reports
6.1 Keystone project
6.2 Other technical development activities
7. Closing address by Shingo Ohmori, director of the Kashima Space ResearchCenter, CRL

A cheerful mascot character of deer \Anton-kun" and a huge soccer ball were painted on thesurface of main re ector of 34 m antenna at Kashima. The painting is a part of bidding activities
for 2002 World Cup Football Games. Kashima Soccer Stadium, located near the Kashima Space
Research Center, may become a venue of the World Cup games in 2002.

3

June 1996

GSI Activity

Reorganization of the IERS
VLBI

Takashi Saito

Geographical Survey InstituteKitasato-1, Tsukuba, Ibaraki 305, Japan
VLBI

GSI participated in 11 international VLBI observations in FY1995. Kashima 26m-antenna, thathas been used for international VLBI observation,
had been xed last year. GSI's transportable VLBI
system (3.8m antenna and transportable container
for observation) has been transported to Korea forJapan - Korea VLBI observation, under the cooperation with NGI ( National Geography Institute, Korea ). We conducted 24-hour observation
4 times, and got the baseline between Kashima26m and Suwon site in Korea. Domestic VLBI
observations for Kashima-Mizusawa and KashimaTsukuba baselines were conducted. New VLBI observation sites, Chichijima and Aira, are under construction. They will have a 10m-class telescope,
S/X receiver and K-4 VLBI equipment. Another
VLBI site with a 25m-30m class antenna will beestablished in GSI Headquarters' eld at Tsukuba.
These new facilities will be available in 1997 - 1998,
and operated by GSI for geodesy and Earth sciences.
GPS

GPS permanent networks, that have two hundred GPS permanent sites, have been operated by
GSI for more than one year. These network has detected crustal deformation concerned with some big
earthquakes such as Hyogo-ken Nanbu EQ (Kobe
EQ), Hokkaido Toho-oki EQ, Sanriku-Haruka-oki
EQ. The network are added more than 400 sites in
FY1995. Furthermore, two or three hundred sites
are going to be established in FY1996. The datafrom this observation network will be available in
the near future for researchers and surveyors whowish to use them.
Organization

A new department Geodetic Observation Centeris established in this year. It operates the continuous observation networks; GPS, tide gauges, tiltmeters and extensometers.

Taizoh Yoshino

Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184, JapanThe International Earth Rotation Service(IERS) was established in 1988. In October, 1990
at Virginia Beach (USA), the Directing Board of
the IERS approved the designation of two technical development centers of VLBI, which are the
Haystack Observatory and the Communications
Research Laboratory (CRL). The IERS strategy
was discussed within the Directing Board held on
11th July 1995 at Boulder during the XXI IUGG
General Assembly (See the Report on the IERS Directing Board Meeting No.16) . One of the mostimportant actions decided to be taken was to distribute the CALL FOR PROPOSALS to the VLBI
community to reorganize the structure of the IERS.
The meaning of this action was explained. In January of 1996, CRL proposed to continue to work
as a VLBI technical development center. It is said
that the discussion on the selection of the proposal
will be held in October, 1996.

4

IERS TDC News No.8

Format of the VLBI Data Pub- pendent Exchange (SINEX) format, which is usable for both VLBI and GPS, might be pertinent
licationfor this purpose.
Kosuke Heki

National Astronomical Observatory
Mizusawa, Iwate 023, Japan(3) Seismologists (earthquake prediction researcher)Those who want to monitor time series of daily
baseline vectors for possible earthquake precursors(the detection could be retrospective). Time seThere are variety of users who might be inter- ries should be given in local coordinates as well as
ested in geodetic VLBI data outputs and the data geocentric coordinates.
should be handed over to them in appropriate formats. They are to be classi ed as follows;(4) Geophysicists, Geologists

Those interested in site velocities and their tectonic implications. Changing rates of the baselineThose who need a VLBI database to perform vectors or site velocities directly estimated by contheir own parameter estimation. Conventional necting multiple VLBI databases would satisfy theMark-3 type database will do.
requirements.
(1) VLBI researchers

Keystone project data are mainly used for the
category 3 purposes but CRL should be preparedThose who want to tie their GPS results to VLBI for every kind of requirments considering potential
coordinates/velocities. Solution (technique) Inde- future users.
(2) Geodesists

Correlators for the Key Stone Project located in the correlation center at Koganei central station.
(Left) Real-time correlators. (Right) Tape-based correlators and automatic tape-exchanger units
for each station.(see Page 17)5June 1996

Data Format of the Key Stone
Either ASCII data les of Postscript graphics
les are accessible in the anonymous FTP area of
Project VLBI Analysis Results the data analysis computer. One can access all
Yasuhiro Koyama

Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314-0012, Japan

1. Introduction
Observed data of the daily VLBI experiment of
the Key Stone Project are analyzed every day automatically. The latest results of the daily analysis
are available to the public in various ways. Any researchers interested in the Key Stone Project data
can access the results over the Internet. At present,
following three methods are available to access theresults.

 e-mail anonymous FTP
 World Wide Web

2. e-mailthese les at kouma.crl.go.jp by giving 'anonymous'for the username and e-mail address for the password. Following sections describe the data le format of the ASCII data les accessible by means ofanonymous FTP.
3.1 Miscellaneous information about eachexperiment

Miscellaneous information for each experimentcan be obtained in the le exp.inf. The time anddate of the rst and last observations in each experiment, along with the data and time when thelatest analysis was done, are given in the le. The
other le, stat.dat, gives statistical information,such as root-mean-square delay residual in the data
analysis, number of data used for the analysis andnumber of data excluded from the analysis. Information on all baselines is stored in a single le.
3.2 Baseline length data

Estimated baseline lengths from every experiments are stored in the le, baseline.dat. All thebaselines are stored in a single le. Standard deviation of the estimated baseline lengths are given in
the last column.
3.3 Site coordinate data

Site coordinates in either global geocentric rectangular coordinate system (XYZ) or the locally dened coordinate system (ENU) are stored in multiple les. There are two les each for all four stations. In case when the site coordinates were xed
as a-priori information for reference station, theerrors in the data les are denoted as 0.00 mm.
Otherwise, the errors are given from the one standard deviation obtained through least-square parameter adjustment estimation. Correlation factors between each coordinate component are also
given. Each line represent the results from a single
experiment.

Baseline lengths and site position displacementsfrom the arbitrarily determined reference position
are formatted in a text le and sent to the e-mailaddresses registered beforehand. The displacements are expressed in the east-west, north-south,and vertical up-down directions. Reference positions have been determined by an analysis basedon the ITRF93 coordinate system upon an experiment performed on January 19, 1995, when two
KSP stations (Kashima and Koganei) and 34m antenna station at Kashima participated in the same
VLBI experiment. Although this method is onlyused internally at present, the e-mail address ofa responsible researcher in Japan Meteorological
Agency (JMA) will be added to the distribution 4. World Wide Web (WWW)
list. JMA will use this information as one of many
data related with the earthquake research aroundBy using one of many browser applications forTokyo.
the World Wide Web, one can view and download
all the les accessible by means of anonymous FTP.
In addition to the data accessible by the anony3. anonymous FTP
mous FTP method, one can display plots of these

6

IERS TDC News No.8

Table 1. [exp.inf]
94/08/29 04:54 -- 94/08/30 05:27
94/12/20 01:00 -- 94/12/21 01:01
95/01/17 08:07 -- 95/01/18 06:04
95/01/19 00:00 -- 95/01/20 00:03
95/01/31 00:00 -- 95/01/31 04:17
95/02/01 00:00 -- 95/02/01 04:18
95/02/02 00:16 -- 95/02/02 04:24
95/02/03 00:00 -- 95/02/03 04:24
95/02/06 00:00 -- 95/02/06 04:17
95/02/07 00:00 -- 95/02/07 04:14

94AUG29XX.out
94DEC21XX.out
95JAN17XX.out
95JAN19XX.out
95JAN31XX.out
95FEB01XX.out
95FEB02XX.out
95FEB03XX.out
95FEB06XX.out
95FEB07XX.out

11-Aug-95 17:09:20
6-Sep-95 11:14:01
16-Feb-96 23:17:45
6-Sep-95 11:14:03
6-Sep-95 11:14:06
6-Sep-95 11:14:06
6-Sep-95 11:14:07
6-Sep-95 11:14:08
6-Sep-95 11:14:08
6-Sep-95 11:14:09

96APR07XX.out
96APR08XX.out
96APR09XX.out

10-Apr-96 14:45:19
10-Apr-96 15:14:27
11-Apr-96 15:01:04..
.
96/04/07 15:00 -- 96/04/07 20:13
96/04/08 15:00 -- 96/04/08 20:17
96/04/09 15:00 -- 96/04/09 20:15

Table 2. [stat.dat]
Exp Code

Duration (Start-End)Baseline

94AUG29XX
94DEC21XX
95JAN19XX
95JAN31XX
95FEB01XX
95FEB02XX
95FEB03XX
95FEB06XX
95FEB07XX

94/08/29 04:54 -- 94/08/30 05:27
94/12/20 01:00 -- 94/12/21 01:01
95/01/19 00:00 -- 95/01/20 00:03
95/01/31 00:00 -- 95/01/31 04:17
95/02/01 00:00 -- 95/02/01 04:18
95/02/02 00:16 -- 95/02/02 04:24
95/02/03 00:00 -- 95/02/03 04:24
95/02/06 00:00 -- 95/02/06 04:17
95/02/07 00:00 -- 95/02/07 04:14

RMS delay(ns)
KASHIM11-KOGANEI.060
KOGANEI -KASHIM11.047
KASHIM11-KOGANEI.069
KASHIM11-KOGANEI.031
KASHIM11-KOGANEI.034
KASHIM11-KOGANEI.042
KASHIM11-KOGANEI.046
KASHIM11-KOGANEI.048
KASHIM11-KOGANEI.059

96APR07XX
96APR08XX
96APR09XX

96/04/07 15:00 -- 96/04/07 20:13
96/04/08 15:00 -- 96/04/08 20:17
96/04/09 15:00 -- 96/04/09 20:15

KASHIM11-KOGANEIKASHIM11-KOGANEIKOGANEI -MIURA

..
.

.024
.021
.027

# of Obs.
good(bad)122(131)139( 54)
151( 40)
40( 2)
37( 5)
36( 5)
36( 6)
33( 9)
33( 6)
86( 3)
32( 58)89( 4)

data graphically and browse detailed output of pa- o sets and their rates (clock parameters) at interrameter estimation software VLBEST for each ex- val of three hours, site coordinates of all stations
periment. To achieve these capabilities, HTML except for a reference station are the parameters to(Hyper Text Makeup Language) les are automat- be adjusted. Theoretical models used in the analically produced according to the available data set. ysis are also described in the VLBEST output.
The WWW homepage is accessible at the URL
http://kouma.crl.go.jp (for Japanese language
homepage, use http://kouma.crl.go.jp/index-J.html 5. In the Future
instead). Figure 1 shows what the homepage of the
At present, the SINEX data format is being conKey Stone Project looks like.
In the detailed output of VLBEST, one can ac- sidered to be adopted to release detailed analycess all the adjusted values estimated in the anal- sis results to the public. The SINEX format isysis. Usually, the hydrostatic atmospheric delay in widely used as a standard by the GPS community,
the zenith direction at interval of three hours, clock and therefore the format will be preferable to exchange data with other organizations. Under the7June 1996

Table 3. [baseline.dat]
94AUG29XX
94DEC21XX
95JAN19XX
95JAN31XX
95FEB01XX
95FEB02XX
95FEB03XX
95FEB06XX
95FEB07XX

MJD
Baseline
BL Length (mm)49593.204 KASHIM11-KOGANEI 109099666.40
49706.042 KASHIM11-KOGANEI 109099655.70
49736.000 KASHIM11-KOGANEI 109099660.10
49748.000 KASHIM11-KOGANEI 109099677.20
49749.000 KASHIM11-KOGANEI 109099682.50
49750.011 KASHIM11-KOGANEI 109099676.60
49751.000 KASHIM11-KOGANEI 109099662.90
49754.000 KASHIM11-KOGANEI 109099653.60
49755.000 KASHIM11-KOGANEI 109099681.50

Error (mm)
7.20
5.40
4.00
8.50
11.50
11.60
12.70
19.60
19.50

..
.
96APR07XX
96APR08XX
96APR09XX

50180.625
50181.625
50182.625

KASHIM11-KOGANEIKASHIM11-KOGANEIKOGANEI -MIURA

109099659.50
109099677.70
57734581.10

2.90
13.70
4.30

Table 4. [koganei.xyz]
94AUG29XX
94DEC21XX
95JAN19XX
95JAN31XX
95FEB01XX
95FEB02XX
95FEB03XX
95FEB06XX
95FEB07XX

MJD
49593.204
49706.042
49736.000
49748.000
49749.000
49750.011
49751.000
49754.000
49755.000

X (mm)X err
Y (mm)Y err
Z (mm)
Z err-3941937455.20 24.85 3368150904.60 18.28 3702235290.20 21.41-3941937470.60 17.33 3368150901.40 11.06 3702235300.70 15.56-3941937480.80 6.28 3368150915.60 5.99 3702235307.90 5.63-3941937479.40 26.66 3368150937.80 18.29 3702235322.50 26.22-3941937413.90 34.19 3368150885.60 26.07 3702235245.30 32.69-3941937526.30 39.74 3368150968.90 25.32 3702235336.60 40.70-3941937479.30 39.95 3368150914.00 26.94 3702235295.30 40.62-3941937436.00 61.20 3368150869.00 44.65 3702235264.30 57.06-3941937466.00 62.33 3368150924.60 40.80 3702235280.60 62.51

Cxy-.8925-.9001-.8243-.8978-.8837-.9345-.9059-.8925-.9124Cxz-.9177-.9520-.8347-.9659-.9634-.9379-.9666-.9679-.9725

Cyz
.8722
.8660
.8064
.8617
.8325
.8661
.8655
.8483
.8755

-3941937481.10 10.40 3368150910.70 8.19 3702235289.70 8.06 -.9034 -.9389-3941937410.10124.12 3368150879.40 86.05 3702235248.70100.38 -.9942 -.9953-3941937480.80 .00 3368150916.60.00 3702235307.90.00.0000 .0000

.8903
.9953
.0000

..
.
96APR07XX 50180.625
96APR08XX 50181.625
96APR09XX 50182.625

Table 5. [koganei.enu]
94AUG29XX
94DEC21XX
95JAN19XX
95JAN31XX
95FEB01XX
95FEB02XX
95FEB03XX
95FEB06XX
95FEB07XX

MJD
49593.204
49706.042
49736.000
49748.000
49749.000
49750.011
49751.000
49754.000
49755.000

E (mm)
E err-7.54 7.30
4.90 5.20.73 2.60-17.06 7.80
-19.92 10.40-10.24 10.40.97 11.40
7.05 18.00-15.73 17.60

N (mm)

N err
1.54 6.80
4.44 4.20.38 2.50
4.44 6.90-9.39 9.20
-16.72 13.00-8.58 11.00
2.52 15.00-18.63 16.00

U (mm)
U err-32.51 36.20-18.57 24.90-.58 9.70
18.79 40.30-94.24 52.20
72.38 60.00-9.70 61.00-78.26 91.90-20.90 94.30

Cen
Ceu
Cnu
.0410
.3630 -.0800
.3570
.6240
.1930
.0890 -.1350 -.1930
.6020
.5340
.3890
.6340
.3500
.1860
.4760
.6990
.4310
.6430
.5750
.4760
.6140
.4330
.1760
.6800
.6280
.4960

..
.
96APR07XX 50180.625
96APR08XX 50181.625
96APR09XX 50182.625

4.65 2.90-17.68 17.10
-.03
.00

-12.68 2.60
-2.59 9.20
.00
.00

-13.60 15.00.0530-97.87180.30 -.6710
-.05
.00
.0000

.2410 -.4370.8920 -.6710
.0000
.0000

8

IERS TDC News No.8

Figure 1. Homepage of the Key Stone Project (URL http://kouma.crl.go.jp).
Key Stone Project, SLR and GPS data will be observed too. These data set will also be analyzed
and released along with the VLBI data.

9June 1996

Current Status of the Key
Stone Project (KSP)
Noriyuki Kurihara

Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314-0012, Japan
Development of the KSP, which monitors crustal
deformation around the Tokyo metropolitan areawith a space geodetic technique (VLBI, SLR andGPS), started in FY1993. Three of four VLBI
stations, Kashima, Koganei and Miura, have been
completed construction and have been carrying out
daily observations. Last station (Tateyama) is justabout ready to start observations. Four SLR stations also have been constructed by the end of FY
1995.

Kashima VLBI station

Miura VLBI station

Kashima SLR station

Tateyama VLBI station

10

IERS TDC News No.8

VLBI Data Analysis System Goddard Space Flight Center of National Aeronautics and Space Administration (NASA). Since all
for the Key Stone Project
the processed data from a Key Stone VLBI experiYasuhiro Koyama

Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314-0012, Japan

1. Introduction
The data analysis software package of the Key
Stone Project, which was nicknamed \Takemikazuchi"1 , is characterized by its highly automateddesign and its operator friendly Graphical User Interface. The software runs on a UNIX workstation(Figure 1) at Koganei Central Station located in
the headquarters of the Communications ResearchLaboratory.
The software utilizes CALC (Version 8.1) andMark-III Database Handler software developed by
1 \Takemikazuchi" is the name of a mythological god whois symbolized by thunderbolt. Kashima Shrine located near
the Kashima Space Research Center is the home of this god,
and the gigantic 'Key Stone' was put on the head of a huge
cat sh by him long time ago to prevent hazardous earthquakes which had been caused by the cat sh, so it was told.

ments are stored in a Mark-III database, the results
can be exchanged with other institutes participating geodetic VLBI activities worldwide. Figure 2
illustrates the data ow of the data analysis software.
As soon as the bandwidth synthesis processing(KOMB) is nished on all the observations taken
in a daily VLBI session, 'KOMB' output les areorganized and two databases (X-band and S-band)
are created from these les. S-band database is
only used for correlated amplitude monitoring purposes, and on the other hand, X-band databaseis used for data analysis in the following steps.
The X-band database is prepared for data analysis by the program DBUPDATE. DBUPDATE
stores various a-priori information in the database.
Next, (CALC) is executed on the X-band databaseto calculate theoretical delay and delay rates andtheir covariance matrices. At this point, the Xband database becomes ready to be analyzed by
the least-square parameter adjustment program
VLBEST. At rst, VLBEST runs with only
clock o sets and their rates of change at all stations
except for a reference station. Kashima station isalways chosen as the reference station whenever thestation participated the session. From the results,
REMAMB resolves delay ambiguities.

Figure 1. HP9000 model 715/100 workstation used for the Keystone VLBI data analysis.

11June 1996

Table 6. List of experiments used for the comparison.
Date of
Experiments
1995.12.3
1995.12.4
1995.12.5
1995.12.6
1995.12.8(# of data actually used in the analysis) / (# of data correlated)(1) KSP Automatic Analysis (2) KSP Manual Analysis (3) K-3 Correlator + SOLVE
58/86
78/86
97/101
61/82
74/82
97/10179/89
80/89
94/100
78/84
80/84
95/98
71/77
72/77
94/99

Next, VLBEST runs again with the same setsof estimate parameters on the ambiguity-resolved
data. From the results, MRKOBS ags out bad
data points which have large residuals. Finally,
VLBEST runs again and the full set of estimation parameters are adjusted. These parameters
are: clock o sets and their rates of change at all
stations except for the reference station, wet component of tropospheric delay (three hour intervals)
at all stations, and site coordinates of all stations
except for the reference station. Unless the rootmean-square of the residual delays exceeds a certain threshold (100 psec), the estimated results aresoon released in a variety of data types and formats. If the RMS residual exceeds the threshold value, an e-mail message is sent to a responsible operator to notify the problem. The operator
investigates the data closely and tries to resolve
the problem. Takemikazuchi provides Graphical
User Interface to support these tasks for the operator. The operator can remove or recover any data
point, insert epoch points for tropospheric delay
and clock parameters, and change the estimation
strategy very easily.
In addition to the normal data analysis procedure just described above, results are revised automatically upon receipt of the weekly and monthly
bulletins of the International Earth Rotation Service (IERS), i.e. Bulletins A and B respectively.
This is necessary since Earth Orientation Parameters (EOP) available at the time of the rst data
analysis are, in fact, predicted values based on thedata in past. The predictions have large uncertainties, especially the last Bulletin A is almost
one week old. The uncertainties of the predictions
are estimated as 3.8 mas for terrestrial pole positions and 1.5 msec for UT10UTC at prediction
length of 10 days (IERS, 1995). These uncertainties correspond to the site position estimation errorof 2.0 mm and 12.0 mm respectively for the baselines with distance of 110 km, which is roughly the
distance between Kashima and Koganei stations.
All the e-mail messages received by the Takemika-

duchi system are analyzed and the EOP data le isupdated according to the Bulletin data if the e-mailwas either Bulletin A or Bulletin B. Whenever the
EOP data le is updated, all the a ected databases
are also updated and processed for data analysis.
As such, the same database is repeatedly analyzed
with updated EOP values at least four times (twotimes with Bulletin A values and two times with
Bulletin B values).

2. Comparison of Results with Conventional Systems
To validate the results obtained by the Key Stone
Project VLBI data analysis system, the estimatedsite position of the Koganei VLBI station was compared with the results obtained by other conventional methods. Table 1 gives the list of experiments with the number of correlated observations
and actually used data for analysis. In the table,(1) and (2) are the results obtained using the KSP
correlator, whereas (3) are the results obtained using the K-3 correlator. For the least-squares parameter adjustment, VLBEST was used in (1)and in (2), whereas SOLVE was used in (3). Differences between (1) and (2) are due to whether
bad data are removed (1) automatically by the program MRKOBS or (2) interactively by using theGraphical User Interface.
The number of correlated observations incolumns (1) and (2) are same since they are basedon the same databases. These numbers are always
less than the numbers in column (3) because there
were still miscellaneous problems during the automatic correlation processing. The numbers of data
actually used in the analysis in the column (1) arealways less than those in column (2). This is, perhaps, because the threshold of delay residuals in
the program MRKOBS is too small, and hencesome valid data are also removed from the later
analysis. Figure 3 shows the estimated site positions of Koganei VLBI station for ve experiments

12

IERS TDC News No.8

Correlation
Bandwidth Synthesis

KATS (Data Processing Sofware)

Database Management Section
PUTM3

Create Databases (X-band & S-band)

DBUPDATE

Updates a-priori data in databases

CALC 8.1

Theoreical Model Calculation

Analysis Section
Esimate Clock
Offsets & Rates

VLBEST

Resolve
Ambiguitties

REMAMB

IERS EOP Bulletins

Esimate Clock
Offsets & Rates

VLBEST

DBUPDATE

Exclude Large
Residual Data

MRKOBSCALC 8.1

Esimate Full
Parameters

VLBEST

Manual Analysis

RMS Delay <100psec.?

NO

Notify Operatr by e-mailYES
Output Results

Post Analysis Section
Figure 2. Flow chart of the Key Stone Project VLBI data analysis.
ties of EOP values, the results were compared withdi erent IERS bulletins. The experiment done on
November 7, 1995 was chosen for the comparison.
The experiment was rst analysed on November
8, 1995 by using EOP predictions released in the
Bulletin A issued on November 2, 1995. The EOP
values are revised three times, rst by Bulletin A
issued on November 9, 1995, and hen two Bulletin
3. E ects of EOP Prediction Uncer- B issued on December 8, 1995 and on January 3,
tainties
1996. Figure 5 shows the di erence of EOP values
according to the nal value in the Bulletin B issuedonJanuary 3, 1996.
To evaluate the e ects of prediction uncertainin the horizontal plane. Uncertainties are expressedas one-sigma standard deviation error ellipses. Figure 4 shows the similar comparison for the verticalaxis. These comparisons do not indicate statistically signi cant di erences between the di erent
approaches of data analysis, as expected.

13

June 1996

1995.12.4

20

20

1995.12.3

(1)

(2)

0

0

(3)
(2)

(3)

-20

0

20

-20

-20

(1)

-20

0

1995.12.5

20

20

20

1995.12.6

(1)

(2)

0

0

(2)

(1)

-20

0

20

-20

0

20

1995.12.8
20North (mm)

(3)

-20

-20

(3)

0

(3)

South

(2)

-20

(1)

-20

0

West

20

East (mm)Figure 3. Estimated site position of Koganei VLBI station compared in the horizontal plane.
As seen in the gure 5, the di erences between
predicted and revised values increase, as the prediction is made for many days in the future. As the
EOP values are revised in the following IERS bulletins, the values converge toward the nal values.
Figure 6 shows the four di erent site position estimates of Koganei VLBI station compared in thehorizontal plane. Each ellipse represents a onesigma standard deviation uncertainty estimated using di erent EOP data sets. Figure 7 compares thesame results on the vertical axis.
All the results except for the rst one estimatedusing the predicted EOP values agree with eachother. The agreement is so good that the error ellipses in the horizontal plane and error bars in thevertical axis are hardly distinguishable. On theother hand, the rst results di er from the otherthree by about 12 mm. Since the nal target of
the Key Stone Project is an accuracy of 2 mm forhorizontal plane and 5 mm for vertical axis, thedi erence of 12 mm is quite serious. Therefore, it
is important to note that the site coordinates estimated right after the experiment is nished may
have large systematic error due to the insucient14

1995.12.5

1995.12.3

1995.12.6

1995.12.4

1995.12.8

0

20

40

IERS TDC News No.8

(3)

(3)

(3)

-20

(2)
(1)

(2)

(3)
(3)

-40

(1) (2)
(1)

(2)
(1)

(2)
(1)

Figure 4. Estimated site position of Koganei VLBI station compared in the vertical axis.
prediction accuracy. In the rst analysis, baseline
results should be used mainly. Three dimensionalsite coordinates are reliable from the second analysis results. It is also important to note that the results of the second analysis are in fact good enough,and such results can be obtained within a week.

To prevent unnecessarily removal of valid data, thealgorithm of MRKOBS should be improved.
The e ects of prediction uncertainties of Earth
Orientation Parameters were also examined. The
results indicated that the three dimensional site coordinates estimated in the rst data analysis needs
to be used cautiously. When high accuracy and reliability of the results are required, as in the case
4. Summaryof the Key Stone Project, only the baseline lengths
after the initial analysis, or the complete results
Daily VLBI observations with three stations, i.e. after the second analysis should be used.
Kashima, Koganei, and Miura stations, started on
December 1, 1995. As a result of automation- Referencesoriented system design, the data processing andanalysis are almost automatically done without IERS Annual Report for 1994, Central Bureau of IERS
- Observatory of Paris, 1995
much e ort. Daily observations begin at 1:00 UT
and end at 6:30 UT. The recorded data tapes at
Kashima and Miura stations are transported to Koganei Central station at 8:00 UT, and arrive thenext morning. Correlation processing nishes for
all the observations by 6:00 UT, and the analysis
results become available by 6:30 UT. Thus, all theprocess tasks are nished within 24 hours from thetime of the last observation.
The comparison of the results with other conventional results showed no signi cant di erences.
From this result, the data analysis system of the
Key Stone Project is con rmed in its functionality.

15

5June 1996

Bulletin A 1995.11.22

Bulletin A 1995.11.29

Bulletin A 1995.11.16

0Bulletin B 1995.12.8

Bulletin A 1995.11.9

δx(m.a.s.)5-5Bulletin A 1995.11.2

Bulletin A 1995.11.22

Bulletin A 1995.11.29

0Bulletin A 1995.11.2
Bulletin B 1995.12.8

Bulletin A 1995.11.16

δy(m.a.s.)5-5Bulletin A 1995.11.9

0Bulletin A 1995.11.2

Bulletin B 1995.12.8-5Bulletin A 1995.11.16

Bulletin A 1995.11.22
Bulletin A 1995.11.9
Bulletin A 1995.11.29

UT1-UTC(msec.)
1

10

20

30

Figure 5. Comparizon of Earth Orientation Parameters (wobble of Earth's rotation pole and UT10UTC)in the di erent IERS bulletins.

16

North (mm)20

IERS TDC News No.8

Bulletin A 1995.11.2

0Bulletin A 1995.11.9

Bulletin B 1995.12.8

-20

South

Bulletin B 1996.1.3

-20

20

0

East (mm)West

Bulletin B 1995.12.8

Bulletin B 1996.1.3

Bulletin A 1995.11.9

Bulletin A 1995.11.2

0
-40

-20

Vertical Axis (mm)2040Figure 6. Estimated site position of Koganei VLBI station compared in the horizontal plane.

Figure 7. Estimated site position of Koganei VLBI station compared in the vertical axis.

17June 1996

Correlation Processing System diagram of the correlation system is shown in Fig.
2. Therefore, the tape position data and the stafor the Key-Stone Projecttus data of all the data recorders can be exchanged
Hitoshi Kiuchi

Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184-8795,
Japan
Abstracts

We have developed an XF type VLBI correlation
processor by making use of Field Programmable
Gate Arrays. This correlator was specially designed for the Key-Stone Project, which is concerned with measuring crustal deformation in the
Metropolitan area. The outline of the correlator is (1) Automatic bit synchronization duringmulti-baseline processing, (2) Network Filing System for storing correlated data, (3) maximum data
rate is 512 Mbps, (4) 2-bit and higher sampled
data processing capability, (5) 16ch high speed (32Mbps/channel) processing, (6) Compact and lightweight, (7) Signal provided by VME back plane.
Using this new correlator, we can improve the precision of the geodetic VLBI and also contribute toradio astronomy VLBI.

1. Correlation Processing System
The periodicity of the time code is not required
for spectrum analysis. Only the sampled data areneeded. The K-4 recorder has helical data tracks,
two longitudinal annotation tracks and a control
track (Fig. 1). The Track Set ID numbers arerecorded on the control track, and can be read at
any tape speed even during fast forward or rewind.
The output interface unit can control the synchronous replay of several Data Recorders, convert
the Track set ID for the data clock, and send data
to a correlator. There is an obvious relationshipbetween the Track Set ID (which is a head control
signal written on the control track) and the timecode block. It is possible to manage the time codeusing the Track set ID and Time code block. For afew seconds the time code data is over written on
the data train in a pre-observation header block.
After the time code block, data timing is checkedby the Track Set ID, which means that the output
data is only digitized raw data during an observation.
In the multi-baseline correlation processing, all
the output interface units are daisy-chain connected via GPIB and a timing control line. A block

via the output-interface units. The replayed datafrom the data recorder is written into a bu er memory. The measured phase di erence between thereplayed and the external 1 PPS signal sent from
the Main Replay system is monitored by the clock.
The measured data is then sent to the main replay
system, and used for the bit synchronization ( nesynchronization) between the main and sub replay
systems. The main replay system (the main output
interface unit and the data recorder) and the sub
replay system (the sub output interface unit andthe data recorder) can be synchronized in one-bit
steps. The delay adjustment is done by controlling
the track set ID position control and subsequent
programmable memory. The signal (raw data) is
unformatted instead of in the Mark-III format. We
are developing an XF type VLBI correlation processor for the K-4 system by making use of Field
Programmable Gate Arrays. The outline of thecorrelator is:(1) Automatic bit synchronization during multibaseline processing,(2) Network (Ethernet) Filing System for storingcorrelated data,(3) 2-bit or higher sampled data processing capability,(4) 16 ch high speed (32 Mbps/channel) processing,(5) Compact and light-weight,(6) Signal provided by VME back plane.
And speci cations are;(1) Fringe phase resolution 32 bit (at K=1),(2) 28 bit integrator (integration time from 1 sec
to 16 sec),(3) maximum clock rate 32 MHz,
(4) Phase calibration signal detector (Pcal detection frequency from 10 kHz to 9990 kHz),(5) 256 kbit delay tracker,(6) A priori calculation is done each correlator,(7) 32 complex lags in each channel,(8) 16 ch XF type correlator,(9) fringe search mode (512 lags).
This correlator was specially designed for the
Key-Stone Project, which is concerned with measuring crustal deformation in the Metropolitan
area. The detected fringes are shown in Fig. 3,
and geodetic results are reported in this issue. The
project utilizes 4 stations in the Metropolitan area,and each station has a new K-4 system and an 11m antenna. Using this new correlator, we can improve the precision of the geodetic VLBI and also
contribute to radio astronomy VLBI. The multibaseline correlation processor (4-station) is shown

18

IERS TDC News No.8

Figure 1. Tape format and data format

Figure 2. Block diagram of correlation processing system

19June 1996

Figure 3. Detected fringes
in Fig. 4. It is also possible to use this correlator
for real-time VLBI.

2. Conclusion
The KSP (new K-4) data acquisition mode includes VLBA and VSOP data modes. Multibaseline correlation processors using Field Programmable Gate Array has been developed.
References[1] Cooper, "Correlators with Two-bit Quantization",Ast. J. Phys., vol.23, pp.5 21-527, 1970.
[2] A.E.E.Rogers, A.E.E.; "Coherence Limits for VeryLong-Baseline Interferome try", IEEE Trans. Instrum. Meas., vol. 30, pp. 283- 286, December
1981.

20

IERS TDC News No.8

Figure 4. Developed multi-baseline correlation processing system. From left : 4 DMS (Digital Massstrage System: automatic tape changer)

21

June 1996

Pulsar VLBI Experiment with 3. Correlation and Analysis
Kashima (Japan) - Kalyazin
Correlation processing was performed by a K3
(Russia) Baseline
correlator, which was developed by CRL. A gating
M. Sekido1 , M. Imae2 , Y. Hanado2 , Y.
Takahashi1 , Y. Koyama1 , Y. P. Ilyasov3 , A.
E. Rodin3 , A. E. Avramenko3 , V. V.
Oreshko3 , and B. A. Poperchenko4
1 Kashima Space Research Center

Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314, Japan
2 Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184, Japan
3 Astro Space Center P.N. Lebedev PhysicalInstitute, Russia
4 Special Research Bureau of the Moscow PowerEngineering Institute, Russia

1. Introduction
Interferometric measurement of a pulsar is oneof the most e ective techniques to measure accurate source positions. Precise measurement of apulsar position will give us information concerning
proper motion and parallax. Interferometric measurements on pulsars have been carried out, but the
number of pulsars whose positions were measured
is still smaller than the total number of known pulsars because newly discovered pulsars are rapidly
increasing due to recent intensive systematic surveys. We have started measuring their positions byusing VLBI between Kashima and Kalyazin. This
report shows the results of the rst experiment.

2. Observations
This Pulsar VLBI observation program is basedon collaboration between the Communications Research Laboratory (CRL) and the Lebedev Physical Institute. Our rst VLBI observation was performed on 14 March 1995. We used a 34m antenna at Kashima and 64m antenna at Kalyazin,which is about 150 km north of Moscow. The baseline length is about 7000 km and minimum fringe
spacing is 7 mas at 1.4 GHz. The system temperature and eciency of the 34m antenna and the
64m antenna are about 40 K and 0.6 respectively
for both antennas. The employed VLBI data acquisition system is Japanese K4 system which iscompatible with the Mark -III mode C.

function was available on the correlator, but wecouldn't use it due to some problems in data processing of gated data. After ordinal cross correlation processing, the result was stored in the Mk-III
database and analyzed with software SOLVE. The
SOLVE is a program developed by NASA for baseline and source position analysis with group delay.
The estimated position of PSR0329+54 is
PSR0329 + 54 :: 3h 32m 59s :369 6 0:01
 : 54 3404300 :627 6 0:08

Now we are developing a new correlator with gating
function to improve the signal to noise ratio. Our
observations will be continued for a few years todetect the proper motion.
Acknowledgements

We thank the sta of Kalyazin 64m antenna operation team, especially V. A. Agafonov,
A. N. Fatiev, and M. A. Dolgov. Also V. V. Oreshko, V. Sternenko, and A. V. Serov, who helped
us with the receiver and atomic standard. Many
thanks to members of CRL Radio astronomy applications section for their support of this experiment.
References

Backer,D. C., Sramek, R. A., 1981, In Pulsars, IAU
Symposium No. 95, edited by W. Sieber and R.
Wielebinski (Reidel, Derdriecht), 205.
Bartel,N., Ratner, M. I., Shapiro,I. I., Cappallo, R. J.
Rogers, A. E. E., Whitney, A. R., 1985. Astrophys.
J., 90, 318
Downs,G. S., Reichley, P. E. 1983, Astrophys. Suppl.
Ser., 53, 169.
Formalont, E. B., Gross, W. M., Lyne, A. G., andManchester, R. N. 1984, M.N.R.A.S.210, 113.
Helfand,D. J., Taylor, J. H., Backus, P. R., and Cordes,
J. M. 1980, Astrophys. J., 237, 206
Taylor,J. H., Manchester, and R. N., Lyne, A. G. 1993,
Astrophys. Suppl. Ser., 88, 529

22

IERS TDC News No.8

Figure 1. Estimated position of PSR0329+54. Our result isand others are as follows: A: Taylor
et al.(1993), B: VLBI by Bartel et al. (1985), C: 35 km-Interferometer by Backer and Sramek (1981),
D: VLA by Formalont et al. (1984), E: Pulse-Time-of-Arrival (PTA) measurement by Downs andReichely(1983), F: PTA measurement by Helfand et al.(1980). Transformation between the deferent
coordinate system is not applied in this gure.

23

June 1996

The Examination of Selenodesy and Planetodesy Using
VLBI and Counter VLBI
Mizuhiko Hosokawa

Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184-8795,
Japan
Recently, the plan of Selenodesy by use of VLBI(RISE: Radio Interferometry for Selenodesy) is
proceeding. In this plan, as the VLBI radio sources
both that on the Moon surface and on board ofsatellites around the moon are considered. As anext step to the selenodesy, we (Hosokawa andImae at CRL and Kawano and Hanada at NAO)
began to examine the planetodesy using counter
VLBI technique. The rst target of the planetodesy is the planet Mars.
With the progress of these projects, a study
group on the mechanics of spacecraft and VLBI
has been organized in last fall. Hosokawa is appointed as the contact person of the group in CRL.
For the realization of these plans, many new technical developments and analysis methods on VLBI
technology will be needed. Let us summarize thetechnical topics and problems of these plans.
There are two important characteristics in theseplans. These are, the radio sources are arti cialones, and they are at the nite distances. Becauseof the former property we will be able to set theintensity and the frequency characteristics of thesources somewhat freely. The latter demands a
new analysis method where the parallactic corrections and the motion of the sources should be taken
into account. The sensitivity to the motion of thesource will provide a new route to the real time
positioning of the space crafts.
In the case of counter VLBI, the former property will be fully applied to the planetodesy plan.
In our examination, all radio sources on Mars areequipped with atomic clocks, so that all the signals
from these sources should be synchronized. Thissynchronization would be done by two-way satellite
time transfer via the Mars-stationary satellite. As
the radio sources, we can choose the carriers or the
spectrum di used ones according to the purpose
and possible system of the plan. Then, we will beable to measure the di erences among propagation
times of the radio signals from the sources on Mars
to the observatory on the Earth. On the other
hand, interplanetary radio propagation would be
a ected by many relativistic e ects that are causedby the complicated motion of the sources and by
the gravitational eld by the massive bodies in the
Solar system. Hence, we have to make the corrections for these e ects.
To summarize, there are many interesting andchallenging subjects on VLBI technology in theplans of Selenodesy and the planetodesy. Therefore it would be worth paying attention to theseplans for us, the VLBI technical development center.

Figure 1. Figure on Counter VLBI.

24

IERS TDC News No.8

A Plan of Interferometric Observations of Jovian Radio
Wave Emissions at Low Frequencies (25 - 35 MHz)
Tetsuro Kondo

Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314-0012, Japan
Jupiter radiates very intense burst-like radio
waves in the decametric range of wavelengths.
These bursts are the most intense received on
Earth, except for emissions from the disturbed sun.
Many investigators have observed Jovian decametric radio emissions (JDR) from the ground, andlater in space since the rst discovery of JDR about
40 years ago, and have studied its various characteristics.
The source regions are thought to be locatedat Jovian northern and southern auroral regions
and/or at the foot of the Io ux tube from evidence
based on a wave generation mechanism and the oc-

currence characteristics of JDR. However so far no
direct observation of source location was made because of large refraction caused by the terrestrial
ionosphere at such a low frequency. It is dicult to
identify absolute source position when the signal ispropagated through the ionosphere.
Usually scintillation of ionosphere e ects havea time scale of several seconds and longer. If
JDR switches its source location between southern and northern hemispheres within suciently
short time scale compared with that of ionosphericscintillation, we could detect relative source motion. Motivated by this idea, we are planning tocarry out interferometric observations of JDR using
two antennas located at Kashima and Hiraiso (bothare branches of Communications Research Laboratory) spanning about 50 km in north-south direction. Figure 1 shows an antenna newly constructed
at Kashima for this study. It is a spatially-crossed
13-element log-periodic antenna with a nominal
frequency coverage of 25-70 MHz installed on a 15
m tower as an azimuth-elevation mount.
Presently the Galileo spacecraft's orbiter is orbiting Jupiter, and will measure the Jupiter system and its magnetosphere for at least two years.
Therefore it provides a good opportunity to makea direct comparison between observations from theground and those in situ.

Figure 1. Antenna for detection of decametric radio waves at Kashima.

25

June 1996-News-News-News-News-News-News-News-News-News-News-News-News-

Letter of Thanks from National Institute of Polar Research
The director of TDC/CRL received a "letter of thanks" in November, 1995 from Dr. Shibuya of
National Institute of Polar Research for the support of TDC at CRL to successful aquirement of the
Antarctic VLBI Project budget. (T.K.)

Letter of thanks from NIPR.

26

IERS TDC News No.8

-News-News-News-News-News-News-News-News-News-News-News-News-First Step Toward Geodetic Real-Time VLBI
| Successful Detection of Fringes on the Baseline Between
Kashima and Koganei Connected by ATM Networks |Communications Research Laboratory (CRL) is developing a real-time VLBI technique for geodetic use in cooperation with Telecommunication Network Laboratory Group of Nippon Telegraph andTelephone Corpolation (NTT). The real-time VLBI means that correlation processing is made in realtime like a connected element interferometer. In May,1996 the rst fringes were successfully detectedon Kashima-Koganei baseline (about 100 km) (Fig.1). In real-time VLBI digitized data of radio signals from quasers are directly transmitted to a central station where a correlator is located using ATM(Asyncronous Transfer Mode with a speed of 256 Mbps) networks consisting of optical ber link insteadof recording on a magnetic tape. (T.K.)

Figure 1. First real-time VLBI fringes after bandwidth synthesis of 8 channels in 8 GHz band for
4C39.25 on the Kashima-Koganei baseline.

27

June 1996

Technical Development Center (TDC) at the Communications Research Laboratory (CRL) is supposed to do1) the development of new observation techniques and new systems for advanced Earth's rotation
observations by VLBI and other space techniques,2) the promotion of research in Earth rotation by advanced methods in VLBI,
3) the distribution of new VLBI technology.
The TDC meeting, attended by the ordinary members from inside the CRL and the special members
from the outside, is held twice a year. The special members advise the committee, concerning the planof technical developments. The TDC newsletter is published biannually by CRL to inform the IERS
community its current activities.
This news was edited by Tetsuro Kondo and Yasuhiro Koyama, Kashima Space Research Center, whoare editorial sta members of TDC at the Communications Research Laboratory, Japan. The editors
wish to thank Dr. O. J. Sovers for his kind help in the correction of the news translated from Japanese
to English.
Inquires on this issue should be addressed to:T. Kondo
Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314, Japan
TEL: +81-299-84-7137
FAX: +81-299-84-7159
e-mail : kondo@crl.go.jp

Summaries of VLBI and related activities at the Communications Research Laboratory are available
from the home page of the Radio Astronomy Applications Section of the Kashima Space Research Centeron the World Wide Web (WWW). The URL to view the home page is : http://apollo.crl.go.jp/

TECHNICAL DEVELOPMENT CENTER NEWS No.8, June, 1996
International Earth Rotation Service - VLBI Technical Development Center News
published by
Communications Research Laboratory, 4-2-1 Nukui-kita, Koganei, Tokyo 184, Japan