By: Chuck Gysi N2DUP
Want some read DX? While some radio hobbyists try to tune in as many low-
power stations as possible, there is no better DX than to try to tune in very-
low-power AM stations that serve very small areas. These stations can range
from flea power to a whopping 10 watts (that's full power for most) on the AM
Travelers Information Stations (TIS) have been around for a while. Many
motorists ignore the highway signs instructing them to tune in these stations
for important information. However, they can be fun to tune in because their
intended listening audience is a very small area and when their signals travel
well outside these areas, the catch can be exciting for radio hobbyists and
interesting for those who operate the stations.
TIS operate on the standard AM broadcast band in the United States.
Through the years, most of these stations have operated on 530 or 1610
kilohertz. The reason for that is these two frequencies were just below and
above what once was the standard AM broadcast band. However, 530 kilohertz
is a clear-channel frequency for Canadian broadcasters and 1610 kilohertz has
become a part of the new expanded AM broadcast band (X band) from 1610 to 1700
While many TIS operate on 530 and 1610 kHz, you'll technically find them
all over the broadcast band on available frequencies that won't cause
interference to other full-power broadcasters. For instance, the TIS operated
by the city of West Branch, Iowa, home of the Herbert Hoover Presidential
Library and Museum, operates on 690 kHz.
Typically, TIS can serve a variety of functions, primarily for motorists.
These stations attempt to cover a chunk of an interstate highway, usually a
mile or two in length (enough time for a one- or two-minute broadcast to be
Road construction is one use for TIS. When road construction is imminent,
sometimes states or local governments will set up a TIS to advise motorists
who regularly travel a given route that construction is about to begin and
that they should seek alternate routes, be prepared for congestion or seek out
For impending construction, these TIS will broadcast information to better
prepare motorists for the coming construction. The idea here is to alleviate
any problems with the road construction. This makes the actual construction
project run a little smoother and perhaps with a little less delay in daily
When construction actually takes place, the TIS will advise motorists of
the work in progress and signs typically will be posted before interchanges to
allow motorists the option of not entering the highway under repair. In these
instances, the TIS will broadcast detour information so motorists can avoid
the construction zone. Sometimes these TIS applications are paired with
enhanced radar advisories. Persons with newer radar detectors usually have
access to a system that will alert them of roadway hazards such as road
construction, motor vehicle accidents and emergency vehicles on the roadway.
The TIS will broadcast road advisories while the radar transmitter system will
send out encoded messages to motorists, too. Usually you find the TIS and the
radar transmitter at the same site. To allow rapid updates to roadway
information being broadcast over TIS sites, most these days (especially the
portable ones) are equipped with cellular telephone receivers connected to the
TIS transmitter. Transportation officials and police have the capability of
dialing the TIS and recording updated traffic information to be broadcast to
motorists. This makes TIS transmitters extremely valuable in the movement of
Motor vehicle accidents can really slow down traffic on congested
highways, especially during rush hours. In these instances, updated
information can be broadcast on TIS units so that motorists know why they are
sitting in traffic, or have an opportunity to detour around the affected area.
In areas that attract tourists, TIS transmitters serve visitors with
information and also serve double duty in an effort to attract even more
visitors. Stations set up to broadcast information for tourist areas might
include dates of major events, a list of major attractions and phone numbers
for additional information. In addition, persons traveling along a major
highway may tune in the station out of curiosity and find that the region
offers an attraction they are interested in and stop, even though the visit
was unplanned. So, you can see these TIS also are somewhat commercial in
nature in that they promote tourism. Keep in mind that some of these TIS are
seasonal in nature, and if it isn't tourism season (like in the winter), then
the TIS may not be transmitting, or it may contain minimal information.
In some large parking lots, you also may find TIS operating. These TIS
applications may direct motorists to open parking areas, especially when some
parking areas become full. They also may direct visitors to alternate modes
of transportation, especially within parks.
Airports also frequently have TIS transmitters. These stations can serve
a host of purposes. Some airports may have more than one TIS, too, so
multiple purposes can be served. For instance, one TIS transmitter may advise
airport visitors where they can park, while others may advise of incoming and
One interesting application of TIS is at highway rest areas where these
transmitters rebroadcast NOAA weather broadcasts from 162-MHz frequencies onto
the TIS transmitter. Usually you won't know about these transmitters unless
you stop at a given rest area offering such service, because highway signs
don't advertise such service. This allows motorists stopping at public rest
areas to get up-to-date weather information many of us like to monitor on VHF
Find a TIS
Where should you look for TIS transmitters? Check 530 and 1610 kHz for
many of these broadcasts. But they aren't limited to these two frequencies.
They can operate anywhere on the AM broadcast band from 530-1710 kHz,
including the new recently expanded AM band (X band) from 1610-1710 kHz). For
instance, there are a series of TIS along the Pennsylvania Turnpike in the
Philadelphia suburbs that operate on 1630 kHz. When the turnpike TIS aren't
transmitting road construction or accident reports, they retransmit the NOAA
weather station on 162.475 MHz in Philadelphia. So, for those without NOAA
weather radios or scanners, they can tune their AM radios for current weather
TIS usually are licensed to city, municipal, county or state governments.
These include road authorities for toll roads and transportation departments.
They come under the local government radio service and have call signs much
like two-way users, such as WNZL582. While these stations are in the Federal
Communications Commission's data base of licensees (you can look them up on
the Web at www.fcc.gov), there are some TIS transmitters you won't find there.
TIS transmitters operated by the federal government are not licensed by the
FCC, but are authorized by a separate federal agency, the Interagency Radio
Advisory Committee. IRAC maintains its own data base of TIS transmitters, but
you'll do a lot better compiling your own list of federal TIS because IRAC
files typically have been closed to the public since the Reagan
administration. Federal TIS usually operate in national parks and other
federal installations with outside visitors.
While TIS transmitters operate at 10 watts, there are other applications
for very low power AM transmitters that typically don't reach more than a city
block in coverage. While TIS transmitters are licensed, there are AM
transmitters that can operate at very low power without a license.
Ever drive down the road and see a house for sale with a "Talking House"
sign in front of it? The sign will instruct passers-by to tune their car
radio to a frequency such as 1620 kHz to hear information about the house for
sale. The broadcast will tell the price, the number of bedrooms, features and
more. Persons don't even have to leave their vehicle or call the Realtor to
find out more about the house unless they really are interested. These
transmitters have proven to be a great tool for real estate sales.
Car dealers also have used these transmitters to promote sales, specials
and to offer information about specific vehicles for sale. What a great tool
these transmitters are (all commercial), especially for those Sunday evening
car shoppers browsing car lots.
Sometimes these flea-power transmitters will promote special events such
as fairs or festivals or specials sales. If the sign tells you to tune in a
certain frequency, you might just want to do so. There may even be an on-air
special deal broadcast that you wouldn't know about unless you tuned in. And
you know why that special deal is being broadcast? It's so those using these
transmitters can gauge their effectiveness.
One interesting application for low-power transmitters has come in the
form of talking billboards. A highway billboard sign will instruct motorists
to tune in a certain frequency for additional information about the product or
service being advertised on the billboard. The broadcast may contain a
special deal, too.
In some sporting arenas now, there are low-power transmitters that relay
actual broadcasts of the game in progress. Because many fans carry headset
radios to these events and regular AM stations may not come in clearly inside
these large arenas, fans can tune their headsets to these low-power
transmitters and hear the game in progress clearly because the transmitter is
inside the arena.
There still are other applications for very-low-power transmitters. Some
neighborhood-based radio stations serve a very limited listening audience, but
can offer timely and needed information for residents of that locale. You'll
find these few and far between, but there are a few around. Consider finding
one of these a great catch!
Some colleges, universities and high schools operate carrier current
stations on the AM broadcast band. While these stations depend on the
electrical wiring on campus to carry their AM signal, you'll be able to tune
them in if you are on or very close to a campus. Some may have a wide
listenership on campus, especially if they offer alternative music.
Drive-in theaters, a dying breed, frequently offer wireless audio for the
movies they show. Instead of putting those ugly boxes inside your car window
to hear the movie being shown, theaters will broadcast the movie audio over an
AM or FM frequency so you can tune them in on your better-sounding car radio.
If you are in the vicinity of a drive-in theater, you'll be able to hear the
audio for the movies. Likewise, some drive-in churches, where you park and
pray, also offer their services over a very-low-power AM or FM transmitter so
those attending can hear the services within the comfortable confines of their
And if you really want to find a very interesting application for very low
power radio, try tuning in a bug! Surveillance transmitters use the FM
broadcast band all the time. Why? Those planting the bugs can sit in a
parked vehicle nearby and tune them in on a car radio without any special
radio equipment. It's simple and easy and works quite well in surveillance
TV and CB
Don't stop tuning around the AM or FM bands for low-power or flea-power
users. You might find the same on TV or CB.
At one time, a transmitter was manufactured to relay your VCR to other TVs
in your home over UHF television frequencies. These so-called Genie units
would rebroadcast your home video and audio over a TV channel you would select
before purchasing your unit, such as Channels 14 through 20. The FCC stepped
in at one point and determined that these transmitters were illegal, but not
before many were sold. You still may find a neighbor with one of these
relaying their cable TV or satellite signals to other TVs in their home. You
might be surprised at what your neighbors are watching, too! Newer versions
of these units have been type-accepted by the FCC for use on the 900-MHz band,
so you may want to try tuning around there for these transmitters. In fact, a
new generation of these transmitters are being made in the 2.4 GHz band.
Don't be surprised to find store security cameras using 900 MHz and 2.4 GHz
frequencies for wireless applications from remote areas to the main security
CB has been used in the past, too, for various purposes, both lawful and
unlawful. Sometimes an annoying endless loop tape will be connected to a CB
transmitter to relay information when it is known a lot of CBers will be in an
area. You may find these at truckers events or those catering to CBers.
In any event, there are plenty of low-power and very-low-power
transmitters out there on AM, FM and other broadcast bands, too. If you tune
around, you'll find these transmitters and have fun. Those TIS transmitters
can reach far at night if you tune around and listening to a TIS more than a
hundred miles away is more exciting than hearing a 50,000-watt powerhouse
from a few states away.