IVS Technology Coordinator Report
Alan Whitney
MIT Haystack Observatory
Abstract:
The main effort of the Technology Coordinator during 2001 was devoted to leading the VSI Technology Coordination
Committee in its effort to develop the VLBI Standard Interface software specification (so-called VSI-S). This specification is
intended to work together with the VSI-H specification approved in August 2000. The goal of the VSI effort is to specify standardized
hardware and software interfaces for a VLBI Data Transmission System (DTS), such that DTS's developed by different groups can
be interchanged with minimal effort at both data-acquisition and data-processing sites.
In June 2001, IVS was honored by the Japanese Ministry of Public Management, Home Affairs, Posts
and Telecommunications for the development of the VSI-H specification. As a result, the VSI-H
specification has received considerable visibility and is being adopted by other disciplines as well.
Because the VSI-H specification is potentially applicable to a broad class of high-speed streaming data
applications, particularly those requiring precise sample-time accountability, VSI has been informally re-christened
as `Versatile Streaming Interface' and may appear on some commercial products in the near future.
The VSI Technology Coordination Committee is nearing completion of the VSI-S specification, which is the
software half of the VSI specification. The goal of the VSI-S specification is to specify a robust, reliable
communication protocol to control a VSI-H-compliant VLBI Data Transmission System (DTS). In this regard, VSI-S addresses
the following issues:
- Specifies a communications structure and protocol.
- Specifies a generalized command and response syntax model to be used by the DTS.
- Specifies a base set of commands to configure and operate a generic DTS adhering to the VSI-H specification.
As of this writing (Jan 2002), the VSI-S specification is nearing completion, with completion expected soon.
Already, several groups worldwide have developed, or are developing, VLBI data systems and components that adhere to the
VSI-H standard. We expect this trend to broaden and accelerate. I wish to extend special thanks to all the other members of the
VSI Technology Committee for their continuing efforts to bring the VSI specification to full reality:
- Wayne Cannon - York University, Canada
- Brent Carlson - DRAO, Canada
- Dick Ferris - ATNF, Australia
- Dave Graham - MPI, Germany
- Ed Himwich - NASA/GSFC, U.S.
- Tetsuro Kondo - CRL, Japan
- Nori Kawaguchi - NAO, Japan
- Ari Mujunen - Metsahovi, Finland
- Misha Popov - ASC, Russia
- Sergei Pogrebenko - JIVE, Netherlands
- Jon Romney - NRAO, U.S.
- Ralph Spencer - Jodrell, England
The full VSI-H specification, along with an interesting historical chronology of its development, is available at http://dopey.haystack.edu/vsi/index.html.
Look for VSI-S to be posted soon!
Other planned and ongoing activities in the technology coordination area are:
- Formation of a few small subgroups with interest in particular technology areas. The members of these subgroups will draw from
IVS technology centers and other experts in the field. These sub-groups, interacting primarily via e-mail, will be asked to develop a list
of concerns and goals and to suggest the steps needed to achieve them. The VLBI Standard Interface group serves as a prototype for this type
of activity. Among the efforts contemplated in the near future is an examination of possible standards for electronic transmission of VLBI data (so-called ``e-VLBI'').
- As an ongoing activity, promote and encourage inclusion of topical sessions on advanced VLBI technology at international meetings and workshops.