S2 Recorder Installed at Kashima 34 m VLBI Station

Mamoru Sekido (sekido(AT)nict.go.jp)

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

1. Introduction

Canadian S2 VLBI data recording (RT) and play back (PT) terminal has been installed at Kashima 34 m VLBI station to extend VLBI observational capability (Figure 1). Kashima 34 m VLBI station has K-4 type1, type2, VSOP terminal (VSOP-T), K-3, and VLBA (Mk-IIIa) recording system. And they are used for various kinds of VLBI experiment, such as geodetic VLBI, Space VLBI, domestic astronomical VLBI (J-Net), Pulsar VLBI, and so on. The newly installed S2-RT/PT is currently aimed for pulsar VLBI observation in Kashima (Japan) - Kalyazin (Russia) - Algonquin (Canada) VLBI network (Polar Bear Array; see Figure 2), and geodetic VLBI experiment between Kashima and Shanghai. Data copying in both direction from S2-PT to VSOP-T and from VSOP-T to S2-RT has also became available by using S2-PT/RT in conjunction with VSOP terminal (CTCU:VSC7220).


Figure 1. Left is S2-RT/PT and right is VSOP backend including Video converter, Sampler, and VSC7220.

2. VLBI Experiments with S2-RT

2.1 Pulsar VLBI

VLBI observation of pulsars for astrometry had been performed between Kashima and Kalyazin (Russia) baseline [Sekido et al., 1999] by using K-4 type1 VLBI system since 1995. The observation network was widely extended by using S2-RT. Algonquin (Canada) - Kalyazin - Kashima pulsar VLBI network (Polar Bear Array) was coordinated. During 18-19 May 2000 the first VLBI observation was performed and Noto VLBI station in Italy was joined in the experiment this time.


Figure 2. Pulsar VLBI observation stations in May 2000 experiment.}

2.2 Geodetic VLBI with Shanghai Station

Shanghai Observatory has mobile VLBI station and S2 VLBI system is used for geodetic VLBI experiment. Fringe test experiment of the mobile station was organized in January 2000 and Kashima 34 m antenna had joined it. Fringe between Kashima and Shanghai was detected successfully by correlation processing at Penticton.

3. Available recording mode

There are two ways to record VLBI data into S2-RT at Kashima station. One is using 16 ch 4 MHz 1 bit sampler provided by Space Geodynamics Laboratory. Data is recorded in 4x16-1 mode in S2-RT. The other is using K-4 type2 sampler and VSOP terminal in combination. In this case, there are several choices of recording mode as listed in Table 1. Actually successful recording was confirmed in 32x4-2 and 16v8-2 (VSOP mode). Other modes will possible but have not tested yet.

Table 1. Possible S2 recording mode through VSOP-T
Wires Clock Modes Total Rate
4 32 MHz 32x4-1, 32x4-2 128Mbps
16 MHz 16x4-1, 16x4-2, 16i4-1 64Mbps
8 MHz 8x4-1, 8x4-2, 8i4-1 32Mbps
4 MHz 4x4-1, 4x4-2 32Mbps
8 16 MHz 16x8-1, 16x8-2, 16i8-1, 16p8-2, 16v8-2 128Mbps
8 MHz 8x8-1, 8x8-2, 8i8-1, 8p8-2 64Mbps
4 MHz 4x8-1, 4x8-2, 4i8-1, 4p8-2 32Mbps
16 8 MHz 8x16-1, 8x16-2 128Mbps
4 MHz 4x16-1, 4x16-2 64Mbps

4. S2 - VSOP-T Copying capability

Since VSOP terminal (CTCU:VSC7220) has been installed at Kashima, all equipment for data copying between VSOP-T and S2 is available as the same with Mitaka. And data copy in both direction, from S2-PT to VSOP-T and from VSOP-T to S2-RT, was confirmed in 32x4-2 and 16v8-2 modes. Other modes in Table 1 will be possible.

References

Sekido, M., M. Imae, Y. Hanado, Y.P. Ilyasov, V.V. Oreshko, A.E. Rodin, S. Hama, J. Nakajima, E. Kawai, Y. Koyama, T. Kondo, N. Kurihara, and M. Hosokawa, Astrometric VLBI observation of PSR 0329+54, Publ. Astron. Soc. Japan, 51, pp.595-601, 1999.

Updated on June 2, 2000. Return to CONTENTS