IVS 2001 Annual Report
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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.

1. VSI-H Wins Award!

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.

2. VLBI Standard Interface - Software (VSI-S)

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:

  1. Specifies a communications structure and protocol.
  2. Specifies a generalized command and response syntax model to be used by the DTS.
  3. 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:

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!

3. Other Activities

Other planned and ongoing activities in the technology coordination area are:
  1. 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'').
  2. As an ongoing activity, promote and encourage inclusion of topical sessions on advanced VLBI technology at international meetings and workshops.

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IVS 2001 Annual Report