ISO 11104-2011 PDF

Full title and description

Space data and information transfer systems — Time code formats. ISO 11104:2011 specifies a small number of standard recommended digital time-code formats for use in data interchange applications between civil space agencies and related systems; it defines unsegmented and segmented time-code representations using the international standard second as the fundamental unit of time.

Abstract

ISO 11104:2011 describes four standard recommended time codes (one unsegmented and three segmented) that represent time as counts of seconds and fractional seconds from a defined epoch. The standard provides format definitions for interoperable time tagging in space data and information transfer systems but does not specify timing performance requirements (stability, precision, accuracy) which remain outside its scope.

General information

• Status: Published (confirmed in ISO review).
• Publication date: December 2011 (ISO edition published 2011-12).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 49.140 (Space systems).
• Edition / version: Edition 3 (ISO 11104:2011).
• Number of pages: 51 pages (ISO published document).

Scope

ISO 11104:2011 specifies recommended digital time-code formats for civil space data interchange applications and related systems. It defines representations (one unsegmented and three segmented) that count seconds and fractional seconds from an epoch and are intended for use in CCSDS-compatible data products and transfers. The standard explicitly excludes requirements for timing performance (e.g., stability, precision, accuracy).

Key topics and requirements

• Definitions of unsegmented (continuous binary count from epoch) and segmented (cascaded modulo counters) time-code formats.
• Specification of four recommended time-code formats (one unsegmented, three segmented) using the international second as the base unit.
• Format rules for representation of integer seconds and fractional seconds and how epochs are treated in time counts.
• Interoperability guidance for data interchange between civil space agencies and CCSDS-related systems; performance metrics are out of scope.
• Reference to earlier technical recommendations and prior ISO editions that were revised by this 2011 edition.

Typical use and users

Engineers and system architects working on spacecraft on-board and ground-segment data systems, telemetry/telecommand formats, mission operations, archive and science data products, and organizations implementing CCSDS-compatible interfaces and interchange formats. Standards authors, test laboratories, and software developers for space data handling also use ISO 11104:2011 as a reference for time-tagging formats.

Related standards

ISO 11104:2011 is linked to earlier editions (ISO 11104:2003 and ISO 11104:1991, both withdrawn and superseded) and originates from CCSDS technical recommendations (for example CCSDS 301.0 references used in earlier editions). It falls under the work of ISO/TC 20/SC 13 (space systems). Users commonly consider this standard alongside CCSDS timing and data formatting documents when implementing space data interchange.

Keywords

time code; time formats; epoch; segmented time code; unsegmented time code; CCSDS; space data; telemetry; time tagging; ISO/TC 20/SC 13.

FAQ

Q: What is this standard?

A: ISO 11104:2011 is an International Standard titled "Space data and information transfer systems — Time code formats" that defines a small set of recommended digital time-code formats for civil space data interchange.

Q: What does it cover?

A: It covers the syntax and representation of time codes (one unsegmented and three segmented formats), how counts of seconds and fractional seconds are represented from an epoch, and interoperability considerations for data interchange; it does not define timing performance metrics such as precision or stability.

Q: Who typically uses it?

A: Space agencies, mission systems engineers, spacecraft and ground-segment software developers, telemetry/telecommand integrators, archives and science-data centers, and standards developers working with CCSDS-compatible systems.

Q: Is it current or superseded?

A: ISO 11104:2011 is the current published edition (edition 3, published December 2011) and the ISO record shows it was last reviewed and confirmed during ISO review processes (the 2011 edition is the active version replacing earlier 1991 and 2003 editions).

Q: Is it part of a series?

A: ISO 11104 is a standalone international standard within the space systems domain maintained under ISO/TC 20/SC 13; it is related by subject matter to CCSDS timing and data-format recommendations rather than being one part of an ISO multi-part series. Earlier national/ISO editions exist (1991, 2003) that were superseded by the 2011 edition.

Q: What are the key keywords?

A: Time code, time formats, epoch, segmented/unsegmented time code, CCSDS, space data interchange, telemetry, time tagging.