ISSN 1882-3432

CONTENTS
Proceedings of the 14th NICT TDC Symposium (Kashima, 25 June, 2015)
First Geodetic Result of Ishioka VGOS Antenna
Yoshihiro Fukuzaki, Kozin Wada, Ryoji Kawabata, Masayoshi Ishimoto, andTakahiro Wakasugi...... 1

On a Wide-Band Bandwidth Synthesis II
Testuro Kondo, and Kazuhiro Takefuji...... 4

Broadband VLBI Data Acquisition System for GALA-V...... 7

Mamoru Sekido, Kazuhiro Takefuji, Masanori Tsutsumi, and Tetsuro Kondo
Development of Wideband Feed

. . . . . 12

Hideki Ujihara, Kazuhiro Takefuji, & Mamoru Sekido
Report on the Test Observation of Hitachi-Takahagi Interferometer
Rinichi Kako, Munetake Momose, Yoshinori Yonekura, and Koichiro Sugiyama. . . . . 14

Observation of Jupiter’s Synchrotron Radiation in the Magnetospheric Vari- . . . . . 16
ation Period : Preliminary Results
Hiroaki Misawa, F. Tsuchiya, S. Satoh, H. Kita, M. Sekido, K. Takefuji,
E. Kawaii, T. Kondo and S. Hasegawa
A Proposal Constructing mm/sub-mm VLBI Network by Japanese/East- . . . . . 20
Asian Power
Makoto Miyoshi, T. Kasuga, M. Tsuboi, M. Takahashi, T. Oka, S. Takekawa,N. Takato, H. Ujihara, H. Ishitsuka, V. Erick, & the CARAVAN teamFirst Japanese 230 GHz VLBI experiment by MICE2015 teamKazuhiro Takefuji, on behalf of MICE2015 team

. . . . . 22

October 2015

1

First Geodetic Result of Ishioka 2. Observing Facilities
VGOS Antenna
In the new project, observing facilities are now
Yoshihiro Fukuzaki(fukuzaki-y96pe@mlit.go.jp),
Kozin Wada, Ryoji Kawabata, Masayoshi
Ishimoto, Takahiro Wakasugi
Geospatial Information Authority of Japan,
Kitasato-1, Tsukuba, Ibaraki, Japan

being constructed. The conceptual design consisting of the six components is depicted in Figure 1.
At present temporary operation rooms are installed
instead of the Operation Building, and it will becompleted by the end of February 2016.
The site name is Ishioka, which is located near
Tsukuba (about 16.6 km-NE from Tsukuba 32-m
antenna).

Abstract: The Geospatial Information Authority ofJapan (GSI) started a new project for constructing
a VGOS station in Japan. The construction of theantenna (radio telescope) has been completed andthe necessary equipment (Front-end, Back-end, Hmaser, and so on) has also been delivered. The
name of the new site is Ishioka, which is located16.6 km away from Tsukuba 32-m antenna.
We brieﬂy report the initial receiving performance of the Ishioka antenna, and the ﬁrst geodetic result of VLBI observations carried out after
February 2015.
1.

Introduction

The Geospatial Information Authority of Japan(GSI) has carried out VLBI observations since1981. In the ﬁrst period from 1981 to 1994, wedeveloped transportable VLBI systems with a 5-m
antenna and a 2.4-m antenna and carried out domestic observations by using them. As a result,
8 sites in Japan were observed and precise positions determined. In addition, Japan-Korea VLBI
observations were carried out by using a transportable 3.8-m antenna in 1995. In these observations, the Kashima 26-m antenna, which was removed in 2002, was used as a main station. Next,
in the second period from 1994 to 1998, GSI established four permanent stations: Tsukuba 32-m,
Shintotsukawa 3.8-m, Chichijima 10-m, and Aira
10-m antennas. Up to the present, regular VLBI
observations by using the four stations have been
carried out. Especially, Tsukuba 32-m antenna isa main station for not only domestic but also international VLBI observations now.
In 2011, GSI started a project for constructing
a new antenna following the VLBI2010 concept,
which is recommended by the International VLBI
Service for Geodesy and Astrometry (IVS) as thenext-generation VLBI system.
This paper gives the outline of the project, theinitial receiving performance of the new antenna,and the ﬁrst geodetic results of VLBI observations
that have been carried out since February 2015.

Figure 1. Conceptual design of the new observing
facilities

3.

Antenna and Front-end

3.1

Antenna

The antenna (radio telescope) is the main partof the observing system (Figure 2). Since a single
antenna is employed, very high slew rates are speciﬁed in order to be compliant with the VLBI2010
concept. In addition, Ring Focus optics was applied for the antenna design in order to match thebeam pattern of the broadband feed. The speciﬁcations of the antenna are listed in Table 1.
3.2

Front-end

According to the VLBI2010 concept, a broadband feed is necessary to achieve high aperture efﬁciency over 2–14 GHz. At present the Eleven feed,
which has been developed at Chalmers Universityof Technology in Sweden, and Quadruple-Ridged
Flared Horn (QRFH), which is developed at California Institute of Technology (Caltech), are thepractical as a broadband feed, so both feed systems are purchased. The employment of the feed
will be determined after the evaluation of the antenna receiving performance with these two feeds.

IVS NICT-TDC News No.35

2

unit a new cable calibration system developed by
National Institute of Information and Communications Technology (NICT) is also employed. The
speciﬁcations of the front-end are shown in Table
2.
Table 2. Speciﬁcations of the front-end.
Parameter
RF frequency range
Polarization
Feed
Dewar

Figure 2. Photo of the new antenna.
Table 1. Speciﬁcations of the new antenna.
Parameter
Diameter
RF frequency range
Optics
Surface accuracy
AZ maximum slew rate
EL maximum slew rate
AZ maximum acceleration rate
EL maximum acceleration rate
Special feature

Value
13.2 m
2–14 GHz
Ring Focus≤ 0.1 mm (rms)12◦/sec
6◦/sec3◦/sec2◦

3 /sec2Reference point canbe measured directlyfrom the ground for colocation.

In the both cases, the feeds and Low Noise Ampliﬁers (LNAs) are integrated into the each cryogenic system, whose physical temperature is lessthan 20 K.
In addition, in order to achieve the compatibility with the legacy S/X band observation, tri-band
feed system is also purchased. By using the triband feed system the measurement of the initialreceiving performance was performed. (See the following section)
The phase and cable calibration system is also
installed. A new type of P-cal unit, which was designed by Haystack observatory, is developed andemployed. In addition, instead of the present D-cal

Physical temperature
Receiver noise temperature
Total gain
Outputfrequency
range
Number of output
Phase and delay calibration

Injectionofcal/noise-source

4.

P-

Value
2–14 GHz
Dual linear polarization
Eleven feed or QRFH
Feed, LNAs, and otherdevices should be included and cooled bycryogenic system.
≤ 20 K≤ 30 K≥ 45 dB
2–14 GHz
2 (for dual linear polarization)
New-type P-cal unit
designed by HaystackObservatory
New cable calibration
system developed by
NICT
pre-feed (Eleven feed)or pre-LNA (QRFH)

Receiving PerformanceFirst of all, the receiving performance of the antenna with tri-band feed system was measured byreceiving the radio signals from some strong radiostars (Cas-A, Taurus-A, Virgo-A). As a result, theSEFDs for X and S band are approximately 1,250
Jy and 1,700 Jy, respectively. This means that theaperture eﬃciencies for X and S band are 77% and59%, respectively, if the system noise temperature
is assumed as 50 K. High receiving performancefor X band is conﬁrmed as the feature of the Ring
Focus optics. (The measurement of the receiving
performance for Ka band is not done yet.)
As a next step QRFH system was installed on theantenna, and the receiving performance was measured. Unfortunately only the sun was detectable,
and it was realized that the modiﬁcation of thecryogenic dewar would be necessary to improve theOctober 2015
sensitivity of QRFH. We have a plan to improve thecryogenic dewar by the end of March 2016.
Finally, Eleven feed system was installed on theantenna, and the receiving performance was measured by receiving the radio signals from somestrong radio stars (Cas-A, Taurus-A, Cygnus-A).
The SEFD values in the frequency range from 3 to
14 GHz are shown in Figure 3. The SEFD values
less than 9 GHz are acceptable (less than 2,000 Jy),but unfortunately the SEFD values more than 10
GHz are getting worse and reaching 7,500 Jy at 14GHz.
On the other hand, RFI is more serious than expected because of the feature of Ring Focus optics.
In the case of Ring Focus optics, the aperture efﬁciency is better but the artiﬁcial radio signal canreach the feed more easily than the usually-used
optics like Cassegrain. In the new station, the RFI
caused by the radio signal for cellular phone is sostrong in the frequency range less than 2.1 GHz
that the saturation of the ampliﬁers for S bandoccurs. In order to avoid the saturation of the S
band ampliﬁers some ﬁlters (High Pass Filter (cutless than 2.2 GHz), Notch Filter (cut 2.1 GHz),
and Band Pass Filter (pass 2.2-2.4 GHz)) are installed in the signal chain of the new antenna, andthe VLBI observation can be carried out normallyat present.

3

for Asia-Oceania region. Totally ten 24-h VLBI
sessions were observed at Ishioka station, and theprecise geodetic results were successfully obtained
for JADE sessions, which were analyzed by GSI
quickly. The results of baseline lengths between
Ishioka and Tsukuba 32-m antenna are listed in
the Table 3. The standard deviation for each session is the range 1–2 mm, which is reasonable for
Ishioka-Tsukuba baseline.
Table 3. Geodetic results of JADE sessions thatwere carried out at Ishioka station
Session
JD1502
JD1503
JD1504
JD1505JD1506
JD1507JD15086.

DateFeb. 19
Mar. 05
Mar. 12Apr. 23
May. 14
Jun. 04
Jun. 11Baseline Length
16,606,288.71 +- 1.58 mm
16,606,290.88 +- 1.04 mm
16,606,285.38 +- 1.39 mm
16,606,291.41 +- 1.31 mm
16,606,293.14 +- 1.50 mm
16,606,290.03 +- 1.27 mm
16,606,291.17 +- 1.34 mm

Summary

A new project for constructing a new antenna inJapan has started. The new station will be fullycompliant with the VLBI2010 concept. The construction of the antenna was completed by the endof March 2014. The measurement of the receiving
performance of the antenna was performed, andhigh aperture eﬃciency for X band was conﬁrmed.
First geodetic VLBI observation was carried out
in February 2015, and ten VLBI observations were
performed till June 2015. As a result, precise coordinates of the new antenna were obtained successfully.
This station will play an important role as a main
station in the Asian region instead of Tsukuba 32m station in the near future.

Figure 3. SEFD values of Ishioka VGOS antenna
7.
with Eleven feed

Acknowledgments

VLBI operation software that is developed by
National Aeronautics and Space Administration
5. First Geodetic Result(NASA) is employed at Ishioka station. InstallaFirst geodetic VLBI observation was carried out tion and customization of this software were perin February 2015 in the Japanese domestic net- formed by NICT under the joint research agreework including GSI’s VLBI stations (Tsukuba 32- ment between GSI and NICT.
m, Aira 10-m, and Chichijima 10-m antenna). Until the middle of June 2015 Ishioka station has participated in two types of VLBI sessions. One isJapanese domestic session JADE and the other is
AOV (Asia-Oceania VLBI group for Geodesy andAstrometry) session, which newly started in 2015

IVS NICT-TDC News No.35

4

On a Wide-Band
Bandwidth Synthesis II
Testuro Kondo (kondo@nict.go.jp)
and Kazuhiro Takefuji

1) deﬁne a reference scan in an observation session,2) do normal fringe search for each band in orderto obtain delay residual Δτn where n is a band
index and calculate cross spectrum after delay
residual is corrected,

Kashima Space Technology Center,
National Institute of Information
and Communications Technology,893-1 Hirai, Kashima, Ibaraki 314-8501, Japan3) phase characteristics of cross spectrum obtained by step 2) is approximated by a 4thorder polynomial for each band, and they become IPC.

1.

4) IDC is given by Δτn −Δτ1 , where Δτ1 is delay
residual at band #1.

Introduction

A technique to carry out the bandwidth synthesis of wideband observation data exceeding a band
width of 10 GHz has been developed. The technique excepting an ionospheric correction portion
has been implemented in the bandwidth synthesizing software “KOMB” [Kondo and Kunimori,
1984; Kondo et al., 1999]. The new KOMB has
been successfully applied to process actual wideband VLBI data obtained on a short baseline ofabout 50km where an ionospheric eﬀect can be neglected. As for the ionospheric correction, we havechecked whether it worked well or not by using
artiﬁcial correlation data simulating the eﬀect ofionosphere. We also got a good result for the ionospheric correction.
2.

Wide-band bandwidth synthesis(WBWS)

Two types of correction are considered in WBWS
software. One is inter-band delay correction thatis necessary to connect each band data in the frequency domain. System delay in a receiving system
is usually diﬀerent for each band. In order to connect diﬀerent bands it is necessary to correct thesystem delay. The other is inner-band phase correction that increases a signal to noise ratio. Ionospheric correction is a kind of this correction, but
it is handled separately and details are describedlater.
We have developed a realistic method to carryout the correction as follows. At ﬁrst, we choose ascan which observes a strong radio source and deﬁne it as a “reference scan”. Normal fringe searchis carried out for each band data of the reference
scan to obtain an observed delay for each band. We
obtain the inter-band delay correction data (IDC)by diﬀerentiating each observed delays. The innerband phase correction data (IPC) (may include theionospheric eﬀect at the reference scan) is obtained
from the cross spectrum of each band after delay
residual is corrected. The method is summarized
as follows,5) apply IDC and IPC obtained this way to raw
correlation data not only for the reference
scan but also for other scans, then carried out
WBWS.
The ionospheric eﬀect in the cross spectrum of thereference scan after the WBWS will not appear,
because it is compensated by the IPC that alreadyincludes the ionospheric eﬀect at the reference scan.
However relative ionospheric eﬀect can appear for ascan other than the reference scan. We can correct
this ionospheric eﬀect from the phase characteristics of cross spectrum as follows,1) get group delays as a function of frequency(these are observed group delays) by calculating average phase gradient against frequency
for each narrow frequency span from a crossspectrum after WBWS.
2) estimate Δτion and ΔT EC from the observed
group delays and a group delay model as follows:τg (f ) = −Δτion + αΔT ECf −2
where α is a constant.
3) estimate only φc from the cross spectrum after
WBWS and a phase model as follows:φ(f ) = −2πf Δτion − 2παΔT ECf −1 + φc
where Δτion and ΔT EC are ﬁxed to those estimated by step 2).
3.

Results of WBWSThe KOMB implemented with a WBWS function is applied to wide-band VLBI data observed on
the baseline between Kashima (NICT) station andIshioka (GSI) station (about 50km length) (Fig.1)
in January, 2015.
Fig.2 shows receiving frequency bands. Bands 1,
2, 3, and 4 are sampled by one sampler. Therefore

October 2015

5

ISHIOKA

48km
KASHIMATOKYO

Figure 1. Location of Kashima-Ishioka baseline.

bandwidth : 1024MHz/band

1 2 3 45
0

2

4

6

8

10

6
12

14

16 GHzdirect sampling

Figure 3. A cross spectrum after WBWS processing
for the reference scan (PRT (processing referencetime): 2015/031 07:16:50 UTC, source: 3C84, integration period: 60 sec).

Figure 2. Receiving frequency bands. Bands 1, 2,
3, and 4 are sampled by one sampler. Bands 5 and6 are sampled by diﬀerent samplers. Each band
width is 1024 MHz.

no system delay among bands appears, and we canassume these four bands as one single band spanning band 1 to 4. Bands 5 and 6 are sampled by
diﬀerent samplers.
Fig.3 shows a cross spectrum after WBWS processing for the reference scan. Note that phases arealigned in a line parallel to the frequency axis, andthis means that WBWS is carried out successfully.
We have processed other scans by using the correction (IDC and IPC) obtained for the reference
scan. Fig.4 shows an example of the results of otherscan data. As shown in the ﬁgure, WBWS is also
carried out successfully. As also shown in the ﬁgure, the ionospheric eﬀect in the phase spectrum
is not clear because of the shortness of a baseline
length.
4.

Evaluation of Ionospheric Correction

VLBI data observed on the Kashima-Ishioka
baseline is not adequate to evaluate the ionosphericcorrection, because the baseline length is too short.
Therefore VLBI data reﬂecting an ionospheric effect are generated from raw correlation data, andthen the ionospheric correction is evaluated. Correlation data simulating the ionospheric eﬀect being
Ri (τ, k), where τ and k are a lag index and a timeindex, are generated from raw correlation data

Figure 4.
An example of WBWS processing
for other scans (PRT (processing reference time):
2015/031 10:22:50 UTC, source: 0552+398, integration period: 60 sec).
R(τ, k) as follows.
1) get a cross spectrum S(f, k) by Fourier transforming R(τ, k) where f is a frequency index.
2) get a cross spectrum Si (f, k) aﬀected by ionospheric phase delay by calculating
Si (f, k) = S(f, k) exp[i{φion (f ) + σφ }]where φion (f ) is given byφion (f ) = −2παΔT ECf −1

IVS NICT-TDC News No.35

6and σφ is an additional phase noise to simulate
a low signal to noise ratio case.
3) get Ri (τ, k) by inverse Fourier transforming
Si (f, k).

Figure 6. Phase spectrum of phase model φ(f ) (upper panel) and residual phase (O − C) after modelﬁting (lower panel). Estimated ΔT EC and Δτion
are 100.4 TECU and 1.28 nsec, respectively.

Figure 5. An example of cross spectrum after
WBWS processing for simulated correlation data.
Raw correlation data are observed on Jan.16, 2015
and set ΔT EC = 100 TECU for the simulation ofionospheric eﬀect. Note that phase characteristics
aﬀected by the ionosphere can be seen.

Acknowledgement: A wide band VLBI experiment
was carried out with the cooperation of Geospatial
Information Authority of Japan (GSI). We would
like to thank GSI VLBI group for approving theuse of Ishioka 13m antenna for this technical development.

References
Fig.5 shows an example of cross spectrum after WBWS processing for simulated correlation Kondo, T. and H. Kunimori, III-5 bandwidth synthesizing software (KOMB), Rev. Radio Res. Lab.,data. In this case raw correlation data observed
Vol.30, No.1, pp.199–216, 1984 (in Japanese).
on Jan.16, 2015 are used to generate correlation
data aﬀected by the ionosphere and ΔT EC is set Kondo, T., M. Sekido, and H. Kiuchi, 3.2.3 KSP bandto 100 TECU (where TECU= 1 × 1016 /m2 ). No
width synthesizing software, J. Commun. Res. Lab.,
Vol.46, No.1, pp.67–76, 1999.
additional phase noise is added. Note that phasecharacteristics aﬀected by the ionosphere can beseen in the phase spectrum.
Fig.6 shows phase spectrum of phase model φ(f )(upper panel) and residual phase (O − C where O:
simulated data, C: model phase) (lower panel) after model ﬁtting. ΔT EC and Δτion are estimatedas 100.4 TECU and 1.28 nsec, respectively. As
shown in the result, ΔT EC used for generating
simulated data is well reproduced. As for Δτion , itis fed back to an observed delay residual.
5.

Conclusion

We have been developing the WBWS softwareand it has been almost completed. WBWS on the
short baseline shows good results. As for the ionospheric correction, the test using simulated data
demonstrates good results too. Actual evaluation
should be carried out by using true long base line
data such as an inter-continental baseline.

October 2015

7

Broadband VLBI Data Acquisition System for GALA-V

Mamoru Sekido (sekido@nict.go.jp)
Kazuhiro Takefuji, Masanori Tsutsumi, andTetsuro Kondo(1) (8) (2)(3) (4) (5) (6) (7)

(17)

(14)

NICT Space-Time Standards Laboratory,
Kashima Space Technology Center,893-1 Hirai, Kashima Ibaraki 314-8501, Japan
Abstract: This paper describes two sorts of VGOS
compatible broadband data acquisition systems(DASs) used in the GALA-V project. One is combination use of analog frequency converter and
ADS3000+ sampler. This system enables narrow frequency channel observation compatible withconventional geodetic mode and ’NASA Proof ofConcept’ system developed by MIT Haystack. Another one is ’Direct Sampling’ mode with highspeed sampler K6/GALAS. Four broad channelsof 1024 MHz width data are obtained at once byhigh speed sampling and its digital signal processing. Advantages of this method is not only simplicity but also stable phase relation among the broadchannels. This is quite important for wide-band
bandwidth synthesis for group delay derivation.

(13) (9) (11)(10) (12)

(15)

(16)

Figure 2. Outlook picture (top) and backside view
(bottom) of the ADS3000+ are displayed. Externalreference input of 10MHz(2),1PPS(1), and internal 10MHz(8) and 1PPS(13) are interfaced with
BNC. RF signal inputs (3,4,5,6) are connected by
SMA. Each of VSI-H output interface (9,10,11,12)
supports data rate up to 2048 Mbps (64 MHz clock
via 32 wires).
2.

VOGS PoC compatible observation and
DBBC sampler ADS3000+

Upper panel of Fig. 1 shows the case of combination use of analog frequency conversion and
ADS3000+ in the GALA-V project. ADS3000+
is upgraded version of multifunctional sampler
1. Introduction
ADS3000[4].
Figure 2 shows the outlook of
NICT is conducting development of VGOS ADS3000+. After analog frequency down convercompatible broadband VLBI observation system
for atomic frequency comparison project named
Table 1. ADS3000+ Sampler Parameters.
GALA-V[1]. This project uses a pair of transInput
portable small diameter antennas as the nodes for
Number of inputs
2frequency comparison. Signal to noise ratio (SNR)
Input Freq. Range
0.01-1.5 GHzof the VLBI observation with these nodes are enOutput
hanced by conjunction with joint observation of
128Msps :8 bitlarge diameter antenna and broad frequency range.
512Msps : 2, 4 bit
SingleBroad
This broad observation frequency range are de1024Msps: 2 bit
Channel Mode
signed to be compatible with VGOS system[2] for
2048Msps: 1 bit
joint observation with VGOS stations. Two kinds
No. of channels: 16of data acquisition systems (DASs) are used in theMulti Channel
Rate: 4,8,16,32,64 Msps
GALA-V project(Fig. 1). One is combination use
DBBC Mode
Bit: 1, 2, 4 bitof analog frequency conversion and digital baseMax data rate/port 4096 Mbps
band conversion (DBBC) sampler ADS3000+. An# output ports
4other one is using ’Direct Sampling’ method[3] byInterface port
VSI-H
using high speed sampler K6/GALAS.
Controltelnet /1000BaseTsion of RF signal to intermediate frequency (IF),IVS NICT-TDC News No.35

8

VSI-H
Frequency Converter
RF signal
PLO
PLO
PLO
PLO
RF signal

K5/PC-VSI

ADS3000+

K5/PC-VSI

ADS3000+

K5/PC-VSI
K5/PC-VSI

10Gbase-SR
K6/GALAS

K5/PC-VSI
K5/PC-VSI

Figure 1. Two sorts of data acquisition systems in the GALA-V project. Upper ﬁgure shows combinationof analog frequency conversion and IF sampling by using ADS3000+. Lower one is the case of ’Direct
Sampling’ by using high speed sampler K6/GALAS.
the IF signal below 1.5 GHz is fed into RF inputof ADS3000+. By using digital baseband conversion (DBBC) function of ADS3000+, conventional
multiple narrow channel data acquisition is carriedout. That is compatible mode with ’NASA Proofof Concept’ (PoC) VGOS system being developedby MIT/Haystack Observatory[5]. The ADS3000+
DBBC function extracts sixteen channels of speciﬁed frequency array. The bandwidth is chosen in
any of 4, 8, 16, or 32 MHz. Frequency array canbe speciﬁed by 1 Hz resolution. Upper side band(USB), lower side band (LSB), and complex data
are selectable for output. For the PoC system compatible observation, 2048 Mbps (=64 Msps × 16 ch
× 2bit) data acquisition is performed by single setof ADS3000+.
Basic observation mode GALA-V project is 1024
MHz width ’Broad Channel’ data acquisition. Twodata input ports of a ADS3000+ are used for capturing two IF signals in this case. Each of 2048
MHz sampling × 1 bit quantization data stream
are output from each of two VSI-H interfaces. Thus
the output can be recorded by any of the VSIH[6] compliant data input module(DOM). We uses
the K5/VSI systems for recording the VSI-H data
stream of ADS3000+. The K5/VSI system is composed of PC-VSI card and high data rate recoding
system with RAID disk drives[7]. Parameters to
represent performances of the ADS3000+ sampler
is summarized in Table 1.

Table 2. K6/GALAS Sampler Parameters.
Input
Number of inputs
Input Freq. Range
Output2
0.1 – 16.4 GHz

SingleBroad
Channel Mode

3200 Msps :1, 2 bit
6400 Msps : 1, 2 bit
12800 Msps: 1 bit

Multi Channel(DBBC) Mode

Nch: 1, 2, 3, 4Rate: 2048 Msps
Bit: 1, 2 bit

Max
data
rate/port# Output port
Output Interface
Data format
Control

8,192 Mbps
4
10GBASE-SR (SFP+)
VDIF/VTP over UDP/IP
telnet/1000BaseTK6/GALAS of 16,384 MHz sampling 3bit quantization. Then signal of 1024 MHz width at speciﬁed frequency band is extracted by DBBC function of the sampler. Frequency bands to be extracted is speciﬁed by 1kHz resolution, and one setof K6/GALAS outputs four data streams of 2048
Mbps (2048 Msps ×1 bit). Output data packets
formatted in the VDIF format[8] are transmitted
from 10GBASE-SR optical ﬁber network by the
VTP/UDP/IP protocol. Figure 3 indicates outlookof the direct sampler K6/GALAS. Output data
stream of the K6/GALAS is captured by a oﬀ-the2.1 Direct Sampler K6/GALAS
shelf computer set equipped with 10GBASE-SR inLower part of the ﬁgure 1 shows another way of terface and RAID-5 disk array system. Software
data acquisition named ’Direct Sampling’[3]. Ana- package for receiving and transmitting VDIF/VTP
log radio frequency (RF) signal up to 16 GHz is data stream has been developed by our group as
fed into two inputs of the sampler. Each of the sig- ’VDIF/VTP Software Suite’[9], and it is freely
nals are converted to digital data by using sampler

October 20159tional S/X and VGOS will be necessary in transition from conventional geodetic observation system
to the VGOS. It is important especially from view
point of stability of the global VLBI solution of terrestrial reference frame. Disadvantage of ’Multiple
Narrow Channel’ mode is complexity of signal synthesis of the many channels. It requires accurate
and stable Phase-calibration (P-CAL) system forcoherent synthesis of the signals in separate channels.
In case of ’Broad Channel’ mode, continuous
1024 MHz bandwidth signal is acquired in a single channel. P-CAL signal is not always necessary
for intra-band phase correction. Bandpass phasecharacteristic can be obtained by cross correlation
spectrum of strong radio source as a reference. If
we could assume the bandpass phase characteristic is stable, phase characteristics of observation
system is calibrated by using the reference crossspectrum.
Figure 3. Upper ﬁgure shows outlook of direct samRegarding on inter-band phase correction for copler K6/GALAS. Radio frequency analog signal is herent broad bandwidth synthesis, P-CAL should
converted to digital signal by 16,384 MHz sampling be necessary especially in case using multiple IF
3 bit quantization. Speciﬁed four 1-GHz bandwidth
samplers after analog frequency conversions. But it
signals (2048Msps × 1bit × 4 bands) are extracted
is not always the case of ’Direct Sampling’ method.
via digital baseband conversion function. The data
is output in the stream of VIDF/UDP packets from Because if signal in the whole frequency range is
10GBASE-SR interfaces. Lower ﬁgure shows back- digitized by single sampling, then inter-band phaseside view of the sampler. Sampling clock is selec- relation should be more stable than analog fretion by connecting one of clock outputs at (1) and quency conversion using phase-lock oscillators and(3) to clock input (2). 3.5mm connectors (4)-(5) mixers. If ’Direct Sampling’ system is stable, we
are RF singal inputs. External reference 10MHz can avoid using P-CAL signal for inter-band bandsignal and 1PPS are input from (9) and (6), re- width synthesis. Even in that case, P-CAL signal isspectively. Returning 1PPS (7) and internal 1PPS useful for monitoring the system stability. Advan(8) are also available. Four 10GBASE-SR inter- tage of ’Direct Sampling’ in the broadband bandfaces (10)-(11) are for data output and 100Base-T width synthesis is described in latter section andEther connector (12) is used for external control.
article by T.Kondo[10].
GALA-V project uses the ’Broad Channel’ ob1
available from a web page Table 2 shows the sam- servation as basic observation mode. Also ’Multiple Narrow Channel’ compatible observation modepling parameter of K6/GALAS.
is supported as a option for joint observation with
3. Discussion
VGOS station of ’PoC’ DAS. Table 3 summarizes
the observation modes of samplers of GALA-V
3.1 Broad Channel and Multiple Narrowproject and VGOS ’PoC’ compatible mode.
Channel Data Acquisition
There are advantages and drawbacks in each 3.2 Direct Sampling and Conventional
Analog Frequency Conversionof ’Broad Channel’ and ’Multiple Narrow Channel’ data acquisition. The important advantage
There are several advantages in ’Direct Samof ’Multiple Narrow Channel’ data acquisition ispling’ method especially for broadband delay obthe backward compatibility with the conventional
servation. The simplicity of the system is obvious
geodetic VLBI mode. Mixed observation of convenfrom Fig.1. Number of the components and analog
system for data acquisition is reduced. Not only
1 http://www2.nict.go.jp/aeri/sts/stmg/K5/
the simplicity, essential advantage of ’Direct samSoftware/VDIF SUDP/VDIF-SUDP-j.html

IVS NICT-TDC News No.35

10

Table 3. Observation modes of the Samplers in GALA-V project and VGOS compatible mode.
Samplers

ADS3000+
64Msps x 16 ch x 2bit
Total: 2048 Mbps

K6/GALAS

Broad Channel Mode

2048Msps x 2band x 1bit
Total: 4096 Mbps

Data Output

PC-VSI or any recorder with
VSI-H interface

2048 Msps x 4 band x 1 bit
Total: 8096 Mbps
10GBASE-SR interface,
VDIF/UDP or VDIF/VTP

Narrow Channel mode(’NASA PoC’ compatible)

N.A.

ΔF

rin

ge

te
Ra

[H

z]

Correlation Amplitude

is ideal way in future VLBI data acquisition, eventhough there is space for improvement in the limited level of quantization in current system.
This advantage might play a key role in derivation of broadband delay observable. Broad bandwidth synthesis to derive group delay requires coherent property of the correlation signal over broadfrequency range. Phase may potentially changeover broad frequency range due to characteristic of
microwave components and over time due to various reasons such as temperature, humidity, mechanical stress on the cables, and so on.
In case of conventional analog frequency converSearch Function (64 x 128) sion, each signal of 1 GHz frequency width passes
through independent analog components. Thus PCAL stability is quite important for coherent synthesis of broadband signal.
In case of ’Direct sampling’, since phase information is frozen at the sampling point overwhole frequency band, coherence degradation can
be avoided after sampling point in principle.
To demonstrate the advantage of ’Direct Sampling’, We have made a broadband VLBI experiment on Kashima 34m - Ishioka 13m[11] baseline
in Jan. 2015. Six 1 GHz bandwidth signals were acquired over 6 GHz – 14 GHz frequency range. Two
broad channels were acquired with single broadec] channel mode of ADS3000+, and other four broad
s
n
[
y
a
channels were captured with multi channel DBBC
ΔDel
mode of direct sampler K6/GALAS. Correlation
Figure 4. Cross Spectrum(Amplitude & Phase) of processing was made on the data of each bandbroadband VLBI observation between Kashima 34m by using software correlator GICO3[12], which was– Ishioka 13m on 30 Jan. 2015(upper panel), and originally developed by M.Kimura and updated by
Fringe of the broad bandwidth synthesis over 8 GHz K.Takefuji of NICT. Then correlation outputs were
bandwidth(lower pannel).
synthesized over the broad frequency range by upgraded bandwidth software “KOMB”[13, 10]. Figure 4 shows the cross spectrum and the fringe
pling’ method is that the RF signal properties ofobtained by this wide-band bandwidth synthesis
phase and amplitude in whole frequency range are(WBWS) over 8GHz width. Theoretical groupfrozen at the time of A/D conversion. Then digitaldelay precision expected from this 8 GHz width
ﬁltering and other signal processing are applied. It

October 2015
bandwidth synthesis reached to 27 femto seconds
in this experiment. This WBWS was successfully
achieved without using P-CAL signal but relying
on the phase stability of the acquisition system.
Please refer to papers[10, 13] for detailed procedureof the WBWS.
4.

Summary

Broadband data acquisition systems developed
for the GALA-V project were described in this paper. The advanced characteristic of ‘Direct Sampling’ method was discussed and demonstrated in
short baseline broadband VLBI observation between Kashima 34m and Ishioka 13m radio telescopes. Direct sampling has potentially great advantage for broadband VLBI observation. The validity of this method have to be examined by real
VLBI observations.
References

11[7] Kimura, M., J. Nakajima, “The implementation of the PC based Giga bit VLBI system”, IVS NICT-TDC News. Vol. 21, pp.3133, 2002.
[8] Whitney, A., M. Kettenis, C. Phillips, and
M. Sekido, “VLBI Data Interchange Format(VDIF)”, Proceedings of IVS 2010 Gleral
Meeting “VLBI2010: From Vision to Reality”
Edited by Dirk Behrend and Karen D. Baver
NASA/CP-2010-215864, pp.192-196., 2010.
[9] Sekido, M., et al., “Development of an eVLBI Data Transport Software Suite with
VDIF”, Proceedings of IVS 2010 General
Meeting “VLBI2010: From Vision to Reality”
Edited by Dirk Behrend and Karen D. Baver
NASA/CP-2010-215864, pp.410-414., 2010[10] Kondo, T., and K. Takefuji, “On a Wide-Band
Bndwidth Synthesis II” IVS NICT-TDC News
No.35, pp.23-27, 2015.

[1] Sekido, M., et al., “Development of Wideband VLBI system (Gala-V)”, proceedings [11] Fukuzaki, Y., et al., “Receiving Performanceof Ishioka VGOS Antenna”, IVS NICT-TDC
of IVS 2014 General Meeting ”VGOS: The
News, No.34, pp.8-10, 2014.
New VLBI Network” Edited by Dirk Behrend,
Karen D. Baver, and Kyla L. Armstrong Sci[12] M.Kimura, ”Development” of the software
ence Press (Beijing) ISBN 978-7-03-042974-2,
correlator for the VERA system II”, IVS
pp.77-81, 2014
NICT-TDC News. No.28, pp.22-25, 2007.
[2] Petrachenko, B., et al., “Design Aspect of[13] Kondo, T., and K. Takefuji, “On a Wide-Band
the VLBI2010 System: Progress Report of
Bndwidth Synthesis” IVS NICT-TDC News
the VLBI2010 Committee”, NASA/TM-2009No.34, pp.23-27, 2014.
214180, 2009.
[3] Takefuji, K., et al., ”High-order Sampling
Techniques of Aliased Signals for Very Long
Baseline Interferometry”, PASP, Vol.124,
pp.1105-1112, 2012.
[4] Takeuchi, H., et al., ”Development of a 4 Gbps
Multifunctional Very Long Baseline Interferometry Data Acquisition System”, PASP, Vol.
118, pp.1739-1748, 2006.
[5] Niell,A., et al., “VGOS Operations andGeodetic Results”, Proceedings of IVS 2014
General Meeting ”VGOS: The New VLBI Network” Edited by Dirk Behrend, Karen D.
Baver, and Kyla L. Armstrong Science Press(Beijing) ISBN 978-7-03-042974-2, pp.97-101,
2014[6] Whitney, A., “VLBI Standard Hardware Interface Speciﬁcation -VSI-H”, http://vlbi.
org/vsi/, 2000.

IVS NICT-TDC News No.35

12Development of
Wideband Feedby 2.4m cassegrain optics with NINJA feed. Distortion of the dish and whole structure was estimated with COMSOL, not to grow its weight too
much. The mass of new optics will be twice of current systems.

Hideki Ujihara (ujihara@nict.go.jp),
Kazuhiro Takefuji and Mamoru Sekido
Kashima Space Technology Center,
National Institute of Information
and Communications Technology,893-1 Hirai, Kashima, Ibaraki 314-8501, Japan
1.

Status of development

New wideband feed has been installed in 34m antenna in this summer. The name of this new feed
is NINJA feed, because of ﬂexibility in its beamwidth. It was designed for 3.2-14.4GHz and was
mounted nearby the prototype of IGUANA Daugh- Figure 2.
ter feed which is for higher frequency, 6.5-15GHz. New feed with WRD350D24-SMA output.
(Fig.1).

Figure 1.NINJA Feed for kashima 34m antenna

The NINJA feed is a type of lensed horn (Fig.1),
which was arranged from a wideband feed for center parabola focus of MARBLE. Two lenses makethe beam width narrower to ﬁt cassegrain focusof 34m antenna Now this feed has been mountedwith WRD350D36 waveguide-SMA converter for
only single linear polarization. Its return loss isshown in (Fig.3).
However, newly developed SMA converter fordual polarization will replace it. Simulation models of the converter have still some resonances(Fig.4),(Fig.5), however they will be removed infew month.
Also, the optics of MARBLE, small VLBI stations with 1.5m and 1.6m dishes, will be replaced

Figure 3.
Return loss of New feed with WRD350D36-SMA
output.

2.

Plans

Complete IGUANA feed is still delayed due to
production schedule of its complexed waveguides
and structure. However, in 34m antenna, we canuse 6.5-15GHz with the prototype daughter feedand NINJA feed for 3.2-14.4GHz.
Dual polarization output will be installed in 2015
for replacement of single-pol output and a DWDM
RF over Fiber-link system for dual-pol will be set
in 34m antenna.

October 2015

13

S-Parameter [dB]

COMSOL 5.1.0.180

Frequency [GHz]
Figure 4. S-paramters with port 0 input

S-Parameter [dB]

COMSOL 5.1.0.180

Frequency [GHz]
Figure 5. S-parameters with port 1 input

IVS NICT-TDC News No.35

14

FRINGE PHASE (deg) CH#:1

180

90
PHASE (deg)

Report on the Test Observation of Hitachi-Takahagi Interferometer

0

-90

-180

Tetsuro Kondo, Mamoru Sekido
NICT, 893-1 Hirai, Kashima, Ibaraki, Japan

0

200

400

FRINGE AMP
600 CH#:1
PP#

800

1000

1200

0

200

400

600
PP#

800

1000

1200

0.09
0.08
0.07
AMPLITUDE

Rinichi Kako, Munetake Momose,
Yoshinori Yonekura, Koichiro Sugiyama
Ibaraki Univ., 2-1-1 Bunkyo, Mito, Ibaraki, Japan

0.06
0.05
0.04
0.03
0.02
0.01
0

Abstract: Hitachi-Takahagi interferometer is being Figure 1. The result of observation of 3C273B. Upstarted up since 2013. This system will enable to per diagram shows fringe phase, and lower shows
make long-term monitoring observation of continu- amplitude. Phase and amplitude vary sinusoidally.
ous wave objects. Last year, correlator which connects each station by optical ﬁber cables and correlates in real time, has been introduced. Then, we
started evaluation of this correlator and K5/VSSP
system.
FRINGE PHASE (deg) CH#:1

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PHASE (deg)

90

0

-90

1.

-180

Introduction

0

200

400

FRINGE AMP
600 CH#:1
PP#

800

1000

1200

Hitachi and Takahagi antenna have been used
for Japanese VLBI Network or single dish observation. Table 1 is the location of these antennas.[1]Now, two interferometric systems have been introduced. One is the K5/VSSP system, composed of
K5/VSSP32 sampler and correlation software. The
Figure 2. Fringe phase and amplitude by the obserother is the hardware correlator, correlate in realvation with the conﬁguration that LO of Takahagi
time.
is 10 kHz lower than that of Hitachi.
0.08

AMPLITUDE

0.07
0.06
0.05
0.04
0.03
0.02
0.01
0

0

2.

Test Observations and Results for the
K5/VSSP System

200

400

600
PP#

800

1000

1200

and narrow ones, and phase line was split into two
components, which are separated 180 degree each
In Aug. 14, 2013, we made observations ofother. This problem was caused by the relation
3C273B by interferometer of K5/VSSP system.
between FFT points and the lag window. Now
Speciﬁcation of observations is shown in Table 2.
K5/VSSP system’s correlation software has been
Figure 1 shows correlative phase and amplitude,
updated, adding option for line spectrum, and thisindicating that these changed sinusoidally. Typiproblem has been solved.
cal period of this sinusoidal change is 1-2 second,and it varies every hour, in other words, it depends 3. Test Observations and Results for Hardon source position. It is conceivable that sinuware Correlator
soidal ﬂuctuation is caused by fringe residual error.
Hardware correlator has been introduced inBase line length of this interferometer is very short,2014,
and the ﬁrst light was achieved in Mar. 3,
about 260 m, and fringe rate is about 0.5 Hz. So
2015(Figure4). Then, we ﬁnd that intense noise
we made observations with the conﬁguration that
the LO of Takahagi is 10 kHz lower than that of Hi- at IF frequency of ∼560 MHz contaminates andtachi. Figure 2 shows the result of this experiment breaks correlation, and fringe phase change every
indicating that sinusoidal ﬂuctuation has been av- moment. We found that the cause of the noise isan inﬂuence of artiﬁcial radio wave for ∼6530-6570
eraged.
Figure 3 shows the result of the observation of MHz. The Hitachi and Takahagi antenna use 1st
methanol maser 188.9+08. It shows that ampli- LO of 6088 MHz and convert 6600-7112 MHz totude line was divided into two components, broad 512-1024 MHz. However, the passband of the band

October 201515

Table 1. Antenna location[1]X [km]
Y [km]
Z [km]-3961.788796 +3243.597525 +3790.597709-3961.881647 +3243.372513 +3790.687466
Base line length: 259.438 m

HitachiTakahagi

SourceDate
Band
Sampling rate

Table 2. Speciﬁcation of K5/VSSP system observations
3C273B
3C273B
188.9+08
2013/8/14 (226)2015/1/8 (008)2015/1/13 (013)
8448 - 8480 MHz
8448 - 8480 MHz
6664 - 6696 MHz···
Takahagi LO is 10 kHz lower than Hitachi···
64 MHz64 MHz64 MHz

VIDEO CROSS SPECTRUM PHASE CH#:1

180

PHASE (deg)

90

0

-90

-180
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-20

-30

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VIDEO
POWER CH#:1-10 CROSS SPECTRUM
010FREQUENCY (MHz)

20

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20

30

-10
-20
POWER (dB)

-30
-40
-50
-60
-70
-80
-90
-10

0
FREQUENCY (MHz)10

Figure 3. The result of observation methanol maser
188.9+08. Phase splits in two, and amplitude overlaps.
pass ﬁlter was 300-1100 MHz, resulting that theleakage of the noise at ∼6530-6570 MHz into the
IF frequency of ∼442-482 MHz. This contaminates
the correlated results at ∼542-582 MHz, since thesampling rate was 1 GHz and no digital ﬁlter wasused. Now, new band pass ﬁlter with the passbandof 550-950 MHz has been introduced, and problemof the noise contamination was cleared.
Fringe rotation was caused by the ﬁrmware defect. Updated ﬁrmware has been installed, and thisproblem is resolved.
4.

Summary

Figure 4. Hardware correlator ﬁrst light. Redline shows amplitude, and green line shows fringe
phase. It shows that noise arises at IF frequencyof ∼560 MHz.
adding option to the correlation software. For
hardware correlator, intense noise and fringe phaserotation occurred. Noise was ﬁltered out by the
new band pass ﬁlter. Fringe rotation was caused
by a ﬁrmware bug. Now, this bug was ﬁxed.
Acknowledgment

Test observations for K5/VSSP system andWe are grateful to NICT for the use of correlation
hardware correlator have been done from 2013. software.
For K5/VSSP system, problems that amplitude
and phase vary sinusoidally and split for line spec- References
trum occurred. Varying would not be the eﬀect[1] Yonekura, Y., Present Status of Ibaraki staof K5/VSSP system because its period is 1-2 section (Takahagi and Hitachi 32m Radio Teleond and was solved by using diﬀerent LO frequency
scopes), IVS NICT-TDC News No.33, 6-7,
for two antennas. Splitting has been solved by
2013.

IVS NICT-TDC News No.35

16

Observation of Jupiter’s Syn- deep inner magnetosphere. The Tohoku University
chrotron Radiation in the Mag- group has started regular JSR observations since
1990’s and revealed that JSR has short term varinetospheric Variation Period : ations with the time scale of several days [1] andsuch the short term variations are general in sevPreliminary Results
Hiroaki Misawa1(misawa@pparc.gp.tohoku.ac.jp),
F. Tsuchiya1 , S. Satoh1 , H. Kita1 ,M. Sekido2 , K. Takefuji2 , E. Kawaii2 ,T. Kondo2 and S. Hasegawa2
1

Planetary Plasma and Atmospheric ResearchCenter, Tohoku University,
6-3 Aoba, Aramaki, Aoba-ku, Sendai Miyagi,
Japan
2
NICT Space-Time Standards Laboratory,
Kashima Space Technology Center,893-1 Hirai, Kashima Ibaraki, Japan

Abstract: Rapid variation of relativistic electronsin Jupiter’s radiation has been inferred with thetime scale of a day or less from the observation of
Jupiter’s synchrotron radiation (JSR) at 327MHz.
The Galileo Jupiter orbiter data showed this rapid
variation has some relation with the magnetic reconﬁguration events (MRE) in the outer magnetosphere, however, the causality of the rapid variation of JSR and MRE have not been known yet.
One plausible causality for MRE is proposed to beenhancement of mass loading originally brought byenhancement of plasma originated from Io. In the
middle of Jan. to May, 2015, obvious Io plasma
enhancement has been identiﬁed by earth-based
optical observations. This phenomena gives us
a good opportunity to directly conﬁrm the relation between the occurrence of rapid variation of
Jupiter’s radiation belt and enhancement of the
Iogenic plasma. We have made a quasi regular
JSR observation at 2.3GHz for about three weeks
in March, 2015. We report a preliminary result of
this JSR observation.
1.

Introduction

It is known that Jupiter has a radiation belt ﬁlledwith relativistic particles like the Earth, though theﬂux and energy of the particles are much larger.
The relativistic particles are trapped by Jupiter’s
intense magnetic ﬁeld and emanate synchrotron radiation. Thus the radio emission (hereafter we callit JSR) has information on dynamics of Jupiter’seral hundreds MHz [2,3]. The characteristic timescale of several days has not been explained by previous understandings for Jupiter’s radiation belt
particles; i.e., the characteristic time scale of representative source process is about two years forthe case of radial diﬀusion of energetic electrons [4]and that of loss process is more than 10 days as
the shortest case for the interaction with Jupiter’s
moons [5]. To interpret this problem, Miyoshi et al.
(1999) [1], Bhardwaj et al. (2009) [6] and Tsuchiya
et al. (2011) [3] showed that the time scale meetswith the enhanced radial diﬀusion for the relativistic particles caused by the solar UV/EUV heating
to Jupiter’s upper atmosphere as originally proposed by Brice and McDonough (1973) [7]. And
Kita et al. (2015) showed that a short term JSR
variation occurred in sync with temperature enhancement of Jupiter’s upper atmosphere during
the solar UV/EUV increasing phase [8].
On the other hand, JSR sometimes shows more
rapid ﬂux variations (RFV) by more than several
tens % whose characteristic time scale is a day
or less. It is quite diﬃcult to explain its physical processes by present theories even though theenhanced radial diﬀusion mentioned above. From
the JSR observation at 327MHz for the period of
the Galileo Jupiter orbiter exploration, Misawa etal. (2013) suggested that some RFV events occurred in sync with the magnetic reconﬁguration
event (MRE) [9] which is a global magnetosphericreccurent disturbance with the repetition period of2∼6 days [10,11,12]. Although a driving force of
MRE has been not understood well, enhancementof plasma mass loading originally brought by enhancement of Iogenic valcanic gases is proposed asa plausible candidate [13]. So far there has been
no observational evidence showing reliable relationship between occurrence of RFV and enhancementof plasma mass loading phenomena.
In the middle of Jan. to April, 2015, remarkable Iogenic gas and plasma enhancements havebeen identiﬁed by a ground-based optical observation [14] and the Hisaki space telescope satellite[EXCEED/Hisaki Science team, private communication]. This phenomena gives us a good opportunity to directly conﬁrm the relation between theoccurrence of RFV and Iogenic plasma. We have

October 2015

Observation

The observation of JSR had been made using the
Kashima 34-m radio telescope at S-band from Mar.
4 to 24, 2015 everyday except 8 to 12 and 21. Our
research group has made JSR observations several
times using this system since 1997 [1]. In these previous observations, we have utilized a power meterto derive the total ﬂux for the wide IF band. However, we utilized a spectrum analyzer in this timeto avoid RFI aﬀecting estimation of the total ﬂux
of JSR whose usual ﬂux density is several Jy. We
sampled the IF band (∼190 MHz) with the resolution bandwidth of 1MHz every 2 sec. An exampleof the sampled spectrum for an hour is shown in
Figure 1.
In the observation of JSR, we made the drift scan
for Jupiter repeatedly every 6.5 minutes and madecalibration of system gain and receiver noise temperature before and after each drift scan by the
Y-factor method. We also inserted observations forradio ﬂux density calibrators such as 3C123, 3C161
and 3C218, and sky-tipping for the azimuthal direction of the radio ﬂux density calibrators andJupiter roughly every 1 hour. The JSR observation had been made for about 9 hours everyday
for the elevation of Jupiter more than roughly 30
degrees.
3.

Data Analysis

In the data analysis, ﬁrstly RFIs are eliminatedfrom the raw spectrum; i.e., wide band RFIs are
eliminated by visual inspection and narrow band
RFIs are eliminated by a median ﬁltering methodwith the bandwidth of 5 MHz. An example of thetotal ﬂux observation for a radio source (3C123)
using this method is shown in Figure 2, where theblue line is the averaged power for the full IF bandand the red line is that for the RFI eliminated IF
band. In the ﬁgure, some power oﬀset is added to
the red line so that the eﬀect of the RFI elimination can be seen easily. Secondly, received powerof Jupiter’s radio emission was derived from eachdrift scan data using the Gaussian ﬁtting method.
Thirdly, the gain of the received power level was-65Power [dBm]

2.

-60

-70

-75

-80

-85
650

700

750
800
Frequency [MHz]

850

900

Figure 1. Example of the observed spectra sampled
every 2sec and overlaid for an hour. The data weretaken in the evening of Mar. 4, 2015 when theradio telescope was pointed to the east southeast at
an elevation angle of 40–70 degrees.
calibrated using the result of the Y-factor method.
Fourthly, the calibrated power level should be compensated using the atmospheric extinction factor
derived by the sky-tipping (at present unexecuted).
Fifthly, absolute radio ﬂux was estimated by comparison with radio ﬂux calibrators. Sixthly, theradio ﬂux was standardized to that at a distance of
4.04 AU which is the generally used mean closest
distance between the earth and Jupiter. Finally
JSR ﬂux was derived by reducing the radio ﬂux ofthe thermal component of Jupiter at S-band; i.e.,
2.02 Jy at 4.04AU [15].
Average Power [dBm]made a quasi regular JSR observation at 2.3GHz
for about three weeks in March, 2015. In this paper, we report a preliminary result of the JSR observation with brief explanation of the newly developed spectrum analysis for reducing inﬂuence of
RFI (Radio Frequency Interference).

17

Time [sec]Figure 2. Example of the total ﬂux observation for
the radio galaxy 3C123 at S-band using a spectrum
analyzer connected to the IF output of the Kashima
34-m radio telescope. The blue line is the averaged
power for the full IF band and the red line is thatfor the RFI eliminated one.

4.

Results and Discussions

The result of derived JSR ﬂux is shown in the
top panel of Figure 3. Each JSR ﬂux was estimated as an averaged value between the radio ﬂux

IVS NICT-TDC News No.35

18

calibrations; i.e., roughly every one hour. The error bars were estimated as the standard deviations
for the JSR ﬂux values. It is well known that the
total JSR ﬂux shows apparent periodic variationin sync with Jupiter’s rotation by about 10% [16],and the apparent variation should be compensatedto determine actual total JSR ﬂux [see 1,17]. However, at present the compensation has not been performed, and simple averaged ﬂux values are plottedin the ﬁgure. In the bottom panel of Figure 3 thedaily solar 10.7cm radio ﬂux (F10.7) expected at
Jupiter is shown, where solar F10.7 is known as agood proxy of solar UV/EUV ﬂux. From Figure 3,
it is shown that there were some short term variations by roughly more than 20% of the normal
ﬂux level and the variations has little correlation
with those of F10.7: The F10.7 variations showed
gradual decrease and increase especially after Mar.
9, while the JSR ﬂux variations showed bumpy nature with the time scale of roughly a few days. This
result implies that the variations were not apparent ones with Jupiter’s rotation, but actual ones
driven by some processes possibly faster than thesolar UV/EUV heating eﬀect.

one is driven by some internal plasma circulation
processes [19]. Kimura et al. (2015) suggested thatthe characteristic duration time of auroral intensity
variations is diﬀerent for these two auroras; that of
the externally driven type is a few days, while thatof the internally driven type is roughly less thana half day (∼ one Jupiter’s rotation period) [19].
In the JSR observation period in March, 2015, theduration time of almost all transient auroras is lessthan a half day and the transient auroras occurred
quasi periodically at an interval of 2-4 days, which
is nearly the same time scale as the previously observed MRE [10,11,12]. These observation results
strongly suggest that some internal plasma circulation processes dominantly occurred during the JSR
observation period, though variations of solar windcompressions on Jupiter occurred several times inthe same period (courtesy of C. Tao).
Due to unevaluation of atmospheric extinction
and apparent variation by Jupiter’s rotation, conﬁrmation of occurrence of RFV during the remarkable gas and plasma enhancement period and alsothat of correspondence between the quasi periodic
auroral variations and JSR ﬂux variations are deferred for future analyses. However the observed
distinctive auroral features (probably) related to
the Iogenic gas and plasma enhancement much encourage our expectancy for revealing how deep the
MRE aﬀects the inner magnetosphere.
5.

Figure 3. Result of the JSR ﬂux observations at
S-band (top panel) and solar 10.7cm radio ﬂux expected at Jupiter (bottom panel) in Mar., 2015.
There was no JSR ﬂux observation for Mar. 8- 12 and 21 due to the other experiments on the
Kashima system.

Acknowledgments

We express our sincere thanks for all staﬀs of
NICT Space-Time Measurement Group, Kashima
Space Technology Center for their assistance on
the JSR observation. We also acknowledge NASA/
GSFC’s Space Physics Data Facility’s OMNIWeb
service for the use of solar 10.7cm radio ﬂux data.
This work was carried out by the joint research program of the Solar-Terrestrial Environment Laboratory (the Institute for Space-Earth Environmental
Research after Oct. 2015), Nagoya University.

As mentioned in Introduction, remarkable Iogenic gas and plasma enhancements have been References
identiﬁed in the middle of Jan. to April, 2015 [14[1] Miyoshi, Y. et al., Observation of short‐term
and Tsuchiya et al., private communication]. Durvariation of Jupiter’s synchrotron radiation,
ing this period, the Hisaki observation also revealed
Geophys. Res. Lett., Vol.26, pp.9–12, 1999.
that Jupiter’s auroral intensity showed some transient variations [EXCEED/Hisaki Science team, [2] Misawa, H., and A. Morioka, Observations ofprivate communication]. It is known that Jupiter’s
Jovian decimetric radiation at a frequency oftransient aurora variations are brought by two dif327 MHz, Adv. Space Res., Vol.26, pp.1537–
ferent processes; i.e., one is externally triggered by
1540, 2000.
compression by solar wind [e.g. 18] and anotherOctober 201519

[3] Tsuchiya, F. et al., Short-term changes in [11] Louarn, P. et al., A study of the large-scale
Jupiter’s synchrotron radiation at 325 MHz:
dynamics of the Jovian magnetosphere using
Enhanced radial diﬀusion in Jupiter’s radithe Galileo plasma wave experiment, Geophys.
ation belt driven by solar UV/EUV heatRes. Lett., Vol.25, pp.2905–2908, 1998.
ing, J. Geophys. Res., Vol.116, doi:10.1029/[12] Krupp, N. et al., Energetic particle bursts
2010JA016303, 2011.
in the predawn Jovian magnetotail, Geophys.
[4] de Pater, I., and C. K. Goertz, Radial diﬀusion
Res. Lett., Vol.25, pp.1249–1252, 1998.
models of energetic electrons and Jupiter’s
synchrotron radiation: 2. Time variability, J. [13] Kronberg, E. A. et al., A possible intrinsic
mechanism for the quasi-periodic dynamics ofGeophys. Res., Vol.99, pp.2271–2287, 1994.
the Jovian magnetosphere, J. Geophys. Res.,[5] Santos-Costa, D., and S. A. Bourdarie, ModVol.112, doi: 10.1029/2006JA011994, 2007.
eling the inner Jovian electron radiation belt
[14] Yoneda, M. et al., Brightening event seen
including non‐equatorial particles, Planet.
in observations of Jupiter’s extended sodium
Space Sci., Vol.49, pp.303–312, 2001.
nebula, Icarus, Vol.261, pp.31-33, 2015.
[6] Bhardwaj, A. et al., GMRT observation of[15] Klein, M. J. et al., Changes in Jupiter’s 13Jupiter s synchrotron radio emission at 610
cm synchrotron radio emission following theMHz, in The Low‐Frequency Radio Universe,
impact of comet Shoemaker-Levy-9, Geophys.
edited by D. J. Aaikia et al., Astron. Soc. Pac.
Res. Lett., Vol.22, pp. 1797-1800, 1995.
Conf. Ser., Vol.407, pp.369–372, 2009.
[7] Brice, N. M., and T. R. McDonough, Jupiter’sradiation belts, Icarus, Vol.18, pp.206–219,
1973.

[16] de Pater, I., 21 cm maps of Jupiter’s radiation belts from all rotational aspects, Astron.
Astrophys., Vol.88, pp. 175–183, 1980.

[8] Kita, H. et al., Relation between the short- [17] Kita, H. et al., Eﬀect of solar UV/EUV heating on the intensity and spatial distribution ofterm variation of the Jovian radiation belt and
Jupiter’s synchrotron radiation, J. Geophys.
thermosphere derived from radio and infraredRes., Vol.118, doi:10.1002/jgra.50568, 2013.
observations, J. Geophys. Res., in printing.
[9] Misawa, H., and T. Mizuguchi, Short-term [18] Clarke, J. T. et al., Response of Jupiter’sand Saturn’s auroral activity to the solar
variation phenomena in Jupiter’s radiation
wind, J. Geophys. Res., Vol.114, doi:10.1029/
belt: Their relation with the magnetospheric
2008JA013694, 2009.
events, Proc. Symp. Planet. Science 2013,
SPS2013-57, 2013.
[19] Kimura, T. et al., Transient internally driven
aurora at Jupiter discovered by Hisaki and[10] Woch, J. et al., Quasi-periodic modulations of
the Hubble Space Telescope, J. Geophys. Res.,
the Jovian magnetotail, Geophys. Res. Lett.,
Vol.42, doi:10.1002/2015GL063272, 2015.
Vol.25, pp.1253–1256, 1998.

IVS NICT-TDC News No.35

20

A
Proposal
Constructing
mm/sub-mm VLBI Network
by Japanese/East-Asian Power

Makoto Miyoshi (makoto.miyoshi@nao.ac.jp),
T. Kasuga (Hosei Univ.), M. Tsuboi(ISAS), M. Takahashi (Aichi Univ. Edu.),T. Oka, S. Takekawa (Keio Univ.), N.
Takato (NAOJ), H. Ujihara (NICT), H.
Ishitsuka, V. Erick (IGP, Peru), & the
CARAVAN teamNational Astronomical Observatory, Japan,
2-21-1, Osawa, Mitaka, Tokyo, Japan 181-8588

Figure 1. Image of black hole shadow calculated by
R. Takahashi (2005). The black hole shadow size
Abstract: We report here the recent progressin SgrA∗ is about 50μasec in diameter.
in CARAVAN-submm and note that a global
mm/sub-mm VLBI network can be constructedby collaborations with astronomical institutions inEast Asia. East Asia has a potential power promoting next black hole imaging observations.
1.

Imaging black holes and CARAVANsubmm

Imaging surroundings of black holes are fascinating observations that mm/sub-mm VLBI canachieve in very near future. For the purpose, Japan
has a dedicated plan, ”CARAVAN-submm”, which
is a project constructing a mm/sub-mm VLBI network at Andes. It contains at least two ﬁxed VLBI
stations and one mobile VLBI station, which isa famous method in Japanese geodetic VLBI experiments since mid in the 1980s (Ichikawa et al.,2009). Using the same method we sample visibility data from shorter baselines around 1000 ∼2000 km at 230GHz eﬀectively and attain higher
quality images at submm VLBI observations thanthose only ﬁxed stations can do. By observing
SgrA∗ , a super massive black hole at our galactic center, we aim imaging observations of the surroundings of the black hole horizon, and pave theway for observing veriﬁcation of the general relativity and open observational black hole astrophysics(Miyoshi et al., 2011) 1 . Next following sections,
we report recent progress of CARAVAN-submm.

Figure 2. CARAVAN-submm at Andes. The
mobile radio telescope CARAVAN-submm moves
around Andes. By changing positions of observations, we can obtain VLBI data from various baseline lengths and directions. In the data the nullpoint should be contained, which is the strong evidence of the existence of a black hole horizon in
the image. We plan to use multi mirror system formaking a light weighted telescope. The CARAVANsubmm will contain at least three of trucks. One forantennas, another for mount, and the other is forelectric power-supply and VLBI recording systemand hydrogen maser. Though we suppose power
supply for operating telescope is commercial base.
2. Observing Site Survey at Andes 2015
The Peruvian and Bolivian Andes are the civilized
We plan to construct the ﬁxed stations at around regions. There are many cities and towns. ComHuancayo Observatory (3370 m in altitude), IGP
mercial based electric power supply is easily obin Peru and at the Chacaltaya Cosmic Ray Observatory (5300 m in altitude) in Bolivia. We per- tained. Also the main roads are developed along
formed new site survey both in Peru and Bolivia for the Andes, therefore the movement of CARAVANinvestigating the precipitable water vapor amounts submm telescope is quite easily preformed.
in 2015. By the infrared water vapor meter used

1 CARAVAN-submm was openly discussed as one of middle class projects in the Astronomy and Astrophysics subcommittee of Science Council of Japan (SCJ) in 2012.

at our previous survey in 2012, we found the precipitable water vapor amounts in the rainy reason

October 2015

21

Figure 3. PWV v.s. Altitude along the road from
Lima to Huancayo in Peru (2015.2.27). The threecolor lines show PWVs measured from diﬀerent absorption lines of water vapor.
Figure 4. Surface accuracy about 15μm r.m.s. wasachieved using a new 30 cm mold (surface accu(February to March in 2015) were worse at least racy: 4μm r.m.s.) by metal spinning method with
two times as compared with those in dry seasons. adding a annealing process.
This means that the best seasons for mm/sub-mm
VLBI observations are limited even in Andes higher chance to construct a global sub-mm VLBI array
mountains.
by East Asian power. East Asia can be the next
3.

Cost reduction of high precision antennas

leading force in the black hole imagings.

In order to realize the cost reduction in making
high precision antennas for receiving millimeter to
sub-millimeter wavelength, we have examined theaccuracy of the palabra surfaces made by metal
spinning method, and found that an accuracy aswell as 60μm r.m.s. is easily obtained (Miyoshi
et al. 2013). Recently we conﬁrmed that surface accuracies about 15μm r.m.s. were achievedby adding an annealing process between spinning
process. Now we have hopeful outlooks that cost
reduced mm/sub-mm antennas as large as 2 m indiameter can be produced by using metal spinning
method.
Figure 5.
JCMT 15 m at Hawaii
http://www.eaobservatory.org/jcmt/
4. A Proposal Constructing mm/sub-mm
VLBI Network by Japanese/East-Asian
Power
References
Astronomical institutions in East Asia have own [1] Miyoshi, M. et al., ,in Proceedings of the 12th
good mm/sub-mm radio telescopes, namely JCMTNICT TDC Symposium (Kashima, June 6,
15m (EAO), ASTE 10m (NAOJ), SPART 10m
2013) , Technical Development Center News,(Osaka Perf.,& NRO,NAOJ), GLT 12m (ASIAA),
NICT, ISSN 1832-3432, 33, 15-17, (2013)
and three of 20m radio telescopes in KVN. Also
[2] Miyoshi, M. et al., A First Black Hole ImNobeyama 45m telescope (NRO,NAOJ) can beager, CARAVAN-sub at Andes, 2011ASPC,4
used for mm/sub-mm VLBI. Adding with a fu39, 279M (2011)
ture plan CARAVAN-submm at Andes, astronomical institutions in East Asia have a potential power[3] Ichikawa, R., A. et al., IVS NICT-TDC News
promoting global mm/sub-mm VLBI observations
No.30, (2009)
if they collaborate each other. East Asia has a long
history of the black hole study, related future plans, [4] Takahashi, R., PASJ, 57,273-277, (2005).
and powerful observing instruments. We have a

IVS NICT-TDC News No.35

22First Japanese 230 GHz VLBI
experiment by MICE2015 teamKazuhiro Takefuji (takefuji@nict.go.jp)1 on
behalf of MICE2015 team1

Kashima Space Technology Center, National
Institute of Information and Communications
Technology, 893-1 Hirai, Kashima, Ibaraki
314-8501, Japan
Abstract: We carried out a 230GHz VLBI experiment on 200 m baseline between Solar Planetary
Atmosphere Research Telescope(SPART) 10m and1.85m telescopes in Nobeyama Radio Observatory(NRO) in the end of April 2015. The project namewas so-called, MICE2015 (Mm Interferometer Collaboration Experiment 2015, PI: Prof. Fujisawa of
Yamaguchi university). We installed VLBI equipment (e.g A/D sampler, recording terminal, stabilized reference signal transfer, and two OCXOs) toeach telescope. We observed an edge of the Moon
as a strong fringe ﬁnder, then successfully we obtained fringes. Here we will report more detail ofthe experiment and the fringe properties.
1.

Introduction

Figure 1. Stabilized reference transfer measurement before shipping. The result of Alan standard
deviation shows 1 ∗ 10−14 in 1sec integration.
2.1

At ﬁrst we laid a 200 meter optical-ﬁber between
13m antenna and 1.85m antenna and installed stabilized reference signal transfer system for just ﬁnding fringe as a ﬁrst step. Table. 1 shows their
speciﬁcation. Before installing, we measured its
stability with DMTD in NICT/Kashima. Figure
1 shows a result of closed loop measurement between its transmitter and receiver. Since the resultof Alan standard deviation shows 1 ∗ 10−14 stability in 1 sec integration, it seems to be suﬃcient(2.3 ∗ 1011 [Hz] ∗ 1 ∗ 10−14 = 2.3 ∗ 10−3 ) for 230
GHz VLBI. We also installed OCXO reference andGPS for positioning and generating 1PPS signal
to each antenna. Down-converted IF signal fromDC to 1GHz range of each antenna was connected
to digital sampler (K6/GALAS), which can sample 16GHz speed. Then, 1GHz bandwidth can berecorded with DBBC functions of the K6/Galas.

Event Horizon Telescope (EHT) promotes
strongly research in obtaining a shadow of the super massive black hole of SgrA∗, M87, and so onby (sub-)mm VLBI [1]. The 200 GHz range VLBI
has a 25 years history [3]. However, the highest
frequency range of Japanese VLBI recorded still
85 GHz[4]. Based on these situations, MICE2015
team focused on making a ﬁrst 230 GHz VLBI in
Japan with using two telescope in Nobeyama for
gaining a mm-VLBI technique and experience.
2.2
2.

MICE2015: First 230 GHz VLBI

Nobeyama has a long history of Japanese radio
astronomy since 1960’s establishing 45m telescope,
Nobeyama millimeter array (NMA) as prototype
ALMA. Nowadays two telescope SPART 10m (Inthose days called No.F in NMA) and 1.85m on
150m baseline have each 230 GHz cryogenic receiver in NRO. However both antennas have no
VLBI equipment, thus VLBI backends including
digital sampler and recorder and stabilized reference signal transfer system were installed after
brought by authors.

Installation of VLBI equipment

VLBI on the Moon edge

Such high frequency, bright sources for detecting
VLBI are not so many. But the edge of the Moon
would be a good candidate [5, see Appendix 10.1].
First we connected stabilized reference 10 MHz signal, which we transfers from SPART 10m to 1.85m.
Then, we observed the Moon for 1 minutes. Just
after recording, we performed a correlation immediately with software correlator GICO3 developed
by NICT. We might have a luck, we could successfully detect fringe (ﬁgure 2). We see 4 Hz residualin rate. This is a predicted rate, whose diﬀerence
caused by SPART 10m down-converter setting. Af-

October 2015

SPART
10
Linear—-3871061.02
3428327.24
3723784.271

OPU1.85
1.85
Circular
200-3871175
34282793723701

Residual rate before/after fitting[Hz]Name
Diameter [m]Pol
Tsys[K]
X[m]
Y[m]
Z[m]

23

0.05
0
-0.05
-0.1
-0.15
-0.2

-0.25
Table 1. A speciﬁcation of each antenna. The XYZ
0 500 1000 1500 2000 2500 3000 3500 4000
position were determined roughly by google map
Time [sec](their longitude and latitude) and GPS (height).
A setting polarization of SPART 10m was initiallycircular, but it was changed to linear pol for detect- Figure 4. Fine tuned residual rate (green) and initial result (red).
ing fringe.
2

3.

Discussion: A coherence computed by
230 GHz fringe

Greve et.al reported that the coherence times
were the order of 10 sec., most probably limitedby the atmosphere in their 215 GHz VLBI [2]. If
we make a 230 GHz VLBI through the the atmosphere with stability in the order of 10−13 , the timeinterval to change the phase about 1 cycle will be
only about 43 sec = 1/(230 ∗ 109 ∗ 10−13 ). Before
we exchange the reference signal source to OCXO,
we observed the Moon for 1 hour. Figure 4 shows
residual rate before (red) and after (green line) ﬁne...
tuning of clock model (τ̇ , τ̈ , τ determined by data)
in an a priori ﬁle for correlation. We could almost
compensate the rate variation. However the 230
GHz fringe phase had still quadric curvature, thenwe removed it by quadric ﬁtting. Finally the residual phase was converted to delay as a time series.
Figure 5 shows the residual delay which includes+1 to -1 ps variation. Then we perform noise analysis by Fourier transform the ﬁgure 5. The resultof Fourier analysis is shown in ﬁgure 6. The ﬁgure has the bending point around 400 sec, as acoherent time. It indicates that white noise component is dominated from 10 sec to 400 sec, but
ﬂicker noise component becomes predominant after 400 sec in case we could remove the quadraticphase change. If the coherence time of ’400 sec.’

1.5
1Delay [ps]ter we obtained fringe, we changed reference signal of both antennas to OCXO reference, whichhas quite high stability developed by JAXA and
NAOJ. We successfully obtained real VLBI (notso long baseline) fringe with rate tuning after the
replacement of reference signal (see ﬁgure 3).

0.5
0
-0.5
-1
-1.5
-2
0

500 1000 1500 2000 2500 3000 3500 4000
Time [sec]Figure 5. A residual delay after ﬁne tuned withclock model and quadric ﬁtting.
appeared only for the case of stabilized reference
signal, it has almost a good agreement in DMTD
result 434[sec] = 1/(230 ∗ 109 ∗ 10−14 ))( ﬁgure. 1).
This experiments were a just ﬁrst step, we would
like to make longer baseline VLBI in future.
Acknowledgements
All Japan VLBI researcher was cooperated to
MICE2015, which includes Yamaguchi univ, Osaka Pref univ, Ibaraki univ, NAOJ, JAXA/ISAS,
NAO, Kyoto univ and NICT/Kashima. The author thanks everyone for supporting the experiment and cooperation.
References[1] S. S. Doeleman, J. Weintroub, A. E. E.
Rogers, R. Plambeck, R. Freund, R. P. J.
Tilanus, P. Friberg, L. M. Ziurys, J. M. Moran,
B. Corey, K. H. Young, D. L. Smythe, M. Titus,IVS NICT-TDC News No.35

24

Amplitude [sec]1e-13[5] A.R. Thompson, J.M. Moran, and G.W. Swenson. Interferometry and Synthesis in Radio Astronomy. Wiley, 2008.

1e-14
1e-15
1e-16
10

100

1000

10000

Wavelength [sec]Figure 6. Power spectrum of the ﬁgure 5. We cansee bending point at near 400 sec.
D. P. Marrone, R. J. Cappallo, D. C.-J. Bock,
G. C. Bower, R. Chamberlin, G. R. Davis, T. P.
Krichbaum, J. Lamb, H. Maness, A. E. Niell,
A. Roy, P. Strittmatter, D. Werthimer, A. R.
Whitney, and D. Woody. Event-horizon-scale
structure in the supermassive black hole candidate at the Galactic Centre. Nature, 455:78–80,
September 2008.
[2] A. Greve, M. Torres, J. E. Wink, M. Grewing,
W. Wild, J. Alcolea, A. Barcia, F. Colomer,
P. de Vincente, J. Gomez-Gonzalez, I. LopezFernandez, D. A. Graham, T. P. Krichbaum,
R. Schwartz, K. J. Standke, A. Witzel, and
A. Baudry. 215 GHz VLBI observations: Detection of fringes on the 1147 KM baseline Pico
Veleta-Plateau de Bure. A&A, 299:L33, July
1995.
[3] S. Padin, D. P. Woody, M. W. Hodges, A. E. E.
Rogers, D. T. Emerson, P. R. Jewell, J. Lamb,
A. Perfetto, and M. C. H. Wright. 223 GHz
VLBI observations of 3C 273. ApJ letter,
360:L11–L13, September 1990.
[4] K. M. Shibata, H.-S. Chung, S. Kameno, D.-G.
Roh, T. Umemoto, K.-D. Kim, K. Asada, S.T. Han, N. Mochizuki, S.-H. Cho, S. SawadaSatoh, H.-G. Kim, T. Bushimata, Y. C. Minh,
T. Miyaji, N. Kuno, H. Mikoshiba, K. Sunada,
M. Inoue, and H. Kobayashi. First mm-VLBI
Observations between the TRAO 14-m andthe NRO 45-m Telescopes: Observations of 86
GHz SiO Masers in VY Canis Majoris. PASJ,
56:475–480, June 2004.

October 201525

4.5e-05

4.5e-05

4e-05

4.0e-05

4.65

3.0e-05
Rate [Hz]Amplitude

3.5e-05
2.5e-05
2.0e-05
1.5e-05

3.5e-05
3e-05

4.6

2.5e-05
2e-05

4.55

1.5e-05

1.0e-05

4.5

5.0e-06
0.0e+00
-1000

-500

0

500

1e-05
5e-06

4.45

1000

0

Delay [Sample]

585

4.5e-05

Epoch: 2015/117 09:20:00
Station-1:
SPART
Station-2:
M185
Source:moon
Length
:59.999943[sec]Sampling :2048000000[sps]Frequency:+230000.000000[MHz]Peak Amp :0.004257[]%
Peak Phs :47.656835[deg]Delay: +591.107971[spl]Rate: +4565.752442[mHz]
SNR:
14.610458

4.0e-05

Amplitude

3.5e-05
3.0e-05
2.5e-05
2.0e-05
1.5e-05
1.0e-05
5.0e-06
0.0e+00-4-2

0
2
Rate [ Hz ]590
595
Delay [Sample]

4

Figure 2. The ﬁrst 230GHz fringe of Moon edge with common reference signal.

0.000121.2e-04

0.15
0.00011.0e-048.0e-05

8e-05
Rate [Hz]Amplitude

0.1
6.0e-05
4.0e-05
2.0e-05

6e-05
0

4e-05

-0.05

0.0e+00
-1000

-500

0

500

1000

Delay [Sample]

1.0e-048.0e-05
6.0e-05
4.0e-05
2.0e-05
0.0e+00-4-2

0
2
Rate [ Hz ]

2e-05

-0.1

0
25

1.2e-04

Amplitude

0.05

4

30
35
Delay [Sample]

40

Epoch
: 2015/117 13:35:00
Station-1:
SPART
Station-2:
M185
Source :moon1335B
Length :59.999943[sec]Sampling : 2048000000[sps]Frequency:+230000.000000[MHz]Peak Amp :0.010663[]%
Peak Phs : -83.102033[deg]Delay: +32.588776[spl]Rate: +33.529441[mHz]
SNR:
37.160270

Figure 3. The ﬁrst 230GHz VLBI fringe of Moon edge with independent reference signal of OCXO.

“IVS NICT Technology Development Center News” (IVS NICT-TDC News) published by the
National Institute of Information and Communications Technology (NICT) (former the Communications Research Laboratory (CRL)) is the continuation of “IVS CRL Technology Development
Center News” (IVS CRL-TDC News). (On April 1, 2004, Communications Research Laboratory(CRL) and Telecommunications Advancement Organization of JAPAN (TAO) were reorganized
as “National Institute of Information and Communications Technology (NICT)”.)
VLBI Technology Development Center (TDC) at NICT is supposed
1) to develop new observation techniques and new systems for advanced Earth’s rotation observations by VLBI and other space techniques,2) to promote research in Earth rotation using VLBI,
3) to distribute new VLBI technology,4) to contribute the standardization of VLBI interface, and5) to deploy the real-time VLBI technique.
The NICT TDC newsletter (IVS NICT-TDC News) is published biannually by NICT.

This news was edited by Mamoru SEKIDO, Kashima Space Technology Center. Inquires on thisissue should be addressed to Mamoru SEKIDO, Kashima Space Technology Center, National
Institute of Information and Communications Technology, 893-1 Hirai, Kashima, Ibaraki 3148501, Japan, e-mail : sekido@nict.go.jp.
Summaries of VLBI and related activities at the National Institute of Information and Communications Technology are on the Web. The URL to view the home page of the Radio Astronomy
Applications Section of the Space-Time Measurement Group of Space-Time Standards Laboratory is : “http://www2.nict.go.jp/aeri/sts/stmg/index e.html”.

IVS NICT TECHNOLOGY DEVELOPMENT CENTER NEWS No.35, October 2015
International VLBI Service for Geodesy and Astrometry
NICT Technology Development Center News
published by
National Institute of Information and Communications Technology, 4-2-1 Nukui-kita, Koganei,
Tokyo 184-8795, Japan