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SAE J2540 - Advanced Traveler Information Systems (ATIS) Family of Standards for Coding of Messages and Phrase Lists


This Fact Sheet was written on Jan 10, 2006. The statuses of the standards at the time were as follows: SAE J2540 was Published in Jul 2002, SAE J2540-1 was published in Jul 2002, SAE J2540-2 was published in Feb 2002, with amendment 1 published in May 2004, and SAE J2540-3 was published in Jan 2002.

This Fact Sheet was written on January 10, 2006.

This Fact Sheet was last verified on October 07, 2009

 Check the ITS Standards Search to see if there has been subsequent development activity.

Overview

Operating rules for efficiently coding textual strings (groupings of alphanumeric characters) for advanced traveler information systems (ATIS) messages can be valuable for communications with limited bandwidth; although the rules may also be applied in cases for which bandwidth is not a concern. National tables (SDO-approved lists of commonly used phrases) that are described in this set of standards provide a reference of text phrases that are each assigned a unique index value, transmitted, and then decoded by the receiving system. Included in the national tables are encodings for the Radio Data System (RDS) phrases, International Traveler Information System (ITIS) phrases, and national street names. These are popular in Europe and are gaining acceptance in the United States as standardized encodings for ASCII character codes.

The SAE J2540 Family of standards supports the exchange of coded textual strings:

  • SAE J2540 - Messages for Handling Strings and Look-Up Tables in ATIS Standards is the base standard that defines the rules for encoding and decoding textual strings for ATIS messages; all of the following phrase lists follow the encoding and decoding rules defined in this standard.
  • SAE J2540-1 - RDS (Radio Data System) Phrase Lists defines the textual messages for expressing phrases commonly used to convey traffic incident information over the limited bandwidth RDS subcarrier transmission media, but may also be used over other media and applications.
  • SAE J2540-2 - ITIS (International Traveler Information Systems) Phrase Lists defines the textual messages used internationally - and therefore including various languages and expressions - intended for use in conveying incident and traffic related events. Many ITIS phrases are reused by other ITS standards.
  • SAE J2540-3 - National Names Phrase List defines the textual messages for conveying the most commonly used street names.
What are these standards for?

The standard, SAE J2540 - Messages for Handling Strings and Look-Up Tables in ATIS Standards, provides the formatting rules used to facilitate the conveyance of information strings between ATIS data transmitters and data receivers. It allows a range of processing options to be used from a common set of rules, and supports universal character sets found in other languages. It provides a simple, uniform method of reconstructing messages for end users. It also allows the use of complex textual strings, incident phrases, and national tables (such as RDS, ITIS and National Names found in SAE J2540-1, SAE J2540-2, and SAE J2540-3, respectively) that can be deployed without making legacy systems obsolete, thus promoting national interoperability and sustainable deployment. Also included are a number of national tables used in the delivery of incident descriptions over some media.

Who uses them?

The SAE J2540 Family of standards are intended for use by both data issuers (e.g., information service providers [ISPs], both public and private) and by data receivers and other end-users of data, such as equipment manufacturers who wish to produce products that receive ATIS messages. These users will find the range of operating rules described in this family of standards useful in developing and improving their systems.

How are they used?

The SAE J2540 Family of standards can be used as a basis for coding messages efficiently. For example, the string "Closed ahead. Stop and go traffic for 5 miles" is encoded as RDS message #421, thus realizing significant reductions in the required bandwidth. The standards can also be used to decode all valid strings regardless of the options used by the sender. While intended for low bandwidth, one-way communications from the ISP to in-vehicle devices, the procedures in the standards can also support a two-way interchange of data. Locally used terms and phrases (e.g., a local table or list) and free text can augment the lists described in the standard.

The ITIS phrase list has been incorporated into ITE’s Traffic Management Data Dictionary and Message Set for External Communications Standard as part of the Event Reporting Messages (ERM). In this way, an ATIS system can communicate with an event-reporting system.

Scope

The SAE J2540 Family of standards are intended to provide information on how textual strings are processed in messages. Such strings typically describe traffic and incident events, street or place names, and other textual information. Messages in related SAE ATIS standards can also utilize this format for all textual strings that appear in the message. By following these standards, equipment manufacturers can ensure that the largest numbers of data sources are compatible with their products. In addition, they will be able to take full advantage of newly created, more complex data sources (when they are created) and still maintain compatibility.

Related documents

The following ITS standards are related and should be considered when using this family of standards:

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