Newsletter of the
ITS Cooperative Deployment Network
(Please read the Disclaimer)
Newsletter of the
ITS Cooperative Deployment Network
(Please read the Disclaimer)
Radio data systems (RDS) employ an FM subcarrier to transmit a steady stream of timely traffic bulletins over a special Traffic Message Channel. Known in Europe by its acronym as "RDS-TMC," the Traffic Message Channel alerts motorists about major incidents and road hazards, overriding, if necessary, on-going music and entertainment programs or even "waking up" the receiver to deliver the announcements. The RDS signals are beamed in the form of "event codes" and "location codes" over a digital data sideband of regular FM audio channel. The event codes cover all possible traffic incidents and hazardous conditions (there are 3,100 agreed event codes in the European RDS-TMC protocol), while the location codes pinpoint the location of incidents. When the coded signals reach the decoder-equipped RDS car radio, they are automatically translated into traffic messages. The messages are delivered in synthesized voice and/or textual form in the listener's own language, so that drivers can understand traffic announcements no matter in what country they may find themselves driving.
The key benefit of RDS technology over conventional car radio is that RDS receivers can filter out all extraneous messages that do not pertain to the traveler's own route by recognizing only location codes programmed in advance into the receiver. Thus, drivers can be listening to other programs without being interrupted by announcements of traffic problems that do not concern them. Conversely, they are kept informed of problems affecting their own route even if they happen not to be listening to the radio, because RDS signals can "wake up" a dormant RDS radio receiver. The fact that motorists can receive emergency messages in their preferred language is another unique and highly valued feature on the European continent where motorists speak many different languages.
All told, 11 European countries have committed to launching RDS-TMC service over the next two years, using a common protocol for the coded message format, known as Alert-C. For the time being, RDS-TMC services will be country-specific, i.e., each country will operate its own national traffic data system and determine the content and quality of the information provided over the Traffic Message Channel. Eventually, however, all individual national systems will be fused into a single, continent-wide information diffusion network, with traffic data exchanged across national borders. Motorists will be able to use their RDS radios in any country and receive uniform quality of data in their chosen language. Such, at least, is the vision and the hope of the European Commission which has been on the forefront of RDS-TMC development and a strong champion of a unified pan-European RDS-TMC system.
Historically, RDS-TMC emerged from discussions between the European Broadcasting Union and the European Conference of the Ministers of Transport. The sponsors assumed that traffic messaging over RDS radio would be provided as a free public service. This is still the philosophy of several participating countries, notably Germany, Austria and Sweden. However, other countries, such as the United Kingdom, France, the Netherlands and Italy, have encouraged the formation of private consortia to finance and operate RDS-TMC services. The best known of them is France's Visionaute which is being financed by Mediamobile, a public-private consortium comprising Télédiffusion de France (the French national broadcasting organization), Renault and Cofiroute, France's largest toll road operator. Similarly, in Italy, private toll road operators and the national broadcaster, RAI, have formed a consortium to operate a national RDS-TMC system using its own database. A newly organized "ALERT Forum," comprising the participating governments, service providers and broadcasters, will coordinate the implementation of RDS-TMC and promote its spread and use across Europe.
U.S. Prospects
In the United States, efforts to apply RDS technology (officially known as RBDS-- Radio Broadcast Data System) to traveler information have begun only recently. The sole commercial venture so far is a service provided by CUE Data Corporation, a company that offers paging services throughout North America. In May 1998, CUE announced the introduction of a traveler information service over CUE's existing nationwide FM subcarrier network that serves its pager messaging system. CUE's network, which consists of 600 FM radio stations, covering 80 percent of the U.S. interstate highway system, is said to be the largest radio data network in the world. CUE's new service, known as TrafficNet, will obtain traffic data from transportation agencies and commercial traffic content providers such as Metro/ETAK and SmartRoute, and transmit it in RDS data format to vehicles equipped with RDS FM receivers with a simple software upgrade. According to Tom Schaffnit, CUE's President, the company intends to offer this service by subscription ($60/year) in 40 major metropolitan markets across the United States. A related subscription service, known as TrafficPage, will offer similar service to owners of dedicated pagers.
Efforts to demonstrate the use of RDS for traveler information are also underway at the ITS Research Laboratory at the University of Michigan, which is sponsoring a pilot test of a simple, low-cost RDS-TMC system. Participating FM stations will transmit data obtained from the traffic surveillance system of the Michigan Department of Transportation and commercial information service providers. The RDS radio receivers, tuned to a designated FM subcarrier frequency, will alert their owners about traffic incidents relating to the driver's frequently traveled route segments stored in the receiver's memory. Unlike the European RDS-TMC system which involves a large "dictionary" of messages and requires a sophisticated receiver to decode the messages, the University of Michigan system will only provide critical information in a concise format, according to Marlin P. Ristenbatt, Research Engineer at the ITS Research Laboratory and co-director of the project. The messages will be limited to the route number and direction, the interchange exit immediately preceding the incident in question, and estimated delay in minutes. Planning for the pilot program has been underway since late 1997. The next stage, to begin later this year, will involve "beta testing" to demonstrate concept viability and test consumer response. If the test is successful, the sponsors hope to deploy the system statewide.
Barriers to Implementation
While interest in RDS technology in North America is rising, there are some serious barriers to be overcome. One of them is a reluctance of the broadcasting industry to embrace RDS technology. Unlike Europe, where radio broadcasting is primarily government controlled and the RDS-TMC protocol could be introduced by a government fiat, the broadcasting industry in North America consists of a multitude of individual, privately-owned stations. Convincing these stations that they should invest in RDS technology will require financial incentives or a showing that there is a tangible market for RDS transmissions. Currently, only 707 FM stations of the approximately 7,000 FM stations in the United States have a capability to broadcast in the RDS format, according to the Electronic Industries Alliance.
A potentially large market for RDS transmissions is the communication of traveler information over car radios. But, unlike Europe where RDS radio receivers are available at prices only slightly higher than those of conventional radios, and are increasingly being installed as standard equipment in new cars, U.S. car manufacturers have adopted a wait-and-see attitude. Only one car model so far -- Cadillac -- offers RDS radios as standard equipment in its 1998 Seville version. It's the classic chicken-and-egg problem, according to industry analysts. Automakers have no incentive to install RDS receivers as standard equipment because there are not enough RDS broadcasts to justify the added expense. And radio stations do not invest in RDS transmission equipment because there is only a limited number of RDS radios that can receive such broadcasts. Electronic equipment manufacturers, in turn, have been slow to embrace RDS technology because of a lack of OEM interest and weak "aftermarket" sales of RDS receivers.
The Standards Debate
Another potential barrier has been the inability of the stakeholders to agree on a common FM subcarrier standard for delivery of traveler information. A single national standard is felt to be desirable in the interest of "national interoperability" and its adoption became a key goal of the National Radio Systems Committee (NRSC), a joint effort of the National Association of Broadcasters and the Consumer Electronics Manufacturers Association (CEMA).
From the outset, the Committee made delivery of dynamic route guidance to mobile users a primary consideration in the selection process -- and this suggested the need for a high speed FM subcarrier with superior signal processing capability. But despite more than three years of deliberations by a special NRSC High Speed Subcarrier Subcommittee and an expenditure, by one estimate, of close to $20 million, no agreement could be reached on a single national standard. "The Subcommittee has reached an impasse in the selection process and is unable to move forward in recommending a single universal standard," David Kelley, co-chair of the committee said in a formal announcement last April. A standard developed by the MITRE Corporation under contract to the Federal Highway Administration -- the Sub-Carrier Traffic Information Channel (STIC) -- was found superior for mobile ATIS applications (perhaps not surprisingly, since it had been designed specifically with that objective in mind), but would require costly receivers and consume significant amounts of power, thus making it impractical for portable and hand-held devices. A second standard named DARC (Data Audio Radio Channel), developed by the Japanese firm NHK Science and Technical Research Laboratories, has a slightly lower data rate (16 kbits/sec vs. 18 kbits/sec for STIC), but DARC receivers are less costly, require less power and use microchip sets that are readily available. A third standard, HSDS (High Speed Data Subcarrier), developed by Seiko specifically for paging applications, is reportedly no longer under consideration.
A number of equipment manufacturers have banded together in a trade association, FMNet, to promote the deployment of the STIC standard. Proponents of the DARC standard are also mobilizing and have formed their own forum, the International DARC Engineering Association (IDEA), to argue the case for DARC-based subcarrier technology. While FMNet members are hoping that the US DOT will eventually endorse the STIC standard, federal officials disclaim any intention to influence the selection process. "It has never been the DOT's position to dictate the outcome, although we welcome any activities that might move the process along," says Mike Schagrin, Standards Program Manager in the ITS Joint Program Office. He draws a parallel with the Dedicated Short Range Communications (DSRC) protocol, where the US DOT also adopted a neutral position while supporting a single interoperable standard
ITS America likewise has taken no sides in the standard debate other than to advocate the selection of a single standard. Otherwise, "chaos will continue to reign at the deployment level," and national interoperability will be seriously compromised, according to Paul Najarian, telecommunication specialist at ITS America. Others, however, think the chances for mandating a single standard are receding. "It's a little late in coming" says CUE Corporation's Tom Schaffnit. Many observers think that an outcome dictated by market forces is more likely. This would seem to favor the waveforms used by CUE Corporation in its TrafficNet service, which already operates a high-speed (16 kbs/sec) DARC-based network in 40 markets, and a lower speed (11.8 kbs/sec) "MBS" network in 550 markets. Traffic messages transmitted over CUE's TrafficNet can be received by any standard RDS receiver or by CUE's custom dual subcarrier receiver which searches first for data on the high speed network, and if none is detected, automatically switches over to the lower speed MBS network. An early example of CUE's capability is its TrafficAlert service in Seattle, provided in cooperation with ETAK and Metro Networks as part of the Smart Trek model deployment initiative.
Whether the waveforms used by CUE will become a de facto standard remains to be seen. Whatever the ultimate outcome of the current debate, however, one thing is already clear. North America is finally joining Europe and Japan in recognizing the value of FM subcarrier technology. Deploying this technology as a traveler communication tool is now only a matter of time.
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