With all of the Federal money available for “Intelligent
Transporation Systems”, smog reduction, etc., it really surprises
me that no one in the US has organized an effort to develop a industry
protocol to send coded traffic info “in the background” to
mobile receivers via RBDS.
I realize that the existing RDS/RBDS standard already provides a TP
flag and the ability to switch from cassette/CD to radio or raise
volume during voice traffic anouncements, but that's early 80's
technology (an enhancement of Blaupunkt's old ARI system) and requires
that the information must be carried “in band”. Therefore,
it conflicts with regular programming and is a “turn-off
factor” to listeners who aren't driving.
In most metro areas, the DOT already has the ability to monitor
traffic speed on most of the major highways, and they can also manually
post the location of accidents or construction delays. This information
is available online on websites like traffic.com. For example, the
Philadelphia real-time map is available at http://www.traffic.com/Philadelphia/index.html.
That's great if you have Web access in your car and don't mind
surfing while you try to drive. I don't know of many drivers who
What we need is a scheme that simply broadcasts this data in
continuous coded form using spare RDS groups. The receivers would
collect it and could either display it visually (in text form by route
number/milepost/exit number — or on a map), or announce it
audibly with a voice synthesizer.
This idea becomes much more practical if you consider that GPS
receivers are rapidly dropping in price, such that it's not a big deal
to factory-install them in cars. Anyone with OnStar or a fancy
navigation system already has one. So let's interface the GPS receiver
with the traffic data decoder so any irrelevant reports are filtered
out. (The broadcast protocol would tag each report with coordinates,
making this feature possible.) There's no need to know what happened 20
miles behind you.
The driver could even store their daily commuting route in memory;
when they pull out of their driveway in the morning they would hear a
“customized” current report. An instant update would be
available by hitting a button.
Of course, location-specific public warning data (enhanced EAS)
could be disseminated this way as well. Getting the datastream to the
broadcaster's encoder would be handled via internet, or by off-air
relay, to keep costs down.
The receiver chipset would be designed to keep the FM tuner
operational in “RBDS decode mode” only whenever the user is
listening to AM. In this mode, the FM section would simply scan for the
closest transmitter carrying the traffic data; operation would be
“transparent” to the user, who would hear the desired AM
Needless to say, the biggest challenge here is getting all of the
players (broadcasters, receiver makers, car guys, chip designers,
departments of transportation, FEMA, etc.) to talk to one another. I
doubt that the FCC would need to get involved here (RBDS is already
legal), so perhaps there's hope.
Mark Humphrey, CPBE
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