brian@ucsd.edu (Brian Kantor) (10/07/90)
Some small stations may use cellular phones, but in this part of the
world, the traffic reporting companies who do that for several
stations use one or more of the Remote Pickup Broadcast channels
allocated to their radio clients. You can easily find them on
channels in the 450 to 451 MHz range, sometimes on repeaters ("mobile
relay") systems and sometimes direct. You should also scan around 161
MHz, as there are a few RPB channels there.
Others use various business-band channels to report the traffic
conditions to a central office, where an announcer actually provides
stations with the report - with these, it's NOT broadcast from the
mobiles. (I think direct rebroadcast of Land Mobile channels isn't
permitted.)
Commonly, stations not using radio circuits used to use automated
tone-activated "cart" tape machines to record these broadcasts - a
sort of very high quality answering machine, but on a leased line.
Some actually used real phone answering machines on POTS lines. Some
use multidrop conference circuits like the auto parts dealers do.
In one town I know about, it was discovered that one of the
announcer-in-a-box traffic report firms was getting its information
from eavesdropping on the OTHER firm that actually had a helicopter
and mobiles - the quality and completeness of the former's reports
dropped noticeably the day the real company changed radio channels.
Later, the real company would occasionally report fake traffic jams
and accidents to their base station using a code word that told the
base that it WAS a fake and not to pass it on for broadcast - but the
eavesdropping reporting firm didn't know the code word and would pass
on the reports. They're not in business anymore.
Oh, then there's the time that Channel X TV sent two of their minicam
units to cover a plane crash they'd heard about on Channel Y's news
dispatch frequency - when they got there, all there was to be found
was channel Y's news director saying something about how he had a
feeling they were going to show up.
Brian